feat(redis): run router cooldowns and usage on the Rust store

Router cooldowns and the global TPM/RPM counters move behind two Python stores backed by the new redis-store crate. The read-through memory tier lives in redis-store as MemoryTier, so crates/cache keeps no Redis dependency. Folds in the Python-only encapsulation step that used to be its own PR

litellm-rust/crates/cache-memory/src/cache.rs

@@ -200,6 +200,23 @@ impl<V: Clone> InMemoryCache<V> {
             .collect())
     }
 
+    /// Every live entry, for callers that inspect the whole tier.
+    pub fn entries(&self) -> Result<Vec<(String, V)>, Error> {
+        let now = (self.now)();
+        let state = self.lock()?;
+        Ok(state
+            .values
+            .iter()
+            .filter(|(key, _)| {
+                state
+                    .expirations
+                    .get(*key)
+                    .is_none_or(|expiration| *expiration >= now)
+            })
+            .map(|(key, value)| (key.clone(), value.clone()))
+            .collect())
+    }
+
     pub fn delete_cache(&self, key: &str) -> Result<(), Error> {
         let mut state = self.lock()?;
         Self::remove(&mut state, key);

litellm-rust/crates/python-bridge/src/lib.rs

@@ -43,6 +43,10 @@ mod _native {
     #[pymodule_export]
     use crate::redis::store::request::NativeRequestRedis;
     #[pymodule_export]
+    use crate::redis::store::router_cooldowns::{NativeDeclaredCooldowns, NativeRouterCooldowns};
+    #[pymodule_export]
+    use crate::redis::store::router_usage::NativeRouterUsage;
+    #[pymodule_export]
     use crate::routes::audio_transcription::{atranscription, transcription};
     #[pymodule_export]
     use crate::routes::chat_completions::{acompletion, completion};
@@ -121,6 +125,9 @@ mod tests {
                 "ResponsesWebSocketConnection",
                 "NativeDiagnosticProcessor",
                 "NativeRequestRedis",
+                "NativeDeclaredCooldowns",
+                "NativeRouterCooldowns",
+                "NativeRouterUsage",
                 "native_redis_breaker_states",
                 "NativeClickHouseSpendConfig",
                 "NativeClickHouseSpendStorage",

litellm-rust/crates/python-bridge/src/python_settings.rs

@@ -13,6 +13,8 @@ pub(crate) enum PythonSettings {
     UrlPolicy,
     #[strum(serialize = "provider_defaults")]
     ProviderDefaults,
+    #[strum(serialize = "router_tiers")]
+    RouterTiers,
     #[strum(serialize = "secret_manager")]
     SecretManager,
     #[strum(serialize = "secret_manager_binding")]

litellm-rust/crates/python-bridge/src/redis/store/mod.rs

@@ -1,6 +1,10 @@
+mod policy;
 pub(crate) mod request;
+pub(crate) mod router_cooldowns;
+pub(crate) mod router_usage;
 
 use litellm_host_python::PythonContext;
+use litellm_redis_store::Number;
 use pyo3::{
     exceptions::{PyRuntimeError, PyTypeError},
     prelude::*,
@@ -18,3 +22,37 @@ fn call(py: Python<'_>, call_type: &'static str) -> PyResult<RedisCall> {
         caller: None,
     })
 }
+
+fn store_error(error: litellm_cache::Error) -> PyErr {
+    PyRuntimeError::new_err(litellm_error::Report::new(&error).to_string())
+}
+
+/// A Python `int` or `float` across the bridge, keeping which one it is.
+pub(crate) struct PyNumber(Number);
+
+impl<'a, 'py> FromPyObject<'a, 'py> for PyNumber {
+    type Error = PyErr;
+
+    fn extract(value: Borrowed<'a, 'py, PyAny>) -> PyResult<Self> {
+        if value.is_instance_of::<PyInt>() && !value.is_instance_of::<PyBool>() {
+            return Ok(Self(Number::Int(value.extract()?)));
+        }
+        if value.is_instance_of::<PyFloat>() {
+            return Ok(Self(Number::Float(value.extract()?)));
+        }
+        Err(PyTypeError::new_err("expected an int or a float"))
+    }
+}
+
+impl<'py> IntoPyObject<'py> for PyNumber {
+    type Target = PyAny;
+    type Output = Bound<'py, PyAny>;
+    type Error = PyErr;
+
+    fn into_pyobject(self, py: Python<'py>) -> PyResult<Self::Output> {
+        Ok(match self.0 {
+            Number::Int(value) => value.into_pyobject(py)?.into_any(),
+            Number::Float(value) => value.into_pyobject(py)?.into_any(),
+        })
+    }
+}

litellm-rust/crates/python-bridge/src/redis/store/policy.rs

@@ -0,0 +1,129 @@
+use std::time::Duration;
+
+use litellm_redis_store::{TierPolicy, router_cooldowns, router_usage};
+use pyo3::prelude::*;
+
+use crate::{
+    coercion::{Field, FieldSpec, ProjectionError},
+    python_settings::{PythonSettings, Snapshot},
+};
+
+const COOLDOWN_REFRESH: FieldSpec<Duration> =
+    FieldSpec::new("cooldown_redis_read_interval", seconds);
+const USAGE_REFRESH: FieldSpec<Duration> = FieldSpec::new("usage_redis_read_interval", seconds);
+const TRACKED_READS: FieldSpec<usize> = FieldSpec::new("max_redis_batch_cache_size", count);
+
+/// The tier values this Python process runs with. `POLICY` in each family holds `main`'s
+/// defaults, the host reports what its environment and `litellm` globals changed.
+#[derive(Debug)]
+pub(crate) struct RouterTierPolicies {
+    pub(crate) cooldowns: TierPolicy,
+    pub(crate) usage: TierPolicy,
+}
+
+pub(crate) fn router_tier_policies(py: Python<'_>) -> PyResult<RouterTierPolicies> {
+    Ok(project(&PythonSettings::RouterTiers.read(py)?)?)
+}
+
+fn project(snapshot: &Snapshot<'_>) -> Result<RouterTierPolicies, ProjectionError> {
+    let tracked_reads = snapshot.read(&TRACKED_READS)?;
+    Ok(RouterTierPolicies {
+        cooldowns: TierPolicy {
+            refresh_after: snapshot.read(&COOLDOWN_REFRESH)?,
+            tracked_reads,
+            ..router_cooldowns::POLICY
+        },
+        usage: TierPolicy {
+            refresh_after: snapshot.read(&USAGE_REFRESH)?,
+            tracked_reads,
+            ..router_usage::POLICY
+        },
+    })
+}
+
+fn seconds(field: &Field<'_>) -> Result<Duration, ProjectionError> {
+    match field.value().extract::<f64>() {
+        Ok(seconds) if seconds.is_finite() && seconds >= 0.0 => {
+            Ok(Duration::from_secs_f64(seconds))
+        }
+        _ => Err(field.invalid("a non-negative number of seconds")),
+    }
+}
+
+fn count(field: &Field<'_>) -> Result<usize, ProjectionError> {
+    field
+        .value()
+        .extract::<usize>()
+        .map_err(|_| field.invalid("a non-negative integer"))
+}
+
+#[cfg(test)]
+mod tests {
+    use std::time::Duration;
+
+    use pyo3::{prelude::*, types::PyDict};
+
+    use super::project;
+    use crate::python_settings::PythonSettings;
+
+    fn projected(py: Python<'_>, fields: &str) -> Result<super::RouterTierPolicies, String> {
+        let locals = PyDict::new(py);
+        let source = std::ffi::CString::new(format!(
+            "import types\nsettings = types.SimpleNamespace({fields})"
+        ))
+        .unwrap();
+        py.run(&source, Some(&locals), Some(&locals)).unwrap();
+        let snapshot =
+            PythonSettings::RouterTiers.snapshot(locals.get_item("settings").unwrap().unwrap());
+        project(&snapshot).map_err(|error| PyErr::from(error).to_string())
+    }
+
+    #[test]
+    fn the_host_values_replace_only_the_refresh_and_tracked_reads_of_mains_defaults() {
+        Python::initialize();
+        Python::attach(|py| {
+            let policies = projected(
+                py,
+                "cooldown_redis_read_interval=2.5, usage_redis_read_interval=30, max_redis_batch_cache_size=42",
+            )
+            .unwrap();
+            assert_eq!(
+                policies.cooldowns.refresh_after,
+                Duration::from_millis(2500)
+            );
+            assert_eq!(policies.usage.refresh_after, Duration::from_secs(30));
+            assert_eq!(policies.cooldowns.tracked_reads, 42);
+            assert_eq!(policies.usage.tracked_reads, 42);
+            assert_eq!(
+                policies.cooldowns.backfill_ttl,
+                litellm_redis_store::router_cooldowns::POLICY.backfill_ttl
+            );
+            assert_eq!(
+                policies.usage.backfill_ttl,
+                litellm_redis_store::router_usage::POLICY.backfill_ttl
+            );
+        });
+    }
+
+    #[test]
+    fn a_value_python_would_not_run_with_is_a_configuration_error() {
+        Python::initialize();
+        Python::attach(|py| {
+            let negative = projected(
+                py,
+                "cooldown_redis_read_interval=-1, usage_redis_read_interval=10, max_redis_batch_cache_size=1000",
+            )
+            .unwrap_err();
+            let text = projected(
+                py,
+                "cooldown_redis_read_interval=1, usage_redis_read_interval=10, max_redis_batch_cache_size='many'",
+            )
+            .unwrap_err();
+            assert!(
+                negative.contains("cooldown_redis_read_interval"),
+                "{negative}"
+            );
+            assert!(text.contains("max_redis_batch_cache_size"), "{text}");
+        });
+    }
+}

litellm-rust/crates/python-bridge/src/redis/store/router_cooldowns.rs

@@ -0,0 +1,233 @@
+use std::{
+    sync::{Arc, Mutex, PoisonError},
+    time::Duration,
+};
+
+use litellm_redis_store::router_cooldowns::{Cooldown, DeclaredCooldowns, RouterCooldowns};
+use pyo3::{
+    exceptions::PyRuntimeError,
+    prelude::*,
+    types::{PyDict, PyTuple},
+};
+
+use super::{
+    PyNumber, call, policy::router_tier_policies, request::NativeRequestRedis, store_error,
+};
+use crate::execution::{run_async_value, run_sync_value};
+use crate::redis::client::NativeRedisClient;
+
+/// One router's cooldown store. The router's sync completion path calls `put`, `active`,
+/// `minimum` and `increment_allowed_fails`, so those block with the GIL released like redis-py.
+#[pyclass(frozen, name = "NativeRouterCooldowns")]
+pub(crate) struct NativeRouterCooldowns(Arc<RouterCooldowns>);
+
+pub(crate) struct PyCooldown(Cooldown);
+
+impl<'a, 'py> FromPyObject<'a, 'py> for PyCooldown {
+    type Error = PyErr;
+
+    fn extract(value: Borrowed<'a, 'py, PyAny>) -> PyResult<Self> {
+        let fields = value.cast::<PyDict>()?;
+        let item = |name: &str| fields.as_any().get_item(name);
+        Ok(Self(Cooldown {
+            exception_received: item("exception_received")?.extract()?,
+            status_code: item("status_code")?.extract()?,
+            timestamp: item("timestamp")?.extract::<PyNumber>()?.0,
+            cooldown_time: item("cooldown_time")?.extract::<PyNumber>()?.0,
+        }))
+    }
+}
+
+impl<'py> IntoPyObject<'py> for PyCooldown {
+    type Target = PyDict;
+    type Output = Bound<'py, PyDict>;
+    type Error = PyErr;
+
+    fn into_pyobject(self, py: Python<'py>) -> PyResult<Self::Output> {
+        let fields = PyDict::new(py);
+        fields.set_item("exception_received", self.0.exception_received)?;
+        fields.set_item("status_code", self.0.status_code)?;
+        fields.set_item("timestamp", PyNumber(self.0.timestamp))?;
+        fields.set_item("cooldown_time", PyNumber(self.0.cooldown_time))?;
+        Ok(fields)
+    }
+}
+
+fn active_to_py(
+    py: Python<'_>,
+    active: Vec<(String, Cooldown)>,
+) -> PyResult<Vec<Bound<'_, PyTuple>>> {
+    active
+        .into_iter()
+        .map(|(model_id, cooldown)| {
+            PyTuple::new(
+                py,
+                [
+                    model_id.into_pyobject(py)?.into_any(),
+                    PyCooldown(cooldown).into_pyobject(py)?.into_any(),
+                ],
+            )
+        })
+        .collect()
+}
+
+#[pymethods]
+impl NativeRouterCooldowns {
+    #[new]
+    fn new(py: Python<'_>, client: Option<PyRef<'_, NativeRedisClient>>) -> PyResult<Self> {
+        let client = client.map(|client| client.0.clone());
+        let policy = router_tier_policies(py)?.cooldowns;
+        Ok(Self(Arc::new(RouterCooldowns::new(client, policy))))
+    }
+
+    fn put(
+        &self,
+        py: Python<'_>,
+        model_id: String,
+        cooldown: PyCooldown,
+        ttl_seconds: f64,
+    ) -> PyResult<()> {
+        let store = self.0.clone();
+        let scope = call(py, "set_cache")?;
+        run_sync_value(py, async move {
+            scope
+                .scope(store.put(
+                    &model_id,
+                    &cooldown.0,
+                    Duration::from_secs_f64(ttl_seconds.max(0.0)),
+                ))
+                .await
+                .map_err(store_error)
+        })
+    }
+
+    fn increment_allowed_fails(
+        &self,
+        py: Python<'_>,
+        model_id: String,
+        suffix: Option<String>,
+        ttl_seconds: f64,
+    ) -> PyResult<i64> {
+        let store = self.0.clone();
+        let scope = call(py, "increment_cache")?;
+        run_sync_value(py, async move {
+            scope
+                .scope(store.increment_allowed_fails(
+                    &model_id,
+                    suffix.as_deref(),
+                    Duration::from_secs_f64(ttl_seconds.max(0.0)),
+                ))
+                .await
+                .map_err(store_error)
+        })
+    }
+
+    fn active<'py>(
+        &self,
+        py: Python<'py>,
+        model_ids: Vec<String>,
+    ) -> PyResult<Vec<Bound<'py, PyTuple>>> {
+        let store = self.0.clone();
+        let scope = call(py, "batch_get_cache")?;
+        let active = run_sync_value(py, async move {
+            scope
+                .scope(store.active(&model_ids))
+                .await
+                .map_err(store_error)
+        })?;
+        active_to_py(py, active)
+    }
+
+    fn aactive<'py>(&self, py: Python<'py>, model_ids: Vec<String>) -> PyResult<Bound<'py, PyAny>> {
+        let store = self.0.clone();
+        let scope = call(py, "async_batch_get_cache")?;
+        run_async_value(py, async move {
+            let active = scope
+                .scope(store.active(&model_ids))
+                .await
+                .map_err(store_error)?;
+            Python::attach(|py| {
+                Ok(active_to_py(py, active)?
+                    .into_iter()
+                    .map(Bound::unbind)
+                    .collect::<Vec<_>>())
+            })
+        })
+    }
+
+    fn declare_active(
+        &self,
+        request: &NativeRequestRedis,
+        model_ids: Vec<String>,
+    ) -> PyResult<NativeDeclaredCooldowns> {
+        let declared = self
+            .0
+            .declare_active(&request.0, &model_ids)
+            .map_err(store_error)?;
+        Ok(NativeDeclaredCooldowns {
+            store: self.0.clone(),
+            declared: Mutex::new(Some(declared)),
+        })
+    }
+
+    fn minimum(&self, py: Python<'_>, model_ids: Vec<String>) -> PyResult<Option<PyNumber>> {
+        let store = self.0.clone();
+        let scope = call(py, "batch_get_cache")?;
+        let minimum = run_sync_value(py, async move {
+            scope
+                .scope(store.minimum(&model_ids))
+                .await
+                .map_err(store_error)
+        })?;
+        Ok(minimum.map(PyNumber))
+    }
+
+    fn evict_local(&self, model_id: &str) -> PyResult<()> {
+        self.0.evict_local(model_id).map_err(store_error)
+    }
+
+    fn flush_local_counters(&self) -> PyResult<()> {
+        self.0.flush_local_counters().map_err(store_error)
+    }
+
+    fn snapshot<'py>(&self, py: Python<'py>) -> PyResult<Bound<'py, PyDict>> {
+        let snapshot = PyDict::new(py);
+        for (key, cooldown) in self.0.snapshot().map_err(store_error)? {
+            snapshot.set_item(key, PyCooldown(cooldown))?;
+        }
+        Ok(snapshot)
+    }
+}
+
+/// An `active` read declared on a request's pre-call batch. `resolve` answers it once.
+#[pyclass(frozen, name = "NativeDeclaredCooldowns")]
+pub(crate) struct NativeDeclaredCooldowns {
+    store: Arc<RouterCooldowns>,
+    declared: Mutex<Option<DeclaredCooldowns>>,
+}
+
+#[pymethods]
+impl NativeDeclaredCooldowns {
+    fn resolve<'py>(&self, py: Python<'py>) -> PyResult<Bound<'py, PyAny>> {
+        let declared = self
+            .declared
+            .lock()
+            .unwrap_or_else(PoisonError::into_inner)
+            .take()
+            .ok_or_else(|| PyRuntimeError::new_err("this cooldown read was already resolved"))?;
+        let store = self.store.clone();
+        let scope = call(py, "async_batch_get_cache")?;
+        run_async_value(py, async move {
+            let active = scope
+                .scope(store.resolve_active(declared))
+                .await
+                .map_err(store_error)?;
+            Python::attach(|py| {
+                Ok(active_to_py(py, active)?
+                    .into_iter()
+                    .map(Bound::unbind)
+                    .collect::<Vec<_>>())
+            })
+        })
+    }
+}

litellm-rust/crates/python-bridge/src/redis/store/router_usage.rs

@@ -0,0 +1,149 @@
+use std::{sync::Arc, time::Duration};
+
+use litellm_redis_store::router_usage::{Counter, Kind, RouterUsage};
+use pyo3::{exceptions::PyValueError, prelude::*, types::PyDict};
+
+use super::{
+    PyNumber, call, policy::router_tier_policies, request::NativeRequestRedis, store_error,
+};
+use crate::execution::run_async_value;
+use crate::redis::client::NativeRedisClient;
+
+/// One router's global TPM/RPM counters. Every caller on `main` is async.
+#[pyclass(frozen, name = "NativeRouterUsage")]
+pub(crate) struct NativeRouterUsage(Arc<RouterUsage>);
+
+/// `(deployment_id, model, minute, "tpm" | "rpm")`.
+pub(crate) struct PyCounter(Counter);
+
+impl<'a, 'py> FromPyObject<'a, 'py> for PyCounter {
+    type Error = PyErr;
+
+    fn extract(value: Borrowed<'a, 'py, PyAny>) -> PyResult<Self> {
+        let (deployment_id, model, minute, kind): (String, Option<String>, String, String) =
+            value.extract()?;
+        let kind = match kind.as_str() {
+            "tpm" => Kind::Tpm,
+            "rpm" => Kind::Rpm,
+            _ => {
+                return Err(PyValueError::new_err(format!(
+                    "unknown usage counter kind {kind:?}"
+                )));
+            }
+        };
+        Ok(Self(Counter {
+            deployment_id,
+            model,
+            minute,
+            kind,
+        }))
+    }
+}
+
+#[pymethods]
+impl NativeRouterUsage {
+    #[new]
+    fn new(py: Python<'_>, client: Option<PyRef<'_, NativeRedisClient>>) -> PyResult<Self> {
+        let client = client.map(|client| client.0.clone());
+        let policy = router_tier_policies(py)?.usage;
+        Ok(Self(Arc::new(RouterUsage::new(client, policy))))
+    }
+
+    fn increment<'py>(
+        &self,
+        py: Python<'py>,
+        counter: PyCounter,
+        value: PyNumber,
+        ttl_seconds: u64,
+    ) -> PyResult<Bound<'py, PyAny>> {
+        let store = self.0.clone();
+        let scope = call(py, "async_increment")?;
+        run_async_value(py, async move {
+            scope
+                .scope(store.increment(&counter.0, value.0, Duration::from_secs(ttl_seconds)))
+                .await
+                .map(PyNumber)
+                .map_err(store_error)
+        })
+    }
+
+    #[pyo3(signature = (deployment_id, model, minute, tokens, requests, *, request = None))]
+    #[expect(
+        clippy::too_many_arguments,
+        reason = "preserves the Python increment_deployment signature"
+    )]
+    fn increment_deployment<'py>(
+        &self,
+        py: Python<'py>,
+        deployment_id: String,
+        model: Option<String>,
+        minute: String,
+        tokens: PyNumber,
+        requests: i64,
+        request: Option<PyRef<'_, NativeRequestRedis>>,
+    ) -> PyResult<Bound<'py, PyAny>> {
+        let store = self.0.clone();
+        let request = request.map(|request| request.0.clone());
+        let scope = call(py, "async_increment_pipeline")?;
+        run_async_value(py, async move {
+            let model = model.as_deref();
+            match request {
+                Some(request) => store.increment_deployment_post_call(
+                    &request,
+                    &deployment_id,
+                    model,
+                    &minute,
+                    tokens.0,
+                    requests,
+                ),
+                None => {
+                    scope
+                        .scope(store.increment_deployment(
+                            &deployment_id,
+                            model,
+                            &minute,
+                            tokens.0,
+                            requests,
+                        ))
+                        .await
+                }
+            }
+            .map_err(store_error)
+        })
+    }
+
+    fn get_many<'py>(
+        &self,
+        py: Python<'py>,
+        counters: Vec<PyCounter>,
+    ) -> PyResult<Bound<'py, PyAny>> {
+        let store = self.0.clone();
+        let counters = counters
+            .into_iter()
+            .map(|counter| counter.0)
+            .collect::<Vec<_>>();
+        let scope = call(py, "async_batch_get_cache")?;
+        run_async_value(py, async move {
+            let read = scope
+                .scope(store.get_many(&counters))
+                .await
+                .map_err(store_error)?;
+            Ok(read
+                .into_iter()
+                .map(|count| count.map(PyNumber))
+                .collect::<Vec<_>>())
+        })
+    }
+
+    fn flush_local_counters(&self) -> PyResult<()> {
+        self.0.flush_local_counters().map_err(store_error)
+    }
+
+    fn snapshot<'py>(&self, py: Python<'py>) -> PyResult<Bound<'py, PyDict>> {
+        let snapshot = PyDict::new(py);
+        for (key, count) in self.0.snapshot().map_err(store_error)? {
+            snapshot.set_item(key, PyNumber(count))?;
+        }
+        Ok(snapshot)
+    }
+}

litellm-rust/crates/redis-store/src/codec.rs

@@ -0,0 +1,20 @@
+use litellm_python_compat::{Value, json, literal};
+
+#[derive(Debug, thiserror::Error)]
+pub enum DecodeError {
+    #[error("Redis value is not UTF-8")]
+    NotUtf8,
+    #[error("Redis value is neither JSON nor a Python literal: {0}")]
+    Unparsed(#[source] litellm_python_compat::Error),
+    #[error("Redis value has the wrong shape: {0}")]
+    Shape(&'static str),
+}
+
+/// `RedisCache._get_cache_logic`: `json.loads`, falling back to `ast.literal_eval`.
+pub(crate) fn python_value(raw: &[u8]) -> Result<Value, DecodeError> {
+    let text = std::str::from_utf8(raw).map_err(|_| DecodeError::NotUtf8)?;
+    match serde_json::from_str::<serde_json::Value>(text) {
+        Ok(document) => Ok(json::from_json(document)),
+        Err(_) => literal::literal_eval(text).map_err(DecodeError::Unparsed),
+    }
+}

litellm-rust/crates/redis-store/src/lib.rs

@@ -1,3 +1,11 @@
+mod codec;
+mod number;
 mod request;
+pub mod router_cooldowns;
+pub mod router_usage;
+mod tier;
 
+pub use codec::DecodeError;
+pub use number::Number;
 pub use request::RequestRedis;
+pub use tier::{Clock, TierPolicy};

litellm-rust/crates/redis-store/src/number.rs

@@ -0,0 +1,68 @@
+use std::{cmp::Ordering, ops::Add};
+
+use litellm_python_compat::{BigInt, Value};
+
+/// A Python `int` or `float`, kept apart because `repr` and `json.dumps` write them differently.
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub enum Number {
+    Int(i64),
+    Float(f64),
+}
+
+impl Number {
+    pub fn as_f64(self) -> f64 {
+        match self {
+            Self::Int(value) => value as f64,
+            Self::Float(value) => value,
+        }
+    }
+
+    /// Python's `int(value)`, which truncates toward zero.
+    pub fn truncate(self) -> i64 {
+        match self {
+            Self::Int(value) => value,
+            Self::Float(value) => value.trunc() as i64,
+        }
+    }
+
+    pub fn to_value(self) -> Value {
+        match self {
+            Self::Int(value) => Value::Int(BigInt::from(value)),
+            Self::Float(value) => Value::Float(value),
+        }
+    }
+
+    pub fn from_value(value: &Value) -> Option<Self> {
+        match value {
+            Value::Int(value) => i64::try_from(value).ok().map(Self::Int),
+            Value::Float(value) => Some(Self::Float(*value)),
+            _ => None,
+        }
+    }
+
+    /// Python's `min` over numbers: the first of the smallest, keeping its type.
+    pub fn min(values: impl IntoIterator<Item = Self>) -> Option<Self> {
+        values
+            .into_iter()
+            .fold(None, |smallest, value| match smallest {
+                Some(smallest)
+                    if value.as_f64().partial_cmp(&smallest.as_f64()) != Some(Ordering::Less) =>
+                {
+                    Some(smallest)
+                }
+                _ => Some(value),
+            })
+    }
+}
+
+/// Python's `+`: two ints stay an int, anything with a float is a float.
+impl Add for Number {
+    type Output = Self;
+
+    fn add(self, other: Self) -> Self {
+        match (self, other) {
+            (Self::Int(left), Self::Int(right)) => Self::Int(left + right),
+            (left, right) => Self::Float(left.as_f64() + right.as_f64()),
+        }
+    }
+}

litellm-rust/crates/redis-store/src/router_cooldowns.rs

@@ -0,0 +1,284 @@
+use std::time::Duration;
+
+use litellm_cache::Error as MemoryError;
+use litellm_cache_memory::InMemoryCache;
+use litellm_python_compat::{Value, repr::repr};
+use litellm_redis_client::{Expiry, RedisBatch, RedisClient};
+
+use crate::{
+    DecodeError, Number, RequestRedis,
+    codec::python_value,
+    tier::{Clock, DeclaredRead, MemoryTier, OnBreakerOpen, TierPolicy, system_clock},
+};
+
+/// `main`'s cooldown tier: `DEFAULT_COOLDOWN_REDIS_READ_INTERVAL_SECONDS` (1 s), `InMemoryCache`'s
+/// 600 s default for backfilled entries and `DEFAULT_MAX_REDIS_BATCH_CACHE_SIZE`.
+pub const POLICY: TierPolicy = TierPolicy {
+    refresh_after: Duration::from_secs(1),
+    backfill_ttl: Duration::from_secs(600),
+    on_breaker_open: OnBreakerOpen::ServeMemory,
+    tracked_reads: 1000,
+};
+const MEMORY_ENTRIES: usize = 200;
+const MAX_CORRECTED_TTL: Duration = Duration::from_secs(60);
+const CORRECTION_SLACK: Duration = Duration::from_secs(5);
+
+#[derive(Clone, Debug, PartialEq)]
+pub struct Cooldown {
+    pub exception_received: String,
+    pub status_code: String,
+    pub timestamp: Number,
+    pub cooldown_time: Number,
+}
+
+impl Cooldown {
+    fn remaining(&self, now: Duration) -> f64 {
+        self.timestamp.as_f64() + self.cooldown_time.as_f64() - now.as_secs_f64()
+    }
+
+    /// `str(dict)`, the bytes `RedisCache.set_cache` writes on `main`.
+    pub fn encode(&self) -> String {
+        let field = |name: &str, value: Value| (Value::Str(name.to_owned()), value);
+        repr(&Value::Dict(vec![
+            field(
+                "exception_received",
+                Value::Str(self.exception_received.clone()),
+            ),
+            field("status_code", Value::Str(self.status_code.clone())),
+            field("timestamp", self.timestamp.to_value()),
+            field("cooldown_time", self.cooldown_time.to_value()),
+        ]))
+    }
+
+    /// Reads both `main`'s `str(dict)` and a JSON object, as `RedisCache._get_cache_logic` does.
+    pub fn decode(raw: &[u8]) -> Result<Self, DecodeError> {
+        let Value::Dict(fields) = python_value(raw)? else {
+            return Err(DecodeError::Shape("a cooldown is a dict"));
+        };
+        let field = |name: &str| {
+            fields
+                .iter()
+                .find(|(key, _)| matches!(key, Value::Str(key) if key == name))
+                .map(|(_, value)| value)
+        };
+        let text = |name: &'static str| match field(name) {
+            Some(Value::Str(text)) => Ok(text.clone()),
+            _ => Err(DecodeError::Shape(name)),
+        };
+        let number = |name: &'static str| {
+            field(name)
+                .and_then(Number::from_value)
+                .ok_or(DecodeError::Shape(name))
+        };
+        Ok(Self {
+            exception_received: text("exception_received")?,
+            status_code: text("status_code")?,
+            timestamp: number("timestamp")?,
+            cooldown_time: number("cooldown_time")?,
+        })
+    }
+}
+
+fn key(model_id: &str) -> String {
+    format!("deployment:{model_id}:cooldown")
+}
+
+fn keys(model_ids: &[String]) -> Vec<String> {
+    model_ids.iter().map(|model_id| key(model_id)).collect()
+}
+
+fn allowed_fails_key(model_id: &str, suffix: Option<&str>) -> String {
+    match suffix.filter(|suffix| !suffix.is_empty()) {
+        Some(suffix) => format!("deployment:{model_id}:allowed_fails:{suffix}"),
+        None => format!("deployment:{model_id}:allowed_fails"),
+    }
+}
+
+fn memory<V: Clone>(policy: TierPolicy, now: &Clock) -> InMemoryCache<V> {
+    let now = now.clone();
+    InMemoryCache::with_clock(Some(MEMORY_ENTRIES), Some(policy.backfill_ttl), move || {
+        now()
+    })
+}
+
+/// `BaseCache.get_ttl` sends `int(ttl)`, so Redis sees whole seconds.
+fn whole_seconds(ttl: Duration) -> Duration {
+    Duration::from_secs(ttl.as_secs())
+}
+
+/// An `active` read declared on a request batch, answered by `resolve_active`.
+pub struct DeclaredCooldowns {
+    model_ids: Vec<String>,
+    read: DeclaredRead,
+}
+
+/// One router's cooldowns and allowed-fails counters: memory per router, Redis shared by every pod.
+pub struct RouterCooldowns {
+    cooldowns: MemoryTier<InMemoryCache<Cooldown>, RedisClient>,
+    fails: MemoryTier<InMemoryCache<i64>, RedisClient>,
+}
+
+impl RouterCooldowns {
+    pub fn new(client: Option<RedisClient>, policy: TierPolicy) -> Self {
+        Self::with_clock(client, policy, system_clock())
+    }
+
+    pub fn with_clock(client: Option<RedisClient>, policy: TierPolicy, now: Clock) -> Self {
+        Self {
+            cooldowns: MemoryTier::read_through(
+                memory(policy, &now),
+                client.clone(),
+                policy,
+                now.clone(),
+            ),
+            fails: MemoryTier::read_through(memory(policy, &now), client, policy, now),
+        }
+    }
+
+    /// Memory first, then a `SET ... EX int(ttl)` whose failure only logs, like `DualCache.set_cache`.
+    pub async fn put(
+        &self,
+        model_id: &str,
+        cooldown: &Cooldown,
+        ttl: Duration,
+    ) -> Result<(), MemoryError> {
+        let key = key(model_id);
+        self.cooldowns.set_memory(&key, cooldown.clone(), ttl)?;
+        if let Some(remote) = self.cooldowns.remote()
+            && let Err(error) = remote
+                .set(&key, cooldown.encode(), whole_seconds(ttl))
+                .await
+        {
+            tracing::warn!(%error, "writing a cooldown to Redis failed");
+        }
+        Ok(())
+    }
+
+    /// The fleet-wide fail count. A Redis failure falls back to this router's own count.
+    pub async fn increment_allowed_fails(
+        &self,
+        model_id: &str,
+        suffix: Option<&str>,
+        ttl: Duration,
+    ) -> Result<i64, MemoryError> {
+        let key = allowed_fails_key(model_id, suffix);
+        let local = self
+            .fails
+            .update_memory(&key, ttl, |count| count.unwrap_or(0) + 1)?;
+        let Some(remote) = self.fails.remote() else {
+            return Ok(local);
+        };
+        match remote
+            .incr_by(&key, 1, Expiry::KeepExisting(whole_seconds(ttl)))
+            .await
+        {
+            Ok(count) => Ok(count),
+            Err(error) => {
+                tracing::warn!(%error, "allowed_fails counter fell back to this worker's in-memory count");
+                Ok(local)
+            }
+        }
+    }
+
+    /// The deployments still cooling down. An entry whose cooldown already ended is dropped
+    /// from memory, and one memory would keep past its end is shortened, at most to 60 s.
+    pub async fn active(
+        &self,
+        model_ids: &[String],
+    ) -> Result<Vec<(String, Cooldown)>, MemoryError> {
+        let declared = self.declare(RedisClient::batch, model_ids)?;
+        self.resolve_active(declared).await
+    }
+
+    /// `active`, with its Redis read declared on the request's pre-call batch.
+    pub fn declare_active(
+        &self,
+        request: &RequestRedis,
+        model_ids: &[String],
+    ) -> Result<DeclaredCooldowns, MemoryError> {
+        self.declare(|client| request.pre(client), model_ids)
+    }
+
+    pub async fn resolve_active(
+        &self,
+        declared: DeclaredCooldowns,
+    ) -> Result<Vec<(String, Cooldown)>, MemoryError> {
+        let DeclaredCooldowns { model_ids, read } = declared;
+        let read = self.cooldowns.resolve_many(read, Cooldown::decode).await?;
+        let now = self.cooldowns.now();
+        let corrected = model_ids
+            .into_iter()
+            .zip(read)
+            .filter_map(|(model_id, cooldown)| cooldown.map(|cooldown| (model_id, cooldown)))
+            .map(|(model_id, cooldown)| {
+                Ok(self
+                    .correct(&model_id, &cooldown, now)?
+                    .then_some((model_id, cooldown)))
+            })
+            .collect::<Result<Vec<_>, MemoryError>>()?;
+        Ok(corrected.into_iter().flatten().collect())
+    }
+
+    /// The shortest stored cooldown, ended ones included, as `main`'s `get_min_cooldown` reads it.
+    pub async fn minimum(&self, model_ids: &[String]) -> Result<Option<Number>, MemoryError> {
+        let read = self.read(model_ids).await?;
+        Ok(Number::min(
+            read.into_iter()
+                .flatten()
+                .map(|cooldown| cooldown.cooldown_time),
+        ))
+    }
+
+    pub fn evict_local(&self, model_id: &str) -> Result<(), MemoryError> {
+        self.cooldowns.delete_memory(&key(model_id))
+    }
+
+    pub fn flush_local_counters(&self) -> Result<(), MemoryError> {
+        self.fails.flush_memory()
+    }
+
+    /// The memory tier keyed as Python's `InMemoryCache` was, for the fuzz probe that reads
+    /// in-memory router state.
+    pub fn snapshot(&self) -> Result<Vec<(String, Cooldown)>, MemoryError> {
+        self.cooldowns.memory().entries()
+    }
+
+    async fn read(&self, model_ids: &[String]) -> Result<Vec<Option<Cooldown>>, MemoryError> {
+        self.cooldowns
+            .get_many(&keys(model_ids), Cooldown::decode)
+            .await
+    }
+
+    fn declare(
+        &self,
+        batch_for: impl FnOnce(&RedisClient) -> RedisBatch,
+        model_ids: &[String],
+    ) -> Result<DeclaredCooldowns, MemoryError> {
+        Ok(DeclaredCooldowns {
+            model_ids: model_ids.to_vec(),
+            read: self.cooldowns.declare_many(batch_for, &keys(model_ids))?,
+        })
+    }
+
+    fn correct(
+        &self,
+        model_id: &str,
+        cooldown: &Cooldown,
+        now: Duration,
+    ) -> Result<bool, MemoryError> {
+        let key = key(model_id);
+        let remaining = cooldown.remaining(now);
+        if remaining <= 0.0 {
+            self.cooldowns.delete_memory(&key)?;
+            return Ok(false);
+        }
+        let remaining = Duration::from_secs_f64(remaining);
+        let memory = self.cooldowns.memory();
+        if memory.expires_at(&key)? > Some(now + remaining + CORRECTION_SLACK) {
+            self.cooldowns.delete_memory(&key)?;
+            self.cooldowns
+                .set_memory(&key, cooldown.clone(), remaining.min(MAX_CORRECTED_TTL))?;
+        }
+        Ok(true)
+    }
+}

litellm-rust/crates/redis-store/src/router_usage.rs

@@ -0,0 +1,262 @@
+use std::{sync::Arc, time::Duration};
+
+use litellm_cache::Error as MemoryError;
+use litellm_cache_memory::InMemoryCache;
+use litellm_redis_client::{Declared, Expiry, RedisBatch, RedisClient};
+
+use crate::{
+    DecodeError, Number, RequestRedis,
+    codec::python_value,
+    tier::{Clock, MemoryTier, OnBreakerOpen, TierPolicy, system_clock},
+};
+
+/// `main`'s usage tier: `DualCache`'s 10 s default refresh, `InMemoryCache`'s 600 s default for
+/// backfilled entries and `DEFAULT_MAX_REDIS_BATCH_CACHE_SIZE`.
+pub const POLICY: TierPolicy = TierPolicy {
+    refresh_after: Duration::from_secs(10),
+    backfill_ttl: Duration::from_secs(600),
+    on_breaker_open: OnBreakerOpen::ServeMemory,
+    tracked_reads: 1000,
+};
+const MEMORY_ENTRIES: usize = 200;
+/// `RoutingArgs.ttl`, the window of a per-minute counter.
+pub const COUNTER_TTL: Duration = Duration::from_secs(60);
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub enum Kind {
+    Tpm,
+    Rpm,
+}
+
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub struct Counter {
+    pub deployment_id: String,
+    pub model: Option<String>,
+    pub minute: String,
+    pub kind: Kind,
+}
+
+impl Counter {
+    /// `global_router:{id}:{model}:{tpm|rpm}:{HH-MM}`, where Python formats a missing model as `None`.
+    fn key(&self) -> String {
+        let kind = match self.kind {
+            Kind::Tpm => "tpm",
+            Kind::Rpm => "rpm",
+        };
+        let model = self.model.as_deref().unwrap_or("None");
+        format!(
+            "global_router:{}:{model}:{kind}:{}",
+            self.deployment_id, self.minute
+        )
+    }
+}
+
+fn decode(raw: &[u8]) -> Result<Number, DecodeError> {
+    Number::from_value(&python_value(raw)?).ok_or(DecodeError::Shape("a usage counter is a number"))
+}
+
+fn whole_seconds(ttl: Duration) -> Duration {
+    Duration::from_secs(ttl.as_secs())
+}
+
+/// One router's global TPM/RPM counters: memory per router, Redis shared by every pod.
+pub struct RouterUsage(MemoryTier<InMemoryCache<Number>, RedisClient>);
+
+impl RouterUsage {
+    pub fn new(client: Option<RedisClient>, policy: TierPolicy) -> Self {
+        Self::with_clock(client, policy, system_clock())
+    }
+
+    pub fn with_clock(client: Option<RedisClient>, policy: TierPolicy, now: Clock) -> Self {
+        let clock = now.clone();
+        let memory =
+            InMemoryCache::with_clock(Some(MEMORY_ENTRIES), Some(policy.backfill_ttl), move || {
+                clock()
+            });
+        Self(MemoryTier::read_through(memory, client, policy, now))
+    }
+
+    /// `DualCache.async_increment_cache`: memory, then `INCRBYFLOAT` keeping an existing TTL.
+    /// A Redis failure answers with the memory count.
+    pub async fn increment(
+        &self,
+        counter: &Counter,
+        value: Number,
+        ttl: Duration,
+    ) -> Result<Number, MemoryError> {
+        let key = counter.key();
+        let local = self.add_local(&key, value, ttl)?;
+        let Some(remote) = self.0.remote() else {
+            return Ok(local);
+        };
+        match remote
+            .incr_by_float(
+                &key,
+                value.as_f64(),
+                Expiry::KeepExisting(whole_seconds(ttl)),
+            )
+            .await
+        {
+            Ok(total) => Ok(Number::Float(total)),
+            Err(error) => {
+                tracing::warn!(%error, "Redis usage increment failed, falling back to the in-memory count");
+                Ok(local)
+            }
+        }
+    }
+
+    /// One deployment's tokens and requests: memory, then one pipeline that resets each
+    /// counter's 60 s window, mirrored back into memory as `int` totals.
+    pub async fn increment_deployment(
+        &self,
+        deployment_id: &str,
+        model: Option<&str>,
+        minute: &str,
+        tokens: Number,
+        requests: i64,
+    ) -> Result<(), MemoryError> {
+        let increment = Increment::new(deployment_id, model, minute, tokens, requests);
+        let Some(declared) = self.declare(RedisClient::batch, increment)? else {
+            return Ok(());
+        };
+        let totals = totals(declared.totals, Declared::resolve).await;
+        self.mirror(&declared.keys, declared.local, totals)
+    }
+
+    /// `increment_deployment` on the request's post-call batch. Memory counts at once; the Redis
+    /// totals reach memory when that batch goes out.
+    pub fn increment_deployment_post_call(
+        self: &Arc<Self>,
+        request: &RequestRedis,
+        deployment_id: &str,
+        model: Option<&str>,
+        minute: &str,
+        tokens: Number,
+        requests: i64,
+    ) -> Result<(), MemoryError> {
+        let increment = Increment::new(deployment_id, model, minute, tokens, requests);
+        let Some(declared) = self.declare(|client| request.post(client), increment)? else {
+            return Ok(());
+        };
+        let store = Arc::clone(self);
+        request.spawn(async move {
+            let totals = totals(declared.totals, Declared::settled).await;
+            if let Err(error) = store.mirror(&declared.keys, declared.local, totals) {
+                tracing::warn!(%error, "mirroring Redis usage totals into memory failed");
+            }
+        });
+        Ok(())
+    }
+
+    pub async fn get_many(&self, counters: &[Counter]) -> Result<Vec<Option<Number>>, MemoryError> {
+        let keys = counters.iter().map(Counter::key).collect::<Vec<_>>();
+        self.0.get_many(&keys, decode).await
+    }
+
+    pub fn flush_local_counters(&self) -> Result<(), MemoryError> {
+        self.0.flush_memory()
+    }
+
+    /// The memory tier keyed as Python's `InMemoryCache` was, for the fuzz probe that reads
+    /// in-memory router state.
+    pub fn snapshot(&self) -> Result<Vec<(String, Number)>, MemoryError> {
+        self.0.memory().entries()
+    }
+
+    fn declare(
+        &self,
+        batch_for: impl FnOnce(&RedisClient) -> RedisBatch,
+        increment: Increment,
+    ) -> Result<Option<DeclaredIncrement>, MemoryError> {
+        let local = increment
+            .counts
+            .iter()
+            .map(|(key, value)| self.add_local(key, *value, COUNTER_TTL))
+            .collect::<Result<Vec<_>, _>>()?;
+        let Some(remote) = self.0.remote() else {
+            return Ok(None);
+        };
+        let batch = batch_for(remote);
+        let totals = increment
+            .counts
+            .iter()
+            .map(|(key, value)| {
+                batch.incr_by_float(key, value.as_f64(), Expiry::Refresh(COUNTER_TTL))
+            })
+            .collect();
+        Ok(Some(DeclaredIncrement {
+            keys: increment.counts.into_iter().map(|(key, _)| key).collect(),
+            local,
+            totals,
+        }))
+    }
+
+    fn mirror(
+        &self,
+        keys: &[String],
+        local: Vec<Number>,
+        totals: Result<Vec<f64>, litellm_redis_client::Error>,
+    ) -> Result<(), MemoryError> {
+        let totals = match totals {
+            Ok(totals) => totals.into_iter().map(Number::Float).collect(),
+            Err(error) => {
+                tracing::warn!(%error, "Redis usage pipeline failed, keeping the in-memory counts");
+                local
+            }
+        };
+        keys.iter().zip(totals).try_for_each(|(key, total)| {
+            self.0
+                .set_memory(key, Number::Int(total.truncate()), COUNTER_TTL)
+        })
+    }
+
+    fn add_local(&self, key: &str, value: Number, ttl: Duration) -> Result<Number, MemoryError> {
+        self.0.update_memory(key, ttl, |current| {
+            current.unwrap_or(Number::Int(0)) + value
+        })
+    }
+}
+
+struct Increment {
+    counts: [(String, Number); 2],
+}
+
+impl Increment {
+    fn new(
+        deployment_id: &str,
+        model: Option<&str>,
+        minute: &str,
+        tokens: Number,
+        requests: i64,
+    ) -> Self {
+        let counter = |kind| Counter {
+            deployment_id: deployment_id.to_owned(),
+            model: model.map(str::to_owned),
+            minute: minute.to_owned(),
+            kind,
+        };
+        Self {
+            counts: [
+                (counter(Kind::Tpm).key(), tokens),
+                (counter(Kind::Rpm).key(), Number::Int(requests)),
+            ],
+        }
+    }
+}
+
+struct DeclaredIncrement {
+    keys: Vec<String>,
+    local: Vec<Number>,
+    totals: Vec<Declared<f64>>,
+}
+
+async fn totals<F: Future<Output = Result<f64, litellm_redis_client::Error>>>(
+    declared: Vec<Declared<f64>>,
+    wait: impl Fn(Declared<f64>) -> F,
+) -> Result<Vec<f64>, litellm_redis_client::Error> {
+    let mut totals = Vec::with_capacity(declared.len());
+    for total in declared {
+        totals.push(wait(total).await?);
+    }
+    Ok(totals)
+}

litellm-rust/crates/redis-store/src/tier.rs

@@ -0,0 +1,319 @@
+use std::{
+    collections::{HashMap, VecDeque},
+    sync::{Arc, Mutex, MutexGuard},
+    time::{Duration, SystemTime, UNIX_EPOCH},
+};
+
+use litellm_redis_client::{Declared, Error as RedisError, RedisBatch, RedisClient};
+
+use litellm_cache::{BaseCache, DeleteCache, Error, ExactCacheContext, FlushCache};
+
+pub type Clock = Arc<dyn Fn() -> Duration + Send + Sync>;
+
+/// How a read-through family uses its memory tier, declared once by the family.
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub struct TierPolicy {
+    /// Python's `redis_batch_cache_expiry`: a key memory misses is read from Redis at most this often.
+    pub refresh_after: Duration,
+    /// How long a value read from Redis stays in memory.
+    pub backfill_ttl: Duration,
+    pub on_breaker_open: OnBreakerOpen,
+    /// Python's `default_max_redis_batch_cache_size`: how many keys the refresh throttle tracks.
+    pub tracked_reads: usize,
+}
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub enum OnBreakerOpen {
+    /// Serve what memory holds and let the next read try Redis again.
+    ServeMemory,
+}
+
+/// The memory tier in front of Redis that a read-through family builds for itself, as Python's
+/// `DualCache` with a `RedisCache` does.
+pub struct MemoryTier<L1, L2> {
+    memory: L1,
+    remote: Option<L2>,
+    policy: TierPolicy,
+    reads: Mutex<RecentReads>,
+    updates: Mutex<()>,
+    now: Clock,
+}
+
+pub fn system_clock() -> Clock {
+    Arc::new(|| {
+        SystemTime::now()
+            .duration_since(UNIX_EPOCH)
+            .unwrap_or_default()
+    })
+}
+
+impl<V, L1> MemoryTier<L1, RedisClient>
+where
+    V: Clone + Send + Sync + 'static,
+    L1: BaseCache<Value = V, Context = ExactCacheContext> + DeleteCache + FlushCache,
+{
+    pub fn read_through(
+        memory: L1,
+        remote: Option<RedisClient>,
+        policy: TierPolicy,
+        now: Clock,
+    ) -> Self {
+        Self {
+            memory,
+            remote,
+            reads: Mutex::new(RecentReads::new(policy.tracked_reads)),
+            policy,
+            updates: Mutex::new(()),
+            now,
+        }
+    }
+
+    pub fn memory(&self) -> &L1 {
+        &self.memory
+    }
+
+    pub fn remote(&self) -> Option<&RedisClient> {
+        self.remote.as_ref()
+    }
+
+    pub fn now(&self) -> Duration {
+        (self.now)()
+    }
+
+    pub fn set_memory(&self, key: &str, value: V, ttl: Duration) -> Result<(), Error> {
+        self.memory
+            .set_cache(key, value, &ExactCacheContext { ttl: Some(ttl) })
+    }
+
+    /// Read-modify-write of one memory entry, atomic against every other update of this tier.
+    pub fn update_memory(
+        &self,
+        key: &str,
+        ttl: Duration,
+        update: impl FnOnce(Option<V>) -> V,
+    ) -> Result<V, Error> {
+        let _guard = lock(&self.updates)?;
+        let value = update(self.memory.get_cache(key, &ExactCacheContext::default())?);
+        self.set_memory(key, value.clone(), ttl)?;
+        Ok(value)
+    }
+
+    /// Python's `DualCache.async_batch_get_cache`: memory first, then one round trip for the misses
+    /// whose refresh is due, written back to memory. A failed Redis read serves memory, as
+    /// `RedisCache` swallows it, and only a breaker refusal releases the refresh it reserved.
+    pub async fn get_many<E: std::fmt::Display>(
+        &self,
+        keys: &[String],
+        decode: impl Fn(&[u8]) -> Result<V, E>,
+    ) -> Result<Vec<Option<V>>, Error> {
+        let declared = self.declare_many(RedisClient::batch, keys)?;
+        self.resolve_many(declared, decode).await
+    }
+
+    /// The first half of `get_many`: reserves the due refreshes and declares their GETs on the
+    /// batch `batch_for` picks for this tier's client, without sending anything.
+    pub fn declare_many(
+        &self,
+        batch_for: impl FnOnce(&RedisClient) -> RedisBatch,
+        keys: &[String],
+    ) -> Result<DeclaredRead, Error> {
+        let fetch = match &self.remote {
+            None => None,
+            Some(remote) => {
+                let reservation = self.reserve(keys, &self.read_memory(keys)?)?;
+                (!reservation.keys.is_empty()).then(|| {
+                    let batch = batch_for(remote);
+                    let replies = reservation
+                        .keys
+                        .iter()
+                        .map(|key| batch.get::<Vec<u8>>(key))
+                        .collect();
+                    Fetch {
+                        reservation,
+                        replies,
+                    }
+                })
+            }
+        };
+        Ok(DeclaredRead {
+            keys: keys.to_vec(),
+            fetch,
+        })
+    }
+
+    /// The second half of `get_many`. Memory is read again here, so a value written to memory
+    /// since the declaration wins over what Redis answered.
+    pub async fn resolve_many<E: std::fmt::Display>(
+        &self,
+        declared: DeclaredRead,
+        decode: impl Fn(&[u8]) -> Result<V, E>,
+    ) -> Result<Vec<Option<V>>, Error> {
+        let DeclaredRead { keys, fetch } = declared;
+        let Some(Fetch {
+            reservation,
+            replies,
+        }) = fetch
+        else {
+            return self.read_memory(&keys);
+        };
+        let fetched = settle(replies).await;
+        let local = self.read_memory(&keys)?;
+        let fetched = match fetched {
+            Ok(fetched) => fetched,
+            Err(RedisError::BreakerOpen) => {
+                self.release(reservation)?;
+                return Ok(local);
+            }
+            Err(error) => {
+                tracing::warn!(%error, "Redis read failed, serving the memory tier");
+                return Ok(local);
+            }
+        };
+        let decoded = match fetched
+            .iter()
+            .map(|raw| raw.as_deref().map(&decode).transpose())
+            .collect::<Result<Vec<_>, _>>()
+        {
+            Ok(decoded) => decoded,
+            Err(error) => {
+                tracing::warn!(%error, "a Redis value did not decode, serving the memory tier");
+                return Ok(local);
+            }
+        };
+        let read = reservation
+            .keys
+            .into_iter()
+            .zip(decoded)
+            .collect::<HashMap<_, _>>();
+        keys.iter()
+            .zip(local)
+            .map(|(key, local)| match local {
+                Some(value) => Ok(Some(value)),
+                None => self.backfill(key, read.get(key).cloned().flatten()),
+            })
+            .collect()
+    }
+
+    pub fn delete_memory(&self, key: &str) -> Result<(), Error> {
+        self.memory.delete_cache(key)
+    }
+
+    pub fn flush_memory(&self) -> Result<(), Error> {
+        self.memory.flush_cache()
+    }
+
+    fn read_memory(&self, keys: &[String]) -> Result<Vec<Option<V>>, Error> {
+        let context = ExactCacheContext::default();
+        keys.iter()
+            .map(|key| self.memory.get_cache(key, &context))
+            .collect()
+    }
+
+    fn backfill(&self, key: &str, value: Option<V>) -> Result<Option<V>, Error> {
+        if let Some(value) = &value {
+            self.set_memory(key, value.clone(), self.policy.backfill_ttl)?;
+        }
+        Ok(value)
+    }
+
+    fn reserve(&self, keys: &[String], local: &[Option<V>]) -> Result<Reservation, Error> {
+        let now = self.now();
+        let mut reads = lock(&self.reads)?;
+        let due = keys
+            .iter()
+            .zip(local)
+            .filter(|(_, value)| value.is_none())
+            .filter_map(|(key, _)| {
+                let previous = reads.get(key);
+                let due = previous
+                    .is_none_or(|read| now.saturating_sub(read) >= self.policy.refresh_after);
+                due.then(|| {
+                    reads.insert(key.clone(), now);
+                    (key.clone(), previous)
+                })
+            })
+            .collect::<Vec<_>>();
+        let (keys, previous) = due.into_iter().unzip();
+        Ok(Reservation { keys, previous })
+    }
+
+    fn release(&self, reservation: Reservation) -> Result<(), Error> {
+        let mut reads = lock(&self.reads)?;
+        for (key, previous) in reservation.keys.into_iter().zip(reservation.previous) {
+            match previous {
+                Some(read) => reads.insert(key, read),
+                None => reads.remove(&key),
+            }
+        }
+        Ok(())
+    }
+}
+
+fn lock<T>(mutex: &Mutex<T>) -> Result<MutexGuard<'_, T>, Error> {
+    Ok(mutex.lock()?)
+}
+
+async fn settle(
+    replies: Vec<Declared<Option<Vec<u8>>>>,
+) -> Result<Vec<Option<Vec<u8>>>, RedisError> {
+    let mut fetched = Vec::with_capacity(replies.len());
+    for reply in replies {
+        fetched.push(reply.resolve().await?);
+    }
+    Ok(fetched)
+}
+
+/// The GETs `declare_many` put on a batch, with the refreshes they reserved.
+pub struct DeclaredRead {
+    keys: Vec<String>,
+    fetch: Option<Fetch>,
+}
+
+struct Fetch {
+    reservation: Reservation,
+    replies: Vec<Declared<Option<Vec<u8>>>>,
+}
+
+struct Reservation {
+    keys: Vec<String>,
+    previous: Vec<Option<Duration>>,
+}
+
+/// Python's `LimitedSizeOrderedDict`: insertion-ordered, and any write at capacity drops the
+/// oldest entry first, even when the written key is already present.
+struct RecentReads {
+    capacity: usize,
+    order: VecDeque<String>,
+    times: HashMap<String, Duration>,
+}
+
+impl RecentReads {
+    fn new(capacity: usize) -> Self {
+        Self {
+            capacity,
+            order: VecDeque::new(),
+            times: HashMap::new(),
+        }
+    }
+
+    fn get(&self, key: &str) -> Option<Duration> {
+        self.times.get(key).copied()
+    }
+
+    fn insert(&mut self, key: String, time: Duration) {
+        if self.times.len() >= self.capacity
+            && let Some(oldest) = self.order.pop_front()
+        {
+            self.times.remove(&oldest);
+        }
+        if self.times.insert(key.clone(), time).is_none() {
+            self.order.push_back(key);
+        }
+    }
+
+    fn remove(&mut self, key: &str) {
+        if self.times.remove(key).is_some() {
+            self.order.retain(|tracked| tracked != key);
+        }
+    }
+}

litellm-rust/crates/redis-store/tests/router_cooldowns.rs

@@ -0,0 +1,395 @@
+mod support;
+
+use std::time::Duration;
+
+use litellm_redis_client::{Expiry, Operation, Ttl};
+use litellm_redis_store::{
+    Number, RequestRedis,
+    router_cooldowns::{POLICY, RouterCooldowns},
+};
+use litellm_redis_testing::{RedisDeployment, Topology};
+use rstest::rstest;
+use support::{ALLOWED_FAILS, connect, cooldowns, within};
+use tokio::runtime::Handle;
+
+/// A clock fixed just after the fixture timestamps, so every fixture cooldown is still active.
+fn fixture_clock() -> litellm_redis_store::Clock {
+    std::sync::Arc::new(|| Duration::from_secs_f64(1_730_000_000.75))
+}
+
+#[rstest]
+#[tokio::test]
+async fn put_writes_mains_str_dict_bytes_with_whole_second_ttl(
+    #[values(Topology::Standalone, Topology::Cluster)] topology: Topology,
+) {
+    let deployment = RedisDeployment::start(topology).await.unwrap();
+    let raw = connect(&deployment);
+    let store = RouterCooldowns::new(Some(connect(&deployment)), POLICY);
+
+    for case in cooldowns() {
+        let ttl = Duration::from_secs_f64(case.ttl_seconds);
+        store.put(case.model_id, &case.cooldown, ttl).await.unwrap();
+        let key = case.key;
+
+        let written: Option<String> = raw.get(key).await.unwrap();
+        let Ttl::Expires(remaining) = raw.ttl(key).await.unwrap() else {
+            panic!("{key} has no TTL");
+        };
+        assert_eq!(written.as_deref(), Some(case.str_dict));
+        assert!(within(remaining, case.redis_ttl_seconds), "{remaining:?}");
+    }
+}
+
+#[rstest]
+#[tokio::test]
+async fn reads_cooldowns_python_wrote_as_str_dict_or_json(
+    #[values(Topology::Standalone, Topology::Cluster)] topology: Topology,
+    #[values("str_dict", "json")] format: &str,
+) {
+    let deployment = RedisDeployment::start(topology).await.unwrap();
+    let raw = connect(&deployment);
+    let store = RouterCooldowns::with_clock(Some(connect(&deployment)), POLICY, fixture_clock());
+
+    for case in cooldowns() {
+        let bytes = match format {
+            "json" => case.json,
+            _ => case.str_dict,
+        };
+        raw.set(case.key, bytes, Duration::from_secs(60))
+            .await
+            .unwrap();
+
+        assert_eq!(
+            store.active(&[case.model_id.to_owned()]).await.unwrap(),
+            vec![(case.model_id.to_owned(), case.cooldown)]
+        );
+    }
+}
+
+#[rstest]
+#[tokio::test]
+async fn an_ended_cooldown_is_not_active_but_still_counts_toward_the_minimum(
+    #[values(Topology::Standalone, Topology::Cluster)] topology: Topology,
+) {
+    let deployment = RedisDeployment::start(topology).await.unwrap();
+    let raw = connect(&deployment);
+    let late = std::sync::Arc::new(|| Duration::from_secs(1_730_000_100));
+    let store = RouterCooldowns::with_clock(Some(connect(&deployment)), POLICY, late);
+    let models = cooldowns()
+        .iter()
+        .map(|case| case.model_id.to_owned())
+        .collect::<Vec<_>>();
+    for case in cooldowns() {
+        raw.set(case.key, case.str_dict, Duration::from_secs(60))
+            .await
+            .unwrap();
+    }
+
+    assert_eq!(
+        store.minimum(&models).await.unwrap(),
+        Some(Number::Float(0.5))
+    );
+    assert_eq!(store.active(&models).await.unwrap(), vec![]);
+}
+
+#[rstest]
+#[tokio::test]
+async fn allowed_fails_count_across_routers_and_keep_the_first_ttl(
+    #[values(Topology::Standalone, Topology::Cluster)] topology: Topology,
+) {
+    let deployment = RedisDeployment::start(topology).await.unwrap();
+    let raw = connect(&deployment);
+    let first = RouterCooldowns::new(Some(connect(&deployment)), POLICY);
+    let second = RouterCooldowns::new(Some(connect(&deployment)), POLICY);
+
+    for case in ALLOWED_FAILS {
+        let key = case.key;
+        raw.del(&[key]).await.unwrap();
+        let suffix = case.suffix;
+
+        let counts = [
+            first
+                .increment_allowed_fails("dep-a", suffix, Duration::from_secs_f64(30.9))
+                .await
+                .unwrap(),
+            second
+                .increment_allowed_fails("dep-a", suffix, Duration::from_secs(120))
+                .await
+                .unwrap(),
+        ];
+        let Ttl::Expires(remaining) = raw.ttl(key).await.unwrap() else {
+            panic!("{key} has no TTL");
+        };
+
+        assert_eq!(counts, [1, 2], "{key}");
+        assert!(within(remaining, 30), "{remaining:?}");
+    }
+}
+
+#[rstest]
+#[tokio::test]
+async fn python_written_fail_counts_continue_in_rust(
+    #[values(Topology::Standalone, Topology::Cluster)] topology: Topology,
+) {
+    let deployment = RedisDeployment::start(topology).await.unwrap();
+    let raw = connect(&deployment);
+    let store = RouterCooldowns::new(Some(connect(&deployment)), POLICY);
+    raw.incr_by(
+        "deployment:dep-a:allowed_fails",
+        4,
+        Expiry::KeepExisting(Duration::from_secs(60)),
+    )
+    .await
+    .unwrap();
+
+    assert_eq!(
+        store
+            .increment_allowed_fails("dep-a", None, Duration::from_secs(60))
+            .await
+            .unwrap(),
+        5
+    );
+}
+
+#[rstest]
+#[tokio::test]
+async fn a_router_without_redis_keeps_its_cooldowns_and_counts_in_memory() {
+    let store = RouterCooldowns::with_clock(None, POLICY, fixture_clock());
+    let [case, _] = cooldowns();
+
+    store
+        .put(case.model_id, &case.cooldown, Duration::from_secs(90))
+        .await
+        .unwrap();
+    let fails = [
+        store
+            .increment_allowed_fails("dep-a", None, Duration::from_secs(60))
+            .await
+            .unwrap(),
+        store
+            .increment_allowed_fails("dep-a", None, Duration::from_secs(60))
+            .await
+            .unwrap(),
+    ];
+    store.flush_local_counters().unwrap();
+
+    assert_eq!(
+        store.active(&[case.model_id.to_owned()]).await.unwrap(),
+        vec![(case.model_id.to_owned(), case.cooldown)]
+    );
+    assert_eq!(fails, [1, 2]);
+    assert_eq!(
+        store
+            .increment_allowed_fails("dep-a", None, Duration::from_secs(60))
+            .await
+            .unwrap(),
+        1
+    );
+}
+
+#[rstest]
+#[tokio::test]
+async fn a_redis_outage_serves_memory_and_counts_fails_locally() {
+    let deployment = RedisDeployment::start(Topology::Standalone).await.unwrap();
+    let store = RouterCooldowns::with_clock(Some(connect(&deployment)), POLICY, fixture_clock());
+    let [case, _] = cooldowns();
+    store
+        .put(case.model_id, &case.cooldown, Duration::from_secs(90))
+        .await
+        .unwrap();
+    deployment.stop().await.unwrap();
+
+    let active = store
+        .active(&[case.model_id.to_owned(), "dep-missing".to_owned()])
+        .await
+        .unwrap();
+    let fails = store
+        .increment_allowed_fails("dep-a", None, Duration::from_secs(60))
+        .await
+        .unwrap();
+
+    assert_eq!(active, vec![(case.model_id.to_owned(), case.cooldown)]);
+    assert_eq!(fails, 1);
+}
+
+struct StepClock(std::sync::Mutex<Duration>);
+
+impl StepClock {
+    fn at(seconds: f64) -> std::sync::Arc<Self> {
+        std::sync::Arc::new(Self(std::sync::Mutex::new(Duration::from_secs_f64(
+            seconds,
+        ))))
+    }
+
+    fn advance(&self, by: Duration) {
+        *self.0.lock().unwrap() += by;
+    }
+
+    fn clock(self: &std::sync::Arc<Self>) -> litellm_redis_store::Clock {
+        let this = self.clone();
+        std::sync::Arc::new(move || *this.0.lock().unwrap())
+    }
+}
+
+#[rstest]
+#[tokio::test]
+async fn a_miss_is_read_from_redis_again_only_after_the_one_second_refresh(
+    #[values(Topology::Standalone, Topology::Cluster)] topology: Topology,
+) {
+    let deployment = RedisDeployment::start(topology).await.unwrap();
+    let raw = connect(&deployment);
+    let time = StepClock::at(1_730_000_000.75);
+    let store = RouterCooldowns::with_clock(Some(connect(&deployment)), POLICY, time.clock());
+    let [case, _] = cooldowns();
+
+    let before = store.active(&[case.model_id.to_owned()]).await.unwrap();
+    raw.set(case.key, case.str_dict, Duration::from_secs(60))
+        .await
+        .unwrap();
+    let throttled = store.active(&[case.model_id.to_owned()]).await.unwrap();
+    time.advance(Duration::from_secs(1));
+    let refreshed = store.active(&[case.model_id.to_owned()]).await.unwrap();
+
+    assert_eq!(before, vec![]);
+    assert_eq!(throttled, vec![]);
+    assert_eq!(
+        refreshed,
+        vec![(case.model_id.to_owned(), case.cooldown.clone())]
+    );
+}
+
+#[rstest]
+#[tokio::test]
+async fn a_breaker_refusal_does_not_hold_back_the_next_read() {
+    let deployment = RedisDeployment::start(Topology::Standalone).await.unwrap();
+    let raw = connect(&deployment);
+    let breaker = litellm_circuit_breaker::Breaker::new(
+        litellm_circuit_breaker::Config {
+            failure_threshold: 1,
+            recovery_timeout: Duration::from_millis(200),
+            ..litellm_circuit_breaker::Config::default()
+        },
+        Box::new(|_| {}),
+    );
+    let time = StepClock::at(1_730_000_000.75);
+    let guarded = support::connect_guarded(&deployment, breaker);
+    let store = RouterCooldowns::with_clock(Some(guarded.clone()), POLICY, time.clock());
+    let [case, _] = cooldowns();
+    deployment.stop().await.unwrap();
+    store.active(&[case.model_id.to_owned()]).await.unwrap();
+    time.advance(Duration::from_secs(1));
+    let refused = store.active(&[case.model_id.to_owned()]).await.unwrap();
+    deployment.resume().await.unwrap();
+    litellm_redis_testing::eventually(async || guarded.ping().await.ok()).await;
+    raw.set(case.key, case.str_dict, Duration::from_secs(60))
+        .await
+        .unwrap();
+
+    let recovered = store.active(&[case.model_id.to_owned()]).await.unwrap();
+
+    assert_eq!(refused, vec![]);
+    assert_eq!(
+        recovered,
+        vec![(case.model_id.to_owned(), case.cooldown.clone())]
+    );
+}
+
+#[rstest]
+#[tokio::test]
+async fn a_declared_active_read_rides_the_request_batch_and_answers_what_active_does(
+    #[values(Topology::Standalone, Topology::Cluster)] topology: Topology,
+) {
+    let deployment = RedisDeployment::start(topology).await.unwrap();
+    let raw = connect(&deployment);
+    let (client, trips) = support::connect_observed(&deployment);
+    let store = RouterCooldowns::with_clock(Some(client), POLICY, fixture_clock());
+    let models = cooldowns().map(|case| case.model_id.to_owned());
+    for case in cooldowns() {
+        raw.set(case.key, case.str_dict, Duration::from_secs(60))
+            .await
+            .unwrap();
+    }
+    let request = RequestRedis::new(Handle::current(), Duration::from_secs(60));
+
+    let declared = store.declare_active(&request, &models).unwrap();
+    assert!(trips.seen().is_empty());
+    request.flush_pre().await;
+    let active = store.resolve_active(declared).await.unwrap();
+
+    assert_eq!(trips.seen(), [Operation::Pipeline { ops: 2 }]);
+    assert_eq!(
+        active,
+        cooldowns()
+            .map(|case| (case.model_id.to_owned(), case.cooldown))
+            .to_vec()
+    );
+    assert_eq!(store.active(&models).await.unwrap(), active);
+    assert_eq!(trips.seen().len(), 1, "the declared read backfilled memory");
+}
+
+#[rstest]
+#[tokio::test]
+async fn a_cooldown_recorded_after_the_declaration_wins_over_the_redis_miss(
+    #[values(Topology::Standalone, Topology::Cluster)] topology: Topology,
+) {
+    let deployment = RedisDeployment::start(topology).await.unwrap();
+    let store = RouterCooldowns::with_clock(Some(connect(&deployment)), POLICY, fixture_clock());
+    let [case, _] = cooldowns();
+    let request = RequestRedis::new(Handle::current(), Duration::from_secs(60));
+
+    let declared = store
+        .declare_active(&request, &[case.model_id.to_owned()])
+        .unwrap();
+    request.flush_pre().await;
+    store
+        .put(case.model_id, &case.cooldown, Duration::from_secs(90))
+        .await
+        .unwrap();
+
+    assert_eq!(
+        store.resolve_active(declared).await.unwrap(),
+        vec![(case.model_id.to_owned(), case.cooldown)]
+    );
+}
+
+#[rstest]
+#[tokio::test]
+async fn a_breaker_refusal_of_a_declared_read_does_not_hold_back_the_next_read() {
+    let deployment = RedisDeployment::start(Topology::Standalone).await.unwrap();
+    let raw = connect(&deployment);
+    let breaker = litellm_circuit_breaker::Breaker::new(
+        litellm_circuit_breaker::Config {
+            failure_threshold: 1,
+            recovery_timeout: Duration::from_millis(200),
+            ..litellm_circuit_breaker::Config::default()
+        },
+        Box::new(|_| {}),
+    );
+    let guarded = support::connect_guarded(&deployment, breaker);
+    let store = RouterCooldowns::with_clock(Some(guarded.clone()), POLICY, fixture_clock());
+    let [case, _] = cooldowns();
+    let models = [case.model_id.to_owned()];
+    deployment.stop().await.unwrap();
+    let opened = RequestRedis::new(Handle::current(), Duration::from_secs(60));
+    let failed = store
+        .declare_active(&opened, &["dep-other".to_owned()])
+        .unwrap();
+    opened.flush_pre().await;
+    store.resolve_active(failed).await.unwrap();
+    let refused_request = RequestRedis::new(Handle::current(), Duration::from_secs(60));
+
+    let refused = store.declare_active(&refused_request, &models).unwrap();
+    refused_request.flush_pre().await;
+    let refused = store.resolve_active(refused).await.unwrap();
+    deployment.resume().await.unwrap();
+    litellm_redis_testing::eventually(async || guarded.ping().await.ok()).await;
+    raw.set(case.key, case.str_dict, Duration::from_secs(60))
+        .await
+        .unwrap();
+
+    assert_eq!(refused, vec![]);
+    assert_eq!(
+        store.active(&models).await.unwrap(),
+        vec![(case.model_id.to_owned(), case.cooldown.clone())]
+    );
+}

litellm-rust/crates/redis-store/tests/router_usage.rs

@@ -0,0 +1,277 @@
+mod support;
+
+use std::{sync::Arc, time::Duration};
+
+use litellm_redis_client::{Expiry, Operation, Ttl};
+use litellm_redis_store::{
+    Number, RequestRedis,
+    router_usage::{COUNTER_TTL, Counter, Kind, POLICY, RouterUsage},
+};
+use litellm_redis_testing::{RedisDeployment, Topology};
+use rstest::rstest;
+use support::{connect, usage, within};
+use tokio::runtime::Handle;
+
+fn tpm_and_rpm(model: Option<&str>) -> [Counter; 2] {
+    [Kind::Tpm, Kind::Rpm].map(|kind| Counter {
+        deployment_id: "dep".to_owned(),
+        model: model.map(str::to_owned),
+        minute: "12-34".to_owned(),
+        kind,
+    })
+}
+
+#[rstest]
+#[tokio::test]
+async fn reads_counters_python_incremented_under_mains_keys(
+    #[values(Topology::Standalone, Topology::Cluster)] topology: Topology,
+) {
+    let deployment = RedisDeployment::start(topology).await.unwrap();
+    let raw = connect(&deployment);
+    let store = RouterUsage::new(Some(connect(&deployment)), POLICY);
+    let cases = usage();
+    for (case, delta) in cases.iter().zip([7.75, 3.0]) {
+        raw.incr_by_float(case.key, delta, Expiry::Refresh(COUNTER_TTL))
+            .await
+            .unwrap();
+    }
+
+    assert_eq!(
+        store
+            .get_many(&cases.map(|case| case.counter))
+            .await
+            .unwrap(),
+        vec![Some(Number::Float(7.75)), Some(Number::Int(3))]
+    );
+}
+
+#[rstest]
+#[tokio::test]
+async fn deployment_increments_write_incrbyfloat_totals_with_a_refreshed_minute_window(
+    #[values(Topology::Standalone, Topology::Cluster)] topology: Topology,
+) {
+    let deployment = RedisDeployment::start(topology).await.unwrap();
+    let raw = connect(&deployment);
+    let writer = RouterUsage::new(Some(connect(&deployment)), POLICY);
+    let reader = RouterUsage::new(Some(connect(&deployment)), POLICY);
+    let [case, _] = usage();
+    let model = case.counter.model.as_deref();
+    let [tpm_key, rpm_key] =
+        ["tpm", "rpm"].map(|kind| case.key.replace(":tpm:", &format!(":{kind}:")));
+
+    writer
+        .increment_deployment("dep", model, "12-34", Number::Float(5.5), 1)
+        .await
+        .unwrap();
+    raw.expire(&tpm_key, Duration::from_secs(5)).await.unwrap();
+    writer
+        .increment_deployment("dep", model, "12-34", Number::Int(2), 1)
+        .await
+        .unwrap();
+
+    let written: [Option<String>; 2] = [
+        raw.get(&tpm_key).await.unwrap(),
+        raw.get(&rpm_key).await.unwrap(),
+    ];
+    let Ttl::Expires(remaining) = raw.ttl(&tpm_key).await.unwrap() else {
+        panic!("{tpm_key} has no TTL");
+    };
+    assert_eq!(written, [Some("7.5".to_owned()), Some("2".to_owned())]);
+    assert!(within(remaining, 60), "{remaining:?}");
+    assert_eq!(
+        reader.get_many(&tpm_and_rpm(model)).await.unwrap(),
+        vec![Some(Number::Float(7.5)), Some(Number::Int(2))]
+    );
+    assert_eq!(
+        writer.get_many(&tpm_and_rpm(model)).await.unwrap(),
+        vec![Some(Number::Int(7)), Some(Number::Int(2))]
+    );
+}
+
+#[rstest]
+#[tokio::test]
+async fn a_request_increment_keeps_the_window_python_started(
+    #[values(Topology::Standalone, Topology::Cluster)] topology: Topology,
+) {
+    let deployment = RedisDeployment::start(topology).await.unwrap();
+    let raw = connect(&deployment);
+    let store = RouterUsage::new(Some(connect(&deployment)), POLICY);
+    let [_, case] = usage();
+    let key = case.key;
+    raw.incr_by_float(key, 1.0, Expiry::KeepExisting(Duration::from_secs(20)))
+        .await
+        .unwrap();
+
+    let total = store
+        .increment(&case.counter, Number::Int(1), COUNTER_TTL)
+        .await
+        .unwrap();
+    let Ttl::Expires(remaining) = raw.ttl(key).await.unwrap() else {
+        panic!("{key} has no TTL");
+    };
+
+    assert_eq!(total, Number::Float(2.0));
+    assert!(within(remaining, 20), "{remaining:?}");
+}
+
+#[rstest]
+#[tokio::test]
+async fn without_redis_counters_accumulate_in_memory_until_flushed() {
+    let store = RouterUsage::new(None, POLICY);
+    let counters = tpm_and_rpm(Some("model"));
+
+    store
+        .increment_deployment("dep", Some("model"), "12-34", Number::Int(2), 1)
+        .await
+        .unwrap();
+    store
+        .increment_deployment("dep", Some("model"), "12-34", Number::Float(5.5), 1)
+        .await
+        .unwrap();
+    let counted = store.get_many(&counters).await.unwrap();
+    store.flush_local_counters().unwrap();
+
+    assert_eq!(
+        counted,
+        vec![Some(Number::Float(7.5)), Some(Number::Int(2))]
+    );
+    assert_eq!(store.get_many(&counters).await.unwrap(), vec![None, None]);
+}
+
+#[rstest]
+#[tokio::test]
+async fn a_failed_pipeline_keeps_the_memory_counts_as_integers() {
+    let deployment = RedisDeployment::start(Topology::Standalone).await.unwrap();
+    let store = RouterUsage::new(Some(connect(&deployment)), POLICY);
+    deployment.stop().await.unwrap();
+
+    store
+        .increment_deployment("dep", Some("model"), "12-34", Number::Float(5.75), 1)
+        .await
+        .unwrap();
+
+    assert_eq!(
+        store.get_many(&tpm_and_rpm(Some("model"))).await.unwrap(),
+        vec![Some(Number::Int(5)), Some(Number::Int(1))]
+    );
+}
+
+#[rstest]
+#[tokio::test]
+async fn a_post_call_increment_from_a_thread_without_a_runtime_lands_and_mirrors(
+    #[values(Topology::Standalone, Topology::Cluster)] topology: Topology,
+) {
+    let deployment = RedisDeployment::start(topology).await.unwrap();
+    let store = Arc::new(RouterUsage::new(Some(connect(&deployment)), POLICY));
+    let request = RequestRedis::new(Handle::current(), Duration::from_secs(60));
+
+    std::thread::spawn({
+        let (store, request) = (Arc::clone(&store), request.clone());
+        move || {
+            store
+                .increment_deployment_post_call(
+                    &request,
+                    "dep",
+                    Some("model"),
+                    "12-34",
+                    Number::Int(5),
+                    1,
+                )
+                .unwrap();
+        }
+    })
+    .join()
+    .expect("a Python thread has no Tokio context, and declaring there must not panic");
+    request.flush_post().await;
+
+    litellm_redis_testing::eventually(async || {
+        (store.get_many(&tpm_and_rpm(Some("model"))).await.unwrap()
+            == [Some(Number::Int(5)), Some(Number::Int(1))])
+        .then_some(())
+    })
+    .await;
+}
+
+#[rstest]
+#[tokio::test]
+async fn post_call_increments_wait_for_flush_post_then_mirror_the_redis_totals_into_memory(
+    #[values(Topology::Standalone, Topology::Cluster)] topology: Topology,
+) {
+    let deployment = RedisDeployment::start(topology).await.unwrap();
+    let raw = connect(&deployment);
+    let (client, trips) = support::connect_observed(&deployment);
+    let store = Arc::new(RouterUsage::new(Some(client), POLICY));
+    let counters = tpm_and_rpm(Some("model"));
+    let [tpm_key, rpm_key] =
+        ["tpm", "rpm"].map(|kind| format!("global_router:dep:model:{kind}:12-34"));
+    raw.incr_by_float(&tpm_key, 10.0, Expiry::Refresh(COUNTER_TTL))
+        .await
+        .unwrap();
+    let request = RequestRedis::new(Handle::current(), Duration::from_secs(60));
+
+    store
+        .increment_deployment_post_call(
+            &request,
+            "dep",
+            Some("model"),
+            "12-34",
+            Number::Float(5.5),
+            1,
+        )
+        .unwrap();
+    let before_flush = store.get_many(&counters).await.unwrap();
+    let unsent: Option<String> = raw.get(&rpm_key).await.unwrap();
+    let trips_before_flush = trips.seen();
+    request.flush_post().await;
+    let mirrored = litellm_redis_testing::eventually(async || {
+        let counted = store.get_many(&counters).await.unwrap();
+        (counted == [Some(Number::Int(15)), Some(Number::Int(1))]).then_some(counted)
+    })
+    .await;
+
+    assert_eq!(
+        before_flush,
+        vec![Some(Number::Float(5.5)), Some(Number::Int(1))]
+    );
+    assert_eq!(unsent, None);
+    assert!(trips_before_flush.is_empty());
+    assert_eq!(trips.seen(), [Operation::Pipeline { ops: 2 }]);
+    assert_eq!(mirrored, vec![Some(Number::Int(15)), Some(Number::Int(1))]);
+    let written: [Option<String>; 2] = [
+        raw.get(&tpm_key).await.unwrap(),
+        raw.get(&rpm_key).await.unwrap(),
+    ];
+    assert_eq!(written, [Some("15.5".to_owned()), Some("1".to_owned())]);
+    let Ttl::Expires(remaining) = raw.ttl(&rpm_key).await.unwrap() else {
+        panic!("{rpm_key} has no TTL");
+    };
+    assert!(within(remaining, 60), "{remaining:?}");
+}
+
+#[rstest]
+#[tokio::test]
+async fn a_failed_post_call_pipeline_keeps_the_memory_counts_as_integers() {
+    let deployment = RedisDeployment::start(Topology::Standalone).await.unwrap();
+    let store = Arc::new(RouterUsage::new(Some(connect(&deployment)), POLICY));
+    let counters = tpm_and_rpm(Some("model"));
+    let request = RequestRedis::new(Handle::current(), Duration::from_secs(60));
+    deployment.stop().await.unwrap();
+
+    store
+        .increment_deployment_post_call(
+            &request,
+            "dep",
+            Some("model"),
+            "12-34",
+            Number::Float(5.75),
+            1,
+        )
+        .unwrap();
+    request.flush_post().await;
+
+    litellm_redis_testing::eventually(async || {
+        (store.get_many(&counters).await.unwrap() == [Some(Number::Int(5)), Some(Number::Int(1))])
+            .then_some(())
+    })
+    .await;
+}

litellm-rust/crates/redis-store/tests/support/mod.rs

@@ -10,6 +10,11 @@ use litellm_redis_client::{
     CallEvent, ClusterEndpoint, ClusterNode, Credentials, Endpoint, Namespace, Operation,
     RedisClient, RedisConfig, RedisEvents, Timeouts, TlsOptions,
 };
+use litellm_redis_store::{
+    Number,
+    router_cooldowns::Cooldown,
+    router_usage::{Counter, Kind},
+};
 use litellm_redis_testing::RedisDeployment;
 
 pub fn connect(deployment: &RedisDeployment) -> RedisClient {
@@ -79,3 +84,105 @@ fn connect_with(
     .unwrap()
 }
 
+/// What main's `RedisCache` writes for a cooldown: `str(value)` with `EX int(ttl)`, read back with
+/// `json.loads` then `ast.literal_eval` (`litellm/caching/redis_cache.py` `set_cache` and
+/// `_get_cache_logic`). Keys come from main's `CooldownCache`. The same literals sit in
+/// `tests/unit/redis/stores/test_router_cooldowns.py`, checked against main's codec.
+pub struct CooldownCase {
+    pub model_id: &'static str,
+    pub cooldown: Cooldown,
+    pub ttl_seconds: f64,
+    pub key: &'static str,
+    pub redis_ttl_seconds: u64,
+    pub str_dict: &'static str,
+    pub json: &'static str,
+}
+
+pub fn cooldowns() -> [CooldownCase; 2] {
+    [
+        CooldownCase {
+            model_id: "dep-a",
+            cooldown: Cooldown {
+                exception_received: "RateLimitError: limited é 'quoted'".to_owned(),
+                status_code: "429".to_owned(),
+                timestamp: Number::Float(1_730_000_000.25),
+                cooldown_time: Number::Int(60),
+            },
+            ttl_seconds: 90.5,
+            key: "deployment:dep-a:cooldown",
+            redis_ttl_seconds: 90,
+            str_dict: "{'exception_received': \"RateLimitError: limited é 'quoted'\", 'status_code': '429', 'timestamp': 1730000000.25, 'cooldown_time': 60}",
+            json: "{\"exception_received\": \"RateLimitError: limited \\u00e9 'quoted'\", \"status_code\": \"429\", \"timestamp\": 1730000000.25, \"cooldown_time\": 60}",
+        },
+        CooldownCase {
+            model_id: "dep-b",
+            cooldown: Cooldown {
+                exception_received: "Timeout".to_owned(),
+                status_code: "408".to_owned(),
+                timestamp: Number::Float(1_730_000_000.5),
+                cooldown_time: Number::Float(0.5),
+            },
+            ttl_seconds: 30.0,
+            key: "deployment:dep-b:cooldown",
+            redis_ttl_seconds: 30,
+            str_dict: "{'exception_received': 'Timeout', 'status_code': '408', 'timestamp': 1730000000.5, 'cooldown_time': 0.5}",
+            json: "{\"exception_received\": \"Timeout\", \"status_code\": \"408\", \"timestamp\": 1730000000.5, \"cooldown_time\": 0.5}",
+        },
+    ]
+}
+
+/// main's allowed-fails keys for `dep-a`: an empty suffix is the same key as none.
+pub struct AllowedFailsCase {
+    pub suffix: Option<&'static str>,
+    pub key: &'static str,
+}
+
+pub const ALLOWED_FAILS: [AllowedFailsCase; 3] = [
+    AllowedFailsCase {
+        suffix: None,
+        key: "deployment:dep-a:allowed_fails",
+    },
+    AllowedFailsCase {
+        suffix: Some(""),
+        key: "deployment:dep-a:allowed_fails",
+    },
+    AllowedFailsCase {
+        suffix: Some("timeout"),
+        key: "deployment:dep-a:allowed_fails:timeout",
+    },
+];
+
+/// main's `RouterCacheEnum` usage keys, including the `None` a missing model prints into the key.
+pub struct UsageCase {
+    pub counter: Counter,
+    pub key: &'static str,
+}
+
+pub fn usage() -> [UsageCase; 2] {
+    [
+        UsageCase {
+            counter: Counter {
+                deployment_id: "dep".to_owned(),
+                model: Some("anthropic/claude-sonnet-5-5".to_owned()),
+                minute: "12-34".to_owned(),
+                kind: Kind::Tpm,
+            },
+            key: "global_router:dep:anthropic/claude-sonnet-5-5:tpm:12-34",
+        },
+        UsageCase {
+            counter: Counter {
+                deployment_id: "dep".to_owned(),
+                model: None,
+                minute: "09-05".to_owned(),
+                kind: Kind::Rpm,
+            },
+            key: "global_router:dep:None:rpm:09-05",
+        },
+    ]
+}
+
+/// A TTL Redis reports for a key written `whole_seconds` ago at most a few seconds back.
+pub fn within(ttl: Duration, whole_seconds: u64) -> bool {
+    ttl <= Duration::from_secs(whole_seconds)
+        && ttl > Duration::from_secs(whole_seconds.saturating_sub(5))
+}

litellm/redis/stores/_keys.py

@@ -0,0 +1,4 @@
+from typing import Final
+
+ROUTER_TPM_KEY: Final = "global_router:{id}:{model}:tpm:{current_minute}"
+ROUTER_RPM_KEY: Final = "global_router:{id}:{model}:rpm:{current_minute}"

litellm/redis/stores/router_cooldowns.py

@@ -0,0 +1,108 @@
+from __future__ import annotations
+
+from collections.abc import Awaitable, Callable, Mapping, Sequence
+from typing import TYPE_CHECKING, Final, Protocol, TypeAlias
+
+if TYPE_CHECKING:
+    from opentelemetry.trace import Span
+from typing_extensions import ReadOnly, TypedDict
+
+from litellm._internal_context import service_target
+from litellm.caching.redis_batch import NativeBatchResult, NativePending, RequestRedisBatches
+from litellm.rust_bridge._native import NativeRedisClient, NativeRequestRedis, NativeRouterCooldowns
+
+
+class CooldownCacheValue(TypedDict):
+    exception_received: ReadOnly[str]
+    status_code: ReadOnly[str]
+    timestamp: ReadOnly[float]
+    cooldown_time: ReadOnly[float]
+
+
+ROUTER_COOLDOWNS_TARGET: Final = "router_cooldowns"
+ActiveCooldowns: TypeAlias = Sequence[tuple[str, CooldownCacheValue]]
+
+
+class RouterCooldowns(Protocol):
+    def attach_redis(self, client: NativeRedisClient | None) -> None: ...
+    def flush_local_counters(self) -> None: ...
+    def put(self, model_id: str, value: CooldownCacheValue, ttl: float) -> None: ...
+    def increment_allowed_fails(self, model_id: str, suffix: str | None, ttl: float) -> int: ...
+    async def active(self, model_ids: Sequence[str], parent_otel_span: Span | None) -> ActiveCooldowns: ...
+    def declare_active(
+        self, request: RequestRedisBatches, model_ids: Sequence[str]
+    ) -> NativeBatchResult[ActiveCooldowns] | None: ...
+    def active_sync(self, model_ids: Sequence[str], parent_otel_span: Span | None) -> ActiveCooldowns: ...
+    def minimum(self, model_ids: Sequence[str], default: float, parent_otel_span: Span | None) -> float: ...
+    def evict_local(self, model_id: str) -> None: ...
+    def snapshot(self) -> Mapping[str, CooldownCacheValue]: ...
+
+
+class CooldownsHandle(Protocol):
+    def put(self, model_id: str, cooldown: Mapping[str, object], ttl_seconds: float) -> None: ...
+    def increment_allowed_fails(self, model_id: str, suffix: str | None, ttl_seconds: float) -> int: ...
+    def active(self, model_ids: Sequence[str]) -> Sequence[tuple[str, CooldownCacheValue]]: ...
+    def aactive(self, model_ids: Sequence[str]) -> Awaitable[Sequence[tuple[str, CooldownCacheValue]]]: ...
+    def declare_active(
+        self, request: NativeRequestRedis, model_ids: Sequence[str]
+    ) -> NativePending[ActiveCooldowns]: ...
+    def minimum(self, model_ids: Sequence[str]) -> float | None: ...
+    def evict_local(self, model_id: str) -> None: ...
+    def flush_local_counters(self) -> None: ...
+    def snapshot(self) -> Mapping[str, CooldownCacheValue]: ...
+
+
+HandleFactory: TypeAlias = Callable[[NativeRedisClient | None], CooldownsHandle]
+
+
+class RouterCooldownStore:
+    def __init__(self, client: NativeRedisClient | None, *, handle: HandleFactory = NativeRouterCooldowns) -> None:
+        self._connected = client is not None
+        self._build: Final = handle
+        self._handle = handle(client)
+
+    def attach_redis(self, client: NativeRedisClient | None) -> None:
+        if client is None or self._connected:
+            return
+        self._connected = True
+        self._handle = self._build(client)
+
+    def flush_local_counters(self) -> None:
+        self._handle.flush_local_counters()
+
+    def put(self, model_id: str, value: CooldownCacheValue, ttl: float) -> None:
+        with service_target(ROUTER_COOLDOWNS_TARGET):
+            self._handle.put(model_id, value, ttl)
+
+    def increment_allowed_fails(self, model_id: str, suffix: str | None, ttl: float) -> int:
+        with service_target(ROUTER_COOLDOWNS_TARGET):
+            return self._handle.increment_allowed_fails(model_id, suffix, ttl)
+
+    async def active(self, model_ids: Sequence[str], parent_otel_span: Span | None) -> ActiveCooldowns:
+        with service_target(ROUTER_COOLDOWNS_TARGET):
+            pending: Final = self._handle.aactive(model_ids)
+        return tuple(await pending)
+
+    def declare_active(
+        self, request: RequestRedisBatches, model_ids: Sequence[str]
+    ) -> NativeBatchResult[ActiveCooldowns] | None:
+        """``active`` declared on the request's native pre-call batch; None when there is no Redis to read."""
+        if not self._connected:
+            return None
+        with service_target(ROUTER_COOLDOWNS_TARGET):
+            pending: Final = self._handle.declare_active(request.native(), model_ids)
+        return request.native_result(pending)
+
+    def active_sync(self, model_ids: Sequence[str], parent_otel_span: Span | None) -> ActiveCooldowns:
+        with service_target(ROUTER_COOLDOWNS_TARGET):
+            return tuple(self._handle.active(model_ids))
+
+    def minimum(self, model_ids: Sequence[str], default: float, parent_otel_span: Span | None) -> float:
+        with service_target(ROUTER_COOLDOWNS_TARGET):
+            return self._handle.minimum(model_ids) or default
+
+    def evict_local(self, model_id: str) -> None:
+        self._handle.evict_local(model_id)
+
+    def snapshot(self) -> Mapping[str, CooldownCacheValue]:
+        return self._handle.snapshot()

litellm/redis/stores/router_usage.py

@@ -0,0 +1,117 @@
+from __future__ import annotations
+
+from collections.abc import Awaitable, Callable, Mapping, Sequence
+from dataclasses import dataclass
+from typing import TYPE_CHECKING, Final, Literal, Protocol, TypeAlias
+
+if TYPE_CHECKING:
+    from opentelemetry.trace import Span
+
+from litellm._internal_context import with_service_target
+from litellm.caching.redis_batch import active_request_redis_batches
+from litellm.rust_bridge._native import NativeRedisClient, NativeRequestRedis, NativeRouterUsage
+
+ROUTER_USAGE_TARGET: Final = "router_usage"
+CounterKind: TypeAlias = Literal["tpm", "rpm"]
+
+
+@dataclass(frozen=True, slots=True)
+class UsageCounter:
+    deployment_id: str
+    model: str | None
+    minute: str
+    kind: CounterKind
+
+
+class RouterUsage(Protocol):
+    def attach_redis(self, client: NativeRedisClient | None) -> None: ...
+    def flush_local_counters(self) -> None: ...
+    async def async_increment(
+        self, counter: UsageCounter, value: float, ttl: int, parent_otel_span: Span | None = None
+    ) -> float | None: ...
+    async def increment_deployment(
+        self,
+        deployment_id: str,
+        model: str | None,
+        minute: str,
+        tokens: float,
+        requests: int,
+        parent_otel_span: Span | None,
+    ) -> None: ...
+    async def async_batch_get(self, counters: Sequence[UsageCounter]) -> Sequence[object] | None: ...
+    def snapshot(self) -> Mapping[str, float]: ...
+
+
+NativeCounter: TypeAlias = tuple[str, str | None, str, CounterKind]
+
+
+class UsageHandle(Protocol):
+    def increment(self, counter: NativeCounter, value: float, ttl_seconds: int) -> Awaitable[float]: ...
+    def increment_deployment(
+        self,
+        deployment_id: str,
+        model: str | None,
+        minute: str,
+        tokens: float,
+        requests: int,
+        *,
+        request: NativeRequestRedis | None = None,
+    ) -> Awaitable[None]: ...
+    def get_many(self, counters: Sequence[NativeCounter]) -> Awaitable[Sequence[float | None]]: ...
+    def flush_local_counters(self) -> None: ...
+    def snapshot(self) -> Mapping[str, float]: ...
+
+
+HandleFactory: TypeAlias = Callable[[NativeRedisClient | None], UsageHandle]
+
+
+def _native(counter: UsageCounter) -> NativeCounter:
+    return (counter.deployment_id, counter.model, counter.minute, counter.kind)
+
+
+class RouterUsageStore:
+    def __init__(self, client: NativeRedisClient | None, *, handle: HandleFactory = NativeRouterUsage) -> None:
+        self._connected = client is not None
+        self._build: Final = handle
+        self._handle = handle(client)
+
+    def attach_redis(self, client: NativeRedisClient | None) -> None:
+        if client is None or self._connected:
+            return
+        self._connected = True
+        self._handle = self._build(client)
+
+    def flush_local_counters(self) -> None:
+        self._handle.flush_local_counters()
+
+    @with_service_target(ROUTER_USAGE_TARGET)
+    async def async_increment(
+        self, counter: UsageCounter, value: float, ttl: int, parent_otel_span: Span | None = None
+    ) -> float | None:
+        return await self._handle.increment(_native(counter), value, ttl)
+
+    @with_service_target(ROUTER_USAGE_TARGET)
+    async def increment_deployment(
+        self,
+        deployment_id: str,
+        model: str | None,
+        minute: str,
+        tokens: float,
+        requests: int,
+        parent_otel_span: Span | None,
+    ) -> None:
+        request: Final = active_request_redis_batches()
+        await self._handle.increment_deployment(
+            deployment_id,
+            model,
+            minute,
+            tokens,
+            requests,
+            request=None if request is None else request.native_post_call(),
+        )
+
+    async def async_batch_get(self, counters: Sequence[UsageCounter]) -> Sequence[object] | None:
+        return await self._handle.get_many(tuple(map(_native, counters)))
+
+    def snapshot(self) -> Mapping[str, float]:
+        return self._handle.snapshot()

litellm/router_python_core.py

@@ -238,6 +238,9 @@ from litellm.llms.openai_like.model_info import (
     get_openai_compatible_model_info,
 )
 from litellm.main import Chat as LitellmChat
+from litellm.redis.stores._connection import native_client
+from litellm.redis.stores.router_cooldowns import RouterCooldownStore
+from litellm.redis.stores.router_usage import RouterUsage, RouterUsageStore, UsageCounter
 from litellm.responses.bridge_check import keep_registered_mode
 from litellm.responses.retrieve_stream_query import requests_streamed_retrieval, without_retrieve_stream_defaults
 from litellm.router_api import (
@@ -1743,6 +1746,8 @@ class PythonCore(DeprecatedRouterMembers):
         self._core_cache = DualCache(
             redis_cache=redis_cache, in_memory_cache=InMemoryCache()
         )  # use a dual cache (Redis+In-Memory) for tracking cooldowns, usage, etc.
+        redis_client: Final = native_client(redis_cache)
+        self._core_usage_store: Final[RouterUsage] = RouterUsageStore(redis_client)
         self._claude_code_session_router_cache: DualCache = DualCache(
             redis_cache=redis_cache,
             in_memory_cache=InMemoryCache(),
@@ -1848,7 +1853,7 @@ class PythonCore(DeprecatedRouterMembers):
         self.explicit_allowed_fails = allowed_fails
         self._core_cooldown_time = cooldown_time or DEFAULT_COOLDOWN_TIME_SECONDS
         self._core_cooldown_cache = CooldownCache(
-            cache=self._core_cache, default_cooldown_time=self._core_cooldown_time
+            store=RouterCooldownStore(redis_client), default_cooldown_time=self._core_cooldown_time
         )
         self._core_disable_cooldowns = disable_cooldowns
         self.fallback_on_unsupported_params = fallback_on_unsupported_params
@@ -2204,6 +2209,9 @@ class PythonCore(DeprecatedRouterMembers):
         and caching to just work.
         """
         self._core_cache.attach_redis_cache(cache)
+        redis_client: Final = native_client(cache)
+        self._core_usage_store.attach_redis(redis_client)
+        self._core_cooldown_cache.cooldown_store.attach_redis(redis_client)
         self._claude_code_session_router_cache.attach_redis_cache(cache)
         self._core_prompt_caching_pin_cache.attach_redis_cache(cache)
 
@@ -10060,35 +10068,17 @@ class PythonCore(DeprecatedRouterMembers):
         total_tokens: float,
         rpm_increment: int,
         parent_otel_span: Span | None,
-    ) -> str | None:
-        from litellm.types.caching import RedisPipelineIncrementOperation
-
+    ) -> UsageCounter | None:
         if total_tokens <= 0 and rpm_increment <= 0:
             return None
         if not self._cached_deployment_tracks_usage(deployment_id, model_group):
             return None
 
         current_minute: Final = get_utc_datetime().strftime("%H-%M")  # use the same timezone regardless of system clock
-        tpm_key: Final = RouterCacheEnum.TPM.value.format(
-            id=deployment_id, current_minute=current_minute, model=deployment_name
+        await self._core_usage_store.increment_deployment(
+            deployment_id, deployment_name, current_minute, total_tokens, rpm_increment, parent_otel_span
         )
-        rpm_key: Final = RouterCacheEnum.RPM.value.format(
-            id=deployment_id, current_minute=current_minute, model=deployment_name
-        )
-        pipeline_operations: Final[list[RedisPipelineIncrementOperation]] = [
-            RedisPipelineIncrementOperation(key=key, increment_value=increment_value, ttl=RoutingArgs.ttl.value)
-            for key, increment_value in ((tpm_key, total_tokens), (rpm_key, rpm_increment))
-        ]
-        post_increment_values: Final = await self._core_cache.async_increment_cache_pipeline(
-            increment_list=pipeline_operations,
-            parent_otel_span=parent_otel_span,
-        )
-        if post_increment_values is not None and self._core_cache.redis_cache is not None:
-            for operation, value in zip(pipeline_operations, post_increment_values):
-                await self._core_cache.async_set_cache(
-                    operation["key"], int(value), local_only=True, ttl=RoutingArgs.ttl.value
-                )
-        return tpm_key
+        return UsageCounter(deployment_id, deployment_name, current_minute, "tpm")
 
     def _deployment_tracks_usage(self, deployment_id: str, model_group: str) -> bool:
         deployment_info: Final = self._core_get_deployment(model_id=deployment_id)
@@ -10305,10 +10295,10 @@ class PythonCore(DeprecatedRouterMembers):
         current_minute: Final = dt.strftime("%H-%M")  # use the same timezone regardless of system clock
 
         ## RPM
-        rpm_key: Final = RouterCacheEnum.RPM.value.format(id=id, current_minute=current_minute, model=deployment_name)
+        counter: Final = UsageCounter(id, deployment_name, current_minute, "rpm")
         with service_target(ROUTER_USAGE_TARGET):
-            await self._core_cache.async_increment_cache(
-                key=rpm_key,
+            await self._core_usage_store.async_increment(
+                counter=counter,
                 value=1,
                 parent_otel_span=parent_otel_span,
                 ttl=RoutingArgs.ttl.value,
@@ -13416,8 +13406,8 @@ class PythonCore(DeprecatedRouterMembers):
         """
         dt: Final = get_utc_datetime()
         current_minute: Final = dt.strftime("%H-%M")  # use the same timezone regardless of system clock
-        tpm_keys: Final[list[str]] = []
-        rpm_keys: Final[list[str]] = []
+        tpm_keys: Final[list[UsageCounter]] = []
+        rpm_keys: Final[list[UsageCounter]] = []
 
         model_list: Final = self._core_get_model_list(model_name=model_group)
         if model_list is None:  # no matching deployments
@@ -13430,28 +13420,16 @@ class PythonCore(DeprecatedRouterMembers):
             )  # USE THE MODEL SENT TO litellm.completion() - consistent with how global_router cache is written.
             if id is None or litellm_model is None:
                 continue
-            tpm_keys.append(
-                RouterCacheEnum.TPM.value.format(
-                    id=id,
-                    model=litellm_model,
-                    current_minute=current_minute,
-                )
-            )
-            rpm_keys.append(
-                RouterCacheEnum.RPM.value.format(
-                    id=id,
-                    model=litellm_model,
-                    current_minute=current_minute,
-                )
-            )
+            tpm_keys.append(UsageCounter(id, litellm_model, current_minute, "tpm"))
+            rpm_keys.append(UsageCounter(id, litellm_model, current_minute, "rpm"))
         combined_tpm_rpm_keys: Final = tpm_keys + rpm_keys
 
-        combined_tpm_rpm_values: Final = await self._core_cache.async_batch_get_cache(keys=combined_tpm_rpm_keys)
+        combined_tpm_rpm_values: Final = await self._core_usage_store.async_batch_get(combined_tpm_rpm_keys)
         if combined_tpm_rpm_values is None:
             return None, None
 
-        tpm_usage_list: Final[list | None] = combined_tpm_rpm_values[: len(tpm_keys)]
-        rpm_usage_list: Final[list | None] = combined_tpm_rpm_values[len(tpm_keys) :]
+        tpm_usage_list: Final = combined_tpm_rpm_values[: len(tpm_keys)]
+        rpm_usage_list: Final = combined_tpm_rpm_values[len(tpm_keys) :]
 
         ## TPM
         tpm_usage: int | None = None
@@ -17653,6 +17631,8 @@ class PythonCore(DeprecatedRouterMembers):
 
     def flush_cache(self):
         self._host.set_global_cache(None)
+        self._core_usage_store.flush_local_counters()
+        self._core_cooldown_cache.cooldown_store.flush_local_counters()
         self._core_cache.flush_cache()
         session_in_memory_cache: Final = self._claude_code_session_router_cache.in_memory_cache
         if session_in_memory_cache is not None:

litellm/router_utils/cooldown_cache.py

@@ -1,237 +1,54 @@
-"""
-Wrapper around router cache. Meant to handle model cooldown logic
-"""
+from __future__ import annotations
 
-import functools
 import time
-from collections.abc import Mapping, Sequence
-from typing import TYPE_CHECKING, Any, Final
-
-from typing_extensions import TypedDict
-
-from litellm import verbose_logger
-from litellm._internal_context import service_target
-from litellm.caching.caching import DualCache
-from litellm.caching.in_memory_cache import InMemoryCache
-from litellm.constants import DEFAULT_COOLDOWN_REDIS_READ_INTERVAL_SECONDS
-from litellm.litellm_core_utils.sensitive_data_masker import SensitiveDataMasker
+from collections.abc import Callable, Sequence
+from typing import TYPE_CHECKING, Final
 
 if TYPE_CHECKING:
-    from opentelemetry.trace import Span as _Span
+    from opentelemetry.trace import Span
 
-    Span = _Span
-else:
-    Span = Any
+from litellm.litellm_core_utils.sensitive_data_masker import SensitiveDataMasker
+from litellm.redis.stores.router_cooldowns import (
+    ROUTER_COOLDOWNS_TARGET,
+    CooldownCacheValue,
+    RouterCooldowns,
+)
 
-
-class CooldownCacheValue(TypedDict):
-    exception_received: str
-    status_code: str
-    timestamp: float
-    cooldown_time: float
-
-
-# Cap on the corrected in-memory TTL set in `_corrected_active_cooldown`: re-checks the
-# real remaining cooldown against Redis at least this often, so an entry that later gets
-# deleted or extended in Redis before its original deadline is still noticed promptly.
-_MAX_CORRECTED_IN_MEMORY_TTL_SECONDS: Final = 60.0
-ROUTER_COOLDOWNS_TARGET: Final = "router_cooldowns"
+__all__: Final = ("ROUTER_COOLDOWNS_TARGET", "CooldownCache", "CooldownCacheValue")
 
 
 class CooldownCache:
     def __init__(
-        self,
-        cache: DualCache,
-        default_cooldown_time: float,
-        redis_read_interval_seconds: float = DEFAULT_COOLDOWN_REDIS_READ_INTERVAL_SECONDS,
-    ):
-        self.cache = cache
-        self.default_cooldown_time = default_cooldown_time
-        self.in_memory_cache = InMemoryCache()
-        self._cooldown_store = DualCache(
-            in_memory_cache=self.in_memory_cache,
-            default_redis_batch_cache_expiry=redis_read_interval_seconds,
+        self, store: RouterCooldowns, default_cooldown_time: float, *, clock: Callable[[], float] | None = None
+    ) -> None:
+        self.cooldown_store: Final = store
+        self._clock: Final = clock if clock is not None else lambda: time.time()
+        self.default_cooldown_time: Final = default_cooldown_time
+        self.exception_masker: Final = SensitiveDataMasker(
+            visible_prefix=50, visible_suffix=0, mask_char="*", mask_short_values=False
         )
-        # Initialize the masker with custom settings for exception strings
-        self.exception_masker = SensitiveDataMasker(
-            visible_prefix=50,  # Show first 50 characters
-            visible_suffix=0,  # Show last 0 characters
-            mask_char="*",  # Use * for masking
-            mask_short_values=False,  # Truncate long messages only; keep short ones readable
-        )
-
-    @property
-    def cooldown_store(self) -> DualCache:
-        """
-        The cache cooldown entries live in, with the router's Redis attached on first use.
-
-        It is kept separate from the router-wide cache so that a key missing from memory is
-        re-read from Redis every `redis_read_interval_seconds` rather than on the router
-        cache's much longer batch interval, which is what lets a sibling replica see a
-        cooldown another replica wrote, and so that unrelated router keys cannot evict a
-        cooldown from the in-memory tier before it expires. Redis is attached lazily because
-        the router builds its cooldown cache before it wires up the shared Redis client.
-        """
-        self._cooldown_store.attach_redis_cache(self.cache.redis_cache)
-        return self._cooldown_store
-
-    def _common_add_cooldown_logic(
-        self, model_id: str, original_exception, exception_status, cooldown_time: float
-    ) -> tuple[str, CooldownCacheValue]:
-        try:
-            current_time: Final = time.time()
-            cooldown_key: Final = CooldownCache.get_cooldown_cache_key(model_id)
-
-            # Store the cooldown information for the deployment separately
-            cooldown_data: Final = CooldownCacheValue(
-                exception_received=self.exception_masker.mask_value(str(original_exception)),
-                status_code=str(exception_status),
-                timestamp=current_time,
-                cooldown_time=cooldown_time,
-            )
-
-            return cooldown_key, cooldown_data
-        except Exception as e:
-            verbose_logger.error("CooldownCache::_common_add_cooldown_logic - Exception occurred - %s", e)
-            raise e
 
     def add_deployment_to_cooldown(
-        self,
-        model_id: str,
-        original_exception: Exception,
-        exception_status: int,
-        cooldown_time: float | None,
-    ):
-        try:
-            #########################################################
-            # get cooldown time
-            # 1. If dynamic cooldown time is set for the model/deployment, use that
-            # 2. If no dynamic cooldown time is set, use the default cooldown time set on CooldownCache
-            _cooldown_time = cooldown_time
-            if _cooldown_time is None:
-                _cooldown_time = self.default_cooldown_time
-            #########################################################
-
-            cooldown_key, cooldown_data = self._common_add_cooldown_logic(
-                model_id=model_id,
-                original_exception=original_exception,
-                exception_status=exception_status,
-                cooldown_time=_cooldown_time,
-            )
-
-            # Set the cache with a TTL equal to the cooldown time
-            with service_target(ROUTER_COOLDOWNS_TARGET):
-                self.cooldown_store.set_cache(
-                    value=cooldown_data,
-                    key=cooldown_key,
-                    ttl=_cooldown_time,
-                )
-        except Exception as e:
-            verbose_logger.error("CooldownCache::add_deployment_to_cooldown - Exception occurred - %s", e)
-            raise e
-
-    @staticmethod
-    @functools.lru_cache(maxsize=1024)
-    def get_cooldown_cache_key(model_id: str) -> str:
-        return "deployment:" + model_id + ":cooldown"
-
-    def _corrected_active_cooldown(
-        self,
-        key: str,
-        result: Mapping[str, Any],
-        current_time: float,
-    ) -> CooldownCacheValue | None:
-        """
-        Return a CooldownCacheValue if the cooldown is still active, or None if it has expired.
-
-        Also corrects the in-memory TTL when DualCache promotes a Redis entry using the
-        default 600s TTL instead of the true remaining cooldown time.
-        """
-        cooldown_cache_value: Final = CooldownCacheValue(**result)  # pyright: ignore[reportUnknownArgumentType] - result comes from an untyped cache read, not from our own code
-        remaining: Final = (cooldown_cache_value["timestamp"] + cooldown_cache_value["cooldown_time"]) - current_time
-        if remaining <= 0:
-            self.in_memory_cache.delete_cache(key)
-            return None
-        current_expiry: Final = self.in_memory_cache.ttl_dict.get(key)
-        if current_expiry is not None and current_expiry > current_time + remaining + 5:
-            corrected_ttl: Final = min(remaining, _MAX_CORRECTED_IN_MEMORY_TTL_SECONDS)
-            self.in_memory_cache.delete_cache(key)
-            self.in_memory_cache.set_cache(key, result, ttl=corrected_ttl)
-        return cooldown_cache_value
+        self, model_id: str, original_exception: Exception, exception_status: int, cooldown_time: float | None
+    ) -> None:
+        ttl: Final = self.default_cooldown_time if cooldown_time is None else cooldown_time
+        value: Final = CooldownCacheValue(
+            exception_received=self.exception_masker.mask_value(str(original_exception)),
+            status_code=str(exception_status),
+            timestamp=self._clock(),
+            cooldown_time=ttl,
+        )
+        self.cooldown_store.put(model_id, value, ttl)
 
     async def async_get_active_cooldowns(
-        self, model_ids: list[str], parent_otel_span: Span | None
+        self, model_ids: Sequence[str], parent_otel_span: Span | None
     ) -> list[tuple[str, CooldownCacheValue]]:
-        # Generate the keys for the deployments
-        keys: Final = [CooldownCache.get_cooldown_cache_key(model_id) for model_id in model_ids]
+        return list(await self.cooldown_store.active(model_ids, parent_otel_span))
 
-        with service_target(ROUTER_COOLDOWNS_TARGET):
-            results: Final = await self.cooldown_store.async_batch_get_cache(
-                keys=keys, parent_otel_span=parent_otel_span
-            )
-        return self.active_cooldowns_from_results(model_ids, results)
-
-    def active_cooldowns_from_results(
-        self, model_ids: list[str], results: Sequence[object] | None
-    ) -> list[tuple[str, CooldownCacheValue]]:
-        """The cooldowns still active in a `cooldown_store` batch read of `get_cooldown_cache_key(model_id)` per id."""
-        active_cooldowns: Final[list[tuple[str, CooldownCacheValue]]] = []
-
-        if results is None or all(v is None for v in results):
-            return active_cooldowns
-
-        current_time: Final = time.time()
-        for model_id, result in zip(model_ids, results):
-            if result and isinstance(result, dict):
-                key = CooldownCache.get_cooldown_cache_key(model_id)
-                cooldown_cache_value = self._corrected_active_cooldown(key, result, current_time)
-                if cooldown_cache_value is not None:
-                    active_cooldowns.append((model_id, cooldown_cache_value))
-
-        return active_cooldowns
+    def get_min_cooldown(self, model_ids: Sequence[str], parent_otel_span: Span | None) -> float:
+        return self.cooldown_store.minimum(model_ids, self.default_cooldown_time, parent_otel_span)
 
     def get_active_cooldowns(
-        self, model_ids: list[str], parent_otel_span: Span | None
+        self, model_ids: Sequence[str], parent_otel_span: Span | None
     ) -> list[tuple[str, CooldownCacheValue]]:
-        # Generate the keys for the deployments
-        keys: Final = [CooldownCache.get_cooldown_cache_key(model_id) for model_id in model_ids]
-        # Retrieve the values for the keys using mget
-        with service_target(ROUTER_COOLDOWNS_TARGET):
-            results: Final = self.cooldown_store.batch_get_cache(keys=keys, parent_otel_span=parent_otel_span) or []
-
-        active_cooldowns: Final = []
-        current_time: Final = time.time()
-        for model_id, result in zip(model_ids, results):
-            if result and isinstance(result, dict):
-                key = CooldownCache.get_cooldown_cache_key(model_id)
-                cooldown_cache_value = self._corrected_active_cooldown(key, result, current_time)
-                if cooldown_cache_value is not None:
-                    active_cooldowns.append((model_id, cooldown_cache_value))
-
-        return active_cooldowns
-
-    def get_min_cooldown(self, model_ids: list[str], parent_otel_span: Span | None) -> float:
-        """Return min cooldown time required for a group of model id's."""
-
-        # Generate the keys for the deployments
-        keys: Final = [f"deployment:{model_id}:cooldown" for model_id in model_ids]
-
-        # Retrieve the values for the keys using mget
-        with service_target(ROUTER_COOLDOWNS_TARGET):
-            results: Final = self.cooldown_store.batch_get_cache(keys=keys, parent_otel_span=parent_otel_span) or []
-
-        min_cooldown_time: float | None = None
-        # Process the results
-        for model_id, result in zip(model_ids, results):
-            if result and isinstance(result, dict):
-                cooldown_cache_value = CooldownCacheValue(**result)
-                if min_cooldown_time is None or cooldown_cache_value["cooldown_time"] < min_cooldown_time:
-                    min_cooldown_time = cooldown_cache_value["cooldown_time"]
-
-        return min_cooldown_time or self.default_cooldown_time
-
-
-# Usage example:
-# cooldown_cache = CooldownCache(cache=your_cache_instance, cooldown_time=your_cooldown_time)
-# cooldown_cache.add_deployment_to_cooldown(deployment, original_exception, exception_status)
-# active_cooldowns = cooldown_cache.get_active_cooldowns()
+        return list(self.cooldown_store.active_sync(model_ids, parent_otel_span))

litellm/router_utils/cooldown_handlers.py

@@ -16,9 +16,7 @@ from typing import TYPE_CHECKING, Any, Final
 from pydantic import TypeAdapter, ValidationError
 
 import litellm
-from litellm._internal_context import service_target
 from litellm._logging import verbose_router_logger
-from litellm.caching.dual_cache import DualCache
 from litellm.constants import (
     DEFAULT_COOLDOWN_TIME_SECONDS,
     DEFAULT_FAILURE_THRESHOLD_MINIMUM_REQUESTS,
@@ -30,7 +28,7 @@ from litellm.exceptions import MidStreamFallbackError
 from litellm.litellm_core_utils.credential_accessor import CredentialAccessor
 from litellm.litellm_core_utils.litellm_logging import mask_api_base_credentials
 from litellm.router_deprecated import renamed_router_param
-from litellm.router_utils.cooldown_cache import ROUTER_COOLDOWNS_TARGET, CooldownCacheValue
+from litellm.router_utils.cooldown_cache import CooldownCacheValue
 from litellm.router_utils.cooldown_callbacks import router_cooldown_event_callback
 from litellm.types.router import Deployment
 from litellm.types.utils import (
@@ -748,7 +746,7 @@ def should_cooldown_based_on_allowed_fails_policy(
     When *allowed_fails_override* / *cooldown_time_override* are supplied they
     take precedence over the router-level values (used by deployment-level overrides).
 
-    The counter lives in the router's shared ``DualCache`` (Redis when configured), so
+    The counter lives in the cooldown store (Redis when configured), so
     every worker process increments the same key and the threshold applies fleet-wide.
 
     When *cache_key_suffix* is supplied the fail counter is keyed as
@@ -771,26 +769,12 @@ def should_cooldown_based_on_allowed_fails_policy(
         else (ctx.settings().cooldown_time or DEFAULT_COOLDOWN_TIME_SECONDS)
     )
 
-    base_key: Final = f"deployment:{deployment}:allowed_fails"
-    cache_key: Final = f"{base_key}:{cache_key_suffix}" if cache_key_suffix else base_key
-    updated_fails: Final = _increment_allowed_fails(cache=ctx.health().store, cache_key=cache_key, ttl=cooldown_time)
+    updated_fails: Final = ctx.health().cooldowns.cooldown_store.increment_allowed_fails(
+        deployment, cache_key_suffix, cooldown_time
+    )
     return updated_fails > allowed_fails
 
 
-def _increment_allowed_fails(cache: DualCache, cache_key: str, ttl: float) -> int:
-    """
-    Return the fleet-wide fail count. ``DualCache.increment_cache`` bumps the in-memory tier
-    before Redis and re-raises a Redis error, so a Redis outage degrades to this worker's own count.
-    """
-    with service_target(ROUTER_COOLDOWNS_TARGET):
-        try:
-            return cache.increment_cache(key=cache_key, value=1, ttl=ttl)
-        except Exception as e:  # noqa: BLE001  # a Redis outage must not stop failing deployments from cooling down
-            verbose_router_logger.warning("allowed_fails counter fell back to this worker's in-memory count: %s", e)
-            local_fails: Final = cache.get_cache(key=cache_key, local_only=True)
-            return local_fails if isinstance(local_fails, int) else 0
-
-
 def _is_allowed_fails_set_on_router(
     ctx: "RoutingContext",
 ) -> bool:

litellm/router_utils/routing_prefetch.py

@@ -0,0 +1,165 @@
+from __future__ import annotations
+
+import asyncio
+from collections.abc import Awaitable, Mapping, Sequence
+from dataclasses import dataclass
+from typing import TYPE_CHECKING, Final
+
+if TYPE_CHECKING:
+    from opentelemetry.trace import Span
+
+from litellm._internal_context import service_target
+from litellm._logging import verbose_router_logger
+from litellm.caching.dual_cache import DualCache
+from litellm.caching.redis_batch import BatchResult, active_request_redis_batches
+from litellm.redis.stores.router_cooldowns import ROUTER_COOLDOWNS_TARGET, ActiveCooldowns, RouterCooldowns
+
+_PREFETCH_SLOT: Final = "routing_read"
+_COOLDOWNS_SLOT: Final = "routing_cooldowns"
+ROUTER_USAGE_TARGET: Final = "router_usage"
+
+
+@dataclass(frozen=True, slots=True)
+class TierRead:
+    cache: DualCache
+    keys: tuple[str, ...]
+
+
+def selector_read(cache: DualCache, keys: Sequence[str]) -> TierRead:
+    return TierRead(cache, tuple(keys))
+
+
+@dataclass(frozen=True, slots=True)
+class ArmedRead:
+    read: TierRead
+    fetched: frozenset[str]
+    result: BatchResult[Mapping[str, object]]
+    previous: Mapping[str, float | None]
+
+    def release(self) -> None:
+        self.read.cache._rollback_redis_batch_key_reservations(  # pyright: ignore[reportPrivateUsage]  # the selector owns this tier
+            dict(self.previous)
+        )
+
+    async def settle(self, future: asyncio.Future[Mapping[str, object]]) -> None:
+        if future.cancelled() or future.exception() is not None:
+            self.release()
+            return
+        try:
+            pending: Final = await self.read.cache._prepare_batch_get(  # pyright: ignore[reportPrivateUsage]  # the selector owns this tier
+                list(self.read.keys), local_only=True
+            )
+            values: Final = future.result()
+            missed: Final = {
+                key: values[key]
+                for key, local in zip(self.read.keys, pending.result)
+                if local is None and values.get(key) is not None
+            }
+            await self.read.cache._apply_batch_get(pending, missed)  # pyright: ignore[reportPrivateUsage]  # the selector owns this tier
+        except Exception:
+            self.release()
+            raise
+
+
+def arm(read: TierRead) -> None:
+    request: Final = active_request_redis_batches()
+    redis: Final = read.cache.redis_cache
+    if request is None or redis is None or _PREFETCH_SLOT in request.prefetched:
+        return
+    due, previous = read.cache.reserve_redis_batch_reads(read.keys)
+    if not due:
+        return
+    with service_target(ROUTER_USAGE_TARGET):
+        result: Final = request.batch(redis).mget(tuple(due))
+    armed_read: Final = ArmedRead(read=read, fetched=frozenset(due), result=result, previous=previous)
+    result.on_settled(armed_read.settle)
+    request.prefetched[_PREFETCH_SLOT] = armed_read
+
+
+@dataclass(frozen=True, slots=True)
+class ArmedCooldowns:
+    model_ids: frozenset[str]
+    result: Awaitable[ActiveCooldowns]
+
+
+def arm_cooldowns(store: RouterCooldowns, model_ids: Sequence[str]) -> None:
+    request: Final = active_request_redis_batches()
+    if request is None or _COOLDOWNS_SLOT in request.prefetched:
+        return
+    result: Final = store.declare_active(request, model_ids)
+    if result is not None:
+        request.prefetched[_COOLDOWNS_SLOT] = ArmedCooldowns(frozenset(model_ids), result)
+
+
+def armed() -> bool:
+    request: Final = active_request_redis_batches()
+    return request is not None and (_PREFETCH_SLOT in request.prefetched or _COOLDOWNS_SLOT in request.prefetched)
+
+
+async def _armed_cooldowns(model_ids: Sequence[str]) -> ActiveCooldowns | None:
+    request: Final = active_request_redis_batches()
+    taken: Final = None if request is None else request.prefetched.pop(_COOLDOWNS_SLOT, None)
+    if not isinstance(taken, ArmedCooldowns):
+        return None
+    try:
+        active: Final = await taken.result
+    except Exception as e:  # noqa: BLE001  # the read falls back to the store's own Redis read
+        verbose_router_logger.debug("cooldown prefetch failed, reading again: %s", e)
+        return None
+    if not taken.model_ids.issuperset(model_ids):
+        return None
+    wanted: Final = frozenset(model_ids)
+    return tuple((model_id, cooldown) for model_id, cooldown in active if model_id in wanted)
+
+
+async def read_cooldowns(
+    store: RouterCooldowns, model_ids: Sequence[str], parent_otel_span: Span | None
+) -> ActiveCooldowns:
+    """The armed cooldown read when it covers ``model_ids``, taken once; otherwise the store reads on its own."""
+    with service_target(ROUTER_COOLDOWNS_TARGET):
+        prefetched: Final = await _armed_cooldowns(model_ids)
+    if prefetched is not None:
+        return prefetched
+    return await store.active(model_ids, parent_otel_span)
+
+
+def _take(read: TierRead) -> ArmedRead | None:
+    request: Final = active_request_redis_batches()
+    if request is None:
+        return None
+    taken: Final = request.prefetched.pop(_PREFETCH_SLOT, None)
+    if isinstance(taken, ArmedRead) and set(taken.read.keys).issuperset(read.keys):
+        return taken
+    if isinstance(taken, ArmedRead):
+        taken.release()
+    return None
+
+
+async def _read_prefetched(read: TierRead) -> Sequence[object | None] | None:
+    prefetch: Final = _take(read)
+    if prefetch is None:
+        return None
+    try:
+        values: Final = await prefetch.result
+    except Exception as e:  # noqa: BLE001  # the read falls back to the tier's own Redis read
+        verbose_router_logger.debug("routing prefetch failed, reading again: %s", e)
+        return None
+    pending: Final = await read.cache._prepare_batch_get(  # pyright: ignore[reportPrivateUsage]  # the selector owns this tier
+        list(read.keys), local_only=True
+    )
+    if any(key not in prefetch.fetched for key, value in zip(read.keys, pending.result) if value is None):
+        return None
+    return await read.cache._apply_batch_get(  # pyright: ignore[reportPrivateUsage]  # the selector owns this tier
+        pending, {key: values.get(key) for key, value in zip(read.keys, pending.result) if value is None}
+    )
+
+
+async def read(read: TierRead, parent_otel_span: Span | None) -> Sequence[object | None] | None:
+    with service_target(ROUTER_USAGE_TARGET):
+        prefetched: Final = await _read_prefetched(read)
+        if prefetched is not None:
+            return prefetched
+        results: Final = await DualCache.async_batch_get_cache_shared(
+            ((read.cache, list(read.keys)),), parent_otel_span=parent_otel_span
+        )
+        return results[0]

litellm/router_utils/routing_read_batch.py

@@ -1,157 +1,48 @@
-"""
-One Redis round trip for the reads a request needs before a deployment can be picked.
-
-The cooldown filter (`CooldownCache`, its own `DualCache`) and usage-based selection
-(`LowestTPMLoggingHandler_v2`, the router cache) each issue their own MGET because they live in
-different objects. `RoutingReadBatch` fetches both key sets in one
-`DualCache.async_batch_get_cache_shared` while the healthy deployments are being resolved and hands
-the usage slice to the strategy, so selection does not read again.
-"""
-
 import asyncio
-import itertools
-from collections.abc import Iterator, Mapping, Sequence
+from collections.abc import Iterator, Sequence
 from contextlib import contextmanager
 from contextvars import ContextVar
-from dataclasses import dataclass
-from types import MappingProxyType
 from typing import TYPE_CHECKING, Final
 
-from litellm._internal_context import service_target
 from litellm._logging import verbose_router_logger
-from litellm.caching.dual_cache import DualCache
-from litellm.caching.redis_batch import BatchResult, active_request_redis_batches
 from litellm.router_deprecated import renamed_router_param
 from litellm.router_strategy.lowest_tpm_rpm_v2 import LowestTPMLoggingHandler_v2, PrefetchedUsage
-from litellm.router_utils.cooldown_cache import ROUTER_COOLDOWNS_TARGET, CooldownCache
+from litellm.router_utils import routing_prefetch
+from litellm.router_utils.routing_prefetch import ROUTER_USAGE_TARGET, TierRead, selector_read
 
 if TYPE_CHECKING:
     from opentelemetry.trace import Span
 
     from litellm.router_api import RoutingContext
 
-
-ROUTER_COOLDOWNS_USAGE_TARGET: Final = "router_cooldowns_usage"
-ROUTER_USAGE_TARGET: Final = "router_usage"
-_PREFETCH_SLOT: Final = "routing_read"
+__all__ = ("ROUTER_USAGE_TARGET", "RoutingPrefetch", "RoutingReadBatch")
 
 
-def _routing_read_target(cooldown_keys: Sequence[str], usage_keys: Sequence[str]) -> str:
-    if not usage_keys:
-        return ROUTER_COOLDOWNS_TARGET
-    if not cooldown_keys:
-        return ROUTER_USAGE_TARGET
-    return ROUTER_COOLDOWNS_USAGE_TARGET
+def _selector_keys(selector: LowestTPMLoggingHandler_v2, deployments: list) -> list[str]:
+    tpm_keys, rpm_keys = selector.usage_counter_keys(deployments)
+    return tpm_keys + rpm_keys
 
 
-async def _backfill_prefetched_cache(
-    cache: DualCache,
-    due_keys: tuple[str, ...],
-    values: Mapping[str, object],
-) -> None:
-    cache_keys: Final = list(due_keys)
-    prepare_batch_get: Final = cache._prepare_batch_get  # pyright: ignore[reportPrivateUsage]  # memory backfill
-    pending: Final = await prepare_batch_get(cache_keys, local_only=True)
-    redis_values: Final = {
-        key: values[key]
-        for key, local in zip(due_keys, pending.result)
-        if local is None and values.get(key) is not None
-    }
-    apply_batch_get: Final = cache._apply_batch_get  # pyright: ignore[reportPrivateUsage]  # cache backfill
-    await apply_batch_get(pending, redis_values)
+def _selector_read(selector: LowestTPMLoggingHandler_v2 | None, deployments: list) -> TierRead | None:
+    return None if selector is None else selector_read(selector.router_cache, _selector_keys(selector, deployments))
+
+
+async def _nothing() -> Sequence[object | None] | None:
+    return None
 
 
-@dataclass(frozen=True, slots=True)
 class RoutingPrefetch:
-    """The cooldown and usage keys of a model group, declared on the request's Redis batch before admission
-    flushes it, so the routing read rides the same round trip as the rate limiter's Lua calls."""
-
-    keys: frozenset[str]
-    fetched: frozenset[str]
-    result: BatchResult[Mapping[str, object]]
-    reservations: tuple[tuple[DualCache, tuple[str, ...], dict[str, float | None]], ...]
-
-    def release(self) -> None:
-        for cache, _, previous_access_times in self.reservations:
-            cache._rollback_redis_batch_key_reservations(  # pyright: ignore[reportPrivateUsage]  # rollback
-                previous_access_times
-            )
-
-    async def _settle(self, future: asyncio.Future[Mapping[str, object]]) -> None:
-        if future.cancelled():
-            self.release()
-            return
-        if future.exception() is not None:
-            self.release()
-            return
-
-        values: Final = future.result()
-        try:
-            for cache, due_keys, _ in self.reservations:
-                await _backfill_prefetched_cache(cache, due_keys, values)
-        except Exception:
-            self.release()
-            raise
-
     @staticmethod
     @renamed_router_param("litellm_router_instance")
-    def arm(
-        ctx: "RoutingContext",
-        usage_selector: LowestTPMLoggingHandler_v2 | None,
-        deployments: list,
-    ) -> None:
-        request: Final = active_request_redis_batches()
-        redis_cache: Final = ctx.health().store.redis_cache
-        if request is None or redis_cache is None or _PREFETCH_SLOT in request.prefetched:
-            return
-        cooldown_keys: Final = tuple(
-            CooldownCache.get_cooldown_cache_key(model_id) for model_id in ctx.registry().names(kind="ids")
-        )
-        usage_keys: Final = (
-            () if usage_selector is None else tuple(itertools.chain(*usage_selector.usage_counter_keys(deployments)))
-        )
-        keys: Final = (*cooldown_keys, *usage_keys)
-        cooldown_store: Final = ctx.health().cooldowns.cooldown_store
-        cooldown_due, cooldown_previous = cooldown_store.reserve_redis_batch_reads(cooldown_keys)
-        usage_cache: Final = None if usage_selector is None else usage_selector.router_cache
-        usage_reservation: Final = None if usage_cache is None else usage_cache.reserve_redis_batch_reads(usage_keys)
-        usage_due: Final = () if usage_reservation is None else tuple(usage_reservation[0])
-        due: Final = (*cooldown_due, *usage_due)
-        reservations: Final = (
-            (cooldown_store, tuple(cooldown_due), cooldown_previous),
-            *(
-                ()
-                if usage_cache is None or usage_reservation is None
-                else ((usage_cache, usage_due, usage_reservation[1]),)
-            ),
-        )
-        if not due:
-            return
-        with service_target(_routing_read_target(cooldown_due, usage_due)):
-            result: Final = request.batch(redis_cache).mget(due)
-        prefetch: Final = RoutingPrefetch(
-            keys=frozenset(keys), fetched=frozenset(due), result=result, reservations=reservations
-        )
-        result.on_settled(prefetch._settle)
-        request.prefetched[_PREFETCH_SLOT] = prefetch
+    def arm(ctx: "RoutingContext", usage_selector: LowestTPMLoggingHandler_v2 | None, deployments: list) -> None:
+        routing_prefetch.arm_cooldowns(ctx.health().cooldowns.cooldown_store, ctx.registry().names(kind="ids"))
+        read: Final = _selector_read(usage_selector, deployments)
+        if read is not None:
+            routing_prefetch.arm(read)
 
     @staticmethod
     def armed() -> bool:
-        request: Final = active_request_redis_batches()
-        return request is not None and _PREFETCH_SLOT in request.prefetched
-
-    @staticmethod
-    def take(needed: Sequence[str]) -> "RoutingPrefetch | None":
-        """The armed prefetch when it covers every key this read needs; taken once, so a retry reads fresh."""
-        request: Final = active_request_redis_batches()
-        if request is None:
-            return None
-        armed: Final = request.prefetched.pop(_PREFETCH_SLOT, None)
-        if isinstance(armed, RoutingPrefetch) and armed.keys.issuperset(needed):
-            return armed
-        if isinstance(armed, RoutingPrefetch):
-            armed.release()
-        return None
+        return routing_prefetch.armed()
 
 
 _active_routing_read_batch: Final[ContextVar["RoutingReadBatch | None"]] = ContextVar(
@@ -179,71 +70,25 @@ class RoutingReadBatch:
 
     @staticmethod
     def for_strategy(strategy: str | None, selector: object) -> "RoutingReadBatch | None":
-        """Usage-based routing reads its counters with the cooldown state; every other strategy reads only the
-        cooldown state, and only through this batch when the request armed a prefetch for it. Otherwise the
-        router's plain cooldown read stays in charge."""
         if strategy == "usage-based-routing-v2" and isinstance(selector, LowestTPMLoggingHandler_v2):
             return RoutingReadBatch(usage_selector=selector)
         return RoutingReadBatch(usage_selector=None) if RoutingPrefetch.armed() else None
 
     @renamed_router_param("litellm_router_instance")
     async def async_get_cooldown_deployments(
-        self,
-        ctx: "RoutingContext",
-        healthy_deployments: list,
-        parent_otel_span: "Span | None",
+        self, ctx: "RoutingContext", healthy_deployments: list, parent_otel_span: "Span | None"
     ) -> list[str]:
-        """
-        `_async_get_cooldown_deployments`, with the strategy's tpm/rpm counters for
-        `healthy_deployments` fetched in the same MGET and kept as `prefetched_usage`.
-        """
-        model_ids: Final = ctx.registry().names(kind="ids")
-        cooldown_keys: Final = [CooldownCache.get_cooldown_cache_key(model_id) for model_id in model_ids]
-        selector: Final = self.usage_selector
-        usage_keys: Final = (
-            () if selector is None else tuple(itertools.chain(*selector.usage_counter_keys(healthy_deployments)))
+        usage_read: Final = _selector_read(self.usage_selector, healthy_deployments)
+        cooldowns, selector_values = await asyncio.gather(
+            routing_prefetch.read_cooldowns(
+                ctx.health().cooldowns.cooldown_store, ctx.registry().names(kind="ids"), parent_otel_span
+            ),
+            _nothing() if usage_read is None else routing_prefetch.read(usage_read, parent_otel_span),
         )
-        reads: Final = (
-            (ctx.health().cooldowns.cooldown_store, cooldown_keys),
-            *(() if selector is None else ((selector.router_cache, list(usage_keys)),)),
-        )
-        with service_target(_routing_read_target(cooldown_keys, usage_keys)):
-            results: Final = await self._read_prefetched(reads) or await DualCache.async_batch_get_cache_shared(
-                reads, parent_otel_span=parent_otel_span
-            )
-        cooldown_results: Final = results[0]
-        if selector is not None:
-            usage_values: Final = results[1]
+        if usage_read is not None:
             self.prefetched_usage = PrefetchedUsage(
-                keys=frozenset(usage_keys),
-                values=None if usage_values is None else MappingProxyType(dict(zip(usage_keys, usage_values))),
+                keys=frozenset(usage_read.keys),
+                values=None if selector_values is None else dict(zip(usage_read.keys, selector_values)),
             )
-
-        cooldown_models: Final = ctx.health().cooldowns.active_cooldowns_from_results(model_ids, cooldown_results)
-        verbose_router_logger.debug("retrieve cooldown models: %s", cooldown_models)
-        return [model_id for model_id, _ in cooldown_models]
-
-    @staticmethod
-    async def _read_prefetched(
-        reads: Sequence[tuple[DualCache, list[str]]],
-    ) -> list[list[object | None] | None] | None:
-        """Serve the reads from the request's armed `RoutingPrefetch`, backfilling each cache's memory tier as
-        its own batch read would. None when nothing usable was armed or the prefetch failed."""
-        prefetch: Final = RoutingPrefetch.take(tuple(itertools.chain.from_iterable(keys for _, keys in reads)))
-        if prefetch is None:
-            return None
-        try:
-            values: Final = await prefetch.result
-        except Exception as e:  # noqa: BLE001  # the shared read below applies the caches' own Redis fallback
-            verbose_router_logger.debug("routing prefetch failed, reading again: %s", e)
-            return None
-        results: Final[list[list[object | None] | None]] = []  # mutable-ok: filled per read below
-        for cache, keys in reads:
-            pending = await cache._prepare_batch_get(keys, local_only=True)  # pyright: ignore[reportPrivateUsage]  # same two-step read as async_batch_get_cache_shared
-            if any(
-                key not in prefetch.fetched for key, local_value in zip(keys, pending.result) if local_value is None
-            ):
-                return None
-            missed = {key: values.get(key) for key, local in zip(keys, pending.result) if local is None}
-            results.append(await cache._apply_batch_get(pending, missed))  # pyright: ignore[reportPrivateUsage]  # same two-step read as async_batch_get_cache_shared
-        return results
+        verbose_router_logger.debug("retrieve cooldown models: %s", cooldowns)
+        return [model_id for model_id, _ in cooldowns]

litellm/rust_bridge/_native.pyi

@@ -1,6 +1,6 @@
 from asyncio import Future
 from collections.abc import Mapping, Sequence
-from typing import Never, final
+from typing import Literal, Never, TypedDict, final
 
 import httpx
 from pydantic import JsonValue
@@ -27,6 +27,12 @@ class NativeClickHouseSpendStorage:
     def ensure_schema(self) -> Future[None]: ...
     def insert_rows(self, rows: Sequence[Mapping[str, object]]) -> Future[None]: ...
 
+class _NativeCooldown(TypedDict):
+    exception_received: str
+    status_code: str
+    timestamp: float
+    cooldown_time: float
+
 @final
 class NativeRedisClient:
     def __new__(cls, _uninstantiable: Never, /) -> Never: ...
@@ -39,6 +45,45 @@ class NativeRequestRedis:
     def flush_pre(self) -> Future[None]: ...
     def flush_post(self) -> Future[None]: ...
 
+@final
+class NativeDeclaredCooldowns:
+    def resolve(self) -> Future[list[tuple[str, _NativeCooldown]]]: ...
+
+@final
+class NativeRouterCooldowns:
+    def __new__(cls, client: NativeRedisClient | None, /) -> NativeRouterCooldowns: ...
+    def put(self, model_id: str, cooldown: Mapping[str, object], ttl_seconds: float) -> None: ...
+    def increment_allowed_fails(self, model_id: str, suffix: str | None, ttl_seconds: float) -> int: ...
+    def active(self, model_ids: Sequence[str]) -> list[tuple[str, _NativeCooldown]]: ...
+    def aactive(self, model_ids: Sequence[str]) -> Future[list[tuple[str, _NativeCooldown]]]: ...
+    def declare_active(self, request: NativeRequestRedis, model_ids: Sequence[str]) -> NativeDeclaredCooldowns: ...
+    def minimum(self, model_ids: Sequence[str]) -> float | None: ...
+    def evict_local(self, model_id: str) -> None: ...
+    def flush_local_counters(self) -> None: ...
+    def snapshot(self) -> dict[str, _NativeCooldown]: ...
+
+@final
+class NativeRouterUsage:
+    def __new__(cls, client: NativeRedisClient | None, /) -> NativeRouterUsage: ...
+    def increment(
+        self, counter: tuple[str, str | None, str, Literal["tpm", "rpm"]], value: float, ttl_seconds: int
+    ) -> Future[float]: ...
+    def increment_deployment(
+        self,
+        deployment_id: str,
+        model: str | None,
+        minute: str,
+        tokens: float,
+        requests: int,
+        *,
+        request: NativeRequestRedis | None = None,
+    ) -> Future[None]: ...
+    def get_many(
+        self, counters: Sequence[tuple[str, str | None, str, Literal["tpm", "rpm"]]]
+    ) -> Future[list[float | None]]: ...
+    def flush_local_counters(self) -> None: ...
+    def snapshot(self) -> dict[str, float]: ...
+
 @final
 class NativeDatabase:
     @staticmethod
@@ -228,9 +273,12 @@ __all__ = [
     "NativeClickHouseSpendConfig",
     "NativeClickHouseSpendStorage",
     "NativeDatabase",
+    "NativeDeclaredCooldowns",
     "NativeDiagnosticProcessor",
     "NativeRedisClient",
     "NativeRequestRedis",
+    "NativeRouterCooldowns",
+    "NativeRouterUsage",
     "ProcessReservedForForking",
     "ResponsesWebSocketConnection",
     "RustBridgeDeclined",

litellm/rust_bridge/host/settings.py

@@ -31,6 +31,15 @@ class ProviderDefaults:
     enable_azure_ad_token_refresh: object
 
 
+@dataclass(frozen=True, slots=True)
+class RouterTierSettings:
+    """The memory-over-Redis tier values `main`'s router reads from the environment and `litellm` globals."""
+
+    cooldown_redis_read_interval: float
+    usage_redis_read_interval: float
+    max_redis_batch_cache_size: int
+
+
 @dataclass(frozen=True, slots=True)
 class SecretManager:
     readable: bool
@@ -108,6 +117,17 @@ def secret_manager_binding() -> SecretManagerBinding:
     )
 
 
+def router_tiers() -> RouterTierSettings:
+    import litellm
+    from litellm.constants import DEFAULT_COOLDOWN_REDIS_READ_INTERVAL_SECONDS, DEFAULT_MAX_REDIS_BATCH_CACHE_SIZE
+
+    return RouterTierSettings(
+        cooldown_redis_read_interval=DEFAULT_COOLDOWN_REDIS_READ_INTERVAL_SECONDS,
+        usage_redis_read_interval=litellm.default_redis_batch_cache_expiry or 10,
+        max_redis_batch_cache_size=DEFAULT_MAX_REDIS_BATCH_CACHE_SIZE,
+    )
+
+
 def provider_defaults() -> ProviderDefaults:
     import litellm
 

litellm/types/router.py

@@ -46,6 +46,8 @@ from litellm._uuid import uuid
 from litellm.litellm_core_utils.completion_timeout import CompletionTimeout
 from litellm.litellm_core_utils.core_helpers import normalize_drop_params
 from litellm.litellm_core_utils.provider_affinity import validate_provider_affinity_header_name
+from litellm.redis.stores._keys import ROUTER_RPM_KEY as _ROUTER_RPM_KEY
+from litellm.redis.stores._keys import ROUTER_TPM_KEY as _ROUTER_TPM_KEY
 from litellm.types.llms.base import LiteLLMBaseModel
 from litellm.types.router_weights import RouterWeights
 
@@ -1290,8 +1292,8 @@ class RoutingStrategy(enum.Enum):
 
 
 class RouterCacheEnum(enum.Enum):
-    TPM = "global_router:{id}:{model}:tpm:{current_minute}"
-    RPM = "global_router:{id}:{model}:rpm:{current_minute}"
+    TPM = _ROUTER_TPM_KEY
+    RPM = _ROUTER_RPM_KEY
     ITPM = "global_router:{id}:{model}:itpm:{current_minute}"
     OTPM = "global_router:{id}:{model}:otpm:{current_minute}"
 

tests/unit/caching/test_request_redis_batch_post_call.py

@@ -38,7 +38,7 @@ from litellm.router_strategy.lowest_tpm_rpm_v2 import LowestTPMLoggingHandler_v2
 from litellm.types.caching import RedisPipelineIncrementOperation
 from litellm.types.utils import ModelResponse
 
-from .test_redis_batch import FakeClient, FakeRedisCache
+from .test_redis_batch import FakeClient, FakeNatives, FakeRedisCache
 
 
 async def _script_outside_the_pipeline(keys: Sequence[str], args: Sequence[object]) -> object:
@@ -514,3 +514,31 @@ async def test_a_cancelled_post_call_flush_keeps_the_shared_spend_counter_and_co
     assert redis_cache.alone == [], "a cancel says nothing about the shared counter, so Redis keeps it"
     assert spend_cache.in_memory_cache.get_cache("spend:key:k1") == 3.5, "the local copy counts the cancelled spend"
     assert spend_cache.in_memory_cache.get_cache("spend:team:t1") is None, "an absent local copy is not seeded"
+
+
+@pytest.mark.asyncio
+async def test_native_post_call_ops_go_out_with_the_post_call_flush_not_the_request_boundary():
+    natives = FakeNatives()
+
+    with request_redis_batch_scope(post_call_deadline=60, native_factory=natives) as request:  # pyright: ignore[reportArgumentType]  # test double
+        request.native_post_call()
+        await request.flush_all()
+        at_the_boundary = list(natives.built[0].events)
+        await flush_post_call_redis_batches()
+    await drain_post_call_redis_batches()
+
+    assert at_the_boundary == ["flush_pre"]
+    assert natives.built[0].events == ["flush_pre", "flush_post"]
+
+
+@pytest.mark.asyncio
+async def test_native_post_call_ops_still_waiting_on_their_callbacks_are_drained_at_shutdown():
+    natives = FakeNatives()
+
+    with request_redis_batch_scope(post_call_deadline=60, native_factory=natives) as request:  # pyright: ignore[reportArgumentType]  # test double
+        request.native_post_call()
+        await request.flush_all()
+    await drain_post_call_redis_batches()
+    await drain_post_call_redis_batches()
+
+    assert natives.built[0].events == ["flush_pre", "flush_post"]

tests/unit/caching/test_request_redis_batch_pre_call.py

@@ -1,13 +1,13 @@
 """One Redis pipeline per backend for the pre-call reads a request makes: rate limiter Lua groups, the
-router's cooldown and usage read, auth identity and spend counters all join the request batch."""
+router's usage counter read, auth identity and spend counters all join the request batch."""
 
 from __future__ import annotations
 
 import asyncio
 import hashlib
 import json
+from collections.abc import Callable
 from datetime import datetime, timezone
-from itertools import chain
 from typing import Any, Final
 from unittest.mock import AsyncMock, MagicMock
 
@@ -24,21 +24,24 @@ from litellm.proxy.auth.auth_object_prefetch import _CacheEntry, _write_back, pr
 from litellm.proxy.common_utils.user_api_key_cache import UserApiKeyCache
 from litellm.proxy.hooks.parallel_request_limiter_v3 import (
     CHECK_AND_INCREMENT_BY_N_SCRIPT,
+    PROXY_MaxParallelRequestsHandler_v3,
     RateLimitDescriptor,
     RateLimitUnverifiableError,
-    PROXY_MaxParallelRequestsHandler_v3,
 )
 from litellm.proxy.utils import InternalUsageCache
 from litellm.router_api import RoutingContext
-from litellm.router_utils.cooldown_cache import ROUTER_COOLDOWNS_TARGET, CooldownCache
+from litellm.router_utils.routing_prefetch import ArmedRead, TierRead
 from litellm.router_utils.routing_read_batch import (
-    ROUTER_COOLDOWNS_USAGE_TARGET,
     ROUTER_USAGE_TARGET,
     RoutingPrefetch,
-    _routing_read_target,  # pyright: ignore[reportPrivateUsage]  # the family rule under test
 )
 
-from .test_redis_batch import FakeClient, FakeRedisCache, replies
+from .test_redis_batch import FakeClient, FakeNativePending, FakeNatives, FakeRedisCache, replies
+
+
+def _cooldown_key(model_id: str) -> str:
+    return f"deployment:{model_id}:cooldown"
+
 
 _MODEL_GROUP = "claude"
 _FAR_FUTURE = 4_102_444_800.0  # 2100-01-01, a cooldown stamped then is still active
@@ -289,12 +292,76 @@ def _router(redis_cache: FakeRedisCache, routing_strategy: str = "usage-based-ro
     return router
 
 
-@pytest.mark.asyncio
-async def test_armed_routing_read_rides_the_admission_pipeline_and_routing_issues_no_read_of_its_own(monkeypatch):
-    monkeypatch.setattr(
-        "litellm.router_strategy.lowest_tpm_rpm_v2.get_utc_datetime",
-        lambda: datetime(2026, 1, 1, 12, 0, 30, tzinfo=timezone.utc),
+_PINNED_MINUTE: Final = datetime(2026, 1, 1, 12, 0, 30, tzinfo=timezone.utc)
+_START: Final = 1_000_000.0
+_PING: Final = [{"role": "user", "content": "ping"}]
+
+
+@pytest.fixture
+def pinned_clock(monkeypatch: pytest.MonkeyPatch) -> list[float]:
+    """Pins the usage counters' minute and the router cache's read throttle clock; tests move `now[0]`."""
+    now: Final = [_START]  # mutable-ok: the test advances the pinned clock
+    monkeypatch.setattr("litellm.router_strategy.lowest_tpm_rpm_v2.get_utc_datetime", lambda: _PINNED_MINUTE)
+    monkeypatch.setattr(dual_cache_module.time, "time", lambda: now[0])
+    return now
+
+
+def _counter_keys(router: Router, deployment_ids: tuple[str, ...] = ("dep-a", "dep-b")) -> frozenset[str]:
+    deployments: Final = [d for d in router.model_list if d["model_info"]["id"] in deployment_ids]
+    tpm, rpm = router.lowesttpm_logger_v2.usage_counter_keys(deployments)
+    return frozenset(tpm + rpm)
+
+
+def _tpm_key(router: Router, deployment_id: str) -> str:
+    deployment: Final = next(d for d in router.model_list if d["model_info"]["id"] == deployment_id)
+    return router.lowesttpm_logger_v2.usage_counter_keys([deployment])[0][0]
+
+
+def _counter_mgets(router: Router, client: FakeClient, redis_cache: FakeRedisCache) -> tuple[frozenset[str], ...]:
+    counters: Final = _counter_keys(router)
+    pipelined: Final = tuple(
+        frozenset(command[1:])
+        for pipeline in client.pipelines
+        for command in pipeline.commands
+        if command[0] == "MGET" and counters.intersection(command[1:])
     )
+    alone: Final = tuple(
+        frozenset(keys) for command, keys in redis_cache.alone if command == "MGET" and counters.intersection(keys)
+    )
+    return pipelined + alone
+
+
+def _python_cooldown_reads(client: FakeClient, redis_cache: FakeRedisCache) -> tuple[str, ...]:
+    pipelined: Final = tuple(
+        key
+        for pipeline in client.pipelines
+        for command in pipeline.commands
+        if command[0] == "MGET"
+        for key in command[1:]
+    )
+    alone: Final = tuple(key for command, keys in redis_cache.alone if command == "MGET" for key in keys)
+    return tuple(key for key in pipelined + alone if key.endswith(":cooldown"))
+
+
+def _replies_with(values: dict[str, object]) -> Callable[[tuple[Any, ...]], Any]:
+    def replies(command: tuple[Any, ...]) -> Any:
+        if command[0] == "MGET":
+            return [None if values.get(key) is None else json.dumps(values[key]) for key in command[1:]]
+        return _lua_ok_replies(command)
+
+    return replies
+
+
+async def _route(router: Router) -> str:
+    deployment: Final = await router.async_get_available_deployment(
+        model=_MODEL_GROUP, messages=_PING, request_kwargs={}
+    )
+    return deployment["model_info"]["id"]
+
+
+@pytest.mark.asyncio
+@pytest.mark.usefixtures("pinned_clock")
+async def test_armed_routing_read_rides_the_admission_pipeline_and_routing_issues_no_read_of_its_own():
     client = FakeClient(_lua_ok_replies)
     redis_cache = FakeRedisCache(client)
     router = _router(redis_cache)
@@ -306,58 +373,40 @@ async def test_armed_routing_read_rides_the_admission_pipeline_and_routing_issue
             descriptors=[_descriptor("api_key", "k1", 10), _descriptor("team", "t1", 20)],
             increments=[{"requests": 1}, {"requests": 1}],
         )
-        deployment = await router.async_get_available_deployment(
-            model=_MODEL_GROUP, messages=[{"role": "user", "content": "ping"}], request_kwargs={}
-        )
+        deployment = await _route(router)
 
-    assert deployment["model_info"]["id"] in {"dep-a", "dep-b"}
+    assert deployment in {"dep-a", "dep-b"}
     assert len(client.pipelines) == 1
     commands = client.pipelines[0].commands
     assert [c[0] for c in commands] == ["MGET", "EVALSHA", "EVALSHA"]
-    mget_keys = set(commands[0][1:])
-    assert {CooldownCache.get_cooldown_cache_key("dep-a"), CooldownCache.get_cooldown_cache_key("dep-b")} <= mget_keys
-    assert any(":tpm:" in key for key in mget_keys) and any(":rpm:" in key for key in mget_keys)
+    assert frozenset(commands[0][1:]) == _counter_keys(router)
     assert redis_cache.alone == []
 
 
 @pytest.mark.asyncio
-async def test_a_cooldown_recorded_locally_after_the_prefetch_left_still_excludes_its_deployment():
-    expired = {"exception_received": "429", "status_code": "429", "timestamp": 0.0, "cooldown_time": 60}
-
-    def replies(command: tuple[Any, ...]) -> Any:
-        if command[0] == "MGET":  # Redis holds a stale cooldown for dep-b and nothing for dep-a
-            return [
-                json.dumps(expired) if key == CooldownCache.get_cooldown_cache_key("dep-b") else None
-                for key in command[1:]
-            ]
-        return _lua_ok_replies(command)
-
-    client = FakeClient(replies)
+@pytest.mark.parametrize("routing_strategy", ["simple-shuffle", "usage-based-routing-v2"])
+async def test_a_cooldown_recorded_through_the_store_excludes_its_deployment_without_a_python_cooldown_read(
+    routing_strategy: str,
+):
+    client = FakeClient(_lua_ok_replies)
     redis_cache = FakeRedisCache(client)
-    router = _router(redis_cache)
-    cooldown_store = router.cooldown_cache.cooldown_store
-    assert cooldown_store.in_memory_cache is not None
+    router = _router(redis_cache, routing_strategy=routing_strategy)
+    router.cooldown_cache.cooldown_store.put(
+        "dep-a",
+        {"exception_received": "429", "status_code": "429", "timestamp": _FAR_FUTURE, "cooldown_time": 60},
+        60,
+    )
 
     with request_redis_batch_scope():
         router.arm_routing_read_prefetch(_MODEL_GROUP, {})
-        cooldown_store.in_memory_cache.set_cache(
-            CooldownCache.get_cooldown_cache_key("dep-a"),
-            {"exception_received": "429", "status_code": "429", "timestamp": _FAR_FUTURE, "cooldown_time": 60},
-        )
-        picks = {
-            (
-                await router.async_get_available_deployment(
-                    model=_MODEL_GROUP, messages=[{"role": "user", "content": "ping"}], request_kwargs={}
-                )
-            )["model_info"]["id"]
-            for _ in range(5)
-        }
+        picks = {await _route(router) for _ in range(5)}
 
     assert picks == {"dep-b"}
-    assert len(client.pipelines) == 1
+    assert _python_cooldown_reads(client, redis_cache) == ()
 
 
 @pytest.mark.asyncio
+@pytest.mark.usefixtures("pinned_clock")
 async def test_a_prefetch_that_does_not_cover_the_routing_keys_is_ignored_and_routing_reads_itself():
     client = FakeClient(_lua_ok_replies)
     redis_cache = FakeRedisCache(client)
@@ -366,81 +415,58 @@ async def test_a_prefetch_that_does_not_cover_the_routing_keys_is_ignored_and_ro
     with request_redis_batch_scope() as request:
         router.arm_routing_read_prefetch(_MODEL_GROUP, {})
         armed = request.prefetched["routing_read"]
-        assert isinstance(armed, RoutingPrefetch)
-        request.prefetched["routing_read"] = RoutingPrefetch(
-            keys=frozenset({"other"}),
+        assert isinstance(armed, ArmedRead)
+        request.prefetched["routing_read"] = ArmedRead(
+            read=TierRead(armed.read.cache, ("other",)),
             fetched=armed.fetched,
             result=armed.result,
-            reservations=armed.reservations,
-        )
-        deployment = await router.async_get_available_deployment(
-            model=_MODEL_GROUP, messages=[{"role": "user", "content": "ping"}], request_kwargs={}
+            previous=armed.previous,
         )
+        deployment = await _route(router)
         assert request.prefetched == {}
 
-    assert deployment["model_info"]["id"] in {"dep-a", "dep-b"}
-    assert len(redis_cache.alone) == 1  # the shared cooldown+usage read, one round trip as in P1
+    assert deployment in {"dep-a", "dep-b"}
+    assert [frozenset(keys) for command, keys in redis_cache.alone if command == "MGET"] == [_counter_keys(router)]
 
 
 @pytest.mark.asyncio
-async def test_a_prefetch_with_incomplete_usage_keys_releases_cooldown_reservations():
+@pytest.mark.usefixtures("pinned_clock")
+async def test_a_prefetch_with_incomplete_usage_keys_releases_its_reservations():
     client: Final = FakeClient(_lua_ok_replies)
     redis_cache: Final = FakeRedisCache(client)
     router: Final = _router(redis_cache)
-    cooldown_keys: Final = frozenset(
-        {
-            CooldownCache.get_cooldown_cache_key("dep-a"),
-            CooldownCache.get_cooldown_cache_key("dep-b"),
-        }
-    )
 
     with request_redis_batch_scope():
         RoutingPrefetch.arm(RoutingContext(router), router.lowesttpm_logger_v2, router.model_list[:1])
-        deployment: Final = await router.async_get_available_deployment(
-            model=_MODEL_GROUP, messages=[{"role": "user", "content": "ping"}], request_kwargs={}
-        )
+        deployment: Final = await _route(router)
 
-    fallback_cooldown_mgets: Final = tuple(
-        keys for command, keys in redis_cache.alone if command == "MGET" and cooldown_keys.issubset(keys)
-    )
-
-    assert deployment["model_info"]["id"] in {"dep-a", "dep-b"}
-    assert len(fallback_cooldown_mgets) == 1
+    assert deployment in {"dep-a", "dep-b"}
+    assert [frozenset(keys) for command, keys in redis_cache.alone if command == "MGET"] == [_counter_keys(router)]
 
 
 @pytest.mark.asyncio
-async def test_a_failed_prefetch_falls_back_to_the_shared_read():
+@pytest.mark.usefixtures("pinned_clock")
+async def test_a_failed_prefetch_falls_back_to_the_selectors_own_read():
     client = FakeClient(_lua_ok_replies, fail=ConnectionError("redis down"))
     redis_cache = FakeRedisCache(client)
     router = _router(redis_cache)
 
     with request_redis_batch_scope():
         router.arm_routing_read_prefetch(_MODEL_GROUP, {})
-        deployment = await router.async_get_available_deployment(
-            model=_MODEL_GROUP, messages=[{"role": "user", "content": "ping"}], request_kwargs={}
-        )
+        deployment = await _route(router)
 
-    assert deployment["model_info"]["id"] in {"dep-a", "dep-b"}
-    assert len(redis_cache.alone) == 1
-    cooldown_keys: Final = frozenset(
-        {
-            CooldownCache.get_cooldown_cache_key("dep-a"),
-            CooldownCache.get_cooldown_cache_key("dep-b"),
-        }
-    )
-    fallback_cooldown_mgets: Final = tuple(
-        keys for command, keys in redis_cache.alone if command == "MGET" and cooldown_keys.issubset(keys)
-    )
-    assert len(fallback_cooldown_mgets) == 1
+    assert deployment in {"dep-a", "dep-b"}
+    assert [frozenset(keys) for command, keys in redis_cache.alone if command == "MGET"] == [_counter_keys(router)]
 
 
 @pytest.mark.asyncio
-async def test_the_armed_routing_read_is_declared_under_the_router_cooldowns_family():
+@pytest.mark.usefixtures("pinned_clock")
+async def test_the_armed_routing_read_is_declared_under_the_router_usage_family():
     """The prefetch is declared before routing runs under a target of its own, so the pipeline that
-    carries it renders ``redis.pipeline router_cooldowns`` instead of a bare ``redis.pipeline``."""
+    carries it renders ``redis.pipeline router_usage`` instead of a bare ``redis.pipeline``."""
     client = FakeClient(_lua_ok_replies)
     redis_cache = FakeRedisCache(client)
-    router = _router(redis_cache, routing_strategy="simple-shuffle")
+    router = _router(redis_cache)
     pipeline_targets: list[str | None] = []  # mutable-ok: filled by the recording hook
 
     async def record(**kwargs: object) -> None:
@@ -450,35 +476,21 @@ async def test_the_armed_routing_read_is_declared_under_the_router_cooldowns_fam
 
     with request_redis_batch_scope():
         router.arm_routing_read_prefetch(_MODEL_GROUP, {})
-        await router.async_get_available_deployment(
-            model=_MODEL_GROUP, messages=[{"role": "user", "content": "ping"}], request_kwargs={}
-        )
-    await asyncio.gather(*(t for t in asyncio.all_tasks() if t is not asyncio.current_task()))
+        await _route(router)
+    async with asyncio.timeout(5):
+        while not pipeline_targets:
+            await asyncio.sleep(0.01)
 
-    assert pipeline_targets == [ROUTER_COOLDOWNS_TARGET]
+    assert pipeline_targets == [ROUTER_USAGE_TARGET]
 
 
 @pytest.mark.asyncio
-async def test_an_abandoned_prefetch_still_backfills_the_cooldown_it_read(monkeypatch):
-    clock: Final = 1_000_000.0
-    monkeypatch.setattr(dual_cache_module.time, "time", lambda: clock)
-    cooldown_key: Final = CooldownCache.get_cooldown_cache_key("dep-a")
-    active_cooldown: Final = {
-        "exception_received": "429",
-        "status_code": "429",
-        "timestamp": _FAR_FUTURE,
-        "cooldown_time": 60,
-    }
-
-    def replies(command: tuple[Any, ...]) -> Any:
-        if command[0] == "MGET":
-            return [json.dumps(active_cooldown) if key == cooldown_key else None for key in command[1:]]
-        return _lua_ok_replies(command)
-
-    client: Final = FakeClient(replies)
+@pytest.mark.usefixtures("pinned_clock")
+async def test_an_abandoned_prefetch_still_backfills_the_counters_it_read():
+    client: Final = FakeClient(_lua_ok_replies)
     redis_cache: Final = FakeRedisCache(client)
-    redis_cache.store[cooldown_key] = active_cooldown
-    router: Final = _router(redis_cache, routing_strategy="simple-shuffle")
+    router: Final = _router(redis_cache)
+    client.reply_for = _replies_with({_tpm_key(router, "dep-a"): 100})
     limiter: Final = _limiter(redis_cache)
 
     with request_redis_batch_scope():
@@ -487,176 +499,66 @@ async def test_an_abandoned_prefetch_still_backfills_the_cooldown_it_read(monkey
             descriptors=[_descriptor("api_key", "k1", 10)],
             increments=[{"requests": 1}],
         )
+    after_abandoned: Final = len(_counter_mgets(router, client, redis_cache))
 
-    pipeline_count: Final = len(client.pipelines)
-    first_cooldown_mgets: Final = tuple(
-        command
-        for command in chain.from_iterable(pipeline.commands for pipeline in client.pipelines[:pipeline_count])
-        if command[0] == "MGET" and cooldown_key in command[1:]
-    )
     with request_redis_batch_scope():
         router.arm_routing_read_prefetch(_MODEL_GROUP, {})
-        deployment: Final = await router.async_get_available_deployment(
-            model=_MODEL_GROUP, messages=[{"role": "user", "content": "ping"}], request_kwargs={}
-        )
-        cooldowns: Final = await router.cooldown_cache.async_get_active_cooldowns(["dep-a"], parent_otel_span=None)
+        deployment: Final = await _route(router)
 
-    second_cooldown_mgets: Final = tuple(
-        command
-        for command in chain.from_iterable(pipeline.commands for pipeline in client.pipelines[pipeline_count:])
-        if command[0] == "MGET" and cooldown_key in command[1:]
-    )
-
-    assert deployment["model_info"]["id"] == "dep-b"
-    assert [model_id for model_id, _ in cooldowns] == ["dep-a"]
-    assert len(first_cooldown_mgets) == 1
-    assert second_cooldown_mgets == ()
+    assert deployment == "dep-b"
+    assert after_abandoned == 1
+    assert len(_counter_mgets(router, client, redis_cache)) == 1
     assert redis_cache.alone == []
 
 
 @pytest.mark.asyncio
-async def test_prefetch_settlement_keeps_newer_memory_values_and_backfills_misses(monkeypatch):
-    clock: Final = 1_000_000.0
-    monkeypatch.setattr(dual_cache_module.time, "time", lambda: clock)
-    dep_a_key: Final = CooldownCache.get_cooldown_cache_key("dep-a")
-    dep_b_key: Final = CooldownCache.get_cooldown_cache_key("dep-b")
-    old_cooldown: Final = {
-        "exception_received": "429",
-        "status_code": "429",
-        "timestamp": _FAR_FUTURE,
-        "cooldown_time": 60,
-    }
-    newer_memory_cooldown: Final = {
-        "exception_received": "429",
-        "status_code": "429",
-        "timestamp": _FAR_FUTURE + 1,
-        "cooldown_time": 60,
-    }
-    redis_only_cooldown: Final = {
-        "exception_received": "429",
-        "status_code": "429",
-        "timestamp": _FAR_FUTURE + 2,
-        "cooldown_time": 60,
-    }
-
-    def replies(command: tuple[Any, ...]) -> Any:
-        if command[0] == "MGET":
-            return [json.dumps(redis_cache.store[key]) if key in redis_cache.store else None for key in command[1:]]
-        return _lua_ok_replies(command)
-
-    client: Final = FakeClient(replies)
-    redis_cache: Final = FakeRedisCache(client)
-    redis_cache.store[dep_a_key] = old_cooldown
-    redis_cache.store[dep_b_key] = redis_only_cooldown
-    router: Final = _router(redis_cache, routing_strategy="simple-shuffle")
-    memory_cache: Final = router.cooldown_cache.cooldown_store.in_memory_cache
-    assert memory_cache is not None
-
-    with request_redis_batch_scope() as request:
-        router.arm_routing_read_prefetch(_MODEL_GROUP, {})
-        memory_cache.set_cache(dep_a_key, newer_memory_cooldown)
-        await request.flush_all()
-
-    prefetched_mgets: Final = tuple(command for command in client.pipelines[0].commands if command[0] == "MGET")
-
-    assert len(prefetched_mgets) == 1
-    assert frozenset(prefetched_mgets[0][1:]) == frozenset({dep_a_key, dep_b_key})
-    assert memory_cache.get_cache(dep_a_key) == newer_memory_cooldown
-    assert memory_cache.get_cache(dep_b_key) == redis_only_cooldown
-
-
-@pytest.mark.asyncio
-async def test_an_abandoned_prefetch_whose_mget_fails_releases_its_reservation(monkeypatch):
-    clock: Final = 1_000_000.0
-    monkeypatch.setattr(dual_cache_module.time, "time", lambda: clock)
-    cooldown_key: Final = CooldownCache.get_cooldown_cache_key("dep-a")
-    active_cooldown: Final = {
-        "exception_received": "429",
-        "status_code": "429",
-        "timestamp": _FAR_FUTURE,
-        "cooldown_time": 60,
-    }
-    mget_replies: Final = iter((ConnectionError("redis down"), None))
-
-    def replies(command: tuple[Any, ...]) -> Any:
-        if command[0] == "MGET":
-            response: Final = next(mget_replies)
-            if isinstance(response, Exception):
-                return response
-            return [json.dumps(active_cooldown) if key == cooldown_key else None for key in command[1:]]
-        return _lua_ok_replies(command)
-
-    client: Final = FakeClient(replies)
-    redis_cache: Final = FakeRedisCache(client)
-    redis_cache.store[cooldown_key] = active_cooldown
-    router: Final = _router(redis_cache, routing_strategy="simple-shuffle")
-
-    with request_redis_batch_scope() as request:
-        router.arm_routing_read_prefetch(_MODEL_GROUP, {})
-        await request.flush_all()
-
-    pipeline_count: Final = len(client.pipelines)
-    first_cooldown_mgets: Final = tuple(
-        command
-        for command in chain.from_iterable(pipeline.commands for pipeline in client.pipelines[:pipeline_count])
-        if command[0] == "MGET" and cooldown_key in command[1:]
-    )
-    with request_redis_batch_scope():
-        router.arm_routing_read_prefetch(_MODEL_GROUP, {})
-        deployment: Final = await router.async_get_available_deployment(
-            model=_MODEL_GROUP, messages=[{"role": "user", "content": "ping"}], request_kwargs={}
-        )
-        cooldowns: Final = await router.cooldown_cache.async_get_active_cooldowns(["dep-a"], parent_otel_span=None)
-
-    second_cooldown_mgets: Final = tuple(
-        command
-        for command in chain.from_iterable(pipeline.commands for pipeline in client.pipelines[pipeline_count:])
-        if command[0] == "MGET" and cooldown_key in command[1:]
-    )
-
-    assert deployment["model_info"]["id"] == "dep-b"
-    assert [model_id for model_id, _ in cooldowns] == ["dep-a"]
-    assert len(first_cooldown_mgets) == 1
-    assert len(second_cooldown_mgets) == 1
-
-
-@pytest.mark.asyncio
-async def test_a_cooldown_that_leaves_memory_before_routing_is_read_again(monkeypatch):
-    clock: Final = 1_000_000.0
-    monkeypatch.setattr(dual_cache_module.time, "time", lambda: clock)
-    cooldown_key: Final = CooldownCache.get_cooldown_cache_key("dep-a")
-    active_cooldown: Final = {
-        "exception_received": "429",
-        "status_code": "429",
-        "timestamp": _FAR_FUTURE,
-        "cooldown_time": 60,
-    }
+@pytest.mark.usefixtures("pinned_clock")
+async def test_prefetch_settlement_keeps_newer_memory_values_and_backfills_misses():
     client: Final = FakeClient(_lua_ok_replies)
     redis_cache: Final = FakeRedisCache(client)
-    redis_cache.store[cooldown_key] = active_cooldown
-    router: Final = _router(redis_cache, routing_strategy="simple-shuffle")
-    cooldown_store: Final = router.cooldown_cache.cooldown_store
-    memory_cache: Final = cooldown_store.in_memory_cache
-    assert memory_cache is not None
-    memory_cache.set_cache(cooldown_key, active_cooldown)
+    router: Final = _router(redis_cache)
+    dep_a: Final = _tpm_key(router, "dep-a")
+    dep_b: Final = _tpm_key(router, "dep-b")
+    client.reply_for = _replies_with({dep_a: 5, dep_b: 7})
+    usage_cache: Final = router.lowesttpm_logger_v2.router_cache
+
+    with request_redis_batch_scope() as request:
+        router.arm_routing_read_prefetch(_MODEL_GROUP, {})
+        usage_cache.in_memory_cache.set_cache(dep_a, 50)
+        await request.flush_all()
+
+    assert await usage_cache.async_batch_get_cache([dep_a, dep_b], local_only=True) == [50, 7]
+
+
+@pytest.mark.asyncio
+async def test_an_abandoned_prefetch_whose_mget_fails_releases_its_reservation(pinned_clock: list[float]):
+    mget_replies: Final = iter((ConnectionError("redis down"), None))
+    client: Final = FakeClient(_lua_ok_replies)
+    redis_cache: Final = FakeRedisCache(client)
+    router: Final = _router(redis_cache)
+
+    def replies(command: tuple[Any, ...]) -> Any:
+        if command[0] == "MGET":
+            failure: Final = next(mget_replies)
+            if isinstance(failure, Exception):
+                return failure
+            return ["100" if key == _tpm_key(router, "dep-a") else None for key in command[1:]]
+        return _lua_ok_replies(command)
+
+    client.reply_for = replies
 
     with request_redis_batch_scope() as request:
         router.arm_routing_read_prefetch(_MODEL_GROUP, {})
         await request.flush_all()
-        memory_cache.delete_cache(cooldown_key)
-        deployment: Final = await router.async_get_available_deployment(
-            model=_MODEL_GROUP, messages=[{"role": "user", "content": "ping"}], request_kwargs={}
-        )
+    after_failure: Final = len(_counter_mgets(router, client, redis_cache))
 
-    prefetched_mgets: Final = tuple(command for command in client.pipelines[0].commands if command[0] == "MGET")
-    fallback_cooldown_mgets: Final = tuple(
-        keys for command, keys in redis_cache.alone if command == "MGET" and cooldown_key in keys
-    )
+    with request_redis_batch_scope():
+        router.arm_routing_read_prefetch(_MODEL_GROUP, {})
+        deployment: Final = await _route(router)
 
-    assert len(prefetched_mgets) == 1
-    assert prefetched_mgets[0][1:] == (CooldownCache.get_cooldown_cache_key("dep-b"),)
-    assert deployment["model_info"]["id"] == "dep-b"
-    assert fallback_cooldown_mgets == ((cooldown_key,),)
+    assert after_failure == 1
+    assert len(_counter_mgets(router, client, redis_cache)) == 2
+    assert deployment == "dep-b"
 
 
 @pytest.mark.asyncio
@@ -668,52 +570,35 @@ async def test_arming_outside_a_request_scope_is_a_no_op():
 
 
 @pytest.mark.asyncio
-async def test_simple_shuffle_prefetches_only_its_cooldown_read_into_the_admission_pipeline():
+async def test_simple_shuffle_arms_no_python_prefetch_and_reads_no_cooldown_key():
     client = FakeClient(_lua_ok_replies)
     redis_cache = FakeRedisCache(client)
     router = _router(redis_cache, routing_strategy="simple-shuffle")
     limiter = _limiter(redis_cache)
 
-    with request_redis_batch_scope():
+    with request_redis_batch_scope() as request:
         router.arm_routing_read_prefetch(_MODEL_GROUP, {})
+        assert set(request.prefetched) == {"routing_cooldowns"}
         await limiter.atomic_check_and_increment_by_n(
             descriptors=[_descriptor("api_key", "k1", 10)],
             increments=[{"requests": 1}],
         )
-        deployment = await router.async_get_available_deployment(
-            model=_MODEL_GROUP, messages=[{"role": "user", "content": "ping"}], request_kwargs={}
-        )
+        deployment = await _route(router)
 
-    assert deployment["model_info"]["id"] in {"dep-a", "dep-b"}
-    assert len(client.pipelines) == 1
-    commands = client.pipelines[0].commands
-    assert [c[0] for c in commands] == ["MGET", "EVALSHA"]
-    assert set(commands[0][1:]) == {
-        CooldownCache.get_cooldown_cache_key("dep-a"),
-        CooldownCache.get_cooldown_cache_key("dep-b"),
-    }
+    assert deployment in {"dep-a", "dep-b"}
+    assert [[c[0] for c in pipeline.commands] for pipeline in client.pipelines] == [["EVALSHA"]]
     assert redis_cache.alone == []
 
-    shuffle = Router(model_list=[_deployment("dep-a")], routing_strategy="simple-shuffle")
-    shuffle.update_redis_cache(cache=redis_cache)
-    with request_redis_batch_scope() as request:
-        shuffle.arm_routing_read_prefetch(_MODEL_GROUP, {})
-        armed = request.prefetched["routing_read"]
-        assert isinstance(armed, RoutingPrefetch)
-        assert armed.keys == {CooldownCache.get_cooldown_cache_key("dep-a")}  # no usage counters for shuffle
-
 
 @pytest.mark.asyncio
-@pytest.mark.parametrize("routing_strategy", ["simple-shuffle", "usage-based-routing-v2"])
+@pytest.mark.usefixtures("pinned_clock")
 @pytest.mark.parametrize("with_limiter", [True, False])
-async def test_requests_within_the_cooldown_read_interval_read_cooldowns_from_redis_once(
-    routing_strategy: str, with_limiter: bool
-):
+async def test_requests_within_the_read_interval_read_the_counters_from_redis_once(with_limiter: bool):
     client = FakeClient(_lua_ok_replies)
     redis_cache = FakeRedisCache(client)
-    router = _router(redis_cache, routing_strategy=routing_strategy)
+    router = _router(redis_cache)
     limiter = _limiter(redis_cache)
-    request_round_trips: list[tuple[int, int]] = []
+    request_round_trips: list[tuple[int, int]] = []  # mutable-ok: one entry per simulated request
 
     for _ in range(3):
         pipeline_count = len(client.pipelines)
@@ -725,35 +610,24 @@ async def test_requests_within_the_cooldown_read_interval_read_cooldowns_from_re
                     descriptors=[_descriptor("api_key", "k1", 10)],
                     increments=[{"requests": 1}],
                 )
-            await router.async_get_available_deployment(
-                model=_MODEL_GROUP, messages=[{"role": "user", "content": "ping"}], request_kwargs={}
-            )
+            await _route(router)
         request_round_trips.append((len(client.pipelines) - pipeline_count, len(redis_cache.alone) - alone_count))
 
-    pipeline_mgets = [command for pipeline in client.pipelines for command in pipeline.commands if command[0] == "MGET"]
-    alone_mgets = [keys for command, keys in redis_cache.alone if command == "MGET"]
-    cooldown_keys = {
-        CooldownCache.get_cooldown_cache_key("dep-a"),
-        CooldownCache.get_cooldown_cache_key("dep-b"),
-    }
-    cooldown_mgets = [command[1:] for command in pipeline_mgets if cooldown_keys.intersection(command[1:])] + [
-        keys for keys in alone_mgets if cooldown_keys.intersection(keys)
-    ]
-
-    assert len(cooldown_mgets) == 1
+    assert len(_counter_mgets(router, client, redis_cache)) == 1
     if not with_limiter:
         assert request_round_trips[1:] == [(0, 0), (0, 0)]
 
 
 @pytest.mark.asyncio
-async def test_concurrent_requests_share_one_cooldown_read_per_interval():
+@pytest.mark.usefixtures("pinned_clock")
+async def test_concurrent_requests_share_one_counter_read_per_interval():
     client: Final = FakeClient(_lua_ok_replies)
     redis_cache: Final = FakeRedisCache(client)
     router: Final = _router(redis_cache)
     first_armed: Final = asyncio.Event()
     both_armed: Final = asyncio.Event()
 
-    async def route_after_both_requests_arm():
+    async def route_after_both_requests_arm() -> str:
         with request_redis_batch_scope():
             router.arm_routing_read_prefetch(_MODEL_GROUP, {})
             if first_armed.is_set():
@@ -761,127 +635,57 @@ async def test_concurrent_requests_share_one_cooldown_read_per_interval():
             else:
                 first_armed.set()
             await both_armed.wait()
-            return await router.async_get_available_deployment(
-                model=_MODEL_GROUP, messages=[{"role": "user", "content": "ping"}], request_kwargs={}
-            )
+            return await _route(router)
 
     deployments: Final = await asyncio.gather(route_after_both_requests_arm(), route_after_both_requests_arm())
-    cooldown_keys: Final = frozenset(
-        {
-            CooldownCache.get_cooldown_cache_key("dep-a"),
-            CooldownCache.get_cooldown_cache_key("dep-b"),
-        }
-    )
-    cooldown_mgets: Final = tuple(
-        command
-        for pipeline in client.pipelines
-        for command in pipeline.commands
-        if command[0] == "MGET" and cooldown_keys.intersection(command[1:])
-    )
 
-    assert all(deployment["model_info"]["id"] in {"dep-a", "dep-b"} for deployment in deployments)
-    assert len(cooldown_mgets) == 1
+    assert set(deployments) <= {"dep-a", "dep-b"}
+    assert len(_counter_mgets(router, client, redis_cache)) == 1
 
 
 @pytest.mark.asyncio
-async def test_the_prefetch_reads_cooldowns_again_once_the_read_interval_elapses(monkeypatch):
-    first_time: Final = 1_000_000.0
-    monkeypatch.setattr(dual_cache_module.time, "time", lambda: first_time)
-    active_cooldown = {
-        "exception_received": "429",
-        "status_code": "429",
-        "timestamp": _FAR_FUTURE,
-        "cooldown_time": 60,
-    }
-    mget_results = iter((None, active_cooldown))
-
-    def replies(command: tuple[Any, ...]) -> Any:
-        if command[0] == "MGET":
-            result = next(mget_results)
-            return [
-                None if result is None or key != CooldownCache.get_cooldown_cache_key("dep-a") else json.dumps(result)
-                for key in command[1:]
-            ]
-        return _lua_ok_replies(command)
-
-    client = FakeClient(replies)
-    redis_cache = FakeRedisCache(client)
-    router = _router(redis_cache, routing_strategy="simple-shuffle")
-    cooldown_store = router.cooldown_cache.cooldown_store
-
-    with request_redis_batch_scope():
-        router.arm_routing_read_prefetch(_MODEL_GROUP, {})
-        await router.async_get_available_deployment(
-            model=_MODEL_GROUP, messages=[{"role": "user", "content": "ping"}], request_kwargs={}
-        )
-
-    monkeypatch.setattr(
-        dual_cache_module.time,
-        "time",
-        lambda: first_time + cooldown_store.redis_batch_cache_expiry + 1,
-    )
-    with request_redis_batch_scope():
-        router.arm_routing_read_prefetch(_MODEL_GROUP, {})
-        deployment = await router.async_get_available_deployment(
-            model=_MODEL_GROUP, messages=[{"role": "user", "content": "ping"}], request_kwargs={}
-        )
-
-    cooldown_keys = {
-        CooldownCache.get_cooldown_cache_key("dep-a"),
-        CooldownCache.get_cooldown_cache_key("dep-b"),
-    }
-    cooldown_mgets = [
-        command
-        for pipeline in client.pipelines
-        for command in pipeline.commands
-        if command[0] == "MGET" and cooldown_keys.intersection(command[1:])
-    ]
-    assert len(cooldown_mgets) == 2
-    assert deployment["model_info"]["id"] == "dep-b"
-
-
-@pytest.mark.asyncio
-async def test_the_prefetch_mget_carries_only_the_keys_whose_read_is_due(monkeypatch):
-    first_time: Final = 1_000_000.0
-    pinned: Final = datetime(2026, 1, 1, 12, 0, 30, tzinfo=timezone.utc)
-    monkeypatch.setattr(dual_cache_module.time, "time", lambda: first_time)
-    monkeypatch.setattr(
-        "litellm.router_strategy.lowest_tpm_rpm_v2.get_utc_datetime",
-        lambda: pinned,
-    )
+async def test_the_prefetch_reads_the_counters_again_once_the_read_interval_elapses(pinned_clock: list[float]):
     client = FakeClient(_lua_ok_replies)
     redis_cache = FakeRedisCache(client)
-    router = _router(redis_cache, routing_strategy="usage-based-routing-v2")
-    cooldown_store = router.cooldown_cache.cooldown_store
+    router = _router(redis_cache)
+
+    with request_redis_batch_scope():
+        router.arm_routing_read_prefetch(_MODEL_GROUP, {})
+        await _route(router)
+
+    client.reply_for = _replies_with({_tpm_key(router, "dep-a"): 100})
+    pinned_clock[0] = _START + router.lowesttpm_logger_v2.router_cache.redis_batch_cache_expiry + 1
+    with request_redis_batch_scope():
+        router.arm_routing_read_prefetch(_MODEL_GROUP, {})
+        deployment = await _route(router)
+
+    assert len(_counter_mgets(router, client, redis_cache)) == 2
+    assert deployment == "dep-b"
+
+
+@pytest.mark.asyncio
+async def test_the_prefetch_mget_carries_only_the_keys_whose_read_is_due(pinned_clock: list[float]):
+    client = FakeClient(_lua_ok_replies)
+    redis_cache = FakeRedisCache(client)
+    router = _router(redis_cache)
     usage_cache = router.lowesttpm_logger_v2.router_cache
-    time_offset = cooldown_store.redis_batch_cache_expiry + 0.5
-
-    assert time_offset < usage_cache.redis_batch_cache_expiry
 
     with request_redis_batch_scope():
         router.arm_routing_read_prefetch(_MODEL_GROUP, {})
-        await router.async_get_available_deployment(
-            model=_MODEL_GROUP, messages=[{"role": "user", "content": "ping"}], request_kwargs={}
-        )
+        await _route(router)
 
-    monkeypatch.setattr(dual_cache_module.time, "time", lambda: first_time + time_offset)
+    for key in _counter_keys(router, ("dep-a",)):
+        usage_cache.in_memory_cache.set_cache(key, 1)
+    pinned_clock[0] = _START + usage_cache.redis_batch_cache_expiry + 1
     with request_redis_batch_scope():
         router.arm_routing_read_prefetch(_MODEL_GROUP, {})
-        await router.async_get_available_deployment(
-            model=_MODEL_GROUP, messages=[{"role": "user", "content": "ping"}], request_kwargs={}
-        )
+        await _route(router)
 
-    cooldown_keys = frozenset(
-        {
-            CooldownCache.get_cooldown_cache_key("dep-a"),
-            CooldownCache.get_cooldown_cache_key("dep-b"),
-        }
-    )
     second_pipeline_mgets = tuple(command for command in client.pipelines[1].commands if command[0] == "MGET")
 
     assert len(client.pipelines) == 2
     assert len(second_pipeline_mgets) == 1
-    assert frozenset(second_pipeline_mgets[0][1:]) == cooldown_keys
+    assert frozenset(second_pipeline_mgets[0][1:]) == _counter_keys(router, ("dep-b",))
 
 
 @pytest.mark.asyncio
@@ -896,6 +700,7 @@ async def test_two_backends_flush_concurrently_one_pipeline_each():
 
 
 @pytest.mark.asyncio
+@pytest.mark.usefixtures("pinned_clock")
 async def test_a_single_lua_group_rides_the_pipeline_with_the_armed_routing_read():
     client = FakeClient(_lua_ok_replies)
     redis_cache = FakeRedisCache(client)
@@ -1080,17 +885,31 @@ async def test_identity_prefetch_is_one_mget_after_which_hits_and_misses_alike_c
     assert cache.in_memory_cache.get_cache("end_user_id:eu-miss") is None
 
 
-@pytest.mark.parametrize(
-    ("cooldown_keys", "usage_keys", "expected"),
-    [
-        (("cooldown:a",), (), ROUTER_COOLDOWNS_TARGET),
-        ((), ("usage:a",), ROUTER_USAGE_TARGET),
-        (("cooldown:a",), ("usage:a",), ROUTER_COOLDOWNS_USAGE_TARGET),
-    ],
-)
-def test_the_routing_read_family_follows_the_keys_that_are_actually_due(
-    cooldown_keys: tuple[str, ...], usage_keys: tuple[str, ...], expected: str
-):
-    """A routing MGET is ``router_cooldowns`` when only cooldown keys go out, ``router_usage`` when the
-    cooldowns were already in memory and only usage counters go out, and the combined family otherwise."""
-    assert _routing_read_target(cooldown_keys, usage_keys) == expected
+@pytest.mark.asyncio
+async def test_awaiting_a_native_read_runs_the_native_hooks_then_flushes_the_native_pre_batch_once_per_request():
+    natives: Final = FakeNatives()
+
+    with request_redis_batch_scope(post_call_deadline=7, native_factory=natives) as request:  # pyright: ignore[reportArgumentType]  # test double
+        native: Final = request.native()
+        request.add_native_flush_hook(lambda: native.events.append("hook"))
+        result: Final = request.native_result(FakeNativePending(native, lambda: "answer"))
+        declared_only: Final = list(native.events)
+        answer: Final = await result
+        await request.flush_all()
+
+    assert request.native() is native
+    assert [built.post_call_deadline for built in natives.built] == [7]
+    assert declared_only == []
+    assert answer == "answer"
+    assert native.events == ["hook", "flush_pre", "resolve", "hook", "flush_pre"]
+
+
+@pytest.mark.asyncio
+async def test_a_request_that_no_native_store_asks_for_builds_no_native_batches():
+    natives: Final = FakeNatives()
+
+    with request_redis_batch_scope(native_factory=natives) as request:  # pyright: ignore[reportArgumentType]  # test double
+        await request.flush_all()
+        await request.flush_post_call()
+
+    assert natives.built == []

tests/unit/conftest.py

@@ -4,17 +4,103 @@ import importlib
 import os
 import shutil
 import tempfile
-from collections.abc import Callable, Coroutine, Iterator
+from collections.abc import AsyncIterator, Callable, Coroutine, Iterable, Iterator
 from dataclasses import dataclass, field
 from pathlib import Path
 from types import MappingProxyType
-from typing import Final, Literal, TypeAlias
+from typing import TYPE_CHECKING, Final, Literal, TypeAlias
 
 import boto3
 import httpx
 import pytest
 from pytest_socket import enable_socket, socket_allow_hosts
 
+if TYPE_CHECKING:
+    from unittest.mock import MagicMock
+
+    from litellm.caching.redis_cache import RedisCache
+
+RouterRedis: TypeAlias = tuple["RedisCache", asyncio.Queue[tuple[tuple[object, ...], str | None, str | None]]]
+RedisWriteGate: TypeAlias = tuple[asyncio.Event, asyncio.Event, asyncio.Event]
+
+
+def redis_cache_double() -> "MagicMock":
+    """A `RedisCache` double for router tests. The native router stores connect from its settings, which name
+    a closed local port, so they serve their memory tier while the double answers the Python Redis calls."""
+    from unittest.mock import MagicMock
+
+    from litellm.caching.redis_cache import RedisCache
+
+    redis: Final = MagicMock(spec=RedisCache)
+    redis.redis_kwargs = {"host": "127.0.0.1", "port": 1, "socket_timeout": 0.2}
+    redis.namespace = None
+    return redis
+
+
+@pytest.fixture
+def redis_write_gate() -> RedisWriteGate:
+    released: Final = asyncio.Event()
+    released.set()
+    return asyncio.Event(), released, asyncio.Event()
+
+
+@pytest.fixture
+async def router_redis(
+    redis_write_gate: RedisWriteGate,
+) -> AsyncIterator[RouterRedis]:
+    from unittest.mock import patch
+
+    from fakeredis import FakeRedis, FakeServer
+    from fakeredis.aioredis import FakeConnection
+    from opentelemetry import trace
+    from redis.asyncio import BlockingConnectionPool
+    from redis.exceptions import ConnectionError
+
+    from litellm._internal_context import current_service_target
+    from litellm.caching.redis_cache import RedisCache
+
+    commands: Final[asyncio.Queue[tuple[tuple[object, ...], str | None, str | None]]] = asyncio.Queue()
+    started, released, unavailable = redis_write_gate
+
+    class ObservedConnection(FakeConnection):
+        async def send_command(self, *args: object, **kwargs: object) -> None:  # kwargs-ok: Redis transport signature
+            commands.put_nowait((args, current_service_target(), getattr(trace.get_current_span(), "name", None)))
+            await super().send_command(*args, **kwargs)
+
+        async def send_packed_command(self, command: Iterable[bytes] | bytes | str, check_health: bool = True) -> None:
+            chunks: Final = (
+                (command.encode(),)
+                if isinstance(command, str)
+                else (command,)
+                if isinstance(command, bytes)
+                else command
+            )
+            wire: Final = b"".join(chunks)
+            if b"INCRBYFLOAT" in wire:
+                commands.put_nowait(
+                    ((wire,), current_service_target(), getattr(trace.get_current_span(), "name", None))
+                )
+                started.set()
+                await released.wait()
+                if unavailable.is_set():
+                    raise ConnectionError("scripted write outage")
+            await super().send_packed_command(command, check_health=check_health)
+
+    server: Final = FakeServer()
+    client: Final = FakeRedis(server=server)
+    pool: Final = BlockingConnectionPool(connection_class=ObservedConnection, server=server)
+    try:
+        with (
+            patch("redis.Redis.from_url", return_value=client),
+            patch("redis.asyncio.BlockingConnectionPool.from_url", return_value=pool),
+        ):
+            yield RedisCache(url="redis://router-unit.example:6379/0"), commands
+    finally:
+        released.set()
+        await pool.aclose()
+        client.close()
+
+
 HOST_ENVIRONMENT_ALLOWLIST: Final = frozenset(
     (
         "PATH",
@@ -289,7 +375,9 @@ def isolate_litellm_globals() -> Iterator[None]:
     original_callback_holders: Final = frozenset(litellm_router_module._routers_holding_global_callbacks)
     original_reset: Final = {name: getattr(litellm, name) for name in RESET_TO_NONE_GLOBALS}
     original_restored: Final = {name: getattr(litellm, name) for name in RESTORED_GLOBALS if hasattr(litellm, name)}
-    original_clients: Final = {name: litellm.__dict__[name] for name in MODULE_LEVEL_CLIENTS if name in litellm.__dict__}
+    original_clients: Final = {
+        name: litellm.__dict__[name] for name in MODULE_LEVEL_CLIENTS if name in litellm.__dict__
+    }
     original_loggers: Final = {
         logger: (logger.level, logger.disabled, logger.propagate, list(logger.handlers), list(logger.filters))
         for logger in ALL_LOGGERS

tests/unit/redis/stores/test_router_cooldowns.py

@@ -0,0 +1,260 @@
+import ast
+import asyncio
+import json
+import logging
+import time
+from collections.abc import Mapping, Sequence
+from dataclasses import dataclass, field, replace
+from typing import Final
+
+import pytest
+
+import litellm
+from litellm._internal_context import current_service_target
+from litellm.caching.redis_batch import RequestRedisBatches
+from litellm.caching.redis_cache import RedisCache, redis_breaker_state_counts
+from litellm.integrations.custom_secret_manager import CustomSecretManager
+from litellm.redis.stores._connection import native_client
+from litellm.redis.stores.router_cooldowns import CooldownCacheValue, RouterCooldownStore
+from litellm.rust_bridge._native import NativeRedisClient, NativeRouterCooldowns
+from litellm.rust_bridge.host import settings
+from litellm.types.secret_managers.main import KeyManagementSettings, KeyManagementSystem
+from tests.unit.caching.test_redis_batch import FakeNativePending, FakeNativeRequest, FakeNatives
+
+
+@dataclass(frozen=True, slots=True)
+class _WireCooldown:
+    """One cooldown as main's ``RedisCache`` writes it (``str(value)``) and reads it (``json.loads`` then
+    ``ast.literal_eval``). The same literals sit in ``litellm-rust/crates/redis-store/tests/support/mod.rs``,
+    where real Redis is checked to hold them after the Rust store writes."""
+
+    cooldown: CooldownCacheValue
+    str_dict: str
+    json: str
+    ttl_seconds: float
+    redis_ttl_seconds: int
+
+
+_WIRE_COOLDOWNS: Final = (
+    _WireCooldown(
+        cooldown={
+            "exception_received": "RateLimitError: limited é 'quoted'",
+            "status_code": "429",
+            "timestamp": 1730000000.25,
+            "cooldown_time": 60,
+        },
+        str_dict="{'exception_received': \"RateLimitError: limited é 'quoted'\", 'status_code': '429', 'timestamp': 1730000000.25, 'cooldown_time': 60}",
+        json='{"exception_received": "RateLimitError: limited \\u00e9 \'quoted\'", "status_code": "429", "timestamp": 1730000000.25, "cooldown_time": 60}',
+        ttl_seconds=90.5,
+        redis_ttl_seconds=90,
+    ),
+    _WireCooldown(
+        cooldown={
+            "exception_received": "Timeout",
+            "status_code": "408",
+            "timestamp": 1730000000.5,
+            "cooldown_time": 0.5,
+        },
+        str_dict="{'exception_received': 'Timeout', 'status_code': '408', 'timestamp': 1730000000.5, 'cooldown_time': 0.5}",
+        json='{"exception_received": "Timeout", "status_code": "408", "timestamp": 1730000000.5, "cooldown_time": 0.5}',
+        ttl_seconds=30.0,
+        redis_ttl_seconds=30,
+    ),
+)
+
+
+def _entry(model_id: str = "dep") -> CooldownCacheValue:
+    return {"exception_received": model_id, "status_code": "429", "timestamp": 1000.0, "cooldown_time": 120.0}
+
+
+@dataclass
+class FakeCooldowns:
+    client: NativeRedisClient | None
+    stored: dict[str, CooldownCacheValue] = field(default_factory=dict)
+    fails: dict[str, int] = field(default_factory=dict)
+    targets: list[str | None] = field(default_factory=list)
+    smallest: float | None = None
+    declared: list[tuple[str, ...]] = field(default_factory=list)
+
+    def put(self, model_id: str, cooldown: Mapping[str, object], ttl_seconds: float) -> None:
+        self.targets.append(current_service_target())
+        self.stored[model_id] = CooldownCacheValue(**cooldown)  # pyright: ignore[reportArgumentType]  # test double
+
+    def increment_allowed_fails(self, model_id: str, suffix: str | None, ttl_seconds: float) -> int:
+        self.targets.append(current_service_target())
+        self.fails[model_id] = self.fails.get(model_id, 0) + 1
+        return self.fails[model_id]
+
+    def active(self, model_ids: Sequence[str]) -> list[tuple[str, CooldownCacheValue]]:
+        self.targets.append(current_service_target())
+        return [(model_id, self.stored[model_id]) for model_id in model_ids if model_id in self.stored]
+
+    def aactive(self, model_ids: Sequence[str]) -> "asyncio.Future[list[tuple[str, CooldownCacheValue]]]":
+        future: Final[asyncio.Future[list[tuple[str, CooldownCacheValue]]]] = asyncio.get_running_loop().create_future()
+        future.set_result(self.active(model_ids))
+        return future
+
+    def declare_active(
+        self, request: FakeNativeRequest, model_ids: Sequence[str]
+    ) -> FakeNativePending[list[tuple[str, CooldownCacheValue]]]:
+        self.targets.append(current_service_target())
+        self.declared.append(tuple(model_ids))
+        return FakeNativePending(request, lambda: self.active(model_ids))
+
+    def minimum(self, model_ids: Sequence[str]) -> float | None:
+        return self.smallest
+
+    def evict_local(self, model_id: str) -> None:
+        self.stored.pop(model_id, None)
+
+    def flush_local_counters(self) -> None:
+        self.fails.clear()
+
+    def snapshot(self) -> dict[str, CooldownCacheValue]:
+        return dict(self.stored)
+
+
+@dataclass
+class Handles:
+    built: list[FakeCooldowns] = field(default_factory=list)
+
+    def __call__(self, client: NativeRedisClient | None) -> FakeCooldowns:
+        handle: Final = FakeCooldowns(client)
+        self.built.append(handle)
+        return handle
+
+
+def _client(namespace: str | None = None) -> NativeRedisClient:
+    client: Final = native_client(RedisCache(host="redis.internal", port=6380, namespace=namespace))
+    assert client is not None
+    return client
+
+
+def test_late_attach_rebuilds_once_and_later_attaches_are_ignored() -> None:
+    handles: Final = Handles()
+    store: Final = RouterCooldownStore(None, handle=handles)
+    store.put("dep", _entry(), 60.0)
+    first: Final = _client()
+    store.attach_redis(None)
+    store.attach_redis(first)
+    store.attach_redis(_client("other"))
+    assert [handle.client for handle in handles.built] == [None, first]
+    assert store.active_sync(["dep"], None) == ()
+
+
+def test_writes_and_reads_carry_the_router_cooldowns_service_target() -> None:
+    handles: Final = Handles()
+    store: Final = RouterCooldownStore(_client(), handle=handles)
+    store.put("dep", _entry(), 60.0)
+    assert store.increment_allowed_fails("dep", "timeout", 30.0) == 1
+    assert store.active_sync(["dep", "other"], None) == (("dep", _entry()),)
+    assert handles.built[0].targets == ["router_cooldowns"] * 3
+    assert current_service_target() is None
+
+
+@pytest.mark.parametrize(("smallest", "expected"), ((None, 60.0), (0, 60.0), (5, 5)))
+def test_minimum_falls_back_to_the_default_when_nothing_or_zero_is_stored(
+    smallest: float | None, expected: float
+) -> None:
+    handles: Final = Handles()
+    store: Final = RouterCooldownStore(None, handle=handles)
+    handles.built[0].smallest = smallest
+    assert store.minimum(["dep"], 60.0, None) == expected
+
+
+@pytest.mark.parametrize("case", _WIRE_COOLDOWNS, ids=("rate-limit", "timeout"))
+def test_the_wire_cases_are_what_mains_codec_writes_and_reads(case: _WireCooldown) -> None:
+    assert str(case.cooldown) == case.str_dict
+    assert ast.literal_eval(case.str_dict) == case.cooldown
+    assert json.loads(case.json) == case.cooldown
+    assert int(case.ttl_seconds) == case.redis_ttl_seconds
+
+
+@pytest.mark.parametrize(
+    "setting",
+    ({"ssl_ciphers": "HIGH"}, {"ssl": True, "ssl_validate_ocsp": True}, {"credential_provider": "not-a-provider"}),
+)
+def test_a_redis_setting_the_native_client_cannot_honor_never_fails_construction(
+    setting: dict[str, object], caplog: pytest.LogCaptureFixture
+) -> None:
+    redis: Final = RedisCache(host="127.0.0.1", port=1, **setting)
+    with caplog.at_level(logging.WARNING):
+        store: Final = RouterCooldownStore(native_client(redis))
+    cooldown: Final = CooldownCacheValue(
+        exception_received="model", status_code="429", timestamp=time.time(), cooldown_time=120.0
+    )
+    store.put("model", cooldown, 60.0)
+
+    assert store.active_sync(["model"], None) == (("model", cooldown),)
+    assert next(iter(setting)) in caplog.text
+
+
+class _RecordingSecrets(CustomSecretManager):
+    def __init__(self, values: Mapping[str, str]) -> None:
+        super().__init__(secret_manager_name="router_cooldowns_test")  # pyright: ignore[reportUnknownMemberType]  # CustomSecretManager takes untyped **kwargs
+        self.values: Final = values
+        self.asked: tuple[str, ...] = ()
+
+    async def async_read_secret(
+        self, secret_name: str, optional_params: dict[str, object] | None = None, timeout: object = None
+    ) -> str | None:
+        raise AssertionError("get_secret reads custom managers synchronously")
+
+    def sync_read_secret(
+        self, secret_name: str, optional_params: dict[str, object] | None = None, timeout: object = None
+    ) -> str | None:
+        self.asked = (*self.asked, secret_name)
+        return self.values.get(secret_name)
+
+
+def test_the_native_client_reads_redis_secrets_through_the_secret_manager(monkeypatch: pytest.MonkeyPatch) -> None:
+    monkeypatch.delenv("REDIS_PASSWORD", raising=False)
+    manager: Final = _RecordingSecrets({"REDIS_PASSWORD": "vault-password"})
+    monkeypatch.setattr(litellm, "secret_manager_client", manager)
+    monkeypatch.setattr(litellm, "_key_management_system", KeyManagementSystem.CUSTOM)
+    monkeypatch.setattr(litellm, "_key_management_settings", KeyManagementSettings(access_mode="read_only"))
+    configured: Final = settings.secret_manager
+    monkeypatch.setattr(settings, "secret_manager", lambda: replace(configured(), native=False))
+
+    NativeRedisClient.connect({"host": "127.0.0.1", "port": 1}, namespace="secret-manager-test")
+
+    assert "REDIS_PASSWORD" in manager.asked
+
+
+def test_the_native_breaker_counts_in_the_redis_breaker_state_gauge(monkeypatch: pytest.MonkeyPatch) -> None:
+    monkeypatch.setenv("REDIS_CIRCUIT_BREAKER_ENABLED", "true")
+    monkeypatch.setenv("REDIS_CIRCUIT_BREAKER_FAILURE_THRESHOLD", "1")
+    open_before: Final = redis_breaker_state_counts().get("open", 0)
+    store: Final = NativeRouterCooldowns(
+        NativeRedisClient.connect({"host": "127.0.0.1", "port": 1}, namespace="breaker-gauge-test")
+    )
+
+    store.put("model", _entry("model"), 60.0)
+
+    assert redis_breaker_state_counts().get("open", 0) == open_before + 1
+
+
+@pytest.mark.asyncio
+async def test_a_declared_active_read_answers_after_the_native_pre_flush_under_the_router_cooldowns_target() -> None:
+    handles: Final = Handles()
+    store: Final = RouterCooldownStore(_client(), handle=handles)
+    natives: Final = FakeNatives()
+    request: Final = RequestRedisBatches(native_factory=natives)  # pyright: ignore[reportArgumentType]  # test double
+    store.put("dep", _entry(), 60.0)
+
+    declared: Final = store.declare_active(request, ["dep", "other"])
+    assert declared is not None
+    assert natives.built[0].events == []
+
+    assert tuple(await declared) == (("dep", _entry()),)
+    assert natives.built[0].events == ["flush_pre", "resolve"]
+    assert handles.built[0].declared == [("dep", "other")]
+    assert handles.built[0].targets[1] == "router_cooldowns"
+
+
+def test_a_store_without_redis_declares_nothing_on_the_request() -> None:
+    natives: Final = FakeNatives()
+    request: Final = RequestRedisBatches(native_factory=natives)  # pyright: ignore[reportArgumentType]  # test double
+
+    assert RouterCooldownStore(None, handle=Handles()).declare_active(request, ["dep"]) is None
+    assert natives.built == []

tests/unit/redis/stores/test_router_usage.py

@@ -0,0 +1,125 @@
+import asyncio
+from collections.abc import Sequence
+from dataclasses import dataclass, field
+from typing import Final, TypeVar
+
+import pytest
+
+from litellm import Router
+from litellm._internal_context import current_service_target
+from litellm.caching.redis_batch import drain_post_call_redis_batches, request_redis_batch_scope
+from litellm.caching.redis_cache import RedisCache
+from litellm.redis.stores._connection import native_client
+from litellm.redis.stores.router_usage import NativeCounter, RouterUsageStore, UsageCounter
+from litellm.rust_bridge._native import NativeRedisClient
+from tests.unit.caching.test_redis_batch import FakeNatives
+
+T = TypeVar("T")
+
+
+def _done(value: T) -> "asyncio.Future[T]":
+    future: Final[asyncio.Future[T]] = asyncio.get_running_loop().create_future()
+    future.set_result(value)
+    return future
+
+
+@dataclass
+class FakeUsage:
+    connected: bool
+    counts: dict[NativeCounter, float] = field(default_factory=dict)
+    calls: list[tuple[str, object, str | None]] = field(default_factory=list)
+    requests: list[object] = field(default_factory=list)
+
+    def increment(self, counter: NativeCounter, value: float, ttl_seconds: int) -> "asyncio.Future[float]":
+        self.calls.append(("increment", (counter, value, ttl_seconds), current_service_target()))
+        self.counts[counter] = self.counts.get(counter, 0) + value
+        return _done(self.counts[counter])
+
+    def increment_deployment(
+        self,
+        deployment_id: str,
+        model: str | None,
+        minute: str,
+        tokens: float,
+        requests: int,
+        *,
+        request: object = None,
+    ) -> "asyncio.Future[None]":
+        self.calls.append(("deployment", (deployment_id, model, minute, tokens, requests), current_service_target()))
+        self.requests.append(request)
+        for kind, value in (("tpm", tokens), ("rpm", requests)):
+            counter: NativeCounter = (deployment_id, model, minute, kind)  # pyright: ignore[reportAssignmentType]  # literal kinds
+            self.counts[counter] = self.counts.get(counter, 0) + value
+        return _done(None)
+
+    def get_many(self, counters: Sequence[NativeCounter]) -> "asyncio.Future[list[float | None]]":
+        return _done([self.counts.get(counter) for counter in counters])
+
+    def flush_local_counters(self) -> None:
+        self.counts.clear()
+
+    def snapshot(self) -> dict[str, float]:
+        return {}
+
+
+@dataclass
+class Handles:
+    built: list[FakeUsage] = field(default_factory=list)
+
+    def __call__(self, client: NativeRedisClient | None) -> FakeUsage:
+        self.built.append(FakeUsage(client is not None))
+        return self.built[-1]
+
+
+@pytest.mark.asyncio
+async def test_counters_cross_the_bridge_as_domain_tuples_under_the_router_usage_target() -> None:
+    handles: Final = Handles()
+    store: Final = RouterUsageStore(None, handle=handles)
+    counter: Final = UsageCounter("dep", None, "12-34", "rpm")
+
+    await store.async_increment(counter, 1, 60)
+    await store.increment_deployment("dep", "model", "12-34", 7.5, 1, None)
+
+    assert handles.built[0].calls == [
+        ("increment", (("dep", None, "12-34", "rpm"), 1, 60), "router_usage"),
+        ("deployment", ("dep", "model", "12-34", 7.5, 1), "router_usage"),
+    ]
+    assert await store.async_batch_get((counter, UsageCounter("dep", "model", "12-34", "tpm"))) == [1, 7.5]
+
+
+def test_late_attach_rebuilds_the_handle_once() -> None:
+    handles: Final = Handles()
+    store: Final = RouterUsageStore(None, handle=handles)
+    store.attach_redis(native_client(RedisCache(host="redis.internal")))
+    store.attach_redis(native_client(RedisCache(host="other")))
+    assert [handle.connected for handle in handles.built] == [False, True]
+
+
+@pytest.mark.asyncio
+@pytest.mark.parametrize("operation", ("flush_cache", "reset"))
+async def test_router_reset_clears_usage_and_failure_counters(operation: str) -> None:
+    router: Final = Router(model_list=[])
+    usage: Final = router._core_usage_store
+    cooldowns: Final = router._core_cooldown_cache.cooldown_store
+    counters: Final = (UsageCounter("dep", "model", "12-34", "tpm"), UsageCounter("dep", "model", "12-34", "rpm"))
+    await usage.increment_deployment("dep", "model", "12-34", 7, 1, None)
+    assert await usage.async_batch_get(counters) == [7, 1]
+    assert cooldowns.increment_allowed_fails("dep", None, 30.0) == 1
+    getattr(router, operation)()
+    assert await usage.async_batch_get(counters) == [None, None]
+    assert cooldowns.increment_allowed_fails("dep", None, 30.0) == 1
+
+
+@pytest.mark.asyncio
+async def test_inside_a_request_deployment_increments_ride_its_native_post_call_batch_and_the_shutdown_drain():
+    handles: Final = Handles()
+    store: Final = RouterUsageStore(None, handle=handles)
+    natives: Final = FakeNatives()
+
+    await store.increment_deployment("dep", "model", "12-34", 7.5, 1, None)
+    with request_redis_batch_scope(post_call_deadline=60, native_factory=natives) as request:  # pyright: ignore[reportArgumentType]  # test double
+        await store.increment_deployment("dep", "model", "12-34", 2, 1, None)
+    await drain_post_call_redis_batches()
+
+    assert handles.built[0].requests == [None, request.native()]
+    assert natives.built[0].events == ["flush_post"]

tests/unit/router_strategy/test_complexity_router.py

@@ -15992,9 +15992,7 @@ class TestHealthFallbackDispatch:
                     {"primary-id": {"is_healthy": True, "timestamp": time.time()}}
                 )
             else:
-                router.cooldown_cache.cooldown_store.delete_cache(
-                    router.cooldown_cache.get_cooldown_cache_key("primary-id")
-                )
+                router.cooldown_cache.cooldown_store.evict_local("primary-id")
             recovered: Final[dict[str, object]] = {"session_id": "outage"}
             assert await self._request(router, surface, stream, recovered) == "primary"
             assert recovered["routing_decision"]["routed_model"] == "primary"
@@ -16170,9 +16168,7 @@ class TestHealthFallbackDispatch:
                     {"primary-id": {"is_healthy": True, "timestamp": time.time()}}
                 )
             else:
-                router.cooldown_cache.cooldown_store.delete_cache(
-                    router.cooldown_cache.get_cooldown_cache_key("primary-id")
-                )
+                router.cooldown_cache.cooldown_store.evict_local("primary-id")
             recovered: Final[dict[str, object]] = {"session_id": "pinned"}
             assert await self._request(router, "chat", False, recovered) == "primary"
             assert recovered["routing_decision"]["cause"] == "session_affinity_pin"

tests/unit/router_strategy/test_router_tag_routing.py

@@ -4,7 +4,6 @@
 
 import logging
 from typing import Final, Literal
-from unittest.mock import patch
 
 import pytest
 
@@ -1846,23 +1845,20 @@ async def test_tag_fail_open_survives_deployment_narrowing(
 ) -> None:
     router: Final = _fail_open_router(route=route)
     requested_model: Final = "chat" if route == "model" else "chat-test" if route == "wildcard" else "public-chat"
-    with patch("time.time", return_value=1_700_000_000.0):
-        if narrowing == "cooldown":
-            router.cooldown_cache.add_deployment_to_cooldown(
-                model_id="opted-in",
-                original_exception=RuntimeError("unavailable"),
-                exception_status=500,
-                cooldown_time=60,
-            )
-        candidates: Final = await router.async_get_healthy_deployments(
-            model=requested_model,
-            request_kwargs={
-                "litellm_metadata": {"tags": list(tags), "inherited_tags": [], "user_api_key_team_id": "team-a"},
-                **(
-                    {"previous_response_id": _response_id_for_remaining_deployment()} if narrowing == "affinity" else {}
-                ),
-            },
+    if narrowing == "cooldown":
+        router.cooldown_cache.add_deployment_to_cooldown(
+            model_id="opted-in",
+            original_exception=RuntimeError("unavailable"),
+            exception_status=500,
+            cooldown_time=60,
         )
+    candidates: Final = await router.async_get_healthy_deployments(
+        model=requested_model,
+        request_kwargs={
+            "litellm_metadata": {"tags": list(tags), "inherited_tags": [], "user_api_key_team_id": "team-a"},
+            **({"previous_response_id": _response_id_for_remaining_deployment()} if narrowing == "affinity" else {}),
+        },
+    )
     assert isinstance(candidates, (list, tuple))
     assert tuple(deployment["model_info"]["id"] for deployment in candidates) == ("remaining",)
 

tests/unit/router_utils/pre_call_checks/test_session_id_affinity.py

@@ -21,6 +21,7 @@ from litellm.router_utils.pre_call_checks.deployment_affinity_check import (
 )
 
 
+
 def _repinning_router(enabled: bool | None = True) -> litellm.Router:
     return litellm.Router(
         model_list=[
@@ -100,7 +101,7 @@ async def test_session_repin_requires_opt_in_unavailable_original_and_success(
         assert await router.cache.async_get_cache(_repin_key()) == {"model_id": expected}
         assert await router.cache.async_get_cache(_repin_key("caller-2")) == {"model_id": "original"}
         assert await router.cache.async_get_cache(user_key) == {"model_id": "original"}
-        router.cooldown_cache.cooldown_store.flush_cache()
+        router.cooldown_cache.cooldown_store.evict_local("original")
         await _record_replacement_success(router, "other")
         assert await router.cache.async_get_cache(_repin_key()) == {"model_id": expected}
     finally:
@@ -129,7 +130,7 @@ async def test_concurrent_successful_replacements_keep_first_winner() -> None:
         await asyncio.gather(_record_replacement_success(router), _record_replacement_success(router, "other"))
         winner: Final = await router.cache.async_get_cache(_repin_key())
         assert winner in ({"model_id": "replacement"}, {"model_id": "other"})
-        router.cooldown_cache.cooldown_store.flush_cache()
+        router.cooldown_cache.cooldown_store.evict_local("original")
         await _record_replacement_success(router, "original")
         assert await router.cache.async_get_cache(_repin_key()) == winner
     finally:
@@ -320,49 +321,6 @@ async def test_unsuccessful_or_nested_response_envelopes_never_repin(response: M
         router.discard()
 
 
-class _ReadCountingCache(InMemoryCache):
-    def __init__(self) -> None:
-        super().__init__()
-        self.read_keys: tuple[str, ...] = ()
-
-    def get_cache(self, key: str, **kwargs: object) -> object:
-        self.read_keys += (key,)
-        return super().get_cache(key, **kwargs)
-
-
-@pytest.mark.parametrize("case", ["disabled", "no-session", "generated-session", "group-disabled", "active"])
-async def test_repin_cooldown_reads_are_limited_to_active_session_route(case: str) -> None:
-    router: Final = _repinning_router(case != "disabled")
-    reads: Final = _ReadCountingCache()
-    try:
-        router.cooldown_cache.cooldown_store.in_memory_cache = reads
-        callback: Final = next(cb for cb in router.optional_callbacks or () if isinstance(cb, DeploymentAffinityCheck))
-        if case == "group-disabled":
-            callback.model_group_affinity_config = {"repin-group": []}
-        await router._repin_session_after_success(
-            {
-                "model_info": {"id": "replacement"},
-                "metadata": {
-                    "deployment_model_name": "repin-group",
-                    **({"session_id": "repin-session"} if case != "no-session" else {}),
-                    SESSION_ID_GENERATED_METADATA_KEY: case == "generated-session",
-                },
-            },
-            {"status": "completed"},
-        )
-        expected: Final = (
-            {
-                router.cooldown_cache.get_cooldown_cache_key(model_id)
-                for model_id in ("original", "replacement", "other")
-            }
-            if case == "active"
-            else set()
-        )
-        assert set(reads.read_keys) == expected
-    finally:
-        router.discard()
-
-
 class MockResponse:
     def __init__(self, json_data, status_code):
         self._json_data = json_data

tests/unit/router_utils/test_cooldown_cache.py

@@ -1,629 +1,43 @@
-"""
-Unit tests for CooldownCache exception masking functionality
-"""
-
 import time
-from unittest.mock import MagicMock
+from typing import Final
 
 import pytest
 
-# Add the parent directory to the system path
-from litellm._internal_context import current_service_target
-from litellm.caching.dual_cache import DualCache
-from litellm.caching.in_memory_cache import InMemoryCache
-from litellm.litellm_core_utils.sensitive_data_masker import SensitiveDataMasker
-from litellm.router_utils.cooldown_cache import CooldownCache, CooldownCacheValue
+from litellm.redis.stores.router_cooldowns import RouterCooldownStore
+from litellm.router_utils.cooldown_cache import CooldownCache
 
-
-class TestCooldownCacheExceptionMasking:
-    """Test suite for CooldownCache exception masking functionality"""
-
-    @pytest.fixture
-    def cooldown_cache(self):
-        """Create a CooldownCache instance for testing"""
-        mock_dual_cache = MagicMock(spec=DualCache)
-        return CooldownCache(cache=mock_dual_cache, default_cooldown_time=60.0)
-
-    def test_exception_masker_initialization(self, cooldown_cache):
-        """Test that the exception masker is properly initialized"""
-        assert isinstance(cooldown_cache.exception_masker, SensitiveDataMasker)
-        assert cooldown_cache.exception_masker.visible_prefix == 50
-        assert cooldown_cache.exception_masker.visible_suffix == 0
-        assert cooldown_cache.exception_masker.mask_char == "*"
-
-    def test_short_exception_string_not_masked(self, cooldown_cache):
-        """Test that short exception strings are not masked"""
-        short_exception = "Short error"
-        model_id = "test-model"
-        exception_status = 500
-        cooldown_time = 30.0
-
-        cooldown_key, cooldown_data = cooldown_cache._common_add_cooldown_logic(
-            model_id=model_id,
-            original_exception=Exception(short_exception),
-            exception_status=exception_status,
-            cooldown_time=cooldown_time,
+@pytest.mark.parametrize("message", ("Short error", "Rate limit " + "secret" * 100))
+@pytest.mark.parametrize("ttl", (None, 5.5, 30.0))
+def test_cooldown_masks_exception_and_preserves_status_timestamp_and_ttl(message: str, ttl: float | None) -> None:
+    now: Final = time.time()
+    store: Final = RouterCooldownStore(None)
+    cache: Final = CooldownCache(store, default_cooldown_time=60.0, clock=lambda: now)
+    cache.add_deployment_to_cooldown("dep", Exception(message), 429, ttl)
+    expected_ttl: Final = 60.0 if ttl is None else ttl
+    expected_message: Final = message if len(message) <= 50 else message[:50] + "*" * (len(message) - 50)
+    assert cache.get_active_cooldowns(["dep"], None) == [
+        (
+            "dep",
+            {
+                "exception_received": expected_message,
+                "status_code": "429",
+                "timestamp": now,
+                "cooldown_time": expected_ttl,
+            },
         )
-
-        # Short exception should not be masked
-        assert cooldown_data["exception_received"] == short_exception
-        assert cooldown_key == f"deployment:{model_id}:cooldown"
-
-    def test_long_exception_string_masked(self, cooldown_cache):
-        """Test that long exception strings are properly masked"""
-        # Create a long exception string that simulates prompt leakage
-        long_exception = (
-            "litellm.proxy.proxy_server._handle_llm_api_exception(): Exception occurred - "
-            "No deployments available for selected model, Try again in 5 seconds. "
-            "Passed model=anthropic_claude_sonnet_4_v1_0. pre-call-checks=False, "
-            "cooldown_list=[('deepseek_r1-eastus', {'exception_received': "
-            "'litellm.RateLimitError: RateLimitError: Azure_aiException - "
-            '{"error":{"code":"Invalid input","status":422,"message":"invalid input error",'
-            '"details":[{"type":"model_attributes_type","loc":["body"],'
-            '"msg":"Tell me a story about a dragon and a princess in a magical kingdom '
-            "where the dragon is actually protecting the princess from an evil wizard "
-            'who wants to steal her magical powers and use them to conquer the world"}]}'
-        )
-
-        model_id = "test-model"
-        exception_status = 429
-        cooldown_time = 60.0
-
-        cooldown_key, cooldown_data = cooldown_cache._common_add_cooldown_logic(
-            model_id=model_id,
-            original_exception=Exception(long_exception),
-            exception_status=exception_status,
-            cooldown_time=cooldown_time,
-        )
-
-        masked_exception = cooldown_data["exception_received"]
-
-        # Should start with first 50 characters
-        assert masked_exception.startswith(long_exception[:50])
-
-        # Should contain masking characters
-        assert "*" in masked_exception
-
-        # Should be same length (prefix + asterisks)
-        assert len(masked_exception) == len(long_exception)
-
-        # Should not contain the sensitive prompt content
-        assert "Tell me a story about a dragon" not in masked_exception
-        assert "magical kingdom" not in masked_exception
-
-        # Should preserve the error type information at the beginning (first 50 chars)
-        assert masked_exception.startswith("litellm.proxy.proxy_server._handle_llm_api_excepti")
-
-    def test_exception_with_api_keys_masked(self, cooldown_cache):
-        """Test that API keys in exceptions are properly masked"""
-        exception_with_key = (
-            "Authentication failed with api_key=sk-9876567890abcdefghijklmnopqrstuvwxyz "
-            "and token=bearer_token_123456789 for model gpt-4"
-        )
-
-        model_id = "test-model"
-        exception_status = 401
-        cooldown_time = 30.0
-
-        cooldown_key, cooldown_data = cooldown_cache._common_add_cooldown_logic(
-            model_id=model_id,
-            original_exception=Exception(exception_with_key),
-            exception_status=exception_status,
-            cooldown_time=cooldown_time,
-        )
-
-        masked_exception = cooldown_data["exception_received"]
-
-        # Should mask the sensitive content while preserving structure
-        assert masked_exception.startswith("Authentication failed with api_key=sk-98765678")
-        assert "*" in masked_exception
-        assert len(masked_exception) == len(exception_with_key)
-
-    def test_cooldown_data_structure(self, cooldown_cache):
-        """Test that the cooldown data structure is correctly formed"""
-        exception_msg = "Test exception for structure validation"
-        model_id = "test-model"
-        exception_status = 500
-        cooldown_time = 45.0
-
-        cooldown_key, cooldown_data = cooldown_cache._common_add_cooldown_logic(
-            model_id=model_id,
-            original_exception=Exception(exception_msg),
-            exception_status=exception_status,
-            cooldown_time=cooldown_time,
-        )
-
-        # Verify cooldown data structure
-        assert isinstance(cooldown_data, dict)
-        assert "exception_received" in cooldown_data
-        assert "status_code" in cooldown_data
-        assert "timestamp" in cooldown_data
-        assert "cooldown_time" in cooldown_data
-
-        # Verify data types
-        assert isinstance(cooldown_data["exception_received"], str)
-        assert isinstance(cooldown_data["status_code"], str)
-        assert isinstance(cooldown_data["timestamp"], float)
-        assert isinstance(cooldown_data["cooldown_time"], float)
-
-        # Verify values
-        assert cooldown_data["status_code"] == str(exception_status)
-        assert cooldown_data["cooldown_time"] == cooldown_time
-        assert cooldown_data["exception_received"] == exception_msg
-
-    def test_exception_object_conversion(self, cooldown_cache):
-        """Test that different exception types are properly converted to strings"""
-        # Test with different exception types
-        exceptions = [
-            ValueError("Invalid value provided"),
-            KeyError("Missing required key"),
-            RuntimeError("Runtime error occurred"),
-            Exception("Generic exception"),
-        ]
-
-        for exc in exceptions:
-            model_id = f"test-model-{exc.__class__.__name__}"
-
-            cooldown_key, cooldown_data = cooldown_cache._common_add_cooldown_logic(
-                model_id=model_id,
-                original_exception=exc,
-                exception_status=500,
-                cooldown_time=30.0,
-            )
-
-            # Should successfully convert exception to string
-            assert isinstance(cooldown_data["exception_received"], str)
-            assert str(exc) == cooldown_data["exception_received"]  # Short exceptions not masked
-
-    def test_masking_preserves_error_debugging_info(self, cooldown_cache):
-        """Test that masking preserves essential debugging information"""
-        debugging_exception = (
-            "RateLimitError: Rate limit exceeded for model gpt-4. "
-            "Current usage: 1000 tokens/minute. Limit: 500 tokens/minute. "
-            "Request details: model=gpt-4, user_id=user123, "
-            "prompt='Write a comprehensive analysis of the economic implications "
-            "of artificial intelligence adoption in the healthcare sector, including "
-            "potential cost savings, job displacement, and regulatory challenges'"
-        )
-
-        model_id = "gpt-4-deployment"
-        exception_status = 429
-        cooldown_time = 120.0
-
-        cooldown_key, cooldown_data = cooldown_cache._common_add_cooldown_logic(
-            model_id=model_id,
-            original_exception=Exception(debugging_exception),
-            exception_status=exception_status,
-            cooldown_time=cooldown_time,
-        )
-
-        masked_exception = cooldown_data["exception_received"]
-
-        # Should preserve error type and initial debugging info (first 50 chars)
-        assert masked_exception.startswith("RateLimitError: Rate limit exceeded for model gpt-")
-
-        # Should mask the prompt content
-        assert "Write a comprehensive analysis" not in masked_exception
-        assert "healthcare sector" not in masked_exception
-
-        # Should contain masking indicator
-        assert "*" in masked_exception
-
-    def test_error_handling_in_common_add_cooldown_logic(self, cooldown_cache):
-        """Test error handling in the _common_add_cooldown_logic method"""
-        # This test ensures that edge cases are properly handled
-        model_id = "test-model"
-
-        # Test with None exception (edge case) - should be handled gracefully
-        cooldown_key, cooldown_data = cooldown_cache._common_add_cooldown_logic(
-            model_id=model_id,
-            original_exception=None,
-            exception_status=500,
-            cooldown_time=30.0,
-        )
-
-        # Should handle None by converting to string
-        assert cooldown_data["exception_received"] == "None"
-        assert cooldown_key == f"deployment:{model_id}:cooldown"
-
-    def test_custom_masker_settings(self):
-        """Test that custom masker settings work correctly"""
-        mock_dual_cache = MagicMock(spec=DualCache)
-
-        # Create cooldown cache and verify default settings
-        cache = CooldownCache(cache=mock_dual_cache, default_cooldown_time=60.0)
-
-        # Test that we can access and verify the masker configuration
-        assert cache.exception_masker.visible_prefix == 50
-        assert cache.exception_masker.visible_suffix == 0
-        assert cache.exception_masker.mask_char == "*"
-
-        # Test masking behavior with these settings
-        long_string = "A" * 100  # 100 character string
-        masked = cache.exception_masker.mask_value(long_string)
-
-        # Should show first 50 characters, then all asterisks
-        expected = "A" * 50 + "*" * 50
-        assert masked == expected
-
-
-class TestCooldownCacheTTLCorrection:
-    def _make_cooldown_cache(self) -> CooldownCache:
-        in_memory = InMemoryCache()
-        dual_cache = DualCache(in_memory_cache=in_memory)
-        return CooldownCache(cache=dual_cache, default_cooldown_time=60.0)
-
-    def test_expired_entry_evicted_and_not_returned(self):
-        """
-        An entry with timestamp+cooldown_time in the past must be evicted from
-        in-memory cache and excluded from the active cooldown list.
-        """
-        cc = self._make_cooldown_cache()
-        model_id = "expired-deployment"
-        key = CooldownCache.get_cooldown_cache_key(model_id)
-
-        expired_value: CooldownCacheValue = {
-            "exception_received": "Rate limit",
-            "status_code": "429",
-            "timestamp": time.time() - 120.0,
-            "cooldown_time": 60.0,
-        }
-        cc.in_memory_cache.set_cache(key, expired_value, ttl=600)
-
-        active = cc.get_active_cooldowns(model_ids=[model_id], parent_otel_span=None)
-
-        assert active == [], "Expired cooldown entry must not appear in active cooldowns"
-        assert cc.in_memory_cache.get_cache(key) is None, "Expired entry must be evicted from in-memory cache"
-
-    def test_active_entry_is_returned(self):
-        """
-        An entry whose cooldown window has not elapsed must appear in the active list.
-        """
-        cc = self._make_cooldown_cache()
-        model_id = "active-deployment"
-        key = CooldownCache.get_cooldown_cache_key(model_id)
-
-        active_value: CooldownCacheValue = {
-            "exception_received": "Rate limit",
-            "status_code": "429",
-            "timestamp": time.time(),
-            "cooldown_time": 60.0,
-        }
-        cc.in_memory_cache.set_cache(key, active_value, ttl=60)
-
-        active = cc.get_active_cooldowns(model_ids=[model_id], parent_otel_span=None)
-
-        assert len(active) == 1
-        assert active[0][0] == model_id
-
-    def test_ttl_corrected_when_in_memory_expiry_far_exceeds_remaining(self):
-        """
-        When DualCache backfills from Redis using the default 600s TTL, the in-memory
-        TTL must be corrected to min(remaining, 60) seconds.
-        """
-        cc = self._make_cooldown_cache()
-        model_id = "backfilled-deployment"
-        key = CooldownCache.get_cooldown_cache_key(model_id)
-
-        remaining = 30.0
-        value: CooldownCacheValue = {
-            "exception_received": "Rate limit",
-            "status_code": "429",
-            "timestamp": time.time() - (60.0 - remaining),
-            "cooldown_time": 60.0,
-        }
-        cc.in_memory_cache.set_cache(key, value, ttl=600)
-
-        before_expiry = cc.in_memory_cache.ttl_dict.get(key)
-        assert before_expiry is not None
-
-        cc.get_active_cooldowns(model_ids=[model_id], parent_otel_span=None)
-
-        after_expiry = cc.in_memory_cache.ttl_dict.get(key)
-        assert after_expiry is not None
-        corrected_remaining = after_expiry - time.time()
-        assert corrected_remaining <= 60.0, "Corrected TTL must not exceed 60s"
-        assert corrected_remaining > 0, "Corrected TTL must be positive (cooldown still active)"
-
-    @pytest.mark.asyncio
-    async def test_async_expired_entry_evicted(self):
-        """
-        Async path must also evict expired entries.
-        """
-        cc = self._make_cooldown_cache()
-        model_id = "async-expired"
-        key = CooldownCache.get_cooldown_cache_key(model_id)
-
-        expired_value: CooldownCacheValue = {
-            "exception_received": "Rate limit",
-            "status_code": "429",
-            "timestamp": time.time() - 120.0,
-            "cooldown_time": 60.0,
-        }
-        cc.in_memory_cache.set_cache(key, expired_value, ttl=600)
-
-        active = await cc.async_get_active_cooldowns(model_ids=[model_id], parent_otel_span=None)
-
-        assert active == [], "Expired entry must not appear in async active cooldowns"
-        assert cc.in_memory_cache.get_cache(key) is None
-
-    @pytest.mark.asyncio
-    async def test_async_active_entry_is_returned(self):
-        """
-        Async counterpart of test_active_entry_is_returned: an entry whose cooldown
-        window has not elapsed must appear in the async active list too.
-        """
-        cc = self._make_cooldown_cache()
-        model_id = "async-active-deployment"
-        key = CooldownCache.get_cooldown_cache_key(model_id)
-
-        active_value: CooldownCacheValue = {
-            "exception_received": "Rate limit",
-            "status_code": "429",
-            "timestamp": time.time(),
-            "cooldown_time": 60.0,
-        }
-        cc.in_memory_cache.set_cache(key, active_value, ttl=60)
-
-        active = await cc.async_get_active_cooldowns(model_ids=[model_id], parent_otel_span=None)
-
-        assert len(active) == 1
-        assert active[0][0] == model_id
-
-
-class TestCorrectedActiveCooldown:
-    def _make_cooldown_cache(self) -> CooldownCache:
-        in_memory = InMemoryCache()
-        dual_cache = DualCache(in_memory_cache=in_memory)
-        return CooldownCache(cache=dual_cache, default_cooldown_time=60.0)
-
-    def _entry(self, timestamp: float, cooldown_time: float) -> CooldownCacheValue:
-        return CooldownCacheValue(
-            exception_received="Rate limit",
-            status_code="429",
-            timestamp=timestamp,
-            cooldown_time=cooldown_time,
-        )
-
-    def test_expired_entry_returns_none_and_evicts(self):
-        cc = self._make_cooldown_cache()
-        key = "deployment:expired-dep:cooldown"
-        entry = self._entry(timestamp=time.time() - 120.0, cooldown_time=60.0)
-        cc.in_memory_cache.set_cache(key, dict(entry), ttl=600)
-
-        result = cc._corrected_active_cooldown(key, dict(entry), current_time=time.time())
-
-        assert result is None
-        assert cc.in_memory_cache.get_cache(key) is None
-
-    def test_active_entry_within_window_returns_value(self):
-        cc = self._make_cooldown_cache()
-        key = "deployment:active-dep:cooldown"
-        entry = self._entry(timestamp=time.time(), cooldown_time=60.0)
-        cc.in_memory_cache.set_cache(key, dict(entry), ttl=60)
-
-        result = cc._corrected_active_cooldown(key, dict(entry), current_time=time.time())
-
-        assert result is not None
-        assert result["status_code"] == "429"
-
-    def test_inflated_ttl_is_corrected(self):
-        cc = self._make_cooldown_cache()
-        key = "deployment:backfilled-dep:cooldown"
-        remaining = 30.0
-        entry = self._entry(timestamp=time.time() - (60.0 - remaining), cooldown_time=60.0)
-        cc.in_memory_cache.set_cache(key, dict(entry), ttl=600)
-
-        result = cc._corrected_active_cooldown(key, dict(entry), current_time=time.time())
-
-        assert result is not None
-        corrected_expiry = cc.in_memory_cache.ttl_dict.get(key)
-        assert corrected_expiry is not None
-        assert corrected_expiry - time.time() <= 60.0
-
-    def test_normal_ttl_not_modified(self):
-        cc = self._make_cooldown_cache()
-        key = "deployment:normal-dep:cooldown"
-        entry = self._entry(timestamp=time.time(), cooldown_time=60.0)
-        cc.in_memory_cache.set_cache(key, dict(entry), ttl=60)
-        original_expiry = cc.in_memory_cache.ttl_dict.get(key)
-
-        cc._corrected_active_cooldown(key, dict(entry), current_time=time.time())
-
-        after_expiry = cc.in_memory_cache.ttl_dict.get(key)
-        assert after_expiry == original_expiry
-
-
-class SharedRedisDouble:
-    """
-    In-process stand-in for RedisCache, shared by several DualCache instances so that
-    tests can model two proxy replicas talking to one Redis.
-    """
-
-    def __init__(self) -> None:
-        self.store: dict = {}  # mutable-ok: stands in for Redis' own mutable keyspace
-
-    def set_cache(self, key, value, **kwargs):
-        self.store[key] = value
-
-    async def async_set_cache(self, key, value, **kwargs):
-        self.store[key] = value
-
-    def batch_get_cache(self, key_list, parent_otel_span=None, **kwargs):
-        return {key: self.store.get(key) for key in key_list}
-
-    async def async_batch_get_cache(self, key_list, parent_otel_span=None, **kwargs):
-        return {key: self.store.get(key) for key in key_list}
-
-
-class TestCooldownPropagationBetweenReplicas:
-    """
-    A cooldown written by one replica has to reach its siblings quickly. The router's own
-    DualCache re-reads a key that is missing from memory only every 10s, so cooldown reads
-    get their own cache with a much shorter Redis read interval.
-    """
-
-    def _make_replica(self, redis: SharedRedisDouble, read_interval: float | None = None) -> CooldownCache:
-        router_cache = DualCache(in_memory_cache=InMemoryCache(), redis_cache=redis)
-        if read_interval is None:
-            return CooldownCache(cache=router_cache, default_cooldown_time=60.0)
-        return CooldownCache(
-            cache=router_cache,
-            default_cooldown_time=60.0,
-            redis_read_interval_seconds=read_interval,
-        )
-
-    @pytest.mark.asyncio
-    async def test_sibling_replica_sees_cooldown_within_configured_read_interval(self):
-        redis = SharedRedisDouble()
-        replica_a = self._make_replica(redis, read_interval=0.25)
-        replica_b = self._make_replica(redis, read_interval=0.25)
-        model_id = "shared-deployment"
-
-        assert await replica_b.async_get_active_cooldowns([model_id], parent_otel_span=None) == []
-
-        replica_a.add_deployment_to_cooldown(
-            model_id=model_id,
-            original_exception=Exception("Internal server error"),
-            exception_status=500,
-            cooldown_time=60.0,
-        )
-
-        time.sleep(0.3)
-
-        active = await replica_b.async_get_active_cooldowns([model_id], parent_otel_span=None)
-        assert [model_id] == [entry[0] for entry in active], (
-            "sibling replica must pick up a cooldown written by another replica within the read interval"
-        )
-
-    @pytest.mark.asyncio
-    async def test_sibling_replica_sees_cooldown_within_default_read_interval(self):
-        redis = SharedRedisDouble()
-        replica_a = self._make_replica(redis)
-        replica_b = self._make_replica(redis)
-        model_id = "default-interval-deployment"
-
-        assert await replica_b.async_get_active_cooldowns([model_id], parent_otel_span=None) == []
-
-        replica_a.add_deployment_to_cooldown(
-            model_id=model_id,
-            original_exception=Exception("Internal server error"),
-            exception_status=500,
-            cooldown_time=60.0,
-        )
-
-        time.sleep(1.2)
-
-        active = await replica_b.async_get_active_cooldowns([model_id], parent_otel_span=None)
-        assert [model_id] == [entry[0] for entry in active], (
-            "the shipped default read interval must let a sibling replica see a cooldown about a second later"
-        )
-
-    def test_sync_read_path_sees_sibling_cooldown_within_read_interval(self):
-        redis = SharedRedisDouble()
-        replica_a = self._make_replica(redis, read_interval=0.25)
-        replica_b = self._make_replica(redis, read_interval=0.25)
-        model_id = "sync-shared-deployment"
-
-        assert replica_b.get_active_cooldowns([model_id], parent_otel_span=None) == []
-
-        replica_a.add_deployment_to_cooldown(
-            model_id=model_id,
-            original_exception=Exception("Internal server error"),
-            exception_status=500,
-            cooldown_time=60.0,
-        )
-
-        time.sleep(0.3)
-
-        active = replica_b.get_active_cooldowns([model_id], parent_otel_span=None)
-        assert [model_id] == [entry[0] for entry in active]
-
-    @pytest.mark.asyncio
-    async def test_redis_attached_after_construction_is_still_used(self):
-        redis = SharedRedisDouble()
-        router_cache = DualCache(in_memory_cache=InMemoryCache())
-        writer = CooldownCache(cache=router_cache, default_cooldown_time=60.0, redis_read_interval_seconds=0.25)
-        router_cache.attach_redis_cache(redis)
-        reader = self._make_replica(redis, read_interval=0.25)
-        model_id = "late-redis-deployment"
-
-        writer.add_deployment_to_cooldown(
-            model_id=model_id,
-            original_exception=Exception("Internal server error"),
-            exception_status=500,
-            cooldown_time=60.0,
-        )
-
-        active = await reader.async_get_active_cooldowns([model_id], parent_otel_span=None)
-        assert [model_id] == [entry[0] for entry in active], (
-            "a router that wires Redis after building its cooldown cache must still publish cooldowns to it"
-        )
-
-
-class TestCooldownSurvivesUnrelatedCacheTraffic:
-    @pytest.mark.asyncio
-    async def test_unrelated_router_cache_writes_do_not_evict_active_cooldown(self):
-        router_cache = DualCache(in_memory_cache=InMemoryCache())
-        cc = CooldownCache(cache=router_cache, default_cooldown_time=60.0)
-        model_id = "busy-router-deployment"
-
-        cc.add_deployment_to_cooldown(
-            model_id=model_id,
-            original_exception=Exception("Internal server error"),
-            exception_status=500,
-            cooldown_time=30.0,
-        )
-
-        for i in range(400):
-            router_cache.set_cache(key=f"unrelated-router-key-{i}", value={"n": i})
-
-        active = await cc.async_get_active_cooldowns([model_id], parent_otel_span=None)
-        assert [model_id] == [entry[0] for entry in active], (
-            "unrelated router cache traffic must not evict a cooldown that is still running"
-        )
-
-
-class TestCooldownStoreCallsDeclareTheirKeyFamily:
-    """Every cooldown store call runs inside ``service_target("router_cooldowns")`` so the
-    Redis service spans read ``redis.set router_cooldowns`` / ``redis.mget router_cooldowns``,
-    the sync paths included (the async MGET already did)."""
-
-    def _cooldown_cache_with_recording_store(self, seen: list[tuple[str, str | None]]) -> CooldownCache:
-        cc = CooldownCache(cache=DualCache(in_memory_cache=InMemoryCache()), default_cooldown_time=60.0)
-        store = MagicMock()
-
-        def _set_cache(**_kwargs):
-            seen.append(("set", current_service_target()))
-
-        def _batch_get_cache(**_kwargs):
-            seen.append(("mget", current_service_target()))
-            return []
-
-        store.set_cache.side_effect = _set_cache
-        store.batch_get_cache.side_effect = _batch_get_cache
-        cc._cooldown_store = store
-        return cc
-
-    def test_sync_cooldown_write_runs_under_router_cooldowns(self):
-        seen: list[tuple[str, str | None]] = []
-        cc = self._cooldown_cache_with_recording_store(seen)
-
-        cc.add_deployment_to_cooldown(
-            model_id="dep-1",
-            original_exception=Exception("Internal server error"),
-            exception_status=500,
-            cooldown_time=30.0,
-        )
-
-        assert seen == [("set", "router_cooldowns")]
-        assert current_service_target() is None
-
-    def test_sync_cooldown_reads_run_under_router_cooldowns(self):
-        seen: list[tuple[str, str | None]] = []
-        cc = self._cooldown_cache_with_recording_store(seen)
-
-        assert cc.get_active_cooldowns(["dep-1"], parent_otel_span=None) == []
-        assert cc.get_min_cooldown(["dep-1"], parent_otel_span=None) == 60.0
-
-        assert seen == [("mget", "router_cooldowns"), ("mget", "router_cooldowns")]
+    ]
+
+
+@pytest.mark.asyncio
+async def test_sync_and_async_router_cooldown_surfaces_share_active_state() -> None:
+    now: Final = time.time()
+    store: Final = RouterCooldownStore(None)
+    cache: Final = CooldownCache(store, default_cooldown_time=60.0, clock=lambda: now)
+    cache.add_deployment_to_cooldown("dep", Exception("unavailable"), 503, 30.0)
+    expected: Final = [
+        ("dep", {"exception_received": "unavailable", "status_code": "503", "timestamp": now, "cooldown_time": 30.0})
+    ]
+    assert cache.get_active_cooldowns(["absent", "dep"], None) == expected
+    assert await cache.async_get_active_cooldowns(["absent", "dep"], None) == expected
+    assert cache.get_min_cooldown(["dep"], None) == 30.0
+    assert cache.get_min_cooldown(["absent"], None) == 60.0

tests/unit/router_utils/test_cooldown_handlers.py

@@ -16,10 +16,11 @@ import respx
 
 import litellm
 from litellm import Router
-from litellm._internal_context import current_service_target
 from litellm.caching.dual_cache import DualCache
 from litellm.caching.in_memory_cache import InMemoryCache
+from litellm.caching.redis_cache import RedisCache
 from litellm.litellm_core_utils.litellm_logging import mask_api_base_credentials
+from litellm.redis.stores.router_cooldowns import RouterCooldowns, RouterCooldownStore
 from litellm.router_api import RoutingContext
 from litellm.router_utils.cooldown_cache import CooldownCache, CooldownCacheValue
 from litellm.router_utils.cooldown_callbacks import router_cooldown_event_callback
@@ -27,7 +28,6 @@ from litellm.router_utils.cooldown_handlers import (
     _get_deployment_cooldown_policy,
     _has_explicit_allowed_fails_policy_for_exception,
     _has_fallback_group,
-    _increment_allowed_fails,
     _is_cooldown_required,
     _resolve_allowed_fails_from_policy,
     _should_cooldown_based_on_deployment_policy,
@@ -74,6 +74,7 @@ def _ctx_double(
     ctx.settings.return_value.allowed_fails_policy = None
     ctx.settings.return_value.allowed_fails_for.return_value = None
     ctx.health.return_value.store = store if store is not None else DualCache(in_memory_cache=InMemoryCache())
+    ctx.health.return_value.cooldowns = CooldownCache(RouterCooldownStore(None), cooldown_time)
     return ctx
 
 
@@ -360,85 +361,42 @@ class TestShouldCooldownBasedOnDeploymentPolicy:
 
 
 class TestShouldCooldownBasedOnAllowedFailsPolicy:
-    def _make_router(self, cooldown_time: float = 60.0, cache: DualCache | MagicMock | None = None) -> MagicMock:
-        return _ctx_double(cooldown_time=cooldown_time, allowed_fails=0, store=cache)
+    def _make_router(self, cooldown_time: float = 60.0, store: RouterCooldowns | None = None) -> MagicMock:
+        ctx: Final = _ctx_double(cooldown_time=cooldown_time, allowed_fails=0)
+        ctx.health.return_value.cooldowns = CooldownCache(store or RouterCooldownStore(None), cooldown_time)
+        return ctx
 
     def test_cooldown_time_override_zero_is_not_falsy(self):
-        """cooldown_time_override=0 must be honored; it must not fall through to the router-level value."""
-        store = MagicMock()
-        store.increment_cache.return_value = 1
-        ctx = self._make_router(cooldown_time=60.0, cache=store)
-        exc = litellm.RateLimitError("429", "openai", "gpt-4")
-
-        should_cooldown_based_on_allowed_fails_policy(
-            ctx=ctx,
-            deployment="dep-1",
-            original_exception=exc,
-            allowed_fails_override=5,
-            cooldown_time_override=0.0,
-        )
-
-        increment_call = store.increment_cache.call_args
-        assert increment_call is not None
-        assert increment_call[1]["ttl"] == 0.0, (
-            "cooldown_time_override=0 should be used as TTL, not the router-level 60.0"
+        store: Final = MagicMock(spec=RouterCooldowns)
+        store.increment_allowed_fails.return_value = 1
+        ctx: Final = self._make_router(cooldown_time=60.0, store=store)
+        exc: Final = litellm.RateLimitError("429", "openai", "gpt-4")
+        assert not should_cooldown_based_on_allowed_fails_policy(
+            ctx=ctx, deployment="dep-1", original_exception=exc, allowed_fails_override=5, cooldown_time_override=0.0
         )
+        store.increment_allowed_fails.assert_called_once_with("dep-1", None, 0.0)
 
     def test_fail_counter_is_shared_across_router_instances(self):
-        """Two workers (two Router objects over one shared cache) must pool their failures toward allowed_fails."""
-        shared_cache = DualCache(in_memory_cache=InMemoryCache())
-        workers = (self._make_router(cache=shared_cache), self._make_router(cache=shared_cache))
-        exc = litellm.AuthenticationError("401", "openai", "gpt-4")
-
-        results = [
+        shared: Final = RouterCooldownStore(None)
+        workers: Final = tuple(self._make_router(store=shared) for _ in range(2))
+        exc: Final = litellm.AuthenticationError("401", "openai", "gpt-4")
+        results: Final = [
             should_cooldown_based_on_allowed_fails_policy(
-                ctx=workers[i % 2],
-                deployment="dep-1",
-                original_exception=exc,
-                allowed_fails_override=5,
+                ctx=workers[i % 2], deployment="dep-1", original_exception=exc, allowed_fails_override=5
             )
             for i in range(6)
         ]
-
         assert results == [False, False, False, False, False, True]
-        assert shared_cache.get_cache(key="deployment:dep-1:allowed_fails") == 6
 
-    def test_fleet_wide_count_from_redis_decides_cooldown(self):
-        """The Redis (fleet-wide) count decides, even when this process has only seen one failure."""
-        redis_cache = MagicMock()
-        redis_cache.increment_cache.return_value = 6
-        router = self._make_router(cache=DualCache(in_memory_cache=InMemoryCache(), redis_cache=redis_cache))
-        exc = litellm.AuthenticationError("401", "openai", "gpt-4")
-
-        result = should_cooldown_based_on_allowed_fails_policy(
-            ctx=router,
-            deployment="dep-1",
-            original_exception=exc,
-            allowed_fails_override=5,
+    def test_fleet_wide_count_from_the_store_decides_cooldown(self):
+        store: Final = MagicMock(spec=RouterCooldowns)
+        store.increment_allowed_fails.return_value = 6
+        ctx: Final = self._make_router(store=store)
+        exc: Final = litellm.AuthenticationError("401", "openai", "gpt-4")
+        assert should_cooldown_based_on_allowed_fails_policy(
+            ctx=ctx, deployment="dep-1", original_exception=exc, allowed_fails_override=5
         )
-
-        assert result is True
-        redis_cache.increment_cache.assert_called_once_with("deployment:dep-1:allowed_fails", 1, ttl=60.0)
-
-    def test_redis_outage_falls_back_to_this_workers_count(self):
-        """When every Redis increment fails, the worker's own in-memory count must still cool the deployment down."""
-        redis_cache = MagicMock()
-        redis_cache.increment_cache.side_effect = ConnectionError("redis down")
-        router = self._make_router(cache=DualCache(in_memory_cache=InMemoryCache(), redis_cache=redis_cache))
-        exc = litellm.AuthenticationError("401", "openai", "gpt-4")
-
-        results = [
-            should_cooldown_based_on_allowed_fails_policy(
-                ctx=router,
-                deployment="dep-1",
-                original_exception=exc,
-                allowed_fails_override=5,
-            )
-            for _ in range(6)
-        ]
-
-        assert results == [False, False, False, False, False, True]
-        assert redis_cache.increment_cache.call_count == 6
+        store.increment_allowed_fails.assert_called_once_with("dep-1", None, 60.0)
 
 
 class TestRoutingGroupCooldownAlternatives:
@@ -586,38 +544,6 @@ class TestTeamModelCooldownAlternatives:
         )
 
 
-class TestIncrementAllowedFailsServiceTarget:
-    def test_fail_counter_bump_declares_the_router_cooldowns_key_family(self):
-        """The allowed_fails INCR is cooldown bookkeeping, so its service span must read
-        ``redis.incr router_cooldowns`` rather than a bare ``redis.incr``."""
-        seen: list[str | None] = []
-        cache = MagicMock(spec=DualCache)
-
-        def _increment(**_kwargs):
-            seen.append(current_service_target())
-            return 2
-
-        cache.increment_cache.side_effect = _increment
-
-        assert _increment_allowed_fails(cache, "deployment:dep-1:fails", ttl=60.0) == 2
-        assert seen == ["router_cooldowns"]
-        assert current_service_target() is None
-
-    def test_in_memory_fallback_reads_under_the_same_target(self):
-        seen: list[str | None] = []
-        cache = MagicMock(spec=DualCache)
-        cache.increment_cache.side_effect = ConnectionError("redis down")
-
-        def _get(**_kwargs):
-            seen.append(current_service_target())
-            return 4
-
-        cache.get_cache.side_effect = _get
-
-        assert _increment_allowed_fails(cache, "deployment:dep-1:fails", ttl=60.0) == 4
-        assert seen == ["router_cooldowns"]
-
-
 @pytest.fixture()
 def _vcr_outcome_gate(request, vcr):
     install_live_call_probe(request, vcr)
@@ -860,136 +786,57 @@ class TestExceptionTypeCountersTrackedIndependently:
         rate_limit_exc = litellm.RateLimitError("Rate limit", "openai", "gpt-4")
         ise = litellm.InternalServerError("Internal error", "openai", "gpt-4")
 
-        for _ in range(3):
+        assert [
             should_cooldown_based_on_allowed_fails_policy(
                 ctx=RoutingContext(router),
                 deployment="primary",
                 original_exception=rate_limit_exc,
-                allowed_fails_override=5,
+                allowed_fails_override=3,
                 cache_key_suffix="RateLimitError",
             )
-
-        rl_counter = router.cache.get_cache(key="deployment:primary:allowed_fails:RateLimitError") or 0
-        generic_counter = router.cache.get_cache(key="deployment:primary:allowed_fails:generic") or 0
-
-        assert rl_counter == 3, "RateLimitError counter should be 3"
-        assert generic_counter == 0, "generic counter must be untouched by RateLimitError increments"
-
-        should_cooldown_based_on_allowed_fails_policy(
+            for _ in range(3)
+        ] == [False, False, False]
+        assert not should_cooldown_based_on_allowed_fails_policy(
             ctx=RoutingContext(router),
             deployment="primary",
             original_exception=ise,
-            allowed_fails_override=5,
+            allowed_fails_override=1,
+            cache_key_suffix="generic",
+        )
+        assert not should_cooldown_based_on_allowed_fails_policy(
+            ctx=RoutingContext(router),
+            deployment="primary",
+            original_exception=rate_limit_exc,
+            allowed_fails_override=4,
+            cache_key_suffix="RateLimitError",
+        )
+        assert should_cooldown_based_on_allowed_fails_policy(
+            ctx=RoutingContext(router),
+            deployment="primary",
+            original_exception=ise,
+            allowed_fails_override=1,
             cache_key_suffix="generic",
         )
-
-        generic_counter_after = router.cache.get_cache(key="deployment:primary:allowed_fails:generic") or 0
-        rl_counter_after = router.cache.get_cache(key="deployment:primary:allowed_fails:RateLimitError") or 0
-
-        assert generic_counter_after == 1, "generic counter should now be 1"
-        assert rl_counter_after == 3, "RateLimitError counter must remain unchanged after InternalServerError"
 
 
 @pytest.mark.usefixtures("_vcr_outcome_gate", "setup_and_teardown")
 class TestCooldownCacheTTLCorrection:
-    def _make_cooldown_cache(self) -> CooldownCache:
-        in_memory = InMemoryCache()
-        dual_cache = DualCache(in_memory_cache=in_memory)
-        return CooldownCache(cache=dual_cache, default_cooldown_time=60.0)
-
-    def test_expired_entry_evicted_and_not_returned(self):
-        """
-        An entry with timestamp+cooldown_time in the past must be evicted from
-        in-memory cache and excluded from the active cooldown list.
-        """
-        cc = self._make_cooldown_cache()
-        model_id = "expired-deployment"
-        key = CooldownCache.get_cooldown_cache_key(model_id)
-
-        expired_value: CooldownCacheValue = {
-            "exception_received": "Rate limit",
-            "status_code": "429",
-            "timestamp": time.time() - 120.0,
-            "cooldown_time": 60.0,
-        }
-        cc.in_memory_cache.set_cache(key, expired_value, ttl=600)
-
-        active = cc.get_active_cooldowns(model_ids=[model_id], parent_otel_span=None)
-
-        assert active == [], "Expired cooldown entry must not appear in active cooldowns"
-        assert cc.in_memory_cache.get_cache(key) is None, "Expired entry must be evicted from in-memory cache"
-
-    def test_active_entry_is_returned(self):
-        """
-        An entry whose cooldown window has not elapsed must appear in the active list.
-        """
-        cc = self._make_cooldown_cache()
-        model_id = "active-deployment"
-        key = CooldownCache.get_cooldown_cache_key(model_id)
-
-        active_value: CooldownCacheValue = {
-            "exception_received": "Rate limit",
-            "status_code": "429",
-            "timestamp": time.time(),
-            "cooldown_time": 60.0,
-        }
-        cc.in_memory_cache.set_cache(key, active_value, ttl=60)
-
-        active = cc.get_active_cooldowns(model_ids=[model_id], parent_otel_span=None)
-
-        assert len(active) == 1
-        assert active[0][0] == model_id
-
-    def test_ttl_corrected_when_in_memory_expiry_far_exceeds_remaining(self):
-        """
-        When DualCache backfills from Redis using the default 600s TTL, the in-memory
-        TTL must be corrected to min(remaining, 60) seconds.
-        """
-        cc = self._make_cooldown_cache()
-        model_id = "backfilled-deployment"
-        key = CooldownCache.get_cooldown_cache_key(model_id)
-
-        remaining = 30.0
-        value: CooldownCacheValue = {
-            "exception_received": "Rate limit",
-            "status_code": "429",
-            "timestamp": time.time() - (60.0 - remaining),
-            "cooldown_time": 60.0,
-        }
-        cc.in_memory_cache.set_cache(key, value, ttl=600)
-
-        before_expiry = cc.in_memory_cache.ttl_dict.get(key)
-        assert before_expiry is not None
-
-        cc.get_active_cooldowns(model_ids=[model_id], parent_otel_span=None)
-
-        after_expiry = cc.in_memory_cache.ttl_dict.get(key)
-        assert after_expiry is not None
-        corrected_remaining = after_expiry - time.time()
-        assert corrected_remaining <= 60.0, "Corrected TTL must not exceed 60s"
-        assert corrected_remaining > 0, "Corrected TTL must be positive (cooldown still active)"
-
+    @pytest.mark.parametrize(("age", "active"), ((120.0, False), (0.0, True)))
+    @pytest.mark.parametrize("asynchronous", (False, True))
     @pytest.mark.asyncio
-    async def test_async_expired_entry_evicted(self):
-        """
-        Async path must also evict expired entries.
-        """
-        cc = self._make_cooldown_cache()
-        model_id = "async-expired"
-        key = CooldownCache.get_cooldown_cache_key(model_id)
-
-        expired_value: CooldownCacheValue = {
-            "exception_received": "Rate limit",
-            "status_code": "429",
-            "timestamp": time.time() - 120.0,
-            "cooldown_time": 60.0,
-        }
-        cc.in_memory_cache.set_cache(key, expired_value, ttl=600)
-
-        active = await cc.async_get_active_cooldowns(model_ids=[model_id], parent_otel_span=None)
-
-        assert active == [], "Expired entry must not appear in async active cooldowns"
-        assert cc.in_memory_cache.get_cache(key) is None
+    async def test_only_unexpired_cooldowns_are_returned(self, age: float, active: bool, asynchronous: bool):
+        store: Final = RouterCooldownStore(None)
+        cc: Final = CooldownCache(store, default_cooldown_time=60.0)
+        value: Final = CooldownCacheValue(
+            exception_received="Rate limit", status_code="429", timestamp=time.time() - age, cooldown_time=60.0
+        )
+        store.put("deployment", value, 600)
+        result: Final = (
+            await cc.async_get_active_cooldowns(("deployment",), None)
+            if asynchronous
+            else cc.get_active_cooldowns(("deployment",), None)
+        )
+        assert result == ([("deployment", value)] if active else [])
 
 
 @pytest.mark.usefixtures("_vcr_outcome_gate", "setup_and_teardown")
@@ -2202,7 +2049,6 @@ def test_increment_deployment_successes_for_current_minute_does_not_write_to_red
     """
     from litellm.caching.dual_cache import DualCache
     from litellm.caching.in_memory_cache import InMemoryCache
-    from litellm.caching.redis_cache import RedisCache
     from litellm.router_utils.router_callbacks.track_deployment_metrics import (
         increment_deployment_successes_for_current_minute,
     )
@@ -2700,7 +2546,6 @@ async def test_high_traffic_cooldowns_all_healthy_deployments():
             await asyncio.sleep(0.0001)
         except litellm.InternalServerError:
             model_stats[model_id]["failures"] += 1
-            pass
         except Exception as e:
             print("Failed test model stats=", model_stats)
             raise e
@@ -2794,7 +2639,6 @@ async def test_high_traffic_cooldowns_one_bad_deployment():
             await asyncio.sleep(0.0001)
         except litellm.InternalServerError:
             model_stats[model_id]["failures"] += 1
-            pass
         except Exception as e:
             print("Failed test model stats=", model_stats)
             raise e
@@ -2888,10 +2732,8 @@ async def test_high_traffic_cooldowns_one_rate_limited_deployment():
             await asyncio.sleep(0.0001)
         except litellm.InternalServerError:
             model_stats[model_id]["failures"] += 1
-            pass
         except litellm.RateLimitError:
             model_stats[bad_deployment_id]["failures"] += 1
-            pass
         except Exception as e:
             print("Failed test model stats=", model_stats)
             raise e

tests/unit/router_utils/test_health_check_allowed_fails_integration.py

@@ -6,6 +6,7 @@ should increment the same counters used by allowed_fails_policy, using the
 actual exception type from the health check error.
 """
 
+from typing import Final
 from unittest.mock import ANY, patch
 
 import pytest
@@ -146,30 +147,26 @@ class TestGetAllowedFailsFromPolicyWithHealthCheckExceptions:
 class TestHealthCheckCooldownIntegration:
     """Test that health check failures trigger cooldown via set_cooldown_deployments."""
 
-    def test_health_check_failure_increments_failed_calls(self):
-        """Health check failure should increment the failed_calls counter."""
+    def test_health_check_failure_increments_failed_calls(self) -> None:
         from litellm.router_utils.cooldown_handlers import (
             should_cooldown_based_on_allowed_fails_policy,
         )
 
-        router = Router(
+        router: Final = Router(
             model_list=[_make_model("deploy-1"), _make_model("deploy-2", "gpt-5")],
             allowed_fails_policy=AllowedFailsPolicy(TimeoutErrorAllowedFails=3),
         )
 
-        timeout_exc = litellm.Timeout(message="Health check timeout", model="gpt-4", llm_provider="openai")
-
-        # First call: should not cooldown (1 <= 3)
-        result = should_cooldown_based_on_allowed_fails_policy(
-            ctx=RoutingContext(router),
-            deployment="deploy-1",
-            original_exception=timeout_exc,
+        timeout_exc: Final = litellm.Timeout(message="Health check timeout", model="gpt-4", llm_provider="openai")
+        results: Final = tuple(
+            should_cooldown_based_on_allowed_fails_policy(
+                ctx=RoutingContext(router),
+                deployment="deploy-1",
+                original_exception=timeout_exc,
+            )
+            for _ in range(4)
         )
-        assert result is False
-
-        # Check counter was incremented
-        current_fails = router.health().store.get_cache(key="deployment:deploy-1:allowed_fails")
-        assert current_fails == 1
+        assert results == (False, False, False, True)
 
     def test_health_check_failure_triggers_cooldown_at_threshold(self):
         """After exceeding allowed_fails threshold, deployment should enter cooldown."""

tests/unit/router_utils/test_routing_read_batch.py

@@ -1,11 +1,10 @@
 """
-One Redis round trip per request for the router's pre-call reads.
-
-Before `RoutingReadBatch`, `async_get_available_deployment` issued one MGET for the cooldown keys
-(`CooldownCache`) and a second one for the tpm/rpm counters (`LowestTPMLoggingHandler_v2`).
+The router's pre-call reads. Cooldowns go through the native store, and the tpm/rpm selector
+counters (`LowestTPMLoggingHandler_v2`) ride one MGET on the Python Redis.
 """
 
 import time
+from collections.abc import Sequence
 from typing import Final
 from unittest.mock import AsyncMock, MagicMock
 
@@ -13,8 +12,17 @@ import pytest
 
 import litellm
 from litellm import Router
+from litellm.caching.redis_batch import request_redis_batch_scope
 from litellm.caching.redis_cache import RedisCache
+from litellm.redis.stores._connection import native_client
+from litellm.redis.stores.router_cooldowns import CooldownCacheValue, RouterCooldownStore
 from litellm.router_strategy.lowest_tpm_rpm_v2 import LowestTPMLoggingHandler_v2
+from litellm.router_utils import routing_prefetch
+from litellm.rust_bridge._native import NativeRedisClient
+from tests.unit.caching.test_redis_batch import FakeNativePending, FakeNativeRequest, FakeNatives
+from tests.unit.conftest import redis_cache_double
+from tests.unit.redis.stores.test_router_cooldowns import FakeCooldowns
+from tests.unit.redis.stores.test_router_cooldowns import Handles as CooldownHandles
 
 _MODEL_GROUP = "claude"
 _MESSAGES = [{"role": "user", "content": "ping"}]
@@ -34,7 +42,7 @@ def _redis_answering(values_by_key_prefix: dict[str, object]) -> MagicMock:
     def _mget(key_list, parent_otel_span=None):
         return {key: values_by_key_prefix.get(key.rsplit(":", 1)[0], values_by_key_prefix.get(key)) for key in key_list}
 
-    redis = MagicMock(spec=RedisCache)
+    redis = redis_cache_double()
     redis.async_batch_get_cache = AsyncMock(side_effect=_mget)
     return redis
 
@@ -55,18 +63,18 @@ def _redis_key_families(redis: MagicMock) -> list[list[str]]:
     ]
 
 
-def _cooldown(seconds: float) -> dict:
-    return {"exception_received": "429", "status_code": "429", "timestamp": time.time(), "cooldown_time": seconds}
+def _cool_down(router: Router, model_id: str, started: float) -> None:
+    router.cooldown_cache.cooldown_store.put(
+        model_id, {"exception_received": "429", "status_code": "429", "timestamp": started, "cooldown_time": 60}, 60
+    )
 
 
 @pytest.mark.asyncio
-async def test_usage_based_routing_reads_cooldowns_and_counters_in_one_redis_round_trip():
+async def test_usage_based_routing_reads_the_counters_in_one_python_redis_round_trip():
     redis = _redis_answering({})
     router = _router(redis, "usage-based-routing-v2")
 
-    deployment = await router.async_get_available_deployment(
-        model=_MODEL_GROUP, request_kwargs={}, messages=_MESSAGES
-    )
+    deployment = await router.async_get_available_deployment(model=_MODEL_GROUP, request_kwargs={}, messages=_MESSAGES)
 
     assert deployment["model_info"]["id"] in {"dep-a", "dep-b"}
     assert _redis_key_families(redis) == [
@@ -75,10 +83,8 @@ async def test_usage_based_routing_reads_cooldowns_and_counters_in_one_redis_rou
             "dep-a:anthropic/claude-x:tpm",
             "dep-b:anthropic/claude-x:rpm",
             "dep-b:anthropic/claude-x:tpm",
-            "deployment:dep-a:cooldown",
-            "deployment:dep-b:cooldown",
         ]
-    ], "cooldown state and usage counters must arrive in one MGET"
+    ], "the usage counters must arrive in one MGET, without cooldown keys"
 
 
 @pytest.mark.asyncio
@@ -114,21 +120,19 @@ async def test_usage_based_routing_still_batches_when_the_strategy_is_a_fixed_si
             "dep-a:anthropic/claude-x:tpm",
             "dep-b:anthropic/claude-x:rpm",
             "dep-b:anthropic/claude-x:tpm",
-            "deployment:dep-a:cooldown",
-            "deployment:dep-b:cooldown",
         ]
     ], "the subclassed strategy must still get the batched read, not a second MGET"
     router.cache.async_batch_get_cache.assert_not_awaited()
 
 
 @pytest.mark.asyncio
-async def test_simple_shuffle_still_reads_only_cooldowns():
+async def test_simple_shuffle_reads_nothing_from_the_python_redis():
     redis = _redis_answering({})
     router = _router(redis, "simple-shuffle")
 
     await router.async_get_available_deployment(model=_MODEL_GROUP, request_kwargs={}, messages=_MESSAGES)
 
-    assert _redis_key_families(redis) == [["deployment:dep-a:cooldown", "deployment:dep-b:cooldown"]]
+    assert _redis_key_families(redis) == []
 
 
 @pytest.mark.asyncio
@@ -153,18 +157,11 @@ async def test_batched_counters_pick_the_deployment_the_strategy_picks_reading_a
 
 @pytest.mark.asyncio
 async def test_batched_read_still_excludes_a_cooled_down_deployment():
-    redis = _redis_answering(
-        {
-            "dep-a:anthropic/claude-x:tpm": 100,
-            "dep-b:anthropic/claude-x:tpm": 10,
-            "deployment:dep-b:cooldown": _cooldown(seconds=60),
-        }
-    )
+    redis = _redis_answering({"dep-a:anthropic/claude-x:tpm": 100, "dep-b:anthropic/claude-x:tpm": 10})
     router = _router(redis, "usage-based-routing-v2")
+    _cool_down(router, "dep-b", started=time.time())
 
-    deployment = await router.async_get_available_deployment(
-        model=_MODEL_GROUP, request_kwargs={}, messages=_MESSAGES
-    )
+    deployment = await router.async_get_available_deployment(model=_MODEL_GROUP, request_kwargs={}, messages=_MESSAGES)
 
     assert deployment["model_info"]["id"] == "dep-a", "dep-b has the lowest tpm but is cooling down"
     assert redis.async_batch_get_cache.await_count == 1
@@ -172,25 +169,18 @@ async def test_batched_read_still_excludes_a_cooled_down_deployment():
 
 @pytest.mark.asyncio
 async def test_batched_read_ignores_an_expired_cooldown():
-    redis = _redis_answering(
-        {
-            "dep-a:anthropic/claude-x:tpm": 100,
-            "dep-b:anthropic/claude-x:tpm": 10,
-            "deployment:dep-b:cooldown": _cooldown(seconds=-1),
-        }
-    )
+    redis = _redis_answering({"dep-a:anthropic/claude-x:tpm": 100, "dep-b:anthropic/claude-x:tpm": 10})
     router = _router(redis, "usage-based-routing-v2")
+    _cool_down(router, "dep-b", started=time.time() - 61)
 
-    deployment = await router.async_get_available_deployment(
-        model=_MODEL_GROUP, request_kwargs={}, messages=_MESSAGES
-    )
+    deployment = await router.async_get_available_deployment(model=_MODEL_GROUP, request_kwargs={}, messages=_MESSAGES)
 
     assert deployment["model_info"]["id"] == "dep-b"
 
 
 @pytest.mark.asyncio
 async def test_a_failed_batched_read_degrades_like_the_two_failed_reads_did():
-    redis = MagicMock(spec=RedisCache)
+    redis = redis_cache_double()
     redis.async_batch_get_cache = AsyncMock(side_effect=ConnectionError("redis unavailable"))
     routed = _router(redis, "usage-based-routing-v2")
     alone = _router(redis, "usage-based-routing-v2")
@@ -204,17 +194,100 @@ async def test_a_failed_batched_read_degrades_like_the_two_failed_reads_did():
 
     assert str(routed_error.value) == str(alone_error.value)
     assert len(routed.cache.last_redis_batch_access_time) == 0, "a failed read must not throttle the next one"
-    assert len(routed.cooldown_cache.cooldown_store.last_redis_batch_access_time) == 0
 
 
 @pytest.mark.asyncio
 async def test_a_failed_batched_read_leaves_simple_shuffle_routing():
-    redis = MagicMock(spec=RedisCache)
+    redis = redis_cache_double()
     redis.async_batch_get_cache = AsyncMock(side_effect=ConnectionError("redis unavailable"))
     router = _router(redis, "simple-shuffle")
 
-    deployment = await router.async_get_available_deployment(
-        model=_MODEL_GROUP, request_kwargs={}, messages=_MESSAGES
-    )
+    deployment = await router.async_get_available_deployment(model=_MODEL_GROUP, request_kwargs={}, messages=_MESSAGES)
 
     assert deployment["model_info"]["id"] in {"dep-a", "dep-b"}
+
+
+def _armed_store() -> tuple[RouterCooldownStore, CooldownHandles]:
+    handles: Final = CooldownHandles()
+    store: Final = RouterCooldownStore(native_client(RedisCache(host="redis.internal")), handle=handles)
+    store.put("dep-a", {"exception_received": "429", "status_code": "429", "timestamp": 1.0, "cooldown_time": 60}, 60)
+    return store, handles
+
+
+@pytest.mark.asyncio
+async def test_routing_takes_the_armed_cooldown_read_from_the_native_batch_once_then_reads_on_its_own():
+    store, handles = _armed_store()
+    natives: Final = FakeNatives()
+
+    with request_redis_batch_scope(native_factory=natives):  # pyright: ignore[reportArgumentType]  # test double
+        routing_prefetch.arm_cooldowns(store, ["dep-a", "dep-b", "dep-c"])
+        armed: Final = routing_prefetch.armed()
+        first: Final = await routing_prefetch.read_cooldowns(store, ["dep-a", "dep-b"], None)
+        reads_after_first: Final = len(handles.built[0].targets)
+        second: Final = await routing_prefetch.read_cooldowns(store, ["dep-a", "dep-b"], None)
+
+    assert armed
+    assert handles.built[0].declared == [("dep-a", "dep-b", "dep-c")]
+    assert first == second == (("dep-a", store.snapshot()["dep-a"]),)
+    assert natives.built[0].events == ["flush_pre", "resolve"]
+    assert len(handles.built[0].targets) == reads_after_first + 1, "a second read goes to the store"
+
+
+@pytest.mark.asyncio
+async def test_an_armed_cooldown_read_that_does_not_cover_the_routing_ids_is_read_again():
+    store, _ = _armed_store()
+    natives: Final = FakeNatives()
+
+    with request_redis_batch_scope(native_factory=natives):  # pyright: ignore[reportArgumentType]  # test double
+        routing_prefetch.arm_cooldowns(store, ["dep-b"])
+        active: Final = await routing_prefetch.read_cooldowns(store, ["dep-a", "dep-b"], None)
+
+    assert active == (("dep-a", store.snapshot()["dep-a"]),)
+    assert natives.built[0].events == ["flush_pre", "resolve"]
+
+
+def _redis_down() -> list[tuple[str, CooldownCacheValue]]:
+    raise ConnectionError("redis down")
+
+
+class _UnreachableCooldowns(FakeCooldowns):
+    def declare_active(
+        self, request: FakeNativeRequest, model_ids: Sequence[str]
+    ) -> FakeNativePending[list[tuple[str, CooldownCacheValue]]]:
+        super().declare_active(request, model_ids)
+        return FakeNativePending(request, _redis_down)
+
+
+@pytest.mark.asyncio
+async def test_a_failed_armed_cooldown_read_falls_back_to_the_stores_own_read():
+    built: Final[list[FakeCooldowns]] = []
+
+    def unreachable(client: NativeRedisClient | None) -> FakeCooldowns:
+        built.append(_UnreachableCooldowns(client))
+        return built[-1]
+
+    store: Final = RouterCooldownStore(native_client(RedisCache(host="redis.internal")), handle=unreachable)
+    store.put("dep-a", {"exception_received": "429", "status_code": "429", "timestamp": 1.0, "cooldown_time": 60}, 60)
+
+    with request_redis_batch_scope(native_factory=FakeNatives()):  # pyright: ignore[reportArgumentType]  # test double
+        routing_prefetch.arm_cooldowns(store, ["dep-a"])
+        active: Final = await routing_prefetch.read_cooldowns(store, ["dep-a"], None)
+
+    assert built[0].declared == [("dep-a",)]
+    assert active == (("dep-a", store.snapshot()["dep-a"]),)
+
+
+def test_arming_the_cooldown_read_outside_a_request_or_without_redis_declares_nothing():
+    store, handles = _armed_store()
+    offline: Final = CooldownHandles()
+    natives: Final = FakeNatives()
+
+    routing_prefetch.arm_cooldowns(store, ["dep-a"])
+    with request_redis_batch_scope(native_factory=natives):  # pyright: ignore[reportArgumentType]  # test double
+        routing_prefetch.arm_cooldowns(RouterCooldownStore(None, handle=offline), ["dep-a"])
+        armed: Final = routing_prefetch.armed()
+
+    assert handles.built[0].declared == []
+    assert offline.built[0].declared == []
+    assert not armed
+    assert natives.built == []

tests/unit/rust_bridge/host/test_settings.py

@@ -4,6 +4,7 @@ import httpx
 import pytest
 
 import litellm
+from litellm.caching.dual_cache import DualCache
 from litellm.integrations.custom_secret_manager import CustomSecretManager
 from litellm.llms.custom_httpx.http_handler import default_user_agent
 from litellm.rust_bridge.host import settings
@@ -46,6 +47,26 @@ def test_http_settings_reads_the_litellm_globals(monkeypatch: pytest.MonkeyPatch
     )
 
 
+def test_router_tiers_read_the_env_constants_and_the_litellm_global(monkeypatch: pytest.MonkeyPatch) -> None:
+    import litellm.constants
+
+    monkeypatch.setattr(litellm.constants, "DEFAULT_COOLDOWN_REDIS_READ_INTERVAL_SECONDS", 2.5)
+    monkeypatch.setattr(litellm.constants, "DEFAULT_MAX_REDIS_BATCH_CACHE_SIZE", 42)
+    monkeypatch.setattr(litellm, "default_redis_batch_cache_expiry", 30.0)
+
+    assert settings.router_tiers() == settings.RouterTierSettings(
+        cooldown_redis_read_interval=2.5,
+        usage_redis_read_interval=30.0,
+        max_redis_batch_cache_size=42,
+    )
+
+
+def test_router_tiers_fall_back_to_dual_caches_ten_second_refresh(monkeypatch: pytest.MonkeyPatch) -> None:
+    monkeypatch.setattr(litellm, "default_redis_batch_cache_expiry", None)
+
+    assert settings.router_tiers().usage_redis_read_interval == DualCache().redis_batch_cache_expiry
+
+
 def test_http_settings_ignores_environment_overrides(monkeypatch: pytest.MonkeyPatch) -> None:
     monkeypatch.setenv("LITELLM_USER_AGENT", "operator/1")
     monkeypatch.setenv("SSL_VERIFY", "false")
@@ -114,9 +135,7 @@ def test_secret_manager_is_native_only_when_a_readable_system_is_configured(
     monkeypatch.setattr(litellm, "_key_management_system", system)
     monkeypatch.setattr(litellm, "_key_management_settings", KeyManagementSettings(access_mode=access_mode))
 
-    assert settings.secret_manager() == settings.SecretManager(
-        readable=access_mode != "write_only", native=native
-    )
+    assert settings.secret_manager() == settings.SecretManager(readable=access_mode != "write_only", native=native)
 
 
 def test_secret_manager_is_not_readable_without_a_client(monkeypatch: pytest.MonkeyPatch) -> None:

tests/unit/test_internal_context.py

@@ -32,6 +32,7 @@ _CACHE_PARAMETER_HELPERS: Final = frozenset(
         "litellm/llms/anthropic/prompt_cache_prediction.py",
         "litellm/proxy/common_utils/cache_coordinator.py",
         "litellm/proxy/common_utils/user_api_key_cache.py",
+        "litellm/router_utils/routing_prefetch.py",
         "litellm/utils.py",
     }
 )

tests/unit/test_router/test_router.py

@@ -105,6 +105,7 @@ from litellm.utils import _invalidate_model_cost_lowercase_map
 from tests._vcr_conftest_common import install_live_call_probe, record_vcr_outcome
 from tests.fake_openai_endpoint import FAKE_OPENAI_API_BASE
 from tests.large_text import text
+from tests.unit.conftest import redis_cache_double
 import traceback
 import inspect
 from typing import List, Optional
@@ -1410,17 +1411,6 @@ _BATCH_NOT_FOUND = {
 }
 
 
-async def _router_usage_keys(router, timeout: float = 2.0) -> list[str]:
-    loop = asyncio.get_event_loop()
-    deadline = loop.time() + timeout
-    while loop.time() < deadline:
-        keys = sorted(k for k in router.cache.in_memory_cache.cache_dict if k.startswith("global_router:"))
-        if keys:
-            return keys
-        await asyncio.sleep(0.05)
-    return []
-
-
 @pytest.mark.asyncio
 async def test_arouter_aretrieve_batch_does_not_consume_deployment_rate_limits(monkeypatch: pytest.MonkeyPatch):
     """
@@ -1467,11 +1457,13 @@ async def test_arouter_aretrieve_batch_does_not_consume_deployment_rate_limits(m
         )
         response = await router.aretrieve_batch(batch_id=_BATCH_ID)
         payload = await collector.retrieve_batch_payload()
-        usage_keys = await _router_usage_keys(router)
+        requested_usage: Final = await router.get_model_group_usage(_BATCH_GROUP)
+        unrelated_usage: Final = await router.get_model_group_usage(_UNRELATED_BATCH_GROUP)
 
     assert response.id == _BATCH_ID
     assert payload["model_group"] == _BATCH_GROUP
-    assert usage_keys == []
+    assert requested_usage == (None, None)
+    assert unrelated_usage == (None, None)
 
 
 @pytest.mark.parametrize(
@@ -15614,11 +15606,10 @@ class TestClaudeCodeSubagentSessionRouterBinding:
 
     @pytest.mark.asyncio
     async def test_redis_cleanup_failure_does_not_reject_a_subagent_request(self):
-        from litellm.caching.caching import RedisCache
 
         router = self._router()
         del router.complexity_routers["smart-router"]
-        redis_cache = MagicMock(spec=RedisCache)
+        redis_cache = redis_cache_double()
         redis_cache.async_get_cache = AsyncMock(return_value="smart-router")
         redis_cache.async_delete_cache = AsyncMock(side_effect=ConnectionError("redis unavailable"))
         router.update_redis_cache(cache=redis_cache)
@@ -15633,7 +15624,6 @@ class TestClaudeCodeSubagentSessionRouterBinding:
 
     @pytest.mark.asyncio
     async def test_redis_read_failure_does_not_reject_a_subagent_request(self):
-        from litellm.caching.caching import RedisCache
 
         router = self._router()
         request_kwargs = self._request_kwargs(agent_id="agent-1234")
@@ -15643,7 +15633,7 @@ class TestClaudeCodeSubagentSessionRouterBinding:
             cache_key,
             "smart-router",
         )
-        redis_cache = MagicMock(spec=RedisCache)
+        redis_cache = redis_cache_double()
         redis_cache.async_get_cache = AsyncMock(side_effect=Exception("Redis circuit breaker is open"))
         router.update_redis_cache(cache=redis_cache)
 
@@ -15658,10 +15648,9 @@ class TestClaudeCodeSubagentSessionRouterBinding:
 
     @pytest.mark.asyncio
     async def test_redis_write_failures_do_not_reject_main_or_subagent_requests(self):
-        from litellm.caching.caching import RedisCache
 
         router = self._router()
-        redis_cache = MagicMock(spec=RedisCache)
+        redis_cache = redis_cache_double()
         redis_cache.async_get_cache = AsyncMock(return_value="smart-router")
         redis_cache.async_set_cache = AsyncMock(side_effect=Exception("redis unavailable"))
         router.update_redis_cache(cache=redis_cache)
@@ -15685,10 +15674,9 @@ class TestClaudeCodeSubagentSessionRouterBinding:
     async def test_subagents_follow_the_main_threads_latest_router_across_workers(self):
         from types import SimpleNamespace
 
-        from litellm.caching.caching import RedisCache
 
         shared_binding = SimpleNamespace(value=None)
-        shared_redis = MagicMock(spec=RedisCache)
+        shared_redis = redis_cache_double()
         shared_redis.async_get_cache = AsyncMock(side_effect=lambda key, **_: shared_binding.value)
         shared_redis.async_set_cache = AsyncMock(
             side_effect=lambda key, value, **_: setattr(shared_binding, "value", value)
@@ -15716,11 +15704,10 @@ class TestClaudeCodeSubagentSessionRouterBinding:
 
     @pytest.mark.asyncio
     async def test_no_pre_routing_strategies_means_no_session_cache_traffic(self):
-        from litellm.caching.caching import RedisCache
 
         router = self._router()
         router.complexity_routers.clear()
-        redis_cache = MagicMock(spec=RedisCache)
+        redis_cache = redis_cache_double()
         redis_cache.async_get_cache = AsyncMock(return_value=None)
         redis_cache.async_set_cache = AsyncMock()
         redis_cache.async_delete_cache = AsyncMock()
@@ -24307,13 +24294,7 @@ def test_router_keeps_wif_secret_pointers_unresolved(monkeypatch):
 
 
 @pytest.mark.asyncio
-async def test_failure_rpm_increment_declares_the_router_usage_key_family():
-    """The RPM bump a failed call still earns is router usage bookkeeping, so its Redis span
-    reads ``redis.incr router_usage`` rather than a bare ``redis.incr``."""
-    from unittest.mock import AsyncMock
-
-    from litellm._internal_context import current_service_target
-
+async def test_a_failed_call_still_counts_one_rpm():
     router = Router(
         model_list=[
             {
@@ -24323,42 +24304,31 @@ async def test_failure_rpm_increment_declares_the_router_usage_key_family():
             }
         ]
     )
-    seen: list[str | None] = []
-
-    async def _increment(**_kwargs):
-        seen.append(current_service_target())
-
-    with patch.object(router.cache, "async_increment_cache", new=AsyncMock(side_effect=_increment)):
-        await router.async_deployment_callback_on_failure(
-            kwargs={
-                "call_type": "acompletion",
-                "litellm_params": {
-                    "metadata": {"deployment": "openai/gpt-4o", "model_group": "gpt-group"},
-                    "model_info": {"id": "dep-1"},
-                },
+    await router.async_deployment_callback_on_failure(
+        kwargs={
+            "call_type": "acompletion",
+            "litellm_params": {
+                "metadata": {"deployment": "openai/gpt-4o", "model_group": "gpt-group"},
+                "model_info": {"id": "dep-1"},
             },
-            completion_response=None,
-            start_time=None,
-            end_time=None,
-        )
+        },
+        completion_response=None,
+        start_time=None,
+        end_time=None,
+    )
 
-    assert seen == ["router_usage"]
-    assert current_service_target() is None
+    assert _usage_by_kind(router) == {"rpm": 1}
 
-class _SpanRecordingInMemoryCache(InMemoryCache):
-    """Records the live OTel span each read runs under, so the test sees what a Redis span would nest in."""
 
-    def __init__(self) -> None:
-        super().__init__()
-        self.active_span_names: list[str] = []
+def _usage_by_kind(router: Router) -> dict[str, float]:
+    return {key.rsplit(":", 2)[-2]: value for key, value in router._core_usage_store.snapshot().items()}
 
-    async def async_batch_get_cache(self, keys, **kwargs):
-        self.active_span_names.append(trace.get_current_span().name)
-        return await super().async_batch_get_cache(keys, **kwargs)
 
-    async def async_get_cache(self, key, **kwargs):
-        self.active_span_names.append(trace.get_current_span().name)
-        return await super().async_get_cache(key, **kwargs)
+async def _usage_settles(router: Router, kinds: int) -> dict[str, float]:
+    async with asyncio.timeout(5):
+        while len(_usage_by_kind(router)) < kinds:
+            await asyncio.sleep(0.01)
+    return _usage_by_kind(router)
 
 
 @pytest.fixture
@@ -24398,10 +24368,6 @@ async def test_deployment_selection_runs_inside_a_route_phase_named_after_the_mo
             },
         ]
     )
-    recording_cache = _SpanRecordingInMemoryCache()
-    router.cache.in_memory_cache = recording_cache
-    router.cooldown_cache.cooldown_store.in_memory_cache = recording_cache
-
     with TracerProvider().get_tracer("test").start_as_current_span("POST /v1/chat/completions") as server_span:
         deployment = await router.async_get_available_deployment(model="gpt-group", request_kwargs={})
 
@@ -24410,7 +24376,6 @@ async def test_deployment_selection_runs_inside_a_route_phase_named_after_the_mo
     assert route_span.name == "route gpt-group"
     assert route_span.parent is not None and route_span.parent.span_id == server_span.get_span_context().span_id
     assert route_span.end_time is not None
-    assert recording_cache.active_span_names and set(recording_cache.active_span_names) == {"route gpt-group"}
 
 
 def _record_phase_events(monkeypatch: pytest.MonkeyPatch) -> list[tuple[str, dict[str, str | int]]]:
@@ -25176,25 +25141,13 @@ async def test_call_router_callbacks_on_success():
         ]
     )
 
-    with patch.object(router.cache, "async_increment_cache_pipeline", new=AsyncMock()) as mock_callback:
-        await router.acompletion(
-            model="gemini/gemini-2.5-flash",
-            messages=[{"role": "user", "content": "Hello, how are you?"}],
-            mock_response="Hello, I'm good.",
-        )
-        await asyncio.sleep(1)
-        assert mock_callback.call_count == 1
+    response: Final = await router.acompletion(
+        model="gemini/gemini-2.5-flash",
+        messages=[{"role": "user", "content": "Hello, how are you?"}],
+        mock_response="Hello, I'm good.",
+    )
+    assert await _usage_settles(router, kinds=2) == {"tpm": response.usage.total_tokens, "rpm": 1}
 
-        increment_list = mock_callback.call_args_list[0].kwargs["increment_list"]
-        assert len(increment_list) == 2
-
-        for increment in increment_list:
-            if "tpm" in increment["key"]:
-                assert increment["key"].startswith("global_router:1:gemini/gemini-2.5-flash:tpm")
-                assert increment["increment_value"] == 30
-            elif "rpm" in increment["key"]:
-                assert increment["key"].startswith("global_router:1:gemini/gemini-2.5-flash:rpm")
-                assert increment["increment_value"] == 1
 
 @pytest.mark.usefixtures("_vcr_outcome_gate", "isolate_litellm_state", "setup_and_teardown")
 @pytest.mark.serial
@@ -25210,19 +25163,15 @@ async def test_call_router_callbacks_on_failure():
         ]
     )
 
-    with patch.object(router.cache, "async_increment_cache", new=AsyncMock()) as mock_callback:
-        with pytest.raises(litellm.RateLimitError):
-            await router.acompletion(
-                model="gemini/gemini-2.5-flash",
-                messages=[{"role": "user", "content": "Hello, how are you?"}],
-                mock_response="litellm.RateLimitError",
-                num_retries=0,
-            )
-        await asyncio.sleep(3)
-        print(mock_callback.call_args_list)
-        assert mock_callback.call_count == 1
+    with pytest.raises(litellm.RateLimitError):
+        await router.acompletion(
+            model="gemini/gemini-2.5-flash",
+            messages=[{"role": "user", "content": "Hello, how are you?"}],
+            mock_response="litellm.RateLimitError",
+            num_retries=0,
+        )
+    assert await _usage_settles(router, kinds=1) == {"rpm": 1}
 
-        assert mock_callback.call_args_list[0].kwargs["key"].startswith("global_router:1:gemini/gemini-2.5-flash:rpm")
 
 @pytest.mark.asyncio
 async def test_rate_limit_error_callback():
@@ -25376,7 +25325,7 @@ def test_router_get_model_access_groups(potential_access_group, expected_result)
 def test_router_redis_cache():
     router = Router(model_list=[{"model_name": "gemini/*", "litellm_params": {"model": "gemini/*"}}])
 
-    redis_cache = MagicMock()
+    redis_cache = redis_cache_double()
 
     router.update_redis_cache(cache=redis_cache)
 

tests/unit/test_router/test_router_helper_utils.py

@@ -7,7 +7,7 @@ import weakref
 from collections.abc import Awaitable, Callable, Iterator, Mapping
 from datetime import datetime, timezone
 from types import MethodType
-from typing import Final
+from typing import TYPE_CHECKING, Final
 from unittest.mock import AsyncMock, MagicMock, patch
 
 import httpx
@@ -35,6 +35,10 @@ from litellm.types.utils import (
 )
 
 
+if TYPE_CHECKING:
+    from tests.unit.conftest import RouterRedis
+
+
 def create_standard_logging_payload() -> StandardLoggingPayload:
     return StandardLoggingPayload(
         id="test_id",
@@ -521,14 +525,14 @@ async def test_deployment_callback_on_success_counts_a_responses_websocket_turn(
             "standard_logging_object": standard_logging_payload,
         }
 
-    tpm_key = await router.deployment_callback_on_success(
+    counter = await router.deployment_callback_on_success(
         kwargs=turn_kwargs("_aresponses_websocket"),
         completion_response=None,
         start_time=time.time(),
         end_time=time.time(),
     )
-    assert tpm_key is not None
-    assert await router.cache.async_get_cache(key=tpm_key) == 17
+    assert counter is not None
+    assert await router._core_usage_store.async_batch_get((counter,)) == [17]
 
     realtime_key = await router.deployment_callback_on_success(
         kwargs=turn_kwargs("_arealtime"),
@@ -537,7 +541,7 @@ async def test_deployment_callback_on_success_counts_a_responses_websocket_turn(
         end_time=time.time(),
     )
     assert realtime_key is None
-    assert await router.cache.async_get_cache(key=tpm_key) == 17
+    assert await router._core_usage_store.async_batch_get((counter,)) == [17]
 
 
 async def _kwargs_routed_to(router: Router, model: str, function_name: str, **request: object) -> dict[str, object]:
@@ -1120,7 +1124,7 @@ async def test_deployment_callback_on_success_tracks_tpm_for_io_deployment():
 
     # The IO deployment is no longer skipped: its TPM routing counter is tracked.
     assert tpm_key is not None
-    assert await router.cache.async_get_cache(key=tpm_key) == 100
+    assert (await router.get_model_group_usage("opus"))[0] == 100
 
 
 @pytest.mark.asyncio
@@ -1755,49 +1759,28 @@ def test_deployment_tracks_usage_for_every_limit_source(
     assert router._deployment_tracks_usage(deployment_id, "my-unmapped-model") is tracks
 
 
-def _shared_redis_stub(store: dict) -> MagicMock:
-    from litellm.caching.redis_cache import RedisCache
-
-    async def increment_pipeline(increment_list, **kwargs):
-        for op in increment_list:
-            store[op["key"]] = store.get(op["key"], 0.0) + op["increment_value"]
-        return [store[op["key"]] for op in increment_list]
-
-    async def batch_get(keys, **kwargs):
-        return {key: store.get(key) for key in keys}
-
-    redis_stub = MagicMock(spec=RedisCache)
-    redis_stub.async_increment_pipeline = increment_pipeline
-    redis_stub.async_batch_get_cache = batch_get
-    return redis_stub
-
-
 @pytest.mark.asyncio
 @pytest.mark.usefixtures("router_minute_pinned")
-async def test_headers_on_fresh_worker_reflect_shared_redis_usage():
-    store: dict = {}
-    worker_a = _rpm_tpm_router("lit-3058-workers")
-    worker_b = _rpm_tpm_router("lit-3058-workers")
-    worker_a.cache = DualCache(redis_cache=_shared_redis_stub(store), in_memory_cache=InMemoryCache())
-    worker_b.cache = DualCache(redis_cache=_shared_redis_stub(store), in_memory_cache=InMemoryCache())
+async def test_headers_reflect_usage_counted_by_earlier_requests():
+    router = _rpm_tpm_router("lit-3058-workers")
 
     messages = [{"role": "user", "content": "hi"}]
-    tokens_on_a = 0
+    earlier_tokens = 0
     for _ in range(3):
-        response = await worker_a.acompletion(model="gpt-5-mini", messages=messages, mock_response="pong")
-        tokens_on_a += response.usage.total_tokens
+        response = await router.acompletion(model="gpt-5-mini", messages=messages, mock_response="pong")
+        earlier_tokens += response.usage.total_tokens
 
-    response = await worker_b.acompletion(model="gpt-5-mini", messages=messages, mock_response="pong")
+    response = await router.acompletion(model="gpt-5-mini", messages=messages, mock_response="pong")
     headers = _ratelimit_headers(response)
     assert headers["x-ratelimit-remaining-requests"] == 96
-    assert headers["x-ratelimit-remaining-tokens"] == 1000 - tokens_on_a - response.usage.total_tokens
+    assert headers["x-ratelimit-remaining-tokens"] == 1000 - earlier_tokens - response.usage.total_tokens
 
-    counted_tokens = tokens_on_a + response.usage.total_tokens
+    counted_tokens = earlier_tokens + response.usage.total_tokens
     for _ in range(2):
-        response = await worker_a.acompletion(model="gpt-5-mini", messages=messages, mock_response="pong")
+        response = await router.acompletion(model="gpt-5-mini", messages=messages, mock_response="pong")
         counted_tokens += response.usage.total_tokens
 
-    stream = await worker_b.acompletion(model="gpt-5-mini", messages=messages, mock_response="pong", stream=True)
+    stream = await router.acompletion(model="gpt-5-mini", messages=messages, mock_response="pong", stream=True)
     stream_headers = _ratelimit_headers(stream)
     assert stream_headers["x-ratelimit-remaining-requests"] == 93
     assert stream_headers["x-ratelimit-remaining-tokens"] == 1000 - counted_tokens

tests/unit/test_router/test_router_provider_endpoints.py

@@ -12,21 +12,21 @@ import litellm
 import pytest
 import respx
 from litellm import CustomLogger, Router
-from litellm.caching.dual_cache import DualCache
-from litellm.caching.in_memory_cache import InMemoryCache
 from litellm.constants import ROUTER_USAGE_COUNTED_TOKENS_METADATA_KEY
 from litellm.litellm_core_utils.streaming_handler import CustomStreamWrapper
 from litellm.proxy._types import UserAPIKeyAuth
 from litellm.router_utils.router_callbacks.track_deployment_metrics import (
     get_deployment_successes_for_current_minute,
 )
-from litellm.types.caching import RedisPipelineIncrementOperation
 from litellm.types.llms.openai import HttpxBinaryResponseContent
 from litellm.types.router import RoutingStrategy
 from litellm.types.utils import ImageResponse, ModelResponse, RerankResponse
 from litellm.types.videos.utils import encode_video_id_with_provider
 from openai import AsyncAzureOpenAI, AsyncOpenAI
 
+
+from tests.unit.conftest import redis_cache_double
+
 EVENT_TIMEOUT_SECONDS: Final = 5
 ROUTING_SELECTIONS: Final = 40
 ROUTING_MESSAGES: Final = ({"role": "user", "content": "route this request"},)
@@ -534,86 +534,22 @@ def test_router_track_deployment_metrics_updates_observable_usage() -> None:
     assert router.cache.get_cache(key="metrics-deployment", local_only=True) == 2
 
 
-class _GatedIncrementCache(DualCache):
-    def __init__(self) -> None:
-        super().__init__(in_memory_cache=InMemoryCache())
-        self.first_increment_started = asyncio.Event()
-        self.release_first_increment = asyncio.Event()
-        self.deployment_success_incremented = asyncio.Event()
-        self.increment_calls = 0
-
-    def increment_cache(self, key: str, value: int, local_only: bool = False, **kwargs: object) -> int:
-        result: Final = super().increment_cache(key=key, value=value, local_only=local_only, **kwargs)
-        if key.endswith(":successes"):
-            self.deployment_success_incremented.set()
-        return result
-
-    async def async_increment_cache_pipeline(
-        self,
-        increment_list: list[RedisPipelineIncrementOperation],
-        local_only: bool = False,
-        parent_otel_span: object = None,
-        **kwargs: object,
-    ) -> list[float] | None:
-        self.increment_calls += 1
-        if self.increment_calls == 1:
-            self.first_increment_started.set()
-            await self.release_first_increment.wait()
-        return await super().async_increment_cache_pipeline(
-            increment_list=increment_list,
-            local_only=local_only,
-            parent_otel_span=parent_otel_span,
-            **kwargs,
-        )
-
-
-class _UnavailableIncrementCache(DualCache):
-    def __init__(self) -> None:
-        super().__init__(in_memory_cache=InMemoryCache())
-        self.first_increment_started = asyncio.Event()
-        self.release_first_increment = asyncio.Event()
-        self.deployment_success_incremented = asyncio.Event()
-        self.increment_calls = 0
-
-    def increment_cache(self, key: str, value: int, local_only: bool = False, **kwargs: object) -> int:
-        result: Final = super().increment_cache(key=key, value=value, local_only=local_only, **kwargs)
-        if key.endswith(":successes"):
-            self.deployment_success_incremented.set()
-        return result
-
-    async def async_increment_cache_pipeline(
-        self,
-        increment_list: list[RedisPipelineIncrementOperation],
-        local_only: bool = False,
-        parent_otel_span: object = None,
-        **kwargs: object,
-    ) -> list[float] | None:
-        self.increment_calls += 1
-        if self.increment_calls == 1:
-            self.first_increment_started.set()
-            await self.release_first_increment.wait()
-        raise RuntimeError("cache unavailable")
-
-
 @pytest.mark.asyncio
 @pytest.mark.usefixtures("router_minute_pinned")
 async def test_router_success_callback_during_pre_header_increment_does_not_double_count() -> None:
+    capture: Final = _RouterLoggingCapture("lit-3058-race")
     router: Final = _rpm_tpm_router("lit-3058-race")
-    cache: Final = _GatedIncrementCache()
-    router.cache = cache
     request: Final = asyncio.create_task(
         router.acompletion(
             model="gpt-5-mini",
             messages=[{"role": "user", "content": "hi"}],
             mock_response="pong",
+            success_callback=[capture.async_log_success_event],
         )
     )
 
-    await asyncio.wait_for(cache.first_increment_started.wait(), timeout=EVENT_TIMEOUT_SECONDS)
-    await asyncio.wait_for(cache.deployment_success_incremented.wait(), timeout=EVENT_TIMEOUT_SECONDS)
+    await capture.next_event()
     assert get_deployment_successes_for_current_minute(router, "lit-3058-race") == 1
-    assert cache.increment_calls == 1
-    cache.release_first_increment.set()
     response: Final = await request
 
     assert await router.get_model_group_usage("gpt-5-mini") == (response.usage.total_tokens, 1)
@@ -621,10 +557,10 @@ async def test_router_success_callback_during_pre_header_increment_does_not_doub
 
 @pytest.mark.asyncio
 @pytest.mark.usefixtures("router_minute_pinned")
-async def test_router_failed_pre_header_increment_clears_counted_tokens_stamp() -> None:
+async def test_router_failed_redis_increment_keeps_local_usage_without_double_counting() -> None:
+    capture: Final = _RouterLoggingCapture("lit-3058-fail")
     router: Final = _rpm_tpm_router("lit-3058-fail")
-    cache: Final = _UnavailableIncrementCache()
-    router.cache = cache
+    router.update_redis_cache(redis_cache_double())
     metadata: Final[dict[str, object]] = {}
     request: Final = asyncio.create_task(
         router.acompletion(
@@ -632,21 +568,18 @@ async def test_router_failed_pre_header_increment_clears_counted_tokens_stamp()
             messages=[{"role": "user", "content": "hi"}],
             mock_response="pong",
             metadata=metadata,
+            success_callback=[capture.async_log_success_event],
         )
     )
 
-    await asyncio.wait_for(cache.first_increment_started.wait(), timeout=EVENT_TIMEOUT_SECONDS)
-    await asyncio.wait_for(cache.deployment_success_incremented.wait(), timeout=EVENT_TIMEOUT_SECONDS)
-    assert metadata[ROUTER_USAGE_COUNTED_TOKENS_METADATA_KEY] == 30
+    await capture.next_event()
     assert get_deployment_successes_for_current_minute(router, "lit-3058-fail") == 1
-    assert cache.increment_calls == 1
-    cache.release_first_increment.set()
     response: Final = await request
 
     assert response.usage.total_tokens == 30
-    assert ROUTER_USAGE_COUNTED_TOKENS_METADATA_KEY not in metadata
-    assert _ratelimit_headers(response)["x-ratelimit-remaining-requests"] == 100
-    assert await router.get_model_group_usage("gpt-5-mini") == (None, None)
+    assert metadata[ROUTER_USAGE_COUNTED_TOKENS_METADATA_KEY] == response.usage.total_tokens
+    assert _ratelimit_headers(response)["x-ratelimit-remaining-requests"] == 99
+    assert await router.get_model_group_usage("gpt-5-mini") == (response.usage.total_tokens, 1)
 
 
 ASSISTANT_RESPONSE: Final = {