fix(model_prices): add cache-read pricing to Mistral chat models missing it

Mistral bills cached prompt tokens at 10% of the input price for every model, but twelve
active mistral/ chat rows had no cache_read_input_token_cost, so the cost calculator billed
their cache hits at zero. Adds the derived rate to those rows in both registry copies and a
registry invariant test that fails when an active priced Mistral chat row drops the field or
drifts from the 10% ratio

Co-Authored-By: Devin AI <158243242+devin-ai-integration[bot]@users.noreply.github.com>

litellm/model_prices_and_context_window_backup.json

@@ -36785,6 +36785,7 @@
         "supports_tool_choice": true
     },
     "mistral/codestral-mamba-latest": {
+        "cache_read_input_token_cost": 2.5e-08,
         "input_cost_per_token": 2.5e-07,
         "litellm_provider": "mistral",
         "max_input_tokens": 256000,
@@ -36842,6 +36843,7 @@
         "supports_tool_choice": true
     },
     "mistral/devstral-small-latest": {
+        "cache_read_input_token_cost": 1e-08,
         "input_cost_per_token": 1e-07,
         "litellm_provider": "mistral",
         "max_input_tokens": 256000,
@@ -36871,6 +36873,7 @@
         "supports_tool_choice": true
     },
     "mistral/devstral-latest": {
+        "cache_read_input_token_cost": 4e-08,
         "input_cost_per_token": 4e-07,
         "litellm_provider": "mistral",
         "max_input_tokens": 256000,
@@ -36885,6 +36888,7 @@
         "supports_tool_choice": true
     },
     "mistral/devstral-medium-latest": {
+        "cache_read_input_token_cost": 4e-08,
         "input_cost_per_token": 4e-07,
         "litellm_provider": "mistral",
         "max_input_tokens": 256000,
@@ -36986,6 +36990,7 @@
         "source": "https://docs.mistral.ai/models/mistral-embed-23-12"
     },
     "mistral/mistral-medium-3": {
+        "cache_read_input_token_cost": 1.5e-07,
         "input_cost_per_token": 1.5e-06,
         "litellm_provider": "mistral",
         "max_input_tokens": 262144,
@@ -37034,6 +37039,7 @@
         "supports_audio_output": true
     },
     "mistral/voxtral-small-2507": {
+        "cache_read_input_token_cost": 1e-08,
         "input_cost_per_second": 6.666666666666667e-05,
         "input_cost_per_token": 1e-07,
         "litellm_provider": "mistral",
@@ -37049,6 +37055,7 @@
         "supports_tool_choice": true
     },
     "mistral/voxtral-small-latest": {
+        "cache_read_input_token_cost": 1e-08,
         "input_cost_per_second": 6.666666666666667e-05,
         "input_cost_per_token": 1e-07,
         "litellm_provider": "mistral",
@@ -37554,6 +37561,7 @@
         "supports_vision": true
     },
     "mistral/mistral-small": {
+        "cache_read_input_token_cost": 1e-08,
         "input_cost_per_token": 1e-07,
         "litellm_provider": "mistral",
         "max_input_tokens": 32000,
@@ -37680,6 +37688,7 @@
         "supports_vision": true
     },
     "mistral/mistral-tiny": {
+        "cache_read_input_token_cost": 2.5e-08,
         "input_cost_per_token": 2.5e-07,
         "litellm_provider": "mistral",
         "max_input_tokens": 32000,
@@ -37718,6 +37727,7 @@
         "supports_tool_choice": true
     },
     "mistral/open-mistral-nemo": {
+        "cache_read_input_token_cost": 3e-08,
         "input_cost_per_token": 3e-07,
         "litellm_provider": "mistral",
         "max_input_tokens": 128000,
@@ -37803,6 +37813,7 @@
         "supports_vision": true
     },
     "mistral/pixtral-large-latest": {
+        "cache_read_input_token_cost": 2e-07,
         "input_cost_per_token": 2e-06,
         "litellm_provider": "mistral",
         "max_input_tokens": 128000,
@@ -62790,6 +62801,7 @@
         "supports_tool_choice": true
     },
     "mistral/mistral-code-agent-latest": {
+        "cache_read_input_token_cost": 4e-08,
         "input_cost_per_token": 4e-07,
         "litellm_provider": "mistral",
         "max_input_tokens": 256000,

model_prices_and_context_window.json

@@ -36785,6 +36785,7 @@
         "supports_tool_choice": true
     },
     "mistral/codestral-mamba-latest": {
+        "cache_read_input_token_cost": 2.5e-08,
         "input_cost_per_token": 2.5e-07,
         "litellm_provider": "mistral",
         "max_input_tokens": 256000,
@@ -36842,6 +36843,7 @@
         "supports_tool_choice": true
     },
     "mistral/devstral-small-latest": {
+        "cache_read_input_token_cost": 1e-08,
         "input_cost_per_token": 1e-07,
         "litellm_provider": "mistral",
         "max_input_tokens": 256000,
@@ -36871,6 +36873,7 @@
         "supports_tool_choice": true
     },
     "mistral/devstral-latest": {
+        "cache_read_input_token_cost": 4e-08,
         "input_cost_per_token": 4e-07,
         "litellm_provider": "mistral",
         "max_input_tokens": 256000,
@@ -36885,6 +36888,7 @@
         "supports_tool_choice": true
     },
     "mistral/devstral-medium-latest": {
+        "cache_read_input_token_cost": 4e-08,
         "input_cost_per_token": 4e-07,
         "litellm_provider": "mistral",
         "max_input_tokens": 256000,
@@ -36986,6 +36990,7 @@
         "source": "https://docs.mistral.ai/models/mistral-embed-23-12"
     },
     "mistral/mistral-medium-3": {
+        "cache_read_input_token_cost": 1.5e-07,
         "input_cost_per_token": 1.5e-06,
         "litellm_provider": "mistral",
         "max_input_tokens": 262144,
@@ -37034,6 +37039,7 @@
         "supports_audio_output": true
     },
     "mistral/voxtral-small-2507": {
+        "cache_read_input_token_cost": 1e-08,
         "input_cost_per_second": 6.666666666666667e-05,
         "input_cost_per_token": 1e-07,
         "litellm_provider": "mistral",
@@ -37049,6 +37055,7 @@
         "supports_tool_choice": true
     },
     "mistral/voxtral-small-latest": {
+        "cache_read_input_token_cost": 1e-08,
         "input_cost_per_second": 6.666666666666667e-05,
         "input_cost_per_token": 1e-07,
         "litellm_provider": "mistral",
@@ -37554,6 +37561,7 @@
         "supports_vision": true
     },
     "mistral/mistral-small": {
+        "cache_read_input_token_cost": 1e-08,
         "input_cost_per_token": 1e-07,
         "litellm_provider": "mistral",
         "max_input_tokens": 32000,
@@ -37680,6 +37688,7 @@
         "supports_vision": true
     },
     "mistral/mistral-tiny": {
+        "cache_read_input_token_cost": 2.5e-08,
         "input_cost_per_token": 2.5e-07,
         "litellm_provider": "mistral",
         "max_input_tokens": 32000,
@@ -37718,6 +37727,7 @@
         "supports_tool_choice": true
     },
     "mistral/open-mistral-nemo": {
+        "cache_read_input_token_cost": 3e-08,
         "input_cost_per_token": 3e-07,
         "litellm_provider": "mistral",
         "max_input_tokens": 128000,
@@ -37803,6 +37813,7 @@
         "supports_vision": true
     },
     "mistral/pixtral-large-latest": {
+        "cache_read_input_token_cost": 2e-07,
         "input_cost_per_token": 2e-06,
         "litellm_provider": "mistral",
         "max_input_tokens": 128000,
@@ -62790,6 +62801,7 @@
         "supports_tool_choice": true
     },
     "mistral/mistral-code-agent-latest": {
+        "cache_read_input_token_cost": 4e-08,
         "input_cost_per_token": 4e-07,
         "litellm_provider": "mistral",
         "max_input_tokens": 256000,

tests/test_litellm/test_model_prices_schema.py

@@ -274,3 +274,31 @@ def test_every_bedrock_openai_gpt_row_advertises_xhigh(prices: dict):
         and "xhigh" not in (resolve_supported_reasoning_efforts(entry, deployment_is_mapped=True) or ())
     ]
     assert missing == []
+
+
+def is_active_priced_mistral_chat_row(name: str, entry: dict) -> bool:
+    return (
+        name.startswith("mistral/")
+        and entry.get("mode") == "chat"
+        and entry.get("deprecation_date") is None
+        and (entry.get("input_cost_per_token") or 0) > 0
+    )
+
+
+def test_active_mistral_chat_rows_price_cache_reads_below_input(prices: dict):
+    """A Mistral chat row without a cache-read rate bills cached prompt tokens at zero, so every
+    active priced row must carry one, and it must be cheaper than a fresh input token. Mistral
+    bills cached tokens at 10% of the input price for every model (docs.mistral.ai/studio/
+    conversations/advanced/prompt-caching, read 2026-09-18), so the ratio is checked as well."""
+    drifted: Final = [
+        f"{name}: cache_read={entry.get('cache_read_input_token_cost')} input={entry['input_cost_per_token']}"
+        for name, entry in prices.items()
+        if isinstance(entry, dict)
+        and is_active_priced_mistral_chat_row(name, entry)
+        and not (
+            isinstance(entry.get("cache_read_input_token_cost"), float)
+            and 0 < entry["cache_read_input_token_cost"] < entry["input_cost_per_token"]
+            and entry["cache_read_input_token_cost"] == pytest.approx(entry["input_cost_per_token"] / 10)
+        )
+    ]
+    assert drifted == []