diff --git a/lib/crates/fabro-agent/src/cli.rs b/lib/crates/fabro-agent/src/cli.rs
index 1ce8f4870..c6308ec6b 100644
--- a/lib/crates/fabro-agent/src/cli.rs
+++ b/lib/crates/fabro-agent/src/cli.rs
@@ -266,7 +266,7 @@ fn ensure_provider_registered(client: &Client, provider: Provider) -> anyhow::Re
     if client
         .provider_names()
         .iter()
-        .any(|name| *name == provider.as_str())
+        .any(|name| *name == <&'static str>::from(provider))
     {
         return Ok(());
     }
diff --git a/lib/crates/fabro-agent/src/compaction.rs b/lib/crates/fabro-agent/src/compaction.rs
index e153bd181..ab76391d9 100644
--- a/lib/crates/fabro-agent/src/compaction.rs
+++ b/lib/crates/fabro-agent/src/compaction.rs
@@ -112,7 +112,7 @@ function names, error messages, and exact values. Omit pleasantries and conversa
                 "Here is the conversation to summarize:\n\n{rendered}"
             )),
         ],
-        provider:         Some(provider_profile.provider().as_str().to_string()),
+        provider:         Some(provider_profile.provider().to_string()),
         tools:            None,
         tool_choice:      None,
         response_format:  None,
diff --git a/lib/crates/fabro-agent/src/profiles/openai.rs b/lib/crates/fabro-agent/src/profiles/openai.rs
index 83e7a5949..eb5172c94 100644
--- a/lib/crates/fabro-agent/src/profiles/openai.rs
+++ b/lib/crates/fabro-agent/src/profiles/openai.rs
@@ -55,7 +55,7 @@ impl OpenAiProfile {
             Provider::Zai => "Zhipu AI",
             Provider::Minimax => "MiniMax",
             Provider::Inception => "Inception",
-            other => other.as_str(),
+            other => <&'static str>::from(other),
         }
     }
 }
diff --git a/lib/crates/fabro-agent/src/session.rs b/lib/crates/fabro-agent/src/session.rs
index 7a4b846f0..0a814f6be 100644
--- a/lib/crates/fabro-agent/src/session.rs
+++ b/lib/crates/fabro-agent/src/session.rs
@@ -726,7 +726,7 @@ impl Session {
             // Call LLM (streaming) with retry for transient errors
             let retry_emitter = self.event_emitter.clone();
             let retry_session_id = self.id.clone();
-            let retry_provider = self.provider_profile.provider().as_str().to_string();
+            let retry_provider = self.provider_profile.provider().to_string();
             let retry_model = self.provider_profile.model().to_string();
             let retry_policy = RetryPolicy {
                 max_retries: 3,
@@ -991,7 +991,7 @@ impl Session {
         Request {
             model: self.provider_profile.model().to_string(),
             messages,
-            provider: Some(self.provider_profile.provider().as_str().to_string()),
+            provider: Some(self.provider_profile.provider().to_string()),
             tools: if has_tools { Some(tools) } else { None },
             tool_choice: if has_tools {
                 Some(ToolChoice::Auto)
diff --git a/lib/crates/fabro-agent/src/tools.rs b/lib/crates/fabro-agent/src/tools.rs
index e997396e9..6394982d9 100644
--- a/lib/crates/fabro-agent/src/tools.rs
+++ b/lib/crates/fabro-agent/src/tools.rs
@@ -605,7 +605,7 @@ pub(crate) fn make_web_fetch_tool(summarizer: Option<WebFetchSummarizer>) -> Reg
                         let request = Request {
                             model: s.model_id.model_id().to_string(),
                             messages: vec![Message::user(summarization_prompt)],
-                            provider: Some(s.model_id.provider().as_str().to_string()),
+                            provider: Some(s.model_id.provider().to_string()),
                             tools: None,
                             tool_choice: None,
                             response_format: None,
diff --git a/lib/crates/fabro-auth/src/credential.rs b/lib/crates/fabro-auth/src/credential.rs
index aed972797..f881debc5 100644
--- a/lib/crates/fabro-auth/src/credential.rs
+++ b/lib/crates/fabro-auth/src/credential.rs
@@ -97,7 +97,7 @@ pub fn credential_id_for(credential: &AuthCredential) -> Result<String, String>
             "codex_oauth credentials are only valid for OpenAI, got {}",
             credential.provider
         )),
-        (provider, AuthDetails::ApiKey { .. }) => Ok(provider.as_str().to_string()),
+        (provider, AuthDetails::ApiKey { .. }) => Ok(provider.to_string()),
     }
 }
 
diff --git a/lib/crates/fabro-cli/src/shared/provider_auth.rs b/lib/crates/fabro-cli/src/shared/provider_auth.rs
index 7b22bfcf5..23649c258 100644
--- a/lib/crates/fabro-cli/src/shared/provider_auth.rs
+++ b/lib/crates/fabro-cli/src/shared/provider_auth.rs
@@ -85,13 +85,12 @@ pub(crate) async fn validate_api_key(provider: Provider, api_key: &str) -> Resul
     .await
     .map_err(|e| e.to_string())?;
 
-    let probe_model = Catalog::builtin().probe_for_provider(provider).map_or_else(
-        || format!("unknown-{}", provider.as_str()),
-        |model| model.id.clone(),
-    );
+    let probe_model = Catalog::builtin()
+        .probe_for_provider(provider)
+        .map_or_else(|| format!("unknown-{provider}"), |model| model.id.clone());
 
     let params = GenerateParams::new(probe_model, Arc::new(client))
-        .provider(provider.as_str())
+        .provider(<&'static str>::from(provider))
         .prompt("Say OK")
         .max_tokens(16);
 
diff --git a/lib/crates/fabro-llm/src/model_test.rs b/lib/crates/fabro-llm/src/model_test.rs
index fdcd11cf4..fa72ed460 100644
--- a/lib/crates/fabro-llm/src/model_test.rs
+++ b/lib/crates/fabro-llm/src/model_test.rs
@@ -19,11 +19,6 @@ pub enum ModelTestMode {
 }
 
 impl ModelTestMode {
-    #[must_use]
-    pub fn as_str(self) -> &'static str {
-        self.into()
-    }
-
     #[must_use]
     pub const fn timeout_secs(self) -> u64 {
         match self {
@@ -40,13 +35,6 @@ pub enum ModelTestStatus {
     Error,
 }
 
-impl ModelTestStatus {
-    #[must_use]
-    pub fn as_str(self) -> &'static str {
-        self.into()
-    }
-}
-
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub struct ModelTestOutcome {
     pub status:        ModelTestStatus,
@@ -84,7 +72,7 @@ pub async fn run_model_test(
 
 async fn run_basic_test(info: &Model, client: Arc<Client>) -> ModelTestOutcome {
     let params = GenerateParams::new(&info.id, client)
-        .provider(info.provider.as_str())
+        .provider(<&'static str>::from(info.provider))
         .prompt("Say OK")
         .max_tokens(16);
 
@@ -152,7 +140,7 @@ fn build_deep_test_params(info: &Model, client: Arc<Client>) -> Option<GenerateP
     );
 
     let mut params = GenerateParams::new(&info.id, client)
-        .provider(info.provider.as_str())
+        .provider(<&'static str>::from(info.provider))
         .prompt(
             "Use the add tool twice: first add 15 and 27, then add that result to 42. \
              Finally, tell me whether the grand total is even or odd and why.",
diff --git a/lib/crates/fabro-llm/src/providers/anthropic.rs b/lib/crates/fabro-llm/src/providers/anthropic.rs
index 948ba9432..d88f679dc 100644
--- a/lib/crates/fabro-llm/src/providers/anthropic.rs
+++ b/lib/crates/fabro-llm/src/providers/anthropic.rs
@@ -9,9 +9,9 @@ use crate::providers::common::{
     parse_retry_after, send_and_read_response,
 };
 use crate::types::{
-    AdapterTimeout, ContentPart, FinishReason, Message, RateLimitInfo, Request, Response,
-    ResponseFormatType, Role, StreamEvent, ThinkingData, TokenCounts, ToolCall, ToolChoice,
-    ToolDefinition,
+    AdapterTimeout, ContentPart, FinishReason, Message, RateLimitInfo, ReasoningEffort, Request,
+    Response, ResponseFormatType, Role, StreamEvent, ThinkingData, TokenCounts, ToolCall,
+    ToolChoice, ToolDefinition,
 };
 
 /// Provider adapter for the Anthropic Messages API.
@@ -547,13 +547,13 @@ fn extract_thinking_config(
 /// Map a reasoning effort level to a thinking `budget_tokens` value for models
 /// that don't support the `output_config.effort` parameter (e.g.
 /// claude-sonnet-4-5).
-fn effort_to_budget_tokens(effort: &str, max_tokens: i64) -> i64 {
+fn effort_to_budget_tokens(effort: ReasoningEffort, max_tokens: i64) -> i64 {
     let budget = match effort {
-        "low" => max_tokens / 4,
-        "high" => max_tokens * 3 / 4,
-        "xhigh" => max_tokens * 7 / 8,
-        "max" => max_tokens,
-        _ => max_tokens / 2, // "medium" or unknown
+        ReasoningEffort::Low => max_tokens / 4,
+        ReasoningEffort::Medium => max_tokens / 2,
+        ReasoningEffort::High => max_tokens * 3 / 4,
+        ReasoningEffort::XHigh => max_tokens * 7 / 8,
+        ReasoningEffort::Max => max_tokens,
     };
     // Anthropic requires budget_tokens >= 1024
     budget.max(1024)
@@ -1152,12 +1152,12 @@ async fn build_api_request(
         if supports_effort {
             (
                 explicit_thinking,
-                Some(serde_json::json!({"effort": effort.as_str()})),
+                Some(serde_json::json!({"effort": <&'static str>::from(*effort)})),
             )
         } else if explicit_thinking.is_none() {
             // Convert effort level to a thinking budget for models that don't
             // support the effort parameter (e.g. claude-sonnet-4-5).
-            let budget = effort_to_budget_tokens(effort.as_str(), resolved_max_tokens);
+            let budget = effort_to_budget_tokens(*effort, resolved_max_tokens);
             if resolved_max_tokens <= budget {
                 resolved_max_tokens = budget + 1024;
             }
@@ -2251,12 +2251,18 @@ mod tests {
 
     #[test]
     fn effort_to_budget_tokens_xhigh_maps_to_seven_eighths() {
-        assert_eq!(effort_to_budget_tokens("xhigh", 16_000), 14_000);
+        assert_eq!(
+            effort_to_budget_tokens(ReasoningEffort::XHigh, 16_000),
+            14_000
+        );
     }
 
     #[test]
     fn effort_to_budget_tokens_max_maps_to_full_budget() {
-        assert_eq!(effort_to_budget_tokens("max", 16_000), 16_000);
+        assert_eq!(
+            effort_to_budget_tokens(ReasoningEffort::Max, 16_000),
+            16_000
+        );
     }
 
     #[tokio::test]
diff --git a/lib/crates/fabro-llm/src/providers/openai.rs b/lib/crates/fabro-llm/src/providers/openai.rs
index 5ba18de98..1cc76d0d3 100644
--- a/lib/crates/fabro-llm/src/providers/openai.rs
+++ b/lib/crates/fabro-llm/src/providers/openai.rs
@@ -396,7 +396,7 @@ async fn build_api_request(request: &Request, stream: bool, codex_mode: bool) ->
     let reasoning = request
         .reasoning_effort
         .as_ref()
-        .map(|effort| serde_json::json!({"effort": effort.as_str()}));
+        .map(|effort| serde_json::json!({"effort": <&'static str>::from(*effort)}));
     let text = request
         .response_format
         .as_ref()
diff --git a/lib/crates/fabro-llm/src/types.rs b/lib/crates/fabro-llm/src/types.rs
index 46c3a14bb..58e785207 100644
--- a/lib/crates/fabro-llm/src/types.rs
+++ b/lib/crates/fabro-llm/src/types.rs
@@ -434,12 +434,6 @@ pub enum ReasoningEffort {
     Max,
 }
 
-impl ReasoningEffort {
-    pub fn as_str(&self) -> &'static str {
-        (*self).into()
-    }
-}
-
 // --- 3.6 Request ---
 
 #[derive(Debug, Clone, Serialize, Deserialize)]
@@ -1298,8 +1292,10 @@ mod tests {
             Ok(ReasoningEffort::XHigh)
         );
         assert_eq!(ReasoningEffort::from_str("max"), Ok(ReasoningEffort::Max));
-        assert_eq!(ReasoningEffort::XHigh.as_str(), "xhigh");
-        assert_eq!(ReasoningEffort::Max.as_str(), "max");
+        assert_eq!(ReasoningEffort::XHigh.to_string(), "xhigh");
+        assert_eq!(<&'static str>::from(ReasoningEffort::XHigh), "xhigh");
+        assert_eq!(ReasoningEffort::Max.to_string(), "max");
+        assert_eq!(<&'static str>::from(ReasoningEffort::Max), "max");
     }
 
     #[test]
diff --git a/lib/crates/fabro-model/src/billing.rs b/lib/crates/fabro-model/src/billing.rs
index 639c9cd20..f793473de 100644
--- a/lib/crates/fabro-model/src/billing.rs
+++ b/lib/crates/fabro-model/src/billing.rs
@@ -115,13 +115,6 @@ pub enum Speed {
     Fast,
 }
 
-impl Speed {
-    #[must_use]
-    pub fn as_str(self) -> &'static str {
-        self.into()
-    }
-}
-
 #[derive(Debug, Clone, PartialEq, Eq, Hash, Serialize, Deserialize)]
 pub struct ModelRef {
     pub provider: Provider,
diff --git a/lib/crates/fabro-model/src/catalog.rs b/lib/crates/fabro-model/src/catalog.rs
index ef96f2b2a..347907d77 100644
--- a/lib/crates/fabro-model/src/catalog.rs
+++ b/lib/crates/fabro-model/src/catalog.rs
@@ -152,7 +152,7 @@ impl Catalog {
             return Vec::new();
         };
 
-        let Some(fallback_providers) = fallbacks.get(primary.as_str()) else {
+        let Some(fallback_providers) = fallbacks.get(<&'static str>::from(primary)) else {
             return Vec::new();
         };
 
@@ -417,13 +417,13 @@ mod tests {
     }
 
     #[test]
-    fn catalog_providers_roundtrip_through_as_str() {
+    fn catalog_providers_roundtrip_through_static_str() {
         for model in Catalog::builtin().list(None) {
-            let roundtripped = Provider::from_str(model.provider.as_str());
+            let roundtripped = Provider::from_str(<&'static str>::from(model.provider));
             assert_eq!(
                 roundtripped,
                 Ok(model.provider),
-                "catalog model '{}' provider {:?} does not roundtrip through as_str",
+                "catalog model '{}' provider {:?} does not roundtrip through IntoStaticStr",
                 model.id,
                 model.provider
             );
@@ -431,13 +431,13 @@ mod tests {
     }
 
     #[test]
-    fn provider_as_str_roundtrips_through_from_str() {
+    fn provider_static_str_roundtrips_through_from_str() {
         for &provider in Provider::ALL {
-            let roundtripped = Provider::from_str(provider.as_str());
+            let roundtripped = Provider::from_str(<&'static str>::from(provider));
             assert_eq!(
                 roundtripped,
                 Ok(provider),
-                "Provider::{provider:?}.as_str() does not round-trip through from_str"
+                "Provider::{provider:?} IntoStaticStr does not round-trip through from_str"
             );
         }
     }
diff --git a/lib/crates/fabro-model/src/provider.rs b/lib/crates/fabro-model/src/provider.rs
index 966a63075..0e6f0403e 100644
--- a/lib/crates/fabro-model/src/provider.rs
+++ b/lib/crates/fabro-model/src/provider.rs
@@ -120,13 +120,6 @@ impl Provider {
             Self::OpenAiCompatible => "OpenAI Compatible",
         }
     }
-
-    /// Stable lowercase string representation used in `Request.provider`,
-    /// adapter names, and other serialization boundaries.
-    #[must_use]
-    pub fn as_str(self) -> &'static str {
-        self.into()
-    }
 }
 
 #[cfg(test)]
@@ -150,17 +143,20 @@ mod tests {
 
     #[test]
     fn kimi_as_str() {
-        assert_eq!(Provider::Kimi.as_str(), "kimi");
+        assert_eq!(Provider::Kimi.to_string(), "kimi");
+        assert_eq!(<&'static str>::from(Provider::Kimi), "kimi");
     }
 
     #[test]
     fn zai_as_str() {
-        assert_eq!(Provider::Zai.as_str(), "zai");
+        assert_eq!(Provider::Zai.to_string(), "zai");
+        assert_eq!(<&'static str>::from(Provider::Zai), "zai");
     }
 
     #[test]
     fn minimax_as_str() {
-        assert_eq!(Provider::Minimax.as_str(), "minimax");
+        assert_eq!(Provider::Minimax.to_string(), "minimax");
+        assert_eq!(<&'static str>::from(Provider::Minimax), "minimax");
     }
 
     #[test]
@@ -177,7 +173,8 @@ mod tests {
 
     #[test]
     fn inception_as_str() {
-        assert_eq!(Provider::Inception.as_str(), "inception");
+        assert_eq!(Provider::Inception.to_string(), "inception");
+        assert_eq!(<&'static str>::from(Provider::Inception), "inception");
     }
 
     #[test]
diff --git a/lib/crates/fabro-redact/src/safe_url.rs b/lib/crates/fabro-redact/src/safe_url.rs
index 38491ffd7..0661f0667 100644
--- a/lib/crates/fabro-redact/src/safe_url.rs
+++ b/lib/crates/fabro-redact/src/safe_url.rs
@@ -46,6 +46,7 @@ pub enum DisplaySafeUrlError {
 pub struct DisplaySafeUrl(Url);
 
 impl DisplaySafeUrl {
+    /// Parse user-provided URL text; [`FromStr`] delegates here.
     #[inline]
     pub fn parse(input: &str) -> Result<Self, DisplaySafeUrlError> {
         let url = Url::parse(input)?;
@@ -53,15 +54,6 @@ impl DisplaySafeUrl {
         Ok(Self(url))
     }
 
-    /// Create a `DisplaySafeUrl` from an already parsed [`Url`].
-    ///
-    /// This does not perform ambiguity checks because parsed URLs from trusted
-    /// HTTP libraries are not human-entered strings.
-    #[inline]
-    pub fn from_url(url: Url) -> Self {
-        Self(url)
-    }
-
     /// Cast a `&Url` to a `&DisplaySafeUrl` without allocation.
     #[inline]
     pub fn ref_cast(url: &Url) -> &Self {
diff --git a/lib/crates/fabro-server/src/diagnostics.rs b/lib/crates/fabro-server/src/diagnostics.rs
index 5477bb2d1..0e90b34a0 100644
--- a/lib/crates/fabro-server/src/diagnostics.rs
+++ b/lib/crates/fabro-server/src/diagnostics.rs
@@ -146,17 +146,16 @@ async fn check_llm_providers(state: &AppState) -> CheckResult {
 }
 
 fn probe_model(provider: Provider) -> String {
-    Catalog::builtin().probe_for_provider(provider).map_or_else(
-        || format!("unknown-{}", provider.as_str()),
-        |m| m.id.clone(),
-    )
+    Catalog::builtin()
+        .probe_for_provider(provider)
+        .map_or_else(|| format!("unknown-{provider}"), |m| m.id.clone())
 }
 
 async fn probe_llm_provider(client: &LlmClient, provider: Provider) -> Result<(), String> {
     let request = Request {
         model:            probe_model(provider),
         messages:         vec![Message::user("hi")],
-        provider:         Some(provider.as_str().to_string()),
+        provider:         Some(provider.to_string()),
         tools:            None,
         tool_choice:      None,
         response_format:  None,
diff --git a/lib/crates/fabro-server/src/install.rs b/lib/crates/fabro-server/src/install.rs
index 988e0c4da..4c5488b3d 100644
--- a/lib/crates/fabro-server/src/install.rs
+++ b/lib/crates/fabro-server/src/install.rs
@@ -700,7 +700,7 @@ async fn post_install_llm_test(
     match validate_llm_provider(&state, &input).await {
         Ok(()) => Json(serde_json::json!({ "ok": true })).into_response(),
         Err(err) => {
-            warn!(provider = %input.provider.as_str(), error = %err, "install LLM validation failed");
+            warn!(provider = %input.provider, error = %err, "install LLM validation failed");
             install_error_response(StatusCode::UNPROCESSABLE_ENTITY, err)
         }
     }
@@ -732,7 +732,7 @@ async fn put_install_llm(
         if provider.api_key.trim().is_empty() {
             return install_error_response(
                 StatusCode::UNPROCESSABLE_ENTITY,
-                format!("api_key is required for {}", provider.provider.as_str()),
+                format!("api_key is required for {}", provider.provider),
             );
         }
     }
@@ -1675,7 +1675,7 @@ fn redacted_llm(pending_install: &PendingInstall) -> serde_json::Value {
         |llm| {
             serde_json::json!({
                 "providers": llm.providers.iter().map(|provider| serde_json::json!({
-                    "provider": provider.provider.as_str(),
+                    "provider": <&'static str>::from(provider.provider),
                     "configured": true,
                 })).collect::<Vec<_>>()
             })
@@ -1834,7 +1834,7 @@ async fn validate_llm_provider(
         | Provider::OpenAiCompatible => {
             return Err(format!(
                 "{} is not supported by install validation",
-                input.provider.as_str()
+                input.provider
             ));
         }
     };
@@ -1860,7 +1860,7 @@ async fn validate_llm_provider(
     } else {
         Err(format!(
             "{} model lookup failed ({})",
-            input.provider.as_str(),
+            input.provider,
             response.status()
         ))
     }
diff --git a/lib/crates/fabro-server/src/server.rs b/lib/crates/fabro-server/src/server.rs
index 86d440747..51f2fecbc 100644
--- a/lib/crates/fabro-server/src/server.rs
+++ b/lib/crates/fabro-server/src/server.rs
@@ -443,7 +443,7 @@ impl SlackService {
                     id:              props.question_id.clone(),
                     text:            props.question.clone(),
                     stage:           props.stage.clone(),
-                    question_type:   InterviewQuestionType::from_wire_name(&props.question_type),
+                    question_type:   props.question_type.parse().unwrap_or_default(),
                     options:         props.options.clone(),
                     allow_freeform:  props.allow_freeform,
                     timeout_seconds: props.timeout_seconds,
@@ -7532,11 +7532,8 @@ async fn test_model(
     {
         return ApiError::bad_request(auth_issue_message(info.provider, issue)).into_response();
     }
-    if !llm_result
-        .client
-        .provider_names()
-        .contains(&info.provider.as_str())
-    {
+    let provider_name = <&'static str>::from(info.provider);
+    if !llm_result.client.provider_names().contains(&provider_name) {
         return Json(serde_json::json!({
             "model_id": info.id,
             "status": "skip",
@@ -7548,7 +7545,7 @@ async fn test_model(
     let outcome = run_model_test(info, mode, client).await;
     Json(serde_json::json!({
         "model_id": info.id,
-        "status": outcome.status.as_str(),
+        "status": <&'static str>::from(outcome.status),
         "error_message": outcome.error_message,
     }))
     .into_response()
diff --git a/lib/crates/fabro-store/src/run_state.rs b/lib/crates/fabro-store/src/run_state.rs
index 61c0c27d8..146f918eb 100644
--- a/lib/crates/fabro-store/src/run_state.rs
+++ b/lib/crates/fabro-store/src/run_state.rs
@@ -9,9 +9,9 @@ use fabro_types::run_event::{
 };
 use fabro_types::{
     BilledModelUsage, Checkpoint, Conclusion, EventBody, FailureSignature, InterviewQuestionRecord,
-    InterviewQuestionType, NodeStatusRecord, Outcome, PendingInterviewRecord, PullRequestRecord,
-    RunControlAction, RunId, RunProjection, RunSpec, RunStatus, RunSummary, SandboxRecord,
-    StageStatus, StartRecord, TerminalStatus,
+    NodeStatusRecord, Outcome, PendingInterviewRecord, PullRequestRecord, RunControlAction, RunId,
+    RunProjection, RunSpec, RunStatus, RunSummary, SandboxRecord, StageStatus, StartRecord,
+    TerminalStatus,
 };
 use serde_json::Value;
 
@@ -252,9 +252,7 @@ impl RunProjectionReducer for RunProjection {
                             id:              props.question_id.clone(),
                             text:            props.question.clone(),
                             stage:           props.stage.clone(),
-                            question_type:   InterviewQuestionType::from_wire_name(
-                                &props.question_type,
-                            ),
+                            question_type:   props.question_type.parse().unwrap_or_default(),
                             options:         props.options.clone(),
                             allow_freeform:  props.allow_freeform,
                             timeout_seconds: props.timeout_seconds,
diff --git a/lib/crates/fabro-types/src/interview.rs b/lib/crates/fabro-types/src/interview.rs
index da7e3b4a3..332b098c2 100644
--- a/lib/crates/fabro-types/src/interview.rs
+++ b/lib/crates/fabro-types/src/interview.rs
@@ -1,11 +1,21 @@
-use std::fmt;
-
 use serde::{Deserialize, Serialize};
 
 use crate::run_event::InterviewOption;
 
-#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize, Default)]
+#[derive(
+    Debug,
+    Clone,
+    Copy,
+    PartialEq,
+    Eq,
+    Serialize,
+    Deserialize,
+    Default,
+    strum::Display,
+    strum::EnumString,
+)]
 #[serde(rename_all = "snake_case")]
+#[strum(serialize_all = "snake_case")]
 pub enum InterviewQuestionType {
     YesNo,
     MultipleChoice,
@@ -15,31 +25,6 @@ pub enum InterviewQuestionType {
     Confirmation,
 }
 
-impl InterviewQuestionType {
-    #[must_use]
-    pub fn from_wire_name(value: &str) -> Self {
-        match value {
-            "yes_no" => Self::YesNo,
-            "multiple_choice" => Self::MultipleChoice,
-            "multi_select" => Self::MultiSelect,
-            "confirmation" => Self::Confirmation,
-            _ => Self::Freeform,
-        }
-    }
-}
-
-impl fmt::Display for InterviewQuestionType {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        match self {
-            Self::YesNo => write!(f, "yes_no"),
-            Self::MultipleChoice => write!(f, "multiple_choice"),
-            Self::MultiSelect => write!(f, "multi_select"),
-            Self::Freeform => write!(f, "freeform"),
-            Self::Confirmation => write!(f, "confirmation"),
-        }
-    }
-}
-
 #[derive(Debug, Clone, PartialEq, Serialize, Deserialize, Default)]
 pub struct InterviewQuestionRecord {
     #[serde(default)]
@@ -59,3 +44,27 @@ pub struct InterviewQuestionRecord {
     #[serde(default, skip_serializing_if = "Option::is_none")]
     pub context_display: Option<String>,
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn question_type_wire_names_roundtrip() {
+        let cases = [
+            ("yes_no", InterviewQuestionType::YesNo),
+            ("multiple_choice", InterviewQuestionType::MultipleChoice),
+            ("multi_select", InterviewQuestionType::MultiSelect),
+            ("freeform", InterviewQuestionType::Freeform),
+            ("confirmation", InterviewQuestionType::Confirmation),
+        ];
+
+        for (wire, question_type) in cases {
+            assert_eq!(
+                wire.parse::<InterviewQuestionType>().unwrap(),
+                question_type
+            );
+            assert_eq!(question_type.to_string(), wire);
+        }
+    }
+}
diff --git a/lib/crates/fabro-types/src/settings/interp.rs b/lib/crates/fabro-types/src/settings/interp.rs
index fc5e2603c..f3aef95fc 100644
--- a/lib/crates/fabro-types/src/settings/interp.rs
+++ b/lib/crates/fabro-types/src/settings/interp.rs
@@ -49,6 +49,8 @@ impl InterpString {
 
     /// Parse a raw string into its literal/env-var segments.
     ///
+    /// The [`From<String>`] and [`From<&str>`] impls delegate here.
+    ///
     /// Parsing is infallible: the token grammar is intentionally permissive so
     /// that validation happens at consumption time along with env lookup.
     #[must_use]
diff --git a/lib/crates/fabro-validate/src/rules.rs b/lib/crates/fabro-validate/src/rules.rs
index 5be714324..b4e01e47c 100644
--- a/lib/crates/fabro-validate/src/rules.rs
+++ b/lib/crates/fabro-validate/src/rules.rs
@@ -937,7 +937,7 @@ fn check_provider_known(
     }
     let valid: Vec<&str> = fabro_model::Provider::ALL
         .iter()
-        .map(|p| p.as_str())
+        .map(|&p| <&'static str>::from(p))
         .collect();
     let valid_str = valid.join(", ");
     Some(Diagnostic {
diff --git a/lib/crates/fabro-workflow/src/handler/agent.rs b/lib/crates/fabro-workflow/src/handler/agent.rs
index 8ed952359..489d9bb38 100644
--- a/lib/crates/fabro-workflow/src/handler/agent.rs
+++ b/lib/crates/fabro-workflow/src/handler/agent.rs
@@ -254,7 +254,7 @@ impl Handler for AgentHandler {
         let prompt_provider = node
             .provider()
             .map(String::from)
-            .or_else(|| Some(services.run.provider.as_str().to_string()));
+            .or_else(|| Some(services.run.provider.to_string()));
         let prompt_model = node.model().map(String::from);
         let stage_scope = StageScope::for_handler(context, &node.id);
         services.run.emitter.emit_scoped(
@@ -331,7 +331,7 @@ impl Handler for AgentHandler {
         let response_provider = node
             .provider()
             .map(String::from)
-            .or_else(|| Some(services.run.provider.as_str().to_string()))
+            .or_else(|| Some(services.run.provider.to_string()))
             .unwrap_or_default();
         services.run.emitter.emit_scoped(
             &Event::PromptCompleted {
diff --git a/lib/crates/fabro-workflow/src/handler/llm/api.rs b/lib/crates/fabro-workflow/src/handler/llm/api.rs
index 36c93f5c3..a66a3b630 100644
--- a/lib/crates/fabro-workflow/src/handler/llm/api.rs
+++ b/lib/crates/fabro-workflow/src/handler/llm/api.rs
@@ -294,7 +294,7 @@ impl CodergenBackend for AgentApiBackend {
         let provider = node
             .provider()
             .map(String::from)
-            .or_else(|| Some(self.provider.as_str().to_string()));
+            .or_else(|| Some(self.provider.to_string()));
 
         let max_tokens = node.max_tokens().or_else(|| {
             fabro_model::Catalog::builtin()
@@ -335,7 +335,7 @@ impl CodergenBackend for AgentApiBackend {
 
         let result = client.complete(&request).await;
 
-        let default_provider = self.provider.as_str().to_string();
+        let default_provider = self.provider.to_string();
 
         let (response, actual_model, actual_provider) = match result {
             Ok(resp) => (
@@ -500,7 +500,7 @@ impl CodergenBackend for AgentApiBackend {
                 if sdk_err.failover_eligible() && !self.fallback_chain.is_empty() =>
             {
                 let error_msg = sdk_err.to_string();
-                let from_provider = self.provider.as_str().to_string();
+                let from_provider = self.provider.to_string();
                 let from_model = self.model.clone();
 
                 let mut last_err = Error::Llm(sdk_err.clone());
diff --git a/lib/crates/fabro-workflow/src/handler/llm/cli.rs b/lib/crates/fabro-workflow/src/handler/llm/cli.rs
index fe54690f9..d837bfa55 100644
--- a/lib/crates/fabro-workflow/src/handler/llm/cli.rs
+++ b/lib/crates/fabro-workflow/src/handler/llm/cli.rs
@@ -67,7 +67,7 @@ async fn ensure_cli(
 ) -> Result<(), Error> {
     let start = std::time::Instant::now();
     let cli_name = cli.name();
-    let provider_str = provider.as_str();
+    let provider_str = <&'static str>::from(provider);
 
     emitter.emit(&Event::CliEnsureStarted {
         cli_name: cli_name.to_string(),
@@ -520,7 +520,7 @@ impl CodergenBackend for AgentCliBackend {
                 node_id:  node.id.clone(),
                 visit:    stage_scope.visit,
                 mode:     "cli".to_string(),
-                provider: provider.as_str().to_string(),
+                provider: provider.to_string(),
                 model:    model.to_string(),
                 command:  command.clone(),
             },
diff --git a/lib/crates/fabro-workflow/src/handler/prompt.rs b/lib/crates/fabro-workflow/src/handler/prompt.rs
index 786721435..111909d35 100644
--- a/lib/crates/fabro-workflow/src/handler/prompt.rs
+++ b/lib/crates/fabro-workflow/src/handler/prompt.rs
@@ -86,7 +86,7 @@ impl Handler for PromptHandler {
         let prompt_provider = node
             .provider()
             .map(String::from)
-            .or_else(|| Some(services.run.provider.as_str().to_string()));
+            .or_else(|| Some(services.run.provider.to_string()));
         let prompt_model = node.model().map(String::from);
         let stage_scope = StageScope::for_handler(context, &node.id);
         services.run.emitter.emit_scoped(
@@ -138,7 +138,7 @@ impl Handler for PromptHandler {
         let response_provider = node
             .provider()
             .map(String::from)
-            .or_else(|| Some(services.run.provider.as_str().to_string()))
+            .or_else(|| Some(services.run.provider.to_string()))
             .unwrap_or_default();
 
         services.run.emitter.emit_scoped(
diff --git a/lib/crates/fabro-workflow/src/pipeline/retro.rs b/lib/crates/fabro-workflow/src/pipeline/retro.rs
index e9f9420bb..b21975b10 100644
--- a/lib/crates/fabro-workflow/src/pipeline/retro.rs
+++ b/lib/crates/fabro-workflow/src/pipeline/retro.rs
@@ -58,7 +58,7 @@ pub async fn run_retro(options: &RetroOptions, dry_run: bool) -> Option<Retro> {
     let retro_prompt = build_retro_prompt(RETRO_DATA_DIR);
     services.emitter.emit(&Event::RetroStarted {
         prompt:   Some(retro_prompt),
-        provider: Some(services.provider.as_str().to_string()),
+        provider: Some(services.provider.to_string()),
         model:    Some(options.model.clone()),
     });