ask/resume: nonzero exit on refusal and pause_turn stop reasons

crates/mu-ai/src/providers/anthropic_tests.rs

@@ -997,8 +997,11 @@ fn map_stop_reason_known_and_unknown() {
     assert_eq!(map_stop_reason(Some(&A::EndTurn)), StopReason::EndTurn);
     assert_eq!(map_stop_reason(Some(&A::ToolUse)), StopReason::ToolUse);
     assert_eq!(map_stop_reason(Some(&A::MaxTokens)), StopReason::MaxTokens);
-    // unmapped wire reasons (stop_sequence / refusal / pause_turn / unknown)
-    // all fold to EndTurn.
+    // Gen-5 terminal states map to their own core reasons
+    // (mu-provider-drift-2026q3-y43la).
+    assert_eq!(map_stop_reason(Some(&A::Refusal)), StopReason::Refusal);
+    assert_eq!(map_stop_reason(Some(&A::PauseTurn)), StopReason::PauseTurn);
+    // stop_sequence and unknown/absent reasons fold to EndTurn.
     assert_eq!(map_stop_reason(Some(&A::StopSequence)), StopReason::EndTurn);
     assert_eq!(map_stop_reason(Some(&A::Other)), StopReason::EndTurn);
     assert_eq!(map_stop_reason(None), StopReason::EndTurn);

crates/mu-coding/src/ask.rs

@@ -156,6 +156,25 @@ pub async fn run(opts: AskOptions) -> Result<()> {
              closed without a terminal stop event (connection drop or upstream \
              truncation). Output above may be a fragment."
         ),
+        // mu-provider-drift-2026q3-y43la: the gen-5 terminal states must not
+        // exit 0 — a refused ask has no answer, and a server-paused ask ended
+        // early. Same rationale as max_tokens: the nonzero exit keeps
+        // headless scoring pipelines and spawn callers from reading a
+        // non-answer as a clean success. Edge (panel-raised): if a refusal
+        // ever cut a turn that ALSO completed a final_answer call, the
+        // answer still prints above but the exit is nonzero — deliberate:
+        // an answer the safety classifier cut mid-delivery should force
+        // caller scrutiny, not score as clean.
+        Some("refusal") => bail!(
+            "ask refused (stop_reason=refusal): the provider's safety \
+             classifier declined the request or cut generation. There is no \
+             answer; consider a different seat/model."
+        ),
+        Some("pause_turn") => bail!(
+            "response paused (stop_reason=pause_turn): the server paused a \
+             long-running turn and mu does not implement continuation. \
+             Output above may be partial."
+        ),
         _ => Ok(()),
     }
 }

crates/mu-coding/src/resume.rs

@@ -154,6 +154,21 @@ pub async fn run(opts: ResumeOptions) -> Result<()> {
         Some("degraded_eof") => {
             bail!("response degraded (stop_reason=degraded_eof). Output above may be a fragment.")
         }
+        // Same guard as ask.rs (mu-provider-drift-2026q3-y43la): a refused or
+        // server-paused resumed ask must not exit 0 as if it answered.
+        Some("refusal") => {
+            bail!(
+                "ask refused (stop_reason=refusal): the provider's safety classifier \
+                 declined the request or cut generation. There is no answer."
+            )
+        }
+        Some("pause_turn") => {
+            bail!(
+                "response paused (stop_reason=pause_turn): the server paused a \
+                 long-running turn and mu does not implement continuation. Output \
+                 above may be partial."
+            )
+        }
         _ => Ok(()),
     }
 }