Show a banner for dead runs, which record no conclusion

A dead run's projection never gets conclusion.failure, so the banner
never showed. Fall back to the run summary's lifecycle.error, where the
server keeps a dead run's reason, and to a generic headline when that is
empty too.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

apps/fabro-web/app/routes/run-detail.tsx

@@ -156,7 +156,10 @@ export default function RunDetail({ params }: { params: { id: string } }) {
     () => new Map((providersQuery.data?.data ?? []).map((p) => [p.id, p.display_name || p.id])),
     [providersQuery.data],
   );
-  const failure = buildRunFailureView(runStateQuery.data, providerNames);
+  const failure = buildRunFailureView(runStateQuery.data, {
+    providerNames,
+    lifecycleError: runQuery.data?.lifecycle.error?.message,
+  });
 
   const handleLifecycleMutationResult = useCallback(
     (

apps/fabro-web/app/routes/run-detail/failure.test.ts

@@ -32,7 +32,7 @@ function failedRun(
   };
 }
 
-const view = (state: State) => buildRunFailureView(state, NAMES);
+const view = (state: State) => buildRunFailureView(state, { providerNames: NAMES });
 
 describe("buildRunFailureView", () => {
   test("names the step the run stopped at and the provider's real message", () => {
@@ -113,7 +113,20 @@ describe("buildRunFailureView", () => {
     expect(view(failedRun({ message: "denied at review" }, { reason: "approval_denied" }))?.headline).toBe("Approval was denied");
     expect(view(failedRun({ message: "budget of $5 reached" }, { reason: "budget_exhausted" }))?.headline).toBe("The run used up its budget");
     expect(view(failedRun({ message: "sandbox image not found" }, { reason: "sandbox_init_failed" }))?.headline).toBe("The run couldn't start");
-    expect(view(failedRun({ message: "worker exited unexpectedly" }, { kind: "dead" }))?.headline).toBe("Worker exited unexpectedly");
+  });
+
+  test("says why a dead run stopped, though a dead run records no conclusion", () => {
+    const dead = {
+      status: { kind: "dead" },
+      conclusion: null,
+      stages: stages(["build@1", "failed", "2026-10-10T18:05:42Z"]),
+    } as unknown as State;
+    expect(buildRunFailureView(dead, { lifecycleError: "worker exited unexpectedly" })).toMatchObject({
+      stage: "build",
+      headline: "Worker exited unexpectedly",
+      message: "worker exited unexpectedly",
+    });
+    expect(buildRunFailureView(dead)?.headline).toBe("The run's worker stopped before the run finished");
   });
 
   test("shows the end of a command's output, from whichever stream has it", () => {

apps/fabro-web/app/routes/run-detail/failure.ts

@@ -25,18 +25,27 @@ export interface RunFailureView {
 
 type FailureState = Pick<RunProjection, "status" | "conclusion" | "stages">;
 
+export interface RunFailureContext {
+  /** Provider ids to display names, from the provider catalog. */
+  providerNames?: ReadonlyMap<string, string>;
+  /** The run summary's `lifecycle.error`, the only reason a dead run records. */
+  lifecycleError?: string | null;
+}
+
 /**
  * Reads the failure from run state (`conclusion.failure`); the run summary the
- * status popover reads doesn't carry the message or the command's output.
+ * status popover reads doesn't carry the message or the command's output. A
+ * dead run has no conclusion, so its reason comes from the summary instead.
  */
 export function buildRunFailureView(
   state: FailureState | null | undefined,
-  providerNames: ReadonlyMap<string, string> = new Map(),
+  { providerNames = new Map(), lifecycleError = null }: RunFailureContext = {},
 ): RunFailureView | null {
   const kind = state?.status?.kind;
   if (!state || (kind !== "failed" && kind !== "dead")) return null;
   const failure = state.conclusion?.failure;
-  if (!failure?.detail.message || failure.reason === FailureReason.CANCELLED) return null;
+  if (!failure) return kind === "dead" ? deadRunView(state, lifecycleError) : null;
+  if (!failure.detail.message || failure.reason === FailureReason.CANCELLED) return null;
 
   const { message, category } = failure.detail;
   const output = outputTail(failure.detail.exec_output_tail);
@@ -54,6 +63,19 @@ export function buildRunFailureView(
   };
 }
 
+/** A run whose worker went away before the run concluded. */
+function deadRunView(state: FailureState, lifecycleError: string | null): RunFailureView {
+  const message = lifecycleError?.trim() || "The run ended without recording a reason.";
+  return {
+    stage: stoppedAt(state.stages),
+    headline: lifecycleError?.trim() ? firstSentence(message) : "The run's worker stopped before the run finished",
+    nextStep: `Open the failed step's logs for details. To run it again, ${RETRY}.`,
+    message,
+    provider: null,
+    output: null,
+  };
+}
+
 type Advice = Pick<RunFailureView, "headline" | "nextStep">;
 
 const RETRY = "choose Retry from Actions";