Show recorded terminal failure reasons in run evidence

AUDIT_OPEN.md

@@ -547,3 +547,17 @@ proof on the target):**
 Until then the trust statement is: a preview has the preview TARGET's network
 reach, and the target must be chosen as if it ran untrusted code with that
 reach — which is why it is compute-1 and not the Ship host.
+
+### 2026-09-26 — terminal failure evidence
+
+Fixed on this branch: workflow terminal errors with `{error:{message:...}}`
+rendered an empty explanation in the workspace and its API. The timeline now
+reads the recorded detail/message/title or legacy string, and explicitly names
+missing details. Step failures use the same handling. This repairs presentation;
+it does not claim to fix the timeout that produced the event.
+
+Validation: lint; 1,411 runtime tests; 100 script tests with one existing skip;
+136 web tests; production web build. Initial web run through a shared dependency
+symlink loaded duplicate project-error classes and failed two unrelated identity
+checks; installing this worktree's web dependencies resolved both. Original
+failure log retained in the private execution receipts.

web/src/lib/timeline.test.ts

@@ -151,3 +151,23 @@ test("an ask park reads as a question, and its decision as the answer", () => {
   assert.equal(items[1]?.body, "Archive them");
   assert.equal(items[2]?.title, "waiting for approval");
 });
+
+// The production workflow's terminal timeout uses error.message, whereas
+// problem responses use detail/title. Both must reach the workspace evidence.
+test("failure evidence preserves workflow and problem-response causes", () => {
+  for (const [error, expected] of [
+    [{ message: "timeout expired" }, "timeout expired"],
+    [{ title: "Unavailable", detail: "store read timed out" }, "store read timed out"],
+    [{ detail: "", message: "connection reset", title: "Failed" }, "connection reset"],
+    ["model request failed", "model request failed"],
+    [{ message: 42 }, "No error detail was recorded."],
+    [undefined, "No error detail was recorded."],
+  ] as const) {
+    for (const type of ["run-failed", "step-failed"] as const) {
+      const events = [{ v: 1, seq: 1, type, name: "turn-5-think", at: T0, data: { error, attempt: 1 } }] as WorkflowEvent[];
+      const errors = toTimeline(events).filter((item) => item.kind === "error");
+      assert.equal(errors.length, 1);
+      assert.equal(errors[0]?.body, expected);
+    }
+  }
+});

web/src/lib/timeline.ts

@@ -198,11 +198,11 @@ export function toTimeline(events: WorkflowEvent[]): TimelineItem[] {
         break;
       }
       case "step-failed": {
-        const data = event.data as { error?: { message?: string }; attempt?: number } | undefined;
+        const data = event.data as { error?: unknown; attempt?: number } | undefined;
         items.push({
           kind: "error",
           title: `${event.name ?? "step"} failed (attempt ${data?.attempt ?? "?"})`,
-          body: data?.error?.message ?? "",
+          body: failureMessage(data?.error),
           at,
         });
         break;
@@ -247,8 +247,8 @@ export function toTimeline(events: WorkflowEvent[]): TimelineItem[] {
         break;
       }
       case "run-failed": {
-        const error = (event.data as { error?: { detail?: string; title?: string } } | undefined)?.error;
-        items.push({ kind: "error", title: "run failed", body: error?.detail ?? error?.title ?? "", at });
+        const error = (event.data as { error?: unknown } | undefined)?.error;
+        items.push({ kind: "error", title: "run failed", body: failureMessage(error), at });
         break;
       }
       default:
@@ -451,3 +451,14 @@ export function took(ms: number): string {
   const s = ms / 1000;
   return s < 60 ? `${s.toFixed(1)}s` : `${Math.floor(s / 60)}m ${String(Math.round(s % 60)).padStart(2, "0")}s`;
 }
+
+function failureMessage(error: unknown): string {
+  if (typeof error === "string" && error.trim() !== "") return error;
+  if (typeof error === "object" && error !== null) {
+    for (const key of ["detail", "message", "title"] as const) {
+      const value = (error as Record<string, unknown>)[key];
+      if (typeof value === "string" && value.trim() !== "") return value;
+    }
+  }
+  return "No error detail was recorded.";
+}