fix(jobs): rehydrate wire-format timestamps in thin-client list/get (#3026) (#3027)

The thin-client branches receive MinionJob rows as parsed JSON off the
MCP wire — every timestamp an ISO string — while formatJob /
formatJobDetail and the stalled-detection comparison hold a Date
contract (locally hydrated by MinionQueue.rowToJob). `jobs get <id>` on
a thin client crashed with "job.started_at.toISOString is not a
function" the moment the remote routing actually worked (unmasked by
the #2951 scratch-engine fix).

Rehydrate once at the unpack boundary via an exported helper that
coerces valid ISO strings to Dates, leaves Dates/nulls/malformed
strings untouched, and preserves the input type. Unit tests +
source-audit pins for both unpack sites.

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

src/commands/jobs.ts

@@ -143,6 +143,31 @@ export function resolveWorkerConcurrency(args: string[], env: NodeJS.ProcessEnv
   return parsed;
 }
 
+/**
+ * #3026: the thin-client `list`/`get` branches receive jobs as parsed JSON
+ * off the MCP wire, where every timestamp is an ISO string — but formatJob /
+ * formatJobDetail (and the stalled-detection comparison) hold a Date
+ * contract, hydrated locally by MinionQueue.rowToJob. Rehydrate once at the
+ * unpack boundary so both paths hand the formatters real Dates. Exported for
+ * unit tests.
+ */
+const JOB_DATE_FIELDS = [
+  'created_at', 'updated_at', 'started_at', 'finished_at', 'lock_until', 'delay_until',
+] as const;
+
+export function rehydrateJobDates<T>(job: T): T {
+  if (!job || typeof job !== 'object') return job;
+  const rec = job as { [k: string]: unknown };
+  for (const field of JOB_DATE_FIELDS) {
+    const v = rec[field];
+    if (typeof v === 'string') {
+      const d = new Date(v);
+      if (!Number.isNaN(d.getTime())) rec[field] = d;
+    }
+  }
+  return job;
+}
+
 function formatJob(job: MinionJob): string {
   const dur = job.finished_at && job.started_at
     ? `${((job.finished_at.getTime() - job.started_at.getTime()) / 1000).toFixed(1)}s`
@@ -496,7 +521,7 @@ HANDLER TYPES (built in)
         const raw = await callRemoteTool(cfg!, 'list_jobs', {
           status, queue: queueName, limit,
         }, { timeoutMs: 30_000 });
-        jobs = unpackToolResult<MinionJob[]>(raw);
+        jobs = unpackToolResult<MinionJob[]>(raw).map((j) => rehydrateJobDates(j));
       } else {
         try { await queue.ensureSchema(); }
         catch (e) { console.error(e instanceof Error ? e.message : String(e)); process.exit(1); }
@@ -525,7 +550,7 @@ HANDLER TYPES (built in)
       if (isThinClient(cfg)) {
         try {
           const raw = await callRemoteTool(cfg!, 'get_job', { id }, { timeoutMs: 30_000 });
-          job = unpackToolResult<MinionJob | null>(raw);
+          job = rehydrateJobDates(unpackToolResult<MinionJob | null>(raw));
         } catch (e) {
           // The remote op throws `invalid_params` on not-found; surface as
           // the same "Job not found" exit-1 the local path produces.

test/jobs-thin-client-date-rehydration.test.ts

@@ -0,0 +1,78 @@
+/**
+ * #3026: thin-client `jobs list`/`get` receive MinionJob rows as parsed JSON
+ * off the MCP wire — every timestamp an ISO string — while formatJob /
+ * formatJobDetail and the stalled-detection comparison hold a Date contract
+ * (locally hydrated by MinionQueue.rowToJob). Before the fix, `jobs get <id>`
+ * on a thin client crashed with "job.started_at.toISOString is not a
+ * function" the moment the remote routing actually worked (unmasked by
+ * #2951's scratch-engine fix).
+ *
+ * Pins rehydrateJobDates (the unpack-boundary coercion) plus, audit-style,
+ * that both thin-client unpack sites route through it.
+ */
+
+import { describe, test, expect } from 'bun:test';
+import { readFileSync } from 'node:fs';
+import { join } from 'node:path';
+import { rehydrateJobDates } from '../src/commands/jobs.ts';
+
+describe('rehydrateJobDates', () => {
+  test('coerces wire-format ISO strings to Dates on all timestamp fields', () => {
+    const wire = {
+      id: 1192,
+      name: 'autopilot-cycle',
+      status: 'completed',
+      created_at: '2026-07-21T04:02:11.512Z',
+      updated_at: '2026-07-21T04:02:14.930Z',
+      started_at: '2026-07-21T04:02:12.001Z',
+      finished_at: '2026-07-21T04:02:14.900Z',
+      lock_until: '2026-07-21T04:03:12.001Z',
+      delay_until: null,
+    };
+    const job = rehydrateJobDates(wire);
+    expect(job.created_at).toBeInstanceOf(Date);
+    expect(job.updated_at).toBeInstanceOf(Date);
+    expect(job.started_at).toBeInstanceOf(Date);
+    expect(job.finished_at).toBeInstanceOf(Date);
+    expect(job.lock_until).toBeInstanceOf(Date);
+    expect((job.started_at as unknown as Date).toISOString()).toBe('2026-07-21T04:02:12.001Z');
+    // Date math used by formatJob's duration column works post-rehydration.
+    expect((job.finished_at as unknown as Date).getTime() - (job.started_at as unknown as Date).getTime())
+      .toBeCloseTo(2899, 0);
+  });
+
+  test('leaves Dates, nulls, and non-timestamp fields untouched', () => {
+    const started = new Date('2026-07-21T04:02:12.001Z');
+    const job = rehydrateJobDates({
+      id: 7,
+      name: 'sync',
+      status: 'active',
+      created_at: started,
+      started_at: started,
+      finished_at: null,
+      delay_until: undefined,
+    });
+    expect(job.created_at).toBe(started);
+    expect(job.finished_at).toBeNull();
+    expect(job.delay_until).toBeUndefined();
+    expect(job.name).toBe('sync');
+  });
+
+  test('does not fabricate Dates from malformed strings; passes null through', () => {
+    const job = rehydrateJobDates({ id: 8, started_at: 'not-a-date' });
+    expect(job.started_at).toBe('not-a-date');
+    expect(rehydrateJobDates(null)).toBeNull();
+  });
+});
+
+describe('thin-client unpack sites route through rehydrateJobDates (source audit)', () => {
+  const src = readFileSync(join(import.meta.dir, '..', 'src', 'commands', 'jobs.ts'), 'utf8');
+
+  test('list branch rehydrates', () => {
+    expect(src).toContain('unpackToolResult<MinionJob[]>(raw).map((j) => rehydrateJobDates(j))');
+  });
+
+  test('get branch rehydrates', () => {
+    expect(src).toContain('rehydrateJobDates(unpackToolResult<MinionJob | null>(raw))');
+  });
+});