Surface unhealthy-age rollup on dw system:operator-metrics

Renders the workflow-v2 unhealthy-age rollup pinned by the Phase 6
rollout-safety contract on `operator_metrics.tasks.oldest_unhealthy_at`
and `operator_metrics.tasks.max_unhealthy_age_ms` so HTTP-only
operators can read the worst-case duplicate-risk task age (the
earliest of `oldest_dispatch_failed_at`, `oldest_claim_failed_at`,
`oldest_dispatch_overdue_since`, `oldest_lease_expired_at` and the
largest age in milliseconds across them) directly from
`dw system:operator-metrics` without taking a max over four separate
per-path age fields themselves.

`OperatorMetricsCommand::renderTasks()` now emits two new rows right
after the existing "Unhealthy (duplicate-risk roll-up)" summary line
and before the per-path age detail rows:

Oldest unhealthy age:     <ms> ms
Oldest unhealthy at:      <ISO>

Both rows degrade gracefully when the snapshot predates the contract:
the renderer omits each row when its key is absent and the existing
per-path age rendering still surfaces individual lease, ready-due,
dispatch-overdue, claim-failed, and dispatch-failed ages.

Pins `tasks.oldest_unhealthy_at` and `tasks.max_unhealthy_age_ms` on
`schemas/output/operator-metrics.schema.json` next to the existing
unhealthy/per-path age keys, and adds
`test_operator_metrics_schema_pins_unhealthy_age_keys` and
`test_operator_metrics_command_omits_unhealthy_age_when_snapshot_predates_contract`
plus assertions on the existing render smoke test to guard the
schema declaration, the renderer, and the renderer fallback.

Author: durable-workflow-ops

schemas/output/operator-metrics.schema.json

@@ -43,7 +43,9 @@
             "max_claim_failed_age_ms": { "type": ["integer", "null"] },
             "oldest_dispatch_failed_at": { "type": ["string", "null"] },
             "max_dispatch_failed_age_ms": { "type": ["integer", "null"] },
-            "unhealthy": { "type": ["integer", "null"] }
+            "unhealthy": { "type": ["integer", "null"] },
+            "oldest_unhealthy_at": { "type": ["string", "null"] },
+            "max_unhealthy_age_ms": { "type": ["integer", "null"] }
           },
           "additionalProperties": true
         },

src/Commands/SystemCommand/OperatorMetricsCommand.php

@@ -136,6 +136,15 @@ private function renderTasks(OutputInterface $output, array $tasks): void
             (int) ($tasks['dispatch_overdue'] ?? 0),
             (int) ($tasks['lease_expired'] ?? 0),
         ));
+        if (array_key_exists('max_unhealthy_age_ms', $tasks)) {
+            $output->writeln(sprintf(
+                '  Oldest unhealthy age:     %d ms',
+                (int) ($tasks['max_unhealthy_age_ms'] ?? 0),
+            ));
+        }
+        if (is_string($tasks['oldest_unhealthy_at'] ?? null)) {
+            $output->writeln(sprintf('  Oldest unhealthy at:      %s', $tasks['oldest_unhealthy_at']));
+        }
         if (array_key_exists('max_lease_expired_age_ms', $tasks)) {
             $output->writeln(sprintf(
                 '  Oldest lease-expired age: %d ms',

tests/Commands/SystemCommandTest.php

@@ -516,6 +516,8 @@ public function test_operator_metrics_command_renders_rollout_safety_signals():
             'Unhealthy (duplicate-risk roll-up): 11 (dispatch failed 2, claim failed 3, dispatch overdue 4, lease expired 2)',
             $display,
         );
+        self::assertStringContainsString('Oldest unhealthy age:     135000 ms', $display);
+        self::assertStringContainsString('Oldest unhealthy at:      2026-04-24T11:27:45Z', $display);
         self::assertStringContainsString('Oldest lease-expired age: 95000 ms', $display);
         self::assertStringContainsString('Oldest lease expired at:  2026-04-24T11:28:25Z', $display);
         self::assertStringContainsString('Oldest ready-due age:     15000 ms', $display);
@@ -701,6 +703,44 @@ public function test_operator_metrics_schema_pins_dispatch_failed_age_keys(): vo
         self::assertSame(['integer', 'null'], $tasks['max_dispatch_failed_age_ms']['type']);
     }
 
+    public function test_operator_metrics_schema_pins_unhealthy_age_keys(): void
+    {
+        $schema = json_decode(
+            (string) file_get_contents(__DIR__.'/../../schemas/output/operator-metrics.schema.json'),
+            true,
+            flags: JSON_THROW_ON_ERROR,
+        );
+
+        $tasks = $schema['properties']['operator_metrics']['properties']['tasks']['properties'];
+
+        self::assertSame(['string', 'null'], $tasks['oldest_unhealthy_at']['type']);
+        self::assertSame(['integer', 'null'], $tasks['max_unhealthy_age_ms']['type']);
+    }
+
+    public function test_operator_metrics_command_omits_unhealthy_age_when_snapshot_predates_contract(): void
+    {
+        $payload = self::operatorMetricsPayload();
+        unset(
+            $payload['operator_metrics']['tasks']['oldest_unhealthy_at'],
+            $payload['operator_metrics']['tasks']['max_unhealthy_age_ms'],
+        );
+
+        $command = new OperatorMetricsCommand();
+        $command->setServerClient(new SystemFakeClient($payload));
+
+        $tester = new CommandTester($command);
+        self::assertSame(Command::SUCCESS, $tester->execute([]));
+
+        $display = $tester->getDisplay();
+
+        self::assertStringNotContainsString('Oldest unhealthy age:', $display);
+        self::assertStringNotContainsString('Oldest unhealthy at:', $display);
+        self::assertStringContainsString(
+            'Unhealthy (duplicate-risk roll-up): 11',
+            $display,
+        );
+    }
+
     public function test_operator_metrics_schema_pins_run_wait_age_keys(): void
     {
         $schema = json_decode(
@@ -982,6 +1022,8 @@ private static function operatorMetricsPayload(): array
                     'oldest_dispatch_failed_at' => '2026-04-24T11:27:45Z',
                     'max_dispatch_failed_age_ms' => 135000,
                     'unhealthy' => 11,
+                    'oldest_unhealthy_at' => '2026-04-24T11:27:45Z',
+                    'max_unhealthy_age_ms' => 135000,
                 ],
                 'backlog' => [
                     'runnable_tasks' => 7,