Surface dispatch-failed age on dw system:operator-metrics

Renders the workflow-v2 task-path dispatch-failed age pair on the
operator-metrics CLI surface so HTTP-only operators can read "how
long has the worst-case task been sitting with an uncleared dispatch
error?" — the primary transport-failure age indicator on the dispatch
path — directly from `dw system:operator-metrics`.

`OperatorMetricsCommand::renderTasks()` now emits two new rows right
after the existing claim-failed age rows:

Oldest dispatch-failed age: <ms>
Oldest dispatch failed at: <ISO-8601>

Both rows degrade gracefully when the snapshot predates the contract:
the renderer omits the rows and the existing `dispatch failed <count>`
cell on the duplicate-risk roll-up still renders.

Pins `tasks.oldest_dispatch_failed_at` and
`tasks.max_dispatch_failed_age_ms` on
`schemas/output/operator-metrics.schema.json` next to the existing
`oldest_claim_failed_at` / `max_claim_failed_age_ms` pair, and adds
`test_operator_metrics_schema_pins_dispatch_failed_age_keys` plus
`test_operator_metrics_command_omits_dispatch_failed_age_when_snapshot_predates_contract`
to guard the schema declaration and the renderer fallback.

Author: durable-workflow-ops

schemas/output/operator-metrics.schema.json

@@ -41,6 +41,8 @@
             "max_dispatch_overdue_age_ms": { "type": ["integer", "null"] },
             "oldest_claim_failed_at": { "type": ["string", "null"] },
             "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"] }
           },
           "additionalProperties": true

src/Commands/SystemCommand/OperatorMetricsCommand.php

@@ -171,6 +171,15 @@ private function renderTasks(OutputInterface $output, array $tasks): void
         if (is_string($tasks['oldest_claim_failed_at'] ?? null)) {
             $output->writeln(sprintf('  Oldest claim failed at:   %s', $tasks['oldest_claim_failed_at']));
         }
+        if (array_key_exists('max_dispatch_failed_age_ms', $tasks)) {
+            $output->writeln(sprintf(
+                '  Oldest dispatch-failed age: %d ms',
+                (int) ($tasks['max_dispatch_failed_age_ms'] ?? 0),
+            ));
+        }
+        if (is_string($tasks['oldest_dispatch_failed_at'] ?? null)) {
+            $output->writeln(sprintf('  Oldest dispatch failed at: %s', $tasks['oldest_dispatch_failed_at']));
+        }
         $output->writeln('');
     }
 

tests/Commands/SystemCommandTest.php

@@ -524,6 +524,8 @@ public function test_operator_metrics_command_renders_rollout_safety_signals():
         self::assertStringContainsString('Oldest dispatch-overdue since: 2026-04-24T11:29:05Z', $display);
         self::assertStringContainsString('Oldest claim-failed age:  65000 ms', $display);
         self::assertStringContainsString('Oldest claim failed at:   2026-04-24T11:28:55Z', $display);
+        self::assertStringContainsString('Oldest dispatch-failed age: 135000 ms', $display);
+        self::assertStringContainsString('Oldest dispatch failed at: 2026-04-24T11:27:45Z', $display);
 
         self::assertStringContainsString('Runnable tasks:       7', $display);
         self::assertStringContainsString('Delayed tasks:        3', $display);
@@ -680,6 +682,20 @@ public function test_operator_metrics_schema_pins_claim_failed_age_keys(): void
         self::assertSame(['integer', 'null'], $tasks['max_claim_failed_age_ms']['type']);
     }
 
+    public function test_operator_metrics_schema_pins_dispatch_failed_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_dispatch_failed_at']['type']);
+        self::assertSame(['integer', 'null'], $tasks['max_dispatch_failed_age_ms']['type']);
+    }
+
     public function test_operator_metrics_schema_pins_run_wait_age_keys(): void
     {
         $schema = json_decode(
@@ -751,6 +767,27 @@ public function test_operator_metrics_command_omits_claim_failed_age_when_snapsh
         self::assertStringContainsString('claim failed 3', $display);
     }
 
+    public function test_operator_metrics_command_omits_dispatch_failed_age_when_snapshot_predates_contract(): void
+    {
+        $payload = self::operatorMetricsPayload();
+        unset(
+            $payload['operator_metrics']['tasks']['oldest_dispatch_failed_at'],
+            $payload['operator_metrics']['tasks']['max_dispatch_failed_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 dispatch-failed age', $display);
+        self::assertStringNotContainsString('Oldest dispatch failed at', $display);
+        self::assertStringContainsString('dispatch failed 2', $display);
+    }
+
     public function test_operator_metrics_command_omits_activities_block_when_payload_lacks_it(): void
     {
         $payload = self::operatorMetricsPayload();
@@ -840,6 +877,8 @@ private static function operatorMetricsPayload(): array
                     'max_dispatch_overdue_age_ms' => 55000,
                     'oldest_claim_failed_at' => '2026-04-24T11:28:55Z',
                     'max_claim_failed_age_ms' => 65000,
+                    'oldest_dispatch_failed_at' => '2026-04-24T11:27:45Z',
+                    'max_dispatch_failed_age_ms' => 135000,
                     'unhealthy' => 11,
                 ],
                 'backlog' => [