Surface dispatch-overdue wake-latency age on dw system:operator-metrics

The operator-metrics rollout-safety contract now freezes
operator_metrics.tasks.oldest_dispatch_overdue_since (ISO-8601 or null) and
operator_metrics.tasks.max_dispatch_overdue_age_ms (integer milliseconds) as
the wake-latency age surface — the effective COALESCE(last_dispatched_at,
created_at) across dispatch-overdue tasks, which answers "how long has the
oldest ready-but-unclaimed task been waiting for a working dispatch wake?"
from the metric alone.

Render the pair on the Tasks section of `dw system:operator-metrics` as
"Oldest dispatch-overdue age: N ms" and "Oldest dispatch-overdue since: ISO",
sibling to the existing Oldest lease-expired and Oldest ready-due rows.
Pin both keys under `tasks` in schemas/output/operator-metrics.schema.json
for --json consumers so the contract is enforced regardless of the textual
renderer. Extends SystemCommandTest with schema and human-rendering
assertions pinned unconditionally, mirroring the existing stuck-lease and
ready-due age pins.

Author: durable-workflow-ops

schemas/output/operator-metrics.schema.json

@@ -34,6 +34,8 @@
             "max_lease_expired_age_ms": { "type": ["integer", "null"] },
             "oldest_ready_due_at": { "type": ["string", "null"] },
             "max_ready_due_age_ms": { "type": ["integer", "null"] },
+            "oldest_dispatch_overdue_since": { "type": ["string", "null"] },
+            "max_dispatch_overdue_age_ms": { "type": ["integer", "null"] },
             "unhealthy": { "type": ["integer", "null"] }
           },
           "additionalProperties": true

src/Commands/SystemCommand/OperatorMetricsCommand.php

@@ -136,6 +136,15 @@ private function renderTasks(OutputInterface $output, array $tasks): void
         if (is_string($tasks['oldest_ready_due_at'] ?? null)) {
             $output->writeln(sprintf('  Oldest ready-due at:      %s', $tasks['oldest_ready_due_at']));
         }
+        if (array_key_exists('max_dispatch_overdue_age_ms', $tasks)) {
+            $output->writeln(sprintf(
+                '  Oldest dispatch-overdue age: %d ms',
+                (int) ($tasks['max_dispatch_overdue_age_ms'] ?? 0),
+            ));
+        }
+        if (is_string($tasks['oldest_dispatch_overdue_since'] ?? null)) {
+            $output->writeln(sprintf('  Oldest dispatch-overdue since: %s', $tasks['oldest_dispatch_overdue_since']));
+        }
         $output->writeln('');
     }
 

tests/Commands/SystemCommandTest.php

@@ -517,6 +517,8 @@ public function test_operator_metrics_command_renders_rollout_safety_signals():
         self::assertStringContainsString('Oldest lease expired at:  2026-04-24T11:28:25Z', $display);
         self::assertStringContainsString('Oldest ready-due age:     15000 ms', $display);
         self::assertStringContainsString('Oldest ready-due at:      2026-04-24T11:29:45Z', $display);
+        self::assertStringContainsString('Oldest dispatch-overdue age: 55000 ms', $display);
+        self::assertStringContainsString('Oldest dispatch-overdue since: 2026-04-24T11:29:05Z', $display);
 
         self::assertStringContainsString('Runnable tasks:       7', $display);
         self::assertStringContainsString('Delayed tasks:        3', $display);
@@ -634,6 +636,20 @@ public function test_operator_metrics_schema_pins_ready_due_age_keys(): void
         self::assertSame(['integer', 'null'], $tasks['max_ready_due_age_ms']['type']);
     }
 
+    public function test_operator_metrics_schema_pins_dispatch_overdue_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_overdue_since']['type']);
+        self::assertSame(['integer', 'null'], $tasks['max_dispatch_overdue_age_ms']['type']);
+    }
+
     public function test_operator_metrics_command_tolerates_minimal_payload(): void
     {
         $command = new OperatorMetricsCommand();
@@ -677,6 +693,8 @@ private static function operatorMetricsPayload(): array
                     'max_lease_expired_age_ms' => 95000,
                     'oldest_ready_due_at' => '2026-04-24T11:29:45Z',
                     'max_ready_due_age_ms' => 15000,
+                    'oldest_dispatch_overdue_since' => '2026-04-24T11:29:05Z',
+                    'max_dispatch_overdue_age_ms' => 55000,
                     'unhealthy' => 11,
                 ],
                 'backlog' => [