fix(server): preserve backlog deadlines after partial failure

Co-Authored-By: Paperclip <noreply@paperclip.ing>

server/src/services/chat-discord-command-registration-store.test.ts

@@ -860,6 +860,27 @@ suite("Discord command ownership store (real PostgreSQL, no network)", () => {
     expect(errors).toEqual([]);
   });
 
+  it("drains healthy commands promptly while one entry remains in failure backoff", async () => {
+    await reconcileDatabaseWork(db, DELIVERY_QUEUES.chatCommandRegistration);
+    vi.useFakeTimers({ toFake: ["Date", "setTimeout", "clearTimeout"], shouldAdvanceTime: true });
+    const entries = Array.from({ length: 300 }, (_, index) => ({
+      id: `command-${index}`, companyId: `company-${index % 10}`, connectionId: `connection-${index}`, dueAt: 0,
+    }));
+    const check = vi.fn(async (id: string) => {
+      if (id === "command-0") throw new Error("Unavailable credential");
+      return { ...entries.find(entry => entry.id === id)!, dueAt: Date.now() + 300_000 };
+    });
+    const onError = vi.fn();
+    coordinator = createDeliveryWorkCoordinator({ owner: db, canRun: () => true, onError });
+    await registerDiscordCommandWork(coordinator, { load: async () => entries, check }, () => true).ready;
+    await vi.advanceTimersByTimeAsync(15_000);
+    expect(new Set(check.mock.calls.map(([id]) => id)).size).toBe(300);
+    expect(check.mock.calls.filter(([id]) => id === "command-0")).toHaveLength(1);
+    expect(onError).toHaveBeenCalledOnce();
+    await vi.advanceTimersByTimeAsync(45_000);
+    expect(check.mock.calls.filter(([id]) => id === "command-0")).toHaveLength(2);
+    expect(check.mock.calls.filter(([id]) => id !== "command-0")).toHaveLength(299);
+  });
   it("recovers queued scopes after an unknown hint instead of dropping the wake", async () => {
     await reconcileDatabaseWork(db, DELIVERY_QUEUES.chatCommandRegistration);
     vi.useFakeTimers({ toFake: ["Date", "setTimeout", "clearTimeout"], shouldAdvanceTime: true });

server/src/services/delivery-work-coordinator.ts

@@ -78,9 +78,16 @@ export function createDeliveryWorkCoordinator(input: {
           }
         }).catch(error => {
           schedule(task.retryMs);
+          let failure = error;
+          try {
+            const next = input.canRun() ? task.nextRunAt?.() : null;
+            if (next != null && next > Date.now()) schedule(0, next);
+          } catch (deadlineError) {
+            failure = new AggregateError([error, deadlineError], "Delivery failure deadline could not be read");
+          }
           // Logging must never turn a recoverable sweep failure into an
           // unhandled rejection or prevent other queues from running.
-          try { if (!workerStopped) input.onError(error, queue); } catch { /* Recovery remains scheduled. */ }
+          try { if (!workerStopped) input.onError(failure, queue); } catch { /* Recovery remains scheduled. */ }
         }).finally(() => {
           running = null;
           controller = null;