diff --git a/packages/agent-lifecycle/src/index.ts b/packages/agent-lifecycle/src/index.ts
index 6255f60ac..d53bee5bc 100644
--- a/packages/agent-lifecycle/src/index.ts
+++ b/packages/agent-lifecycle/src/index.ts
@@ -25,11 +25,30 @@ type Logger = ReturnType<typeof getLogger>;
  */
 export const IDLE_HIBERNATE_UNDEPLOY_REASON = "idle-hibernate";
 
+/**
+ * `ensureAwake`'s default bound on one call to the injected `wake` port.
+ * A cold wake for a run whose deployed record was parked aside is a real
+ * deploy round-trip to the host, not a local check — long enough to allow
+ * for that, short enough that a wake the host never acks turns into a
+ * rejection (CL-6643) instead of a promise nothing ever observes.
+ */
+export const DEFAULT_WAKE_TIMEOUT_MS = 30_000;
+
 export type CreateAgentLifecycleOptions = {
   /** How long an address may sit idle (no `recordActivity`) before the sweep sleeps it. Required — no default hidden in here. */
   idleSleepMs: number;
   /** How often the sweep runs. Defaults to half the sleep threshold, floored at 5s. */
   sweepIntervalMs?: number;
+  /**
+   * How long one `ensureAwake` call may wait on the injected `wake` port
+   * before treating it as failed. Defaults to `DEFAULT_WAKE_TIMEOUT_MS`.
+   * `wake` itself keeps running past the timeout — this only bounds how
+   * long a caller (and everyone coalesced behind it) waits before this
+   * package gives up and reports a rejection, so a wake the host never
+   * acks can never wedge an address's mail silently for the rest of the
+   * process's life (CL-6643).
+   */
+  wakeTimeoutMs?: number;
   /** Whether the host currently has this address deployed/connected. */
   isRoutable(address: string): boolean;
   /** Tears the address down on the host. Errors are the caller's to throw; the sweep catches and logs them per-address. */
@@ -76,6 +95,7 @@ export function createAgentLifecycle(
   const { idleSleepMs, isRoutable, undeploy, wake, log } = options;
   const sweepIntervalMs =
     options.sweepIntervalMs ?? Math.max(idleSleepMs / 2, 5_000);
+  const wakeTimeoutMs = options.wakeTimeoutMs ?? DEFAULT_WAKE_TIMEOUT_MS;
   const isBusy = options.isBusy ?? (() => false);
 
   const tracked = new Set<string>();
@@ -148,13 +168,41 @@ export function createAgentLifecycle(
   }, sweepIntervalMs);
   if (typeof interval.unref === "function") interval.unref();
 
+  /**
+   * Races `wake(address)` against `wakeTimeoutMs`. A timeout rejects
+   * with a distinct error so a caller (and everything coalesced behind
+   * it) always gets a settled outcome — never a hang — even though the
+   * underlying `wake` call keeps running unobserved past the deadline.
+   */
+  function wakeWithTimeout(address: string): Promise<void> {
+    return new Promise((resolve, reject) => {
+      const timer = setTimeout(() => {
+        reject(
+          new Error(
+            `wake for "${address}" did not settle within ${String(wakeTimeoutMs)}ms`,
+          ),
+        );
+      }, wakeTimeoutMs);
+      wake(address).then(
+        (value) => {
+          clearTimeout(timer);
+          resolve(value);
+        },
+        (cause: unknown) => {
+          clearTimeout(timer);
+          reject(cause);
+        },
+      );
+    });
+  }
+
   async function ensureAwake(address: string): Promise<void> {
     if (isRoutable(address)) return;
 
     const pending = pendingWakes.get(address);
     if (pending !== undefined) return pending;
 
-    const waking = wake(address)
+    const waking = wakeWithTimeout(address)
       .then(() => {
         recordActivity(address);
       })
diff --git a/packages/agent-lifecycle/test/index.test.ts b/packages/agent-lifecycle/test/index.test.ts
index 4afb4df2f..7ced65573 100644
--- a/packages/agent-lifecycle/test/index.test.ts
+++ b/packages/agent-lifecycle/test/index.test.ts
@@ -325,4 +325,50 @@ describe("createAgentLifecycle", () => {
       failure,
     );
   });
+
+  // CL-6643: a run whose deployed record was parked aside (no sidecar
+  // record, cold wake required) can hang inside the injected `wake` port
+  // forever — the sidecar never acks a redeploy it has no state for.
+  // Without a bound, that first hung call never leaves `pendingWakes`
+  // (its `.finally` never runs because the promise it's attached to
+  // never settles), so every later `ensureAwake` for the same address
+  // coalesces onto that same dead promise and hangs too — silently,
+  // forever, for the rest of the process's life. This is the mechanism
+  // behind "message accepted, then silence: no fanout, no wake, no
+  // error" — the caller (`sendMail`) never sees a rejection to report as
+  // an undelivered notice, because nothing ever rejects.
+  test("a wake that never settles does not wedge every later call behind it forever", async () => {
+    const routable = new Set<string>();
+    let wakeCalls = 0;
+
+    const lifecycle = createAgentLifecycle({
+      idleSleepMs: 1_000,
+      wakeTimeoutMs: 20,
+      isRoutable: (address) => routable.has(address),
+      undeploy: async () => undefined,
+      wake: async () => {
+        wakeCalls += 1;
+        // Never resolves and never rejects — the hung sidecar RPC.
+        await new Promise<void>(() => {});
+      },
+      log,
+    });
+    stop = lifecycle.stop;
+
+    // The first caller must not hang forever: the bounded wake times out
+    // and the caller sees a rejection it can turn into an undelivered
+    // notice, instead of an unsettled promise nothing ever observes.
+    await expect(lifecycle.ensureAwake("agent-1@t.test")).rejects.toThrow(
+      /wake/i,
+    );
+    expect(wakeCalls).toBe(1);
+
+    // A second, later call for the same address — the next message sent
+    // to the same workbench — must attempt its own wake rather than
+    // coalescing onto the first call's dead, already-timed-out promise.
+    await expect(lifecycle.ensureAwake("agent-1@t.test")).rejects.toThrow(
+      /wake/i,
+    );
+    expect(wakeCalls).toBe(2);
+  });
 });