diff --git a/plugin/scripts/session-end.mjs b/plugin/scripts/session-end.mjs
index 019149c30..1a8882482 100755
--- a/plugin/scripts/session-end.mjs
+++ b/plugin/scripts/session-end.mjs
@@ -51,7 +51,7 @@ async function main() {
 		headers: authHeaders(),
 		signal: AbortSignal.timeout(3e4)
 	}).catch(() => {});
-	setTimeout(() => process.exit(0), 1500).unref();
+	setTimeout(() => process.exit(0), 500).unref();
 }
 main();
 
diff --git a/src/hooks/session-end.ts b/src/hooks/session-end.ts
index 6a9fc429c..39b9aef78 100644
--- a/src/hooks/session-end.ts
+++ b/src/hooks/session-end.ts
@@ -63,7 +63,7 @@ async function main() {
     }).catch(() => {});
   }
 
-  setTimeout(() => process.exit(0), 1500).unref();
+  setTimeout(() => process.exit(0), 500).unref();
 }
 
 main();
diff --git a/test/session-end-exit-timing.test.ts b/test/session-end-exit-timing.test.ts
new file mode 100644
index 000000000..85a03dcaa
--- /dev/null
+++ b/test/session-end-exit-timing.test.ts
@@ -0,0 +1,77 @@
+import { describe, it, expect, beforeAll, afterAll } from "vitest";
+import { spawn } from "node:child_process";
+import { createServer, type Server } from "node:http";
+import { join } from "node:path";
+import { once } from "node:events";
+
+// Runs the BUILT hook artifact (what ships), not the TypeScript source. CI
+// builds before testing; locally run `npm run build` after editing
+// src/hooks/session-end.ts or this exercises stale code.
+const HOOK = join(
+  import.meta.dirname,
+  "..",
+  "plugin",
+  "scripts",
+  "session-end.mjs",
+);
+
+// A server that accepts the connection and reads the request but never sends a
+// response, so the hook's fire-and-forget `fetch` stays in flight. With the
+// request hanging, the only thing that ends the hook process is its deferred
+// `setTimeout(() => process.exit(0), N).unref()` — which lets us measure N.
+let blackHole: Server;
+let blackHoleUrl: string;
+
+beforeAll(async () => {
+  blackHole = createServer(() => {
+    // Intentionally never respond.
+  });
+  blackHole.listen(0, "127.0.0.1");
+  await once(blackHole, "listening");
+  const address = blackHole.address();
+  const port = typeof address === "object" && address ? address.port : 0;
+  blackHoleUrl = `http://127.0.0.1:${port}`;
+});
+
+afterAll(async () => {
+  blackHole.close();
+  await once(blackHole, "close");
+});
+
+function runHook(
+  stdin: string,
+  env: Record<string, string>,
+): Promise<{ exitCode: number | null; tookMs: number }> {
+  return new Promise((resolve, reject) => {
+    const start = Date.now();
+    const child = spawn(process.execPath, [HOOK], {
+      env: { PATH: process.env["PATH"] ?? "", ...env },
+      stdio: ["pipe", "ignore", "ignore"],
+    });
+    child.on("error", reject);
+    child.on("close", (exitCode) => {
+      resolve({ exitCode, tookMs: Date.now() - start });
+    });
+    child.stdin.write(stdin);
+    child.stdin.end();
+  });
+}
+
+describe("session-end hook exits within Claude Code's shutdown grace (#991)", () => {
+  it("exits well under the old 1500ms cap even when the memory server hangs", async () => {
+    const payload = JSON.stringify({ session_id: "ses_timing_test" });
+    const { exitCode, tookMs } = await runHook(payload, {
+      AGENTMEMORY_URL: blackHoleUrl,
+    });
+
+    expect(exitCode).toBe(0);
+    // Positive control: the hung request must actually hold the process open to
+    // the deferred-exit timer, otherwise the timing assertion is meaningless.
+    expect(tookMs).toBeGreaterThan(250);
+    // The deferred-exit timer must fire comfortably inside Claude Code's
+    // SessionEnd shutdown grace. The bound sits between the fixed 500ms timer
+    // (plus startup) and the old 1500ms cap that overran the grace, so the
+    // harness killed the hook and reported "Hook cancelled" (#991).
+    expect(tookMs).toBeLessThan(1400);
+  });
+});