diff --git a/CHANGELOG.md b/CHANGELOG.md
index c8b51a4..4326da1 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,7 @@
 
 ## Unreleased
 
+- Fix interactive terminal sessions hanging when the upstream never completes the WebSocket handshake: bound the upgrade fetch with the same 10s timeout the runtime adapter fetch in that file already uses.
 - Stop cancelled Share This Mac cursor reconciliation and release video mailbox waits and their timeout tasks promptly, including cancellation before waiter registration, thanks @SebTardif (#114).
 
 ## 0.3.1 - 2026-08-28
diff --git a/src/worker/runtime-adapter-transport.ts b/src/worker/runtime-adapter-transport.ts
index 132df3e..1ce677f 100644
--- a/src/worker/runtime-adapter-transport.ts
+++ b/src/worker/runtime-adapter-transport.ts
@@ -69,7 +69,7 @@ export async function interactiveTerminalFetch(
     session.adapter === runtimeAdapterName
       ? runtimeAdapterFetcher(env, target, fallbackFetcher)
       : fallbackFetcher;
-  return fetcher.fetch(fetchTarget, { headers });
+  return fetcher.fetch(fetchTarget, { headers, signal: AbortSignal.timeout(10_000) });
 }
 
 export async function readRuntimeAdapterResponseBody(response: Response): Promise<unknown> {
diff --git a/tests/runtime-adapter-transport.test.ts b/tests/runtime-adapter-transport.test.ts
index 1e22435..01293bc 100644
--- a/tests/runtime-adapter-transport.test.ts
+++ b/tests/runtime-adapter-transport.test.ts
@@ -158,3 +158,31 @@ test("runtime adapter response parsing is bounded and preserves non-JSON error t
     ResponseBodyLimitError,
   );
 });
+
+test("terminal upgrades bound the upstream handshake with a timeout", async () => {
+  const coordinator = recordingFetcher(new Response(null, { status: 200 }));
+  const fallback = recordingFetcher(new Response(null, { status: 200 }));
+  const env = {
+    CRABBOX_COORDINATOR: coordinator.fetcher,
+    CRABBOX_COORDINATOR_ORIGIN: "https://adapter.example",
+  } as RuntimeEnv;
+  const headers = new Headers({ upgrade: "websocket" });
+
+  await interactiveTerminalFetch(
+    env,
+    { adapter: "runtime-v1" },
+    "wss://adapter.example/v1/terminal",
+    headers,
+    fallback.fetcher,
+  );
+  assert.ok(coordinator.calls[0]?.init?.signal instanceof AbortSignal);
+
+  await interactiveTerminalFetch(
+    env,
+    { adapter: null },
+    "wss://elsewhere.example/v1/terminal",
+    headers,
+    fallback.fetcher,
+  );
+  assert.ok(fallback.calls[0]?.init?.signal instanceof AbortSignal);
+});