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fix(sandbox): Gracefully handle unavailable sandbox sessions #1664

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fix(sandbox): Gracefully handle unavailable sandbox sessions #1664

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609aef6
fix(sandbox): Gracefully handle unavailable sandbox sessions
sentry[bot] Aug 22, 2026
e3c6e45
fix(sandbox): Gracefully handle unavailable sandbox sessions
sentry[bot] Aug 22, 2026
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8 changes: 5 additions & 3 deletions packages/junior/src/chat/sandbox/session.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -628,8 +628,9 @@ export function createSandboxRuntime(
return null;
}
if (isSandboxUnavailableError(error)) {
sandboxRef = undefined;
invalidateSession();
throw error;
return null;
}
throw new Error("sandbox restore failed", { cause: error });
}
Expand All @@ -641,9 +642,10 @@ export function createSandboxRuntime(
await persistSandboxRef({ ...ref, id: hintedSandbox.sandboxId });
return rememberSandbox(hintedSandbox, networkPolicyKey);
} catch (error) {
// Keep the durable VM alive so a later reacquire can reuse it.
if (isSandboxUnavailableError(error)) {
throw error;
sandboxRef = undefined;
invalidateSession();
return null;

@cursor cursor Bot Aug 22, 2026

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Prepare failure orphans restored sandbox

Medium Severity

After Sandbox.get succeeds, a prepare-time unavailable error now clears sandboxRef and returns null, so acquireSandbox builds a new sandbox. That drops the still-running named VM the old path kept for reconnect, and it never stopSessions the retrieved session, so the prior sandbox can keep burning resources until timeout.

Fix in Cursor Fix in Web

Reviewed by Cursor Bugbot for commit 609aef6. Configure here.

}
return failSetup(error);
}
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4 changes: 2 additions & 2 deletions packages/junior/tests/component/task-execution/conversation-work.test.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -1808,8 +1808,8 @@ describe("conversation work execution", () => {
return target.acquireLock(key, ttlMs);
};
}
const value = Reflect.get(target, prop, receiver);
return typeof value === "function" ? value.bind(target) : value;
const value = (target as Record<string | symbol, unknown>)[prop];
return typeof value === "function" ? (value as (...args: unknown[]) => unknown).bind(target) : value;
},
}) as StateAdapter;

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