can1357/oh-my-pi · error · ToolError

Computer session tool bridge is unavailable

Error message

Computer session tool bridge is unavailable

What it means

ComputerSupervisor's constructor takes a callSessionTool dependency; its default value is a function that always throws this ToolError. The default exists only to make the parameter explicit — if the supervisor reaches a point where it needs to invoke a session-side tool and no real bridge was injected, this error surfaces, meaning the supervisor was constructed without wiring the session tool bridge.

Source

Thrown at packages/coding-agent/src/tools/computer/supervisor.ts:157

	readonly #callSessionTool: ComputerSessionToolCaller;
	readonly #timeouts: ComputerSupervisorTimeouts;
	#worker?: ComputerWorkerHandle;
	#startPromise?: Promise<void>;
	#startReject?: (error: unknown) => void;
	#startResolve?: () => void;
	#latestCapabilities?: DesktopCapabilities;
	#pending = new Map<string, PendingRun>();
	#nextId = 0;
	#closed = false;
	#unsubscribeMessage?: () => void;
	#unsubscribeError?: () => void;

	constructor(
		session: ToolSession,
		createWorker: ComputerWorkerFactory = spawnComputerWorker,
		timeouts: ComputerSupervisorTimeouts = DEFAULT_TIMEOUTS,
		callSessionTool: ComputerSessionToolCaller = async () => {
			throw new ToolError("Computer session tool bridge is unavailable");
		},
	) {
		this.#session = session;
		this.#createWorker = createWorker;
		this.#timeouts = timeouts;
		this.#callSessionTool = callSessionTool;
	}

	async capabilities(): Promise<DesktopCapabilities | undefined> {
		return this.#latestCapabilities;
	}

	async run(
		code: string,
		timeoutMs: number,
		snapshot: ComputerSessionSnapshot,
		signal?: AbortSignal,
	): Promise<ComputerRunOk> {

View on GitHub (pinned to 9690622007)

Solutions

1. Pass a real callSessionTool implementation (the adapter that forwards into the ToolSession) as the constructor's third argument.
2. Check the supervisor construction site in the computer tool bootstrap and restore the bridge wiring.
3. In tests, inject a stub bridge if session tool calls are not expected, and assert none occur.

Example fix

// before
const supervisor = new ComputerSupervisor(session, spawnComputerWorker);

// after
const supervisor = new ComputerSupervisor(session, spawnComputerWorker, DEFAULT_TIMEOUTS, (tool, args) =>
  session.callTool(tool, args),
);

// at construction site, ensure the bridge is provided
if (typeof callSessionTool !== "function") {
  throw new Error("ComputerSupervisor requires a callSessionTool bridge");
}
const supervisor = new ComputerSupervisor(session, createWorker, timeouts, callSessionTool);

try {
  await supervisor.run(code, timeout, snapshot, signal);
} catch (err) {
  if (err instanceof ToolError && /session tool bridge is unavailable/.test(err.message)) {
    logger.error("ComputerSupervisor built without session tool bridge — fix DI wiring");
    throw err;
  } else throw err;
}

When it happens

Trigger: Constructing ComputerSupervisor without the third callSessionTool argument and then running computer code that issues a session tool call.

Common situations: Tests or scripts instantiate the supervisor directly with only (session, workerFactory, timeouts); a DI/wiring refactor dropped the bridge argument; production bootstrap forgot to pass the session-tool adapter.

Related errors

• Computer session is closed
• Assertion failed
• ${error.message} (rethrown as ToolError from StructuredSubag
• JS eval worker smoke fell back from the isolated subprocess
• Plan mode is not active.

AI-assisted analysis of can1357/oh-my-pi@9690622007 (2026-08-31). Data as JSON: /api/errors/5a000d6a13c128cc. Report an issue: GitHub.