Bug Description

Several memory leaks occur during long-running opencode sessions, causing RSS to grow continuously:

1. AsyncQueue never terminates (util/queue.ts) - [Symbol.asyncIterator] loops forever with no close mechanism, preventing GC of consumers.

2. Bash tool unbounded string concatenation (tool/bash.ts:167-189) - stdout/stderr appended via output += chunk.toString() with no size limit. Commands producing large output (e.g., find /) cause unbounded memory growth.

3. LSP diagnostics Map never cleared (lsp/client.ts:51) - diagnostics Map accumulates entries indefinitely. shutdown() disposes the connection but doesn't clear the map.

4. Bus subscriptions Map not cleared on dispose (bus/index.ts) - Instance dispose callback fires wildcard subscribers but never calls subscriptions.clear().

5. PTY buffer string concatenation (pty/index.ts:136-150) - session.buffer += data then session.buffer.slice(-BUFFER_LIMIT) causes repeated large string allocation and GC pressure.

6. Instance.disposeAll() not called on process exit (index.ts) - The main finally block calls process.exit() without disposing instances, leaking subprocess handles.

Reproduction

1. Start opencode, run a command producing large output (find / -name "*.ts")
2. Monitor with top -pid <PID> - RSS grows without bound
3. Idle for 10+ minutes - memory does not decrease

Environment

• opencode v1.1.36
• macOS Darwin 24.6.0
• Bun 1.3.5