Killing parent process does not abort sidecar session — orphaned sessions accumulate

[ellisjr]

Description

When a parent bash task is killed (via TaskStop, kill, or SIGTERM), the underlying sidecar session continues running. Orphaned sessions accumulate in sidecar list --status running and consume API resources.

Steps to Reproduce

1. Launch multiple sidecars in background:

   sidecar start --model gemini-pro --no-ui --prompt "Task 1" &
   sidecar start --model gemini-pro --no-ui --prompt "Task 2" &
   sidecar start --model gemini-pro --no-ui --prompt "Task 3" &

2. Kill the parent bash processes (e.g., kill %1 %2 %3)
3. Check sidecar list:

   sidecar list --status running

   All 3 sessions still show as running

Expected Behavior

Killing the parent process should signal the sidecar to abort (e.g., via SIGTERM handler that calls session abort).

Actual Behavior

Sidecar sessions are orphaned. Must manually run sidecar abort <id> for each one.

Impact

In our test session, we accumulated 3 orphaned Gemini Pro sessions that were consuming OpenRouter API credits while doing nothing useful. Users launching multiple parallel sidecars (the documented multi-LLM workflow) are especially likely to hit this.

Suggestion

• Register a SIGTERM/SIGINT handler in the sidecar CLI that aborts the OpenCode session on exit
• Alternatively, implement a heartbeat mechanism where the sidecar session checks if its parent is still alive
• Consider adding a sidecar abort --all convenience command for cleanup