andrewmusselman opened a new issue, #25:
URL: https://github.com/apache/tooling-gofannon/issues/25
### Summary
Long-running agents sometimes need to be interrupted. The earlier "Cancel"
button only aborted the client-side fetch; the server-side task kept running
until completion. The only way to actually stop a run today is to restart the
api container, which kills every other in-flight run too.
### Details
**Problem:**
- No surgical kill exists for a specific run.
- Server-side asyncio.Task continues after browser disconnects.
- `task.cancel()` is too aggressive — raises `CancelledError` mid-await
inside LLM HTTP calls, leaving httpx connections in unclean states.
### Proposed solution
**Cooperative cancellation, layered:**
1. **CancelToken via contextvar** (same pattern as Trace). The agent runtime
checks `should_stop()` between operations.
2. **Enforcement at structural boundaries.** Wrap `tools.call_llm`,
`tools.data_store.*`, and `gofannon_client.call` with an entry check — if
stopping, raise `AgentStopped` immediately without executing. In-flight LLM
calls finish naturally; only the next attempt to do anything observable raises.
**UI:**
- Stop button next to Run; disabled when no run in flight.
- While stopping (after click, before halt): button shows "Stopping… (after
current LLM call completes)" disabled.
- Run's outcome becomes a third status `stopped` — neutral chip color in the
Progress Log (gray with a stop icon, not red).
**Stop semantics for chained agents:**
When agent X is stopping and X has called Y, Y stops too. Stop means the
whole tree. Contextvar makes this trivial.
### Acceptance Criteria
- [ ] Fixed: `CancelToken` contextvar threaded through agent execution
- [ ] Fixed: `tools.call_llm`, `tools.data_store.*`, `gofannon_client.call`
check `should_stop()` on entry
- [ ] Fixed: `POST /runs/{run_id}/stop` sets cancel token, responds 202
- [ ] Fixed: UI Stop button next to Run, disabled appropriately
- [ ] Fixed: "Stopping…" state shown after click until run actually halts
- [ ] Fixed: `RunRecord.status = "stopped"` distinguishable from error
- [ ] Test added: Stop during LLM call halts at next tool boundary (not
mid-await)
- [ ] Test added: Chained sub-agent stops when parent receives stop
- [ ] Test added: Cleanup runs (e.g., http_client.aclose() in finally)
execute before exit
### References
- File: `webapp/packages/api/user-service/services/agent_trace.py` (Trace
contextvar pattern)
- File:
`webapp/packages/api/user-service/dependencies.py:_execute_agent_code`
- File: `webapp/packages/webui/src/pages/AgentCreationFlow/RunsScreen.jsx`
- Tracker: FIXES.md item #6
### Priority
**Medium** - Depends on ISSUE-003 (run registry) for the cancel token to
live somewhere addressable by run_id.
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