# Todo 8 Tool Pre-Message Guard Plan

**Status:** done

## Result

Implemented by subagent and locally verified by the main session.

Commands:

```bash
uv run pytest tests/test_websocket_api.py
uv run pytest
```

Results:

- focused WebSocket/API tests: `10 passed, 1 warning in 0.22s`
- full suite: `16 passed, 1 warning in 0.22s`

## Goal

Prevent the debug UI and provider serializer from generating invalid Chat Completions `tool` messages without `tool_call_id`.

## Problem

The pre-message editor exposes `tool` as a role, but the UI does not collect `tool_call_id`. A manual `tool` pre-message can therefore reach the provider as `{role: "tool", content: "..."}`, which strict compatible providers reject.

## Scope

This todo covers:

- Removing `tool` from the static pre-message role selector for MVP.
- Adding provider-client validation that raises a clear error if a `tool` message lacks `tool_call_id`.
- Tests for the validation and UI markup.

This todo does not cover:

- Adding full manual tool-call transcript editing.
- New EventAgent tools.
- Live LLM smoke.

## Files

- Modify: `src/agent_lab/presentation/static/index.html`
- Modify: `src/agent_lab/infrastructure/chat_client.py`
- Modify/add tests, preferably `tests/test_websocket_api.py`.
- Do not modify: `docs/plans/todos.md`.

## Steps

1. Add a failing test that `OpenAICompatibleChatClient` rejects a `ChatMessage(role="tool", content="...")` without `tool_call_id`.
2. Add a failing test or assertion that the static pre-message role selector does not offer `tool`.
3. Implement the minimal fix:
   - remove `<option value="tool">tool</option>` from the pre-message template.
   - in `_serialize_message`, raise `ValueError("tool messages require tool_call_id")` when role is `tool` and no `tool_call_id` is present.
4. Run:

```bash
uv run pytest tests/test_websocket_api.py
uv run pytest
```

## Verification

Expected result:

- Invalid manual tool messages fail before network I/O.
- UI no longer exposes invalid manual tool pre-message creation.
- Full suite passes.