# Todo 51.1 First Reply and Protocol Matrix Plan

**Status:** in_progress

## Goal

Make the closeout matrix enforce the experiment's primary latency contract and the intended mode-specific protocol surfaces.

## Scope

- Add a ChatAgent `message_delta` before events for volume, schedule, terminate, web search, and parallel volume/schedule scenarios.
- Assert first visible reply precedes the first tool result; silent/terminate flows do not add an unintended second model answer; schedule/parallel add exactly one deterministic template after execution.
- Record each scripted model request.
- For `dual_agent`, assert the initial ChatAgent request has no provider tools and includes the compact enabled event catalog.
- For `chat_agent_tools`, assert the initial request contains exactly the enabled provider schemas and no generated event catalog.
- Assert detected event audit source is `text_event` for dual mode and `provider_resolved` for direct mode.

## Files

- Modify: `tests/test_tool_invocation_comparison.py`

## Verification

- `uv run pytest tests/test_tool_invocation_comparison.py -q`
- repeat parallel cases
- `uv run pytest`
- `git diff --check`