fix: show tool names in assistant message detail timeline (#849)

[microsasa]

Closes #849

Problem

In render_detail.py:_build_event_details, the ASSISTANT_MESSAGE branch parsed toolRequests via as_assistant_message() but silently discarded them. Tool-calling turns (which have content="" by design) rendered as blank rows in the session detail timeline.

Fix

After building parts from outputTokens and content, check data.toolRequests. If non-empty, append a compact "tool: name" / "tools: a, b, c" summary (truncated at 60 chars) to the detail string.

Before:

assistant │ tokens=450  │              ← content reply
assistant │             │              ← tool-calling turn (blank)
```

**After:**
```
assistant │ tokens=450  │              ← content reply
assistant │             │ tools: bash, view

Tests added

• Tool-only turn — content="", outputTokens=0, two toolRequests → detail contains both tool names
• Mixed turn — content="ok", outputTokens=100, one toolRequest → detail contains tokens, content, and tool name
• No tools (regression) — existing content-only behavior unaffected
• Truncation — long tool name lists are truncated at 60 chars with …

Generated by Issue Implementer · ● 6.3M · ◷

[Copilot]

Pull request overview

This PR fixes blank rows in the session detail timeline by surfacing tool-call names for assistant.message events, so tool-only turns render meaningful detail text instead of appearing empty.

Changes:

• Append a compact tool: / tools: summary (truncated to 60 chars) to assistant message timeline details when toolRequests are present.
• Add unit tests covering tool-only turns, mixed content+tool turns, regression behavior with no tools, and truncation behavior.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
src/copilot_usage/render_detail.py	Updates _build_event_details() to include tool request names in assistant message timeline detail strings.
tests/copilot_usage/test_render_detail.py	Adds test coverage for tool request rendering and truncation in _build_event_details().

[github-actions]

Commit pushed: cdc3dda

Generated by Review Responder

[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated no new comments.

[github-actions]

Quality Gate: APPROVED ✅

Changes reviewed:

• src/copilot_usage/render_detail.py (+8 lines): Surfaces toolRequests tool names in _build_event_details for the ASSISTANT_MESSAGE branch, using the existing _truncate helper with singular/plural labels and an "(unknown)" fallback.
• tests/copilot_usage/test_render_detail.py (+123 lines): 6 meaningful tests covering tool-only turns, mixed turns, regression (no tools), truncation, empty names, and singular label logic.

Assessment:

• Code quality: Good — follows existing patterns, uses existing helpers, clean list comprehension with proper edge-case handling.
• Guidelines compliance: Type annotations ✓ | No duck typing ✓ | pytest style ✓ | Docstrings ✓ | Double quotes ✓
• Impact: LOW — display-only change in a rendering helper, non-breaking, no API/model/dependency changes.
• CI: All 8 checks passing.

Low-impact display fix with thorough test coverage. Auto-approving for merge.