Previously narrow_tools_by_keywords returned [] when no category matched,
silently disabling all tools for messages that didn't hit a keyword.
Now:
- Falls back to _FALLBACK_TOOLS (web_search, session_search, session_read,
scratch_read) when no category matches — tools always available for casual use
- Detects explicit "use your tools / look that up / can you check" phrases
and returns the full role tool list (None = all permitted)
- Return type updated to list[str] | None; orchestrator log handles both
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
3eb3ce1146