W2.2 — Telemetry for dynamic tool loading

[edelauna]

Context

We need data to know whether dynamic loading is actually helping: how often the threshold is hit, how big the attached set ends up after the rolling window, how often the model has to call mcp_load, and which ranker tier won. Without telemetry we can't tune the defaults.

Operational; doesn't close a user-facing issue.

Developer Notes

• Events to emit (using whatever telemetry pipeline Roo already uses — check src/services/telemetry if present):
  • dynamic_tools.task_start: { scopedCount, attachedCount, ranker: "embeddings" | "bm25" }.
  • dynamic_tools.mcp_load_invoked: { taskTurn, queryLength, returnedCount, alreadyAttachedCount }.
  • dynamic_tools.rolling_window_step: { turn, addedCount, totalAttached } (only when something changes).
  • dynamic_tools.ranker_fallback: { from: "embeddings", to: "bm25", reason } (when Tier 1 fails).
• Respect existing telemetry opt-out.
• Files: src/services/tools/ToolRouter.ts (most events fire here), src/core/tools/mcpLoadTool.ts (mcp_load_invoked).
• Validation: telemetry events fire in integration tests; opt-out correctly suppresses them.