feat: Automatic developer handover via identity/now.md #181

Problem

When multiple developers work on a feature branch with a shared squad, handing over context to the next developer requires manually telling the squad to "prep for handover." Without this prompt, the incoming developer gets no proactive briefing — they have to remember to ask "catch me up" or re-explain the project state to the squad.

The data to support handover already exists (Scribe commits session logs, decisions, and agent histories to the branch), but nobody synthesizes it into a handover-ready format, and the coordinator does not deep-read it when a new developer arrives.

Root Cause (5 interconnected gaps)

1. Session catch-up is intentionally lazy — the coordinator is told "Do NOT scan logs on every session start" and only does a shallow 2-3 sentence summary even when it detects a different user.
2. now.md is never updated at session end — it is read at session start but the Scribe has no task to write handover state back. It goes stale immediately after init.
3. now.md lacks handover fields — the template only has focus_area and active_issues. No space for what was done, what is in progress, what is pending, blockers, or per-agent status.
4. No proactive handover detection — detecting a different user existed but the response was the same shallow catch-up as an explicit ask.
5. No routing trigger for manual handover prep — developers had to explain the concept of handover in natural language every time.

Proposed Solution

1. Enhanced now.md template — Add last_user, session_count, a full "Last Session Summary" section (done/in-progress/pending/decisions/blockers), and an "Agent Last Touched" table.
2. Scribe session-end update — New Scribe task that updates now.md with comprehensive handover state after every batch of agent work. This becomes the primary handover artifact.
3. Deep handover briefing on user change — Split session catch-up: same user gets lazy summary, different user gets automatic deep briefing from now.md (proactive, no prompt needed).
4. Manual handover routing trigger — Routing entries for "prep for handover", "wrap up", "I am done for today", "session done".

Files Changed

Testing

All 95 tests pass (npm test).