After yesterday’s handover work, the obvious failure mode was: leave a .assist/HANDOVER.md from the last session sitting on disk, kick off assist backlog next in a new session, and have it cheerfully start work without ever reading the handover. So backlog run and backlog next now check for .assist/HANDOVER.md up front via blockedByHandover and refuse to proceed if one exists, telling the user to either start a fresh session (which surfaces the file via the SessionStart hook) or assist handover archive to set it aside intentionally.

Also threw out the prior /recall plumbing — findRecentSessionJsonl, isSdkCliOnly, encodeCwdForProjects, and most of load.ts. The SessionStart hook now surfaces the handover directly, so the session-walking machinery underneath /recall is dead code. handover load is now a thin wrapper around reading the file.