Re-applies three workstreams lost when 793d3d7 committed over uncommitted
edits, reconciled against the parallel track's committed dm.py changes:
- followup-sweeper.py: backfill thread_uuid after successful nudge sends;
record final_nudge_target=main on final-nudge routing (C1/C2)
- response-harvester.py: resolve followups on main-chat replies when
final_nudge_target=main (C3); harvest ALL [RESULT] markers per message
- dm.py: pre-send placement gate (fail closed when post-nav URL lacks the
target thread UUID; skips main) — purely additive over 793d3d7+f268d3d
- sidechat_manager.py: wait_for_chat_list() settle-poll for list population
race (sidebar button renders before titles load)
- new: bin/tests/test_followup_fixes.py (25 tests), bin/placement-audit.py,
bin/dm-log-taxonomy.py, bin/session-probe.py,
docs/SIDECHAT-RELIABILITY.md, docs/UUID-ROTATION.md
Verified: 25/25 tests pass, py_compile clean, sweeper/harvester dry-runs clean.
Known limitation: gate catches wrong-placement, not wrong-mapping (false
autoprovision adopting the parked thread needs a creation check).
operator-main