muxr v3.6.3
Correct the interrupt-reclaim signal (#12). 3.6.2 corroborated a busy state
file against #{session_activity}, which is last-CLIENT-INTERACTION time, not
agent output -- it stays frozen while an unattended agent streams a turn, so
3.6.2 could reclaim (kill) a working-but-unattended session. Readiness now
reads #{window_activity} (last pane output in the active window), which tracks
agent work even detached: a live turn reads quiet ~0s (kept Busy), an
interrupted one grows past the window (reclaimed). Simulated both directions on
real Claude Code 2.1.202 before shipping. The switcher keeps session_activity
for recency sort; only readiness moved. Also repairs muxr's activity floor
generally. ADR 0007.