The two-witness contract from the first review round still granted
destructive authority on ONE silent 1s socket probe: stale heartbeat +
armed tick socket + a single miss returned WEDGED immediately, and the
#86860 consumers take the bounded SIGTERM/SIGKILL path on that verdict.
A short transient synchronous stall (reconnect storm, heavy synchronous
callback, scheduler delay) can outlast one recv timeout, so a lone miss
is exactly the false-wedge class this change exists to prevent.
WEDGED now requires the loop to stay silent across a sustained window:
tick_strikes consecutive misses (default 3, tick_gap_s apart). Any
answer inside the window proves the loop is dispatching and returns
ALIVE; a single miss returns UNKNOWN and keeps the graceful drain path
(which also preserves #86684's cron drain floor). A witness that
vanishes mid-window is ambiguity, never a wedge.
New regression coverage:
- unit: single silent probe recovers to ALIVE; sustained silence is
required for WEDGED; vanishing witness stays UNKNOWN.
- composed (real producer + consumer): heartbeat write stalled while
the loop is frozen for longer than one tick timeout but shorter than
the wedge window -> probe is ALIVE and launchd_restart drains, never
escalates; loop frozen for longer than the window -> WEDGED.
The default probe window is ~3.4s worst case, still far inside the 10s
subprocess query tier.
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