Three keypoint-trust hardening fixes that reuse the codebase's existing
"visible" confidence convention (no new tuning knobs):
- P2-9 zone.py: _foot averaged both ankles unconditionally, so a
hallucinated ankle (conf~0, often pinned to (0,0)) dragged the foot
point into or out of a zone. Now averages only ankles with conf >= 0.2
and falls back to the bbox bottom-centre when neither is trustworthy.
- P2-11 geometry.py: head_below_hips used the NOSE regardless of
confidence. Now returns False when the nose is below the visibility
threshold, so an unconfident/hallucinated nose can't fire the
head-below-hips fall cue. The confident-nose path is unchanged
(test_fall.py stays green).
- P2-10 movenet_pose.py: the CPU MoveNet fallback is single-person, so at
a multi-worker site every worker but one is silently invisible to
fall/zone/ghost detection. Construction now logs a loud startup WARNING
pointing to the Hailo backend.
Tests: test_zone (bbox fallback), test_geometry (low-conf nose), and
test_movenet_pose (caplog warning). Full python suite: 157 passed, 2
skipped.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019Xmn8KZWqiQUguEMRtn6rW
