feat(v1): compose temporal fall event pipeline

v1/tests/test_fall_policy.py

@@ -0,0 +1,53 @@
+from v1.evidence import PoseEvidence
+from v1.fall_policy import FallEvidencePolicy
+from v1.fall_state import FallState
+
+
+def _evidence(horizontal=False, rapid_drop=False, accepted=True):
+    return PoseEvidence(
+        accepted=accepted,
+        horizontal_pose=horizontal,
+        rapid_vertical_change=rapid_drop,
+        horizontal_angle_degrees=10.0 if horizontal else 80.0,
+        hip_center_y=100.0,
+        torso_length=50.0,
+        reason="accepted" if accepted else "missing_pose",
+    )
+
+
+def test_rapid_drop_followed_by_horizontal_pose_within_suspect_window_starts_candidate():
+    policy = FallEvidencePolicy(suspect_window_seconds=0.5)
+
+    onset = policy.evaluate(
+        "P-0001", _evidence(rapid_drop=True), now=0.0, state=FallState.NORMAL
+    )
+    candidate = policy.evaluate(
+        "P-0001", _evidence(horizontal=True), now=0.5, state=FallState.NORMAL
+    )
+
+    assert onset.is_fall_candidate is False
+    assert candidate.is_fall_candidate is True
+
+
+def test_rejected_pose_clears_pending_drop_before_the_next_horizontal_pose():
+    policy = FallEvidencePolicy(suspect_window_seconds=0.5)
+
+    policy.evaluate("P-0001", _evidence(rapid_drop=True), now=0.0, state=FallState.NORMAL)
+    policy.evaluate("P-0001", _evidence(accepted=False), now=0.1, state=FallState.NORMAL)
+    candidate = policy.evaluate(
+        "P-0001", _evidence(horizontal=True), now=0.2, state=FallState.NORMAL
+    )
+
+    assert candidate.accepted is True
+    assert candidate.is_fall_candidate is False
+
+
+def test_upright_pose_is_recovery_evidence_only_after_confirmation():
+    policy = FallEvidencePolicy(suspect_window_seconds=0.5)
+
+    recovery = policy.evaluate(
+        "P-0001", _evidence(horizontal=False), now=4.0, state=FallState.CONFIRMED
+    )
+
+    assert recovery.accepted is True
+    assert recovery.is_recovery_candidate is True