feat: improve webhook filtering, worker status startup handling, and timestamp parsing

- Skip half_hour_report events from webhook posts in people_flow
- Handle pre-existing stale worker status files during startup gracefully
- Make store_dwell_alert timestamp parsing robust against invalid/empty values
- Update lessons learned and todo documentation

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

managed/people_flow_project/tests/test_webhook.py

@@ -5,7 +5,7 @@ import json
 from src.people_flow.webhook import dispatch_json_event
 
 
-def test_dispatch_json_event_omits_tracks_from_webhook_but_keeps_local_log(
+def test_dispatch_json_event_does_not_post_half_hour_report_but_keeps_local_log(
     tmp_path, monkeypatch
 ):
     sent: dict[str, object] = {}
@@ -44,9 +44,4 @@ def test_dispatch_json_event_omits_tracks_from_webhook_but_keeps_local_log(
 
     lines = output.read_text(encoding="utf-8").splitlines()
     assert json.loads(lines[0]) == payload
-    assert sent["url"] == "https://example.test/webhook"
-    assert sent["timeout"] == 7.5
-    assert sent["payload"] == {
-        "event": "half_hour_report",
-        "total_people": 3,
-    }
+    assert sent == {}

managed/people_flow_project/tests/test_worker_status.py

@@ -99,3 +99,29 @@ def test_worker_status_stall_reason_reports_missing_and_stale_status(tmp_path: P
     assert "status=missing" not in reason
     assert "phase=tracking_frame" in reason
     assert "age_seconds=200.0" in reason
+
+
+def test_worker_status_stall_reason_ignores_preexisting_stale_file_during_startup(
+    tmp_path: Path,
+):
+    status_path = tmp_path / "worker_status.json"
+    write_worker_status(
+        status_path,
+        "waiting_to_reconnect",
+        source="rtsp://camera/stream",
+        window_index=0,
+        frame_index=0,
+        last_processed_at=None,
+        note="open_failed",
+    )
+    os.utime(status_path, (100.0, 100.0))
+
+    assert (
+        worker_status_stall_reason(
+            status_path,
+            started_at=250.0,
+            max_age_seconds=180.0,
+            now=300.0,
+        )
+        is None
+    )