fix(phase26): geocode pre-caching (BUG-09) + gate trips on OBD presence (BUG-10)

BUGS.md

@@ -157,6 +157,47 @@ the authoritative, issue-by-issue record lives **here**.
 
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+### BUG-09 — Server trip scrubber geocoding is slow on each step
+- **Status**: `OPEN`
+- **Severity**: Medium (UX)
+- **Area**: `static/js/history.js` `showReplayPoint()` / `scheduleGeocode()`
+- **Phase**: Phase 26
+- **Symptom**: Scrubbing through the trip timeline on the server portal is sluggish — the location
+  name takes a long time to appear because each scrub step fires a fresh `/api/geocode` HTTP
+  request (debounced 600ms). On the Pi this is fast (offline reverse_geocoder), but the server
+  calls Nominatim which adds latency.
+- **Root cause**: Every `showReplayPoint()` call triggers `scheduleGeocode()` → debounced
+  `fetch(/api/geocode...)`. No pre-caching or batch loading.
+- **Fix scope / actions**: Pre-fetch geocode results for ALL trip points when the route is first
+  loaded. Store in a local JS map keyed by rounded coordinate. Show cached label instantly during
+  scrubbing. Only fall back to live fetch for uncached points. Optionally batch-geocode at the
+  server API level too (accept multiple lat/lon pairs).
+- **Acceptance**: Scrubbing through trip replay shows location names near-instantly.
+
+### BUG-10 — GPS-only false trips generated when car is not connected
+- **Status**: `OPEN`
+- **Severity**: Medium (data quality)
+- **Area**: `modules/app_trip.py` `build_trip_summaries()`, `modules/app_sql.py` `refresh_trips()`
+- **Phase**: Phase 26
+- **Symptom**: The Pi generates trips from GPS data alone (GPS jitter/drift) even when the car
+  isn't connected. Since the Pi bench-tests with no OBD, GPS displacement fallback creates
+  phantom "trips" from stationary GPS noise.
+- **Root cause**: The GPS motion fallback (3+ consecutive 8m displacements) can be satisfied by
+  GPS jitter over time, especially indoors or in weak-signal areas. The system doesn't gate trip
+  detection on whether OBD was ever present.
+- **Fix scope / actions**:
+  - **Option A (strict)**: Only start trips when OBD wheel speed has been detected at least once
+    since the app started (a `car_was_connected` flag). No OBD ever = no trips, even with GPS.
+  - **Option B (lenient)**: Increase GPS motion requirements when OBD has never been seen (e.g.
+    require 10+ consecutive displacements of 20m+ instead of 3×8m).
+  - **Recommend Option A** — it matches the real-world use case: the Pi is powered by the car's
+    ignition, so OBD should always be reachable when the car is running. No OBD = bench test,
+    don't generate trips.
+- **Acceptance**: Bench-testing the Pi (no car connected) produces zero trips. Real driving with
+  OBD connected still produces correct trips.
+
+---
+
 ## Resolved bugs
 
 ### BUG-03 — DTC/MIL codes are never persisted; lost on OBD disconnect or reboot