diff --git a/CLAUDE.md b/CLAUDE.md
index 43c994c..54dd5a6 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -1 +1,93 @@
-@AGENTS.md
+# bincio-rec
+
+GPS activity recorder for the bincio ecosystem.
+Companion to **bincio-autarchive** (archive/sync app): rec makes the data, autarchive stores and syncs it.
+
+---
+
+## Concept
+
+A focused, minimal recording app for cycling, running, hiking, and walking.
+Records GPS track + BLE sensor data, saves to GPX, optionally uploads directly to a bincio-activity server.
+Future: live navigation / turn-by-turn instructions.
+
+The app does one thing well: **record**. No browsing, no analysis — that's autarchive's job.
+
+---
+
+## Ecosystem
+
+```
+bincio-rec          →  writes GPX files to shared storage
+bincio-autarchive   →  imports GPX, stores locally, syncs to server
+bincio-activity     →  server: parses GPX, stores activities, serves API
+bincio-auth         →  auth service: issues JWTs for all bincio apps
+```
+
+bincio-rec can also upload directly to bincio-activity via `/api/upload/raw` (same endpoint autarchive uses), with instance URL + API token configured in settings.
+
+---
+
+## Tech Stack
+
+**Expo Prebuild** (not managed Expo, not bare RN).
+
+- Managed Expo ruled out: BLE requires native modules
+- Bare RN ruled out: Expo library ecosystem is valuable (location, notifications, file system)
+- Prebuild gives full native access while keeping Expo tooling and EAS Build
+
+Key libraries:
+- `expo-location` + `expo-task-manager` — background GPS recording
+- `react-native-ble-plx` — BLE sensors (HR, power, cadence)
+- `@maplibre/maplibre-react-native` — live track map, future navigation
+- `expo-notifications` — km milestone alerts, future navigation cues
+- `expo-keep-awake` — keep screen on during recording (user-toggleable)
+- `expo-file-system` — write GPX/JSON to shared storage
+- `expo-sqlite` — local DB for past recordings list
+
+Target: **Android first**, iOS second.
+
+---
+
+## v1 Screens
+
+1. **Sensor pairing** — scan BLE, pair HR monitor / power meter / cadence sensor; persisted
+2. **Recording** — start / pause / resume / stop
+   - Live stats: elapsed time, distance, current+avg speed, HR, power, cadence, elevation gain
+   - Map with track drawn in real time
+   - Keep-awake toggle
+3. **Post-recording summary** — stats overview, title field, save / discard
+4. **Saved recordings** — list of past sessions; tap to export GPX or upload to server
+5. **Settings** — bincio instance URL + API token; km notification toggle; upload format
+
+---
+
+## Output Format
+
+**GPX with Garmin trackpoint extensions** — one `<trkpt>` per second with:
+- lat/lon/elevation from GPS
+- `<gpxtpx:hr>` — heart rate
+- `<gpxtpx:power>` — power (watts)
+- `<gpxtpx:cad>` — cadence (rpm)
+
+bincio-activity already parses this format via `bincio.extract.parsers`.
+
+Files saved to a user-accessible location (iOS Files app / Android shared storage) so bincio-autarchive can import them manually.
+
+---
+
+## Known Platform Concerns
+
+- **Android battery optimization**: aggressive OEMs (Xiaomi, Samsung, Huawei) kill background tasks. Prompt user to whitelist bincio-rec in battery settings on first launch. Every recording app has this problem — no framework-level fix.
+- **iOS background location**: requires `location` background mode in `Info.plist` and "Always" location permission. Fine for sideloading/TestFlight; App Store submission requires clear justification.
+- **iOS foreground notifications**: notification sounds are suppressed when app is in foreground — use `expo-av` audio cue instead for km alerts while screen is on.
+
+---
+
+## Out of Scope (v1)
+
+- Navigation / turn-by-turn routing
+- Auto-pause (stop lights, etc.)
+- Structured workouts / intervals
+- Offline maps
+- Live tracking / sharing
diff --git a/app.json b/app.json
index 0b23c10..521923b 100644
--- a/app.json
+++ b/app.json
@@ -38,6 +38,7 @@
     "web": {
       "favicon": "./assets/favicon.png"
     },
+    "ignorePaths": ["CLAUDE.md"],
     "plugins": [
       "expo-sqlite",
       [