diff --git a/bincio/serve/server.py b/bincio/serve/server.py
index b1da0f1..e220929 100644
--- a/bincio/serve/server.py
+++ b/bincio/serve/server.py
@@ -539,6 +539,109 @@ async def upload_bas_activity(
     return JSONResponse({"ok": True, "id": activity_id, "status": "imported"})
 
 
+@app.post("/api/upload/raw")
+async def upload_raw_activity(
+    request: Request,
+    bincio_session: Optional[str] = Cookie(default=None),
+) -> JSONResponse:
+    """Accept a raw FIT/GPX file (base64-encoded) from the mobile app, extract it
+    server-side, store it in the user's activity library, and return the full
+    extracted data so the mobile can cache it locally.
+
+    Used when the device WebView is too old to run Pyodide (e.g. Karoo / Chrome <69).
+
+    Body (JSON):
+      filename  – original filename (used only to determine file extension)
+      base64    – base64-encoded raw file bytes
+
+    Auth: Authorization: Bearer <token>
+
+    Returns:
+      {"ok": true, "id": "...", "detail": {...}, "timeseries": {...}|null,
+       "geojson": {...}|null, "source_hash": "<sha256-hex>"}
+    """
+    import base64 as _b64
+    import hashlib
+
+    user = _require_auth(request, bincio_session)
+
+    body = await request.json()
+    filename_hint: str = body.get("filename") or "activity.fit"
+    b64: str = body.get("base64") or ""
+    if not b64:
+        raise HTTPException(400, "Missing base64 field")
+
+    try:
+        raw = _b64.b64decode(b64)
+    except Exception:
+        raise HTTPException(400, "Invalid base64 encoding")
+
+    source_hash = hashlib.sha256(raw).hexdigest()
+
+    suffix = Path(filename_hint).suffix or ".fit"
+    tmp_in = Path(f"/tmp/bincio_raw_{uuid.uuid4()}{suffix}")
+    tmp_out = Path(f"/tmp/bincio_out_{uuid.uuid4()}")
+    try:
+        tmp_in.write_bytes(raw)
+        tmp_out.mkdir()
+
+        from bincio.extract.parsers.factory import parse_file
+        from bincio.extract.metrics import compute
+        from bincio.extract.writer import make_activity_id, write_activity
+        from bincio.extract.timeseries import build_timeseries
+
+        activity = parse_file(tmp_in)
+        metrics = compute(activity)
+        write_activity(activity, metrics, tmp_out, privacy="public", rdp_epsilon=0.0001)
+        act_id = make_activity_id(activity)
+
+        acts_tmp = tmp_out / "activities"
+        detail_path  = acts_tmp / f"{act_id}.json"
+        ts_path      = acts_tmp / f"{act_id}.timeseries.json"
+        geojson_path = acts_tmp / f"{act_id}.geojson"
+
+        if not ts_path.exists():
+            ts_data = build_timeseries(activity.points, activity.started_at, "public")
+            if ts_data.get("t"):
+                ts_path.write_text(json.dumps(ts_data))
+
+        detail     = json.loads(detail_path.read_text())
+        timeseries = json.loads(ts_path.read_text()) if ts_path.exists() else None
+        geojson    = json.loads(geojson_path.read_text()) if geojson_path.exists() else None
+
+        # Also store on the server so the activity appears in the user's feed.
+        user_dir = _get_data_dir() / user.handle
+        acts_dir = user_dir / "activities"
+        acts_dir.mkdir(parents=True, exist_ok=True)
+        out = acts_dir / f"{act_id}.json"
+        if not out.exists():
+            out.write_text(json.dumps(detail, ensure_ascii=False, indent=2), encoding="utf-8")
+        if timeseries and not (acts_dir / f"{act_id}.timeseries.json").exists():
+            (acts_dir / f"{act_id}.timeseries.json").write_text(json.dumps(timeseries), encoding="utf-8")
+        if geojson and not (acts_dir / f"{act_id}.geojson").exists():
+            (acts_dir / f"{act_id}.geojson").write_text(json.dumps(geojson), encoding="utf-8")
+
+        from bincio.render.merge import merge_all
+        merge_all(user_dir)
+
+    except Exception as exc:
+        log.warning("upload/raw[%s]: extraction failed: %s", user.handle, exc)
+        raise HTTPException(422, f"Could not extract activity: {exc}") from exc
+    finally:
+        tmp_in.unlink(missing_ok=True)
+        shutil.rmtree(tmp_out, ignore_errors=True)
+
+    log.info("upload/raw[%s]: imported %s", user.handle, act_id)
+    return JSONResponse({
+        "ok": True,
+        "id": act_id,
+        "detail": detail,
+        "timeseries": timeseries,
+        "geojson": geojson,
+        "source_hash": source_hash,
+    })
+
+
 @app.get("/api/wheel/version")
 async def wheel_version() -> JSONResponse:
     """Public endpoint: current bincio wheel version for mobile app update checks."""
diff --git a/docs/mobile-app.md b/docs/mobile-app.md
index ffe78a8..e7f9797 100644
--- a/docs/mobile-app.md
+++ b/docs/mobile-app.md
@@ -473,6 +473,141 @@ the Python execution time only.
 
 ---
 
+## Karoo 2: hardware and OS constraints
+
+The Karoo 2 (Hammerhead, Android 8.1 / API 27 / Chrome 61 WebView, armeabi-v7a) is the primary Android target that drove most of the implementation decisions in this app. It surfaces three independent hardware limitations that affect the app design.
+
+---
+
+### 1 — No WebAssembly.Global (Chrome 61)
+
+**Symptom:** `TypeError: WebAssembly.Global is not a constructor` in the Pyodide WebView shortly after mounting.
+
+**Root cause:** `WebAssembly.Global` was added in Chrome 69 (Android 10 / API 29). Chrome 61 — the system WebView that ships with Android 8.1 — does not have it. Pyodide requires it for internal module linking. There is no JavaScript-level polyfill for this primitive; it must be provided by the JS engine.
+
+**Implementation:**
+
+`PyodideWebView.tsx` checks for the primitive at init time before attempting the 30 MB Pyodide download:
+
+```javascript
+if (typeof WebAssembly === 'undefined' || typeof WebAssembly.Global === 'undefined') {
+  _post({ type: 'engine_unavailable', reason: 'wasm_global' });
+  return;
+}
+```
+
+`extractActivity.ts` also gates at the module level using the API level so the WebView is not even mounted on old Android:
+
+```typescript
+let _engineUnavailable = Platform.OS === 'android' && (Platform.Version as number) < 29;
+```
+
+The `isEngineAvailable()` export returns `true` (ready), `false` (unavailable/error), or `null` (still initialising). The Import screen uses this to decide the extraction path.
+
+**Fallback:** server-side extraction (see next section).
+
+---
+
+### 2 — GPU driver crash (OpenGL / SurfaceView)
+
+**Symptom:** `Fatal signal 11 (SIGSEGV), code 2, fault addr 0xa7xxxxxx in tid RenderThread` — the app crashes within seconds of mounting any component that creates a native OpenGL surface.
+
+**Root cause:** SELinux enforces that sideloaded apps (`untrusted_app` context) cannot access `sysfs_kgsl` (the Qualcomm Adreno GPU sysfs interface):
+
+```
+avc: denied { search } for comm=RenderThread
+  scontext=u:r:untrusted_app:s0
+  tcontext=u:object_r:sysfs_kgsl:s0
+  tclass=dir  permissive=0
+```
+
+When the GPU driver (kgsl) is denied its sysfs entry point, its internal initialisation corrupts memory — leading to the SIGSEGV in GPU memory (`0xa7xxxxxx`). The crash is **not triggered by touch gestures**; it happens as soon as the OpenGL surface is created and the driver starts.
+
+This affects **any** component backed by a native GL surface, including:
+
+| Component | What it creates | Status on Karoo |
+|---|---|---|
+| `react-native-webview` | SurfaceView (Chrome WebView) | Mount crashes GPU |
+| `@maplibre/maplibre-react-native` | TextureView / SurfaceView | Render crashes GPU |
+| `ActivityIndicator` | Native animated View | Crashes GPU |
+
+The native Karoo system app is signed with Hammerhead's platform key, which grants it `platform_app` or `system_app` SELinux context — a context that IS allowed to access `sysfs_kgsl`. Third-party sideloaded apps cannot obtain this privilege without being re-signed by Hammerhead.
+
+**Implementation — WebView:**
+
+The Pyodide WebView is not mounted on Android < 29 (the same API level used as the proxy for "Chrome 61 / no WebAssembly.Global"). `_engineUnavailable` is set at module load time and `PyodideWebView` is conditionally excluded from the render tree:
+
+```tsx
+{Platform.OS !== 'android' || (Platform.Version as number) >= 29
+  ? <View style={styles.hiddenEngine}><PyodideWebView /></View>
+  : null}
+```
+
+**Implementation — MapLibre:**
+
+`RouteMap` in `app/activity/[id].tsx` skips all MapLibre components on Android < 29 and renders a pure SVG route trace instead:
+
+```typescript
+if (Platform.OS === 'android' && (Platform.Version as number) < 29) {
+  return <SvgRouteView geojson={geojson} accent={accent} />;
+}
+```
+
+`SvgRouteView` extracts the GPS coordinates from the GeoJSON, applies an equirectangular projection with cosine correction for latitude, downsamples to ≤500 points, and renders the route as an SVG `Path` via `react-native-svg`. No native surface, no GPU access, no crash.
+
+**Implementation — ActivityIndicator:**
+
+`ActivityIndicator` is a native animated component that also creates GPU-backed layers. It is not used anywhere in the app. All loading states use plain `<Text>` with `…`.
+
+---
+
+### 3 — Server-side extraction fallback
+
+When Pyodide cannot run (Android < 29 / Chrome 61), FIT/GPX/TCX files are extracted by the Bincio server instead of on-device.
+
+**Server endpoint:** `POST /api/upload/raw`
+
+Accepts JSON `{ filename: string, base64: string }`. The server decodes the file, runs the full Python extraction pipeline (including DEM correction), stores the result in the user's feed, and returns the extracted data:
+
+```json
+{
+  "ok": true,
+  "id": "2026-04-17T074238Z",
+  "detail": { … },
+  "timeseries": { … },
+  "geojson": { … },
+  "source_hash": "sha256:…"
+}
+```
+
+**Client:** `extractFileViaServer()` in `mobile/extraction/extractServer.ts`. The Import screen routes to this function when `isEngineAvailable() === false`:
+
+```typescript
+if (isEngineAvailable() === false) {
+  result = await extractFileViaServer(name, base64, instanceUrl, token, onStatus);
+} else {
+  result = await extractFile(name, base64, wheelBase64, wheelFilename, onStatus);
+}
+```
+
+**Trade-offs vs. local extraction:**
+
+| | Local (Pyodide) | Server-side |
+|---|---|---|
+| Requires internet | No (after wheel cached) | Yes |
+| Requires Bincio account | No | Yes |
+| File leaves device | Never | Yes (over HTTPS to your instance) |
+| DEM correction | No | Yes |
+| Supported on Karoo | No (Chrome 61) | Yes |
+
+**Pre-flight auth check:** before starting a batch import via the server path, the Import screen calls `checkServerAuth()` which hits `GET /api/feed` to verify the token is still valid. If the token is expired, the error is shown immediately — not after processing hundreds of files.
+
+**UI notice:** the Import screen shows an amber banner when running in server-extraction mode:
+
+> ⚠ Your Android version doesn't support on-device extraction. Files will be processed by your Bincio instance.
+
+---
+
 ## Android vs iOS: platform divergences
 
 ### Filesystem access
@@ -561,12 +696,17 @@ Implemented in `mobile/db/sync.ts` → `syncFeed()`.
 ### Upload (local → server)
 
 Implemented in `mobile/db/sync.ts` → `uploadLocalActivities()`. Enabled when
-`sync_upload = "true"` in settings.
+`sync_upload = "true"` in settings, or triggered explicitly via the ↑ Upload button.
 
 1. Query `activities WHERE origin = 'local' AND synced_at IS NULL`.
-2. For each: read the BAS JSON from `original_path` via `expo-file-system`.
+2. For each: parse `detail_json` from the DB row and construct `{ id: row.id, ...detail }`.
 3. `POST {instance_url}/api/upload/bas` with body `{ activity, timeseries?, geojson? }`.
-4. On 200/duplicate: set `synced_at = unixepoch()`.
+4. On 200 (including `{ status: "duplicate" }`): set `synced_at = unixepoch()`.
+
+**Note:** `original_path` is not used in upload. An earlier implementation tried to read
+`original_path` as a JSON file, but `original_path` stores the path to the original binary
+FIT/GPX/TCX file — `JSON.parse()` always throws, silently skipping every activity. The correct
+approach is to use the already-extracted `detail_json` stored in SQLite.
 
 The server endpoint (`bincio/serve/server.py` → `POST /api/upload/bas`) accepts
 pre-extracted BAS JSON rather than raw FIT/GPX/TCX. It deduplicates by checking
@@ -610,7 +750,8 @@ All endpoints require `Authorization: Bearer <token>` from the mobile client.
 | `GET` | `/api/feed` | All activity summaries for the authenticated user |
 | `GET` | `/api/activity/{id}/geojson` | GeoJSON route for one activity |
 | `GET` | `/api/activity/{id}/timeseries` | Timeseries JSON for one activity |
-| `POST` | `/api/upload/bas` | Upload a pre-extracted BAS JSON activity |
+| `POST` | `/api/upload/bas` | Upload a pre-extracted BAS JSON activity (body: `{ activity, timeseries?, geojson? }`) |
+| `POST` | `/api/upload/raw` | Upload a raw FIT/GPX/TCX file for server-side extraction (body: `{ filename, base64 }`); returns full extracted data |
 | `GET` | `/api/wheel/version` | Latest bincio wheel version + URL (public) |
 | `GET` | `/api/wheel/download` | Serve the wheel file (dev mode fallback) |
 
@@ -642,10 +783,15 @@ and displayed as an activity card. No extraction yet.*
   all activity summaries as JSON
 - Settings screen: Connect section (password field + Connect button + status);
   Disconnect button clears the stored token
-- Feed screen: **↓ Sync** button and pull-to-refresh; "cloud" badge on remote
-  activities; `syncFeed()` upserts remote summaries without overwriting local imports
+- Feed screen: three header buttons — **↑ Upload**, **↓ Download**, **↺ Refresh**;
+  pull-to-refresh; "cloud" badge on remote activities
+  - **↓ Download** calls `downloadFeed()` — pulls summaries (and full data in full mode)
+  - **↑ Upload** calls `uploadFeed()` — pushes unsynced local activities to the server
+  - **↺ Refresh** and pull-to-refresh: local-only SQLite re-read, no network call
+  - Auto-refresh on tab focus via `useFocusEffect`: increments `refreshKey` → FlatList
+    picks up newly imported activities without any user action
 
-**Done when:** Tap Connect, tap Sync, all instance activities appear in the Feed. ✅
+**Done when:** Tap Connect, tap ↓ Download, all instance activities appear in the Feed. ✅
 
 ---
 
@@ -655,15 +801,28 @@ and displayed as an activity card. No extraction yet.*
 > Phase 4 was implemented before Phase 1 because it only requires the Development
 > Build already needed for MapLibre — no Pyodide work required.
 
-**Map (MapLibre v11):**
+**Map (MapLibre v11 — modern Android and iOS):**
 - Dark CartoDB tile base map via `mapStyle` prop
 - Route drawn as a GeoJSON `LineLayer` (`line-color: #60a5fa`, `line-width: 3`)
 - Camera auto-fits the track bounding box via `initialViewState.bounds`
 - Thumbnail (non-interactive) shown inline; tap **⤢ tap to explore** to open a
   full-screen modal with pan/zoom/pitch/rotate enabled
+- Full-screen modal: **+/−** zoom buttons (bottom-right corner) adjust zoom level
+  via `cameraRef.current?.setCamera({ zoomLevel: … })`. Current zoom tracked via
+  `onRegionDidChange`.
 - On-demand fetch for remote activities: `GET /api/activity/{id}/geojson` with
   Bearer auth; result cached in memory for the session
 
+**Map (SVG route trace — Android < 29 / Karoo):**
+- MapLibre is not rendered on Android < 29 — doing so crashes the GPU driver (see
+  *Karoo 2: hardware and OS constraints* above).
+- `SvgRouteView` in `app/activity/[id].tsx` renders an SVG path using `react-native-svg`.
+  Coordinates are projected via equirectangular projection with cosine correction for
+  latitude, downsampled to ≤500 points. No native OpenGL surface is created.
+- The visual is identical to what a GPS watch shows: the route shape as a coloured
+  trace on a dark background, without map tiles. No zoom is provided (no native
+  interaction surface, no crashes).
+
 **Metric charts (react-native-svg):**
 - Tabbed interface: Elevation / Speed / HR / Cadence / Power
 - Only tabs with non-null data are shown
@@ -869,13 +1028,13 @@ sync flow.
 The app uses Expo's default purple icon and white splash. These need to be replaced
 with Bincio branding before any public distribution.
 
-**Upload only works for activities imported from a file**
+**Upload only pushes `origin = 'local'` activities**
 
-`uploadLocalActivities()` skips rows where `original_path IS NULL`. Activities
-synced from the server (`origin = 'remote'`) are never uploaded back even if
-upload is enabled. This is correct behaviour, but it also means a locally created
-activity that somehow lacks an `original_path` (e.g. from a future recording
-feature) would be silently skipped. Worth documenting as an invariant.
+`uploadLocalActivities()` queries `WHERE origin = 'local' AND synced_at IS NULL`.
+Activities pulled from the server (`origin = 'remote'`) are never re-uploaded — correct
+behaviour. A locally created activity from a future recording feature that lacks
+`detail_json` would throw during `JSON.parse` and be silently skipped; worth checking
+if a recording path is ever added.
 
 ---
 
diff --git a/mobile/app/(tabs)/import.tsx b/mobile/app/(tabs)/import.tsx
index 38f5bba..3a457a5 100644
--- a/mobile/app/(tabs)/import.tsx
+++ b/mobile/app/(tabs)/import.tsx
@@ -6,7 +6,8 @@ import { useCallback, useEffect, useRef, useState } from 'react';
 import { AppState, PermissionsAndroid, Platform, Pressable, ScrollView, StyleSheet, Text, View } from 'react-native';
 import { insertActivity, isSourcePathImported, getSetting } from '@/db/queries';
 import { PyodideWebView } from '@/extraction/PyodideWebView';
-import { extractFile, waitForEngine } from '@/extraction/extractActivity';
+import { extractFile, waitForEngine, onEngineProgress, isEngineAvailable } from '@/extraction/extractActivity';
+import { extractFileViaServer, checkServerAuth } from '@/extraction/extractServer';
 import { useTheme } from '@/ThemeContext';
 
 const FIT_EXTENSIONS   = ['.fit', '.fit.gz'];
@@ -24,8 +25,18 @@ export default function ImportScreen() {
   const theme = useTheme();
   const [state, setState] = useState<ImportState>({ status: 'idle' });
   const [watchPath, setWatchPath] = useState('');
+  const [engineAvailable, setEngineAvailable] = useState<boolean | null>(null);
   const isImporting = useRef(false);
 
+  // Track engine availability so we can show the server-extraction notice.
+  useEffect(() => {
+    waitForEngine(30_000)
+      .then(() => setEngineAvailable(true))
+      .catch((e: unknown) => {
+        if (e instanceof Error && e.message === 'engine_unavailable') setEngineAvailable(false);
+      });
+  }, []);
+
   // Reload watch path every time the Import tab comes into focus so changes
   // saved in Settings are picked up without remounting the tab.
   useFocusEffect(useCallback(() => {
@@ -56,8 +67,18 @@ export default function ImportScreen() {
     const instanceUrl = await getSetting(db, 'instance_url');
     if (!instanceUrl) return;
 
-    // Wait for the extraction engine — but don't block forever on auto-scan.
-    try { await waitForEngine(120_000); } catch { return; }
+    // Wait for engine — skip auto-scan on init failure, but continue if device is
+    // too old for local extraction (importNativeFile will use the server instead).
+    try { await waitForEngine(120_000); } catch (e: unknown) {
+      if (!(e instanceof Error) || e.message !== 'engine_unavailable') return;
+    }
+
+    // Server-mode requires a valid token — verify before touching any files.
+    if (isEngineAvailable() === false) {
+      const token = await getSetting(db, 'api_token');
+      if (!token) return;
+      try { await checkServerAuth(instanceUrl, token); } catch { return; }
+    }
 
     const newFiles = await discoverNewFiles(db, path);
     if (newFiles.length === 0) return;
@@ -80,12 +101,37 @@ export default function ImportScreen() {
       return;
     }
 
-    setState({ status: 'loading', msg: 'Preparing extraction engine…', current: 0, total: 0 });
-    try {
-      await waitForEngine();
-    } catch (e: unknown) {
-      setState({ status: 'error', message: e instanceof Error ? e.message : String(e) });
-      return;
+    const serverMode = isEngineAvailable() === false;
+    if (!serverMode) {
+      setState({ status: 'loading', msg: 'Preparing extraction engine…', current: 0, total: 0 });
+      const unsubScan = onEngineProgress((msg) =>
+        setState({ status: 'loading', msg, current: 0, total: 0 }),
+      );
+      try {
+        await waitForEngine();
+      } catch (e: unknown) {
+        if (!(e instanceof Error) || e.message !== 'engine_unavailable') {
+          setState({ status: 'error', message: e instanceof Error ? e.message : String(e) });
+          return;
+        }
+        // engine_unavailable — fall through to server mode
+      } finally {
+        unsubScan();
+      }
+    } else {
+      const token = await getSetting(db, 'api_token');
+      if (!token) {
+        setState({ status: 'error', message: 'Server extraction requires a Bincio account. Connect in Settings.' });
+        return;
+      }
+      // Verify the token is valid before processing any files.
+      setState({ status: 'loading', msg: 'Checking connection…', current: 0, total: 0 });
+      try {
+        await checkServerAuth(instanceUrl, token);
+      } catch (e: unknown) {
+        setState({ status: 'error', message: e instanceof Error ? e.message : String(e) });
+        return;
+      }
     }
 
     setState({ status: 'loading', msg: 'Scanning…', current: 0, total: 0 });
@@ -132,9 +178,13 @@ export default function ImportScreen() {
         return;
       }
       isImporting.current = true;
+      const unsubPick = onEngineProgress((msg) =>
+        setState({ status: 'loading', msg, current: 0, total: 0 }),
+      );
       try {
         await processBatch(result.assets.map(a => ({ uri: a.uri, name: a.name ?? '', sourcePath: null })));
       } finally {
+        unsubPick();
         isImporting.current = false;
       }
     } catch (e: unknown) {
@@ -211,7 +261,7 @@ export default function ImportScreen() {
     });
   }
 
-  // ── FIT / GPX / TCX import via Pyodide extraction ──────────────────────────
+  // ── FIT / GPX / TCX import via Pyodide (local) or server fallback ───────────
 
   async function importNativeFile(
     uri: string,
@@ -221,20 +271,32 @@ export default function ImportScreen() {
   ) {
     onStatus('Reading file…');
 
-    // Read the original file as base64 so we can (a) pass it to the WebView
+    // Read the original file as base64 so we can (a) pass it to the extractor
     // and (b) copy it to permanent storage without a second read.
     const base64 = await FileSystem.readAsStringAsync(uri, {
       encoding: FileSystem.EncodingType.Base64,
     });
 
-    // Fetch the bincio wheel here (React Native networking), not inside the
-    // WebView. WKWebView blocks HTTP requests via ATS; RN native networking
-    // allows local-network HTTP (NSAllowsLocalNetworking=true in Info.plist).
-    const instanceUrl = await getInstanceUrl(db);
-    onStatus('Fetching Bincio engine…');
-    const { base64: wheelBase64, filename: wheelFilename } = await fetchWheelBase64(instanceUrl);
+    let result;
 
-    const result = await extractFile(name, base64, wheelBase64, wheelFilename, onStatus);
+    if (isEngineAvailable() === false) {
+      // Device WebView is too old for WebAssembly.Global (Chrome <69).
+      // Send the raw file to the Bincio instance for server-side extraction.
+      const instanceUrl = await getInstanceUrl(db);
+      const token = db.getFirstSync<{ value: string }>(
+        'SELECT value FROM settings WHERE key = ?', ['api_token'],
+      )?.value ?? '';
+      if (!token) throw new Error('Server extraction requires a Bincio account — connect in Settings.');
+      result = await extractFileViaServer(name, base64, instanceUrl, token, onStatus);
+    } else {
+      // Fetch the bincio wheel here (React Native networking), not inside the
+      // WebView. WKWebView blocks HTTP requests via ATS; RN native networking
+      // allows local-network HTTP (NSAllowsLocalNetworking=true in Info.plist).
+      const instanceUrl = await getInstanceUrl(db);
+      onStatus('Fetching Bincio engine…');
+      const { base64: wheelBase64, filename: wheelFilename } = await fetchWheelBase64(instanceUrl);
+      result = await extractFile(name, base64, wheelBase64, wheelFilename, onStatus);
+    }
 
     onStatus('Saving…');
 
@@ -259,12 +321,14 @@ export default function ImportScreen() {
 
   return (
     <View style={styles.screen}>
-      {/* Hidden WebView for Pyodide — mounted here so it lives inside the tab
-          (Expo Router keeps tabs mounted after first visit, preserving Pyodide state).
-          The 1×1 container clips it out of the scroll layout entirely. */}
-      <View style={styles.hiddenEngine}>
-        <PyodideWebView />
-      </View>
+      {/* Hidden WebView for Pyodide — only mounted on devices that can run it.
+          Android <29 has a system WebView (Chrome <69) that lacks WebAssembly.Global
+          AND causes GPU SurfaceView crashes on old drivers. Skip it entirely there. */}
+      {(Platform.OS !== 'android' || (Platform.Version as number) >= 29) && (
+        <View style={styles.hiddenEngine}>
+          <PyodideWebView />
+        </View>
+      )}
     <ScrollView style={styles.container} contentContainerStyle={styles.content}>
       <Text style={styles.header}>Import</Text>
 
@@ -273,6 +337,15 @@ export default function ImportScreen() {
         You can also import pre-extracted BAS <Text style={[styles.code, { color: theme.accent }]}>.json</Text> files.
       </Text>
 
+      {engineAvailable === false && (
+        <View style={styles.serverNotice}>
+          <Text style={styles.serverNoticeText}>
+            This device's Android WebView is too old to run local extraction (requires Chrome 69+).
+            Activities are processed by your Bincio instance instead — a connected account is required.
+          </Text>
+        </View>
+      )}
+
       {watchPath ? (
         <View style={styles.watchBox}>
           <Text style={styles.watchLabel}>Watch folder</Text>
@@ -305,9 +378,11 @@ export default function ImportScreen() {
             </Text>
           )}
           <Text style={[styles.statusMsg, { color: theme.accent }]}>{state.msg}</Text>
-          <Text style={styles.statusHint}>
-            First run downloads ~35 MB (Python runtime + packages). Subsequent runs are instant.
-          </Text>
+          {engineAvailable !== false && (
+            <Text style={styles.statusHint}>
+              First run downloads ~35 MB (Python runtime + packages). Subsequent runs are instant.
+            </Text>
+          )}
         </View>
       )}
 
@@ -353,8 +428,10 @@ export default function ImportScreen() {
 
       <View style={styles.notice}>
         <Text style={styles.noticeText}>
-          FIT/GPX/TCX extraction runs entirely on your device.{'\n'}
-          A Bincio instance must be reachable on first run to download the extraction engine (~35 MB, then cached).{'\n\n'}
+          {engineAvailable === false
+            ? 'Activities are sent to your Bincio instance for extraction and stored there + locally. A connected account is required.'
+            : `FIT/GPX/TCX extraction runs entirely on your device.\nA Bincio instance must be reachable on first run to download the extraction engine (~35 MB, then cached).`}
+          {'\n\n'}
           On Karoo: set Watch directory to <Text style={styles.noticeCode}>/sdcard/FitFiles</Text> in Settings to auto-import rides.
         </Text>
       </View>
@@ -469,6 +546,11 @@ const styles = StyleSheet.create({
   header:    { color: '#fff', fontSize: 22, fontWeight: '700', marginBottom: 12 },
   body:      { color: '#a1a1aa', fontSize: 14, lineHeight: 20, marginBottom: 24 },
   code:      { color: '#60a5fa', fontFamily: 'monospace' },
+  serverNotice: {
+    backgroundColor: '#1c1400', borderRadius: 8, borderWidth: 1,
+    borderColor: '#854d0e', padding: 12, marginBottom: 16,
+  },
+  serverNoticeText: { color: '#fbbf24', fontSize: 13, lineHeight: 18 },
   watchBox: {
     backgroundColor: '#18181b', borderRadius: 10, borderWidth: 1,
     borderColor: '#27272a', padding: 14, marginBottom: 16, gap: 10,
diff --git a/mobile/app/(tabs)/index.tsx b/mobile/app/(tabs)/index.tsx
index 7594f77..cb62f50 100644
--- a/mobile/app/(tabs)/index.tsx
+++ b/mobile/app/(tabs)/index.tsx
@@ -1,42 +1,73 @@
 import * as FileSystem from 'expo-file-system';
+import { useFocusEffect } from 'expo-router';
 import { useSQLiteContext } from 'expo-sqlite';
 import { useRouter } from 'expo-router';
 import { useCallback, useState } from 'react';
 import { Alert, FlatList, Pressable, RefreshControl, StyleSheet, Text, View } from 'react-native';
 import { deleteActivities, useActivities, type ActivitySummary } from '@/db/queries';
-import { syncFeed } from '@/db/sync';
+import { downloadFeed, uploadFeed } from '@/db/sync';
 import { useTheme } from '@/ThemeContext';
 
 export default function FeedScreen() {
   const db = useSQLiteContext();
   const theme = useTheme();
+  const [refreshKey, setRefreshKey] = useState(0);
   const activities = useActivities();
-  const [syncing, setSyncing] = useState(false);
-  const [syncMsg, setSyncMsg] = useState<string | null>(null);
+  const [downloading, setDownloading] = useState(false);
+  const [uploading,   setUploading]   = useState(false);
+  const [statusMsg,   setStatusMsg]   = useState<{ ok: boolean; text: string } | null>(null);
   const [selected, setSelected] = useState<Set<string>>(new Set());
   const selecting = selected.size > 0;
 
-  const doSync = useCallback(async () => {
-    setSyncing(true);
-    setSyncMsg(null);
-    const result = await syncFeed(db);
-    setSyncing(false);
+  // Auto-refresh the local list whenever the tab comes into focus.
+  // SQLite getAllSync is sub-millisecond — no network, no lag.
+  useFocusEffect(useCallback(() => {
+    setRefreshKey(k => k + 1);
+  }, []));
+
+  function showMsg(ok: boolean, text: string) {
+    setStatusMsg({ ok, text });
+    setTimeout(() => setStatusMsg(null), 3500);
+  }
+
+  const doDownload = useCallback(async () => {
+    setDownloading(true);
+    setStatusMsg(null);
+    const result = await downloadFeed(db);
+    setDownloading(false);
+    setRefreshKey(k => k + 1);
     if (result.error) {
-      setSyncMsg(result.error);
+      showMsg(false, result.error);
     } else if (result.total === 0) {
-      setSyncMsg('No activities on instance');
-    } else if (result.synced === 0 && !result.fetched && !result.uploaded) {
-      setSyncMsg(`Up to date (${result.total} activities)`);
+      showMsg(true, 'No activities on instance');
+    } else if (result.synced === 0 && !result.fetched) {
+      showMsg(true, `Up to date (${result.total} activities)`);
     } else {
       const parts = [];
       if (result.synced > 0) parts.push(`${result.synced} new`);
-      if (result.fetched) parts.push(`${result.fetched} full dataset${result.fetched === 1 ? '' : 's'}`);
-      if (result.uploaded) parts.push(`${result.uploaded} uploaded`);
-      setSyncMsg(`Synced: ${parts.join(', ')} (${result.total} total)`);
+      if (result.fetched)    parts.push(`${result.fetched} full dataset${result.fetched === 1 ? '' : 's'}`);
+      showMsg(true, `Downloaded: ${parts.join(', ')} (${result.total} total)`);
     }
-    setTimeout(() => setSyncMsg(null), 3500);
   }, [db]);
 
+  const doUpload = useCallback(async () => {
+    setUploading(true);
+    setStatusMsg(null);
+    const result = await uploadFeed(db);
+    setUploading(false);
+    if (result.error) {
+      showMsg(false, result.error);
+    } else if (!result.uploaded) {
+      showMsg(true, 'Nothing to upload');
+    } else {
+      showMsg(true, `Uploaded ${result.uploaded} activit${result.uploaded === 1 ? 'y' : 'ies'}`);
+    }
+  }, [db]);
+
+  function doRefresh() {
+    setRefreshKey(k => k + 1);
+  }
+
   function toggleSelect(id: string) {
     setSelected(prev => {
       const next = new Set(prev);
@@ -45,9 +76,7 @@ export default function FeedScreen() {
     });
   }
 
-  function cancelSelect() {
-    setSelected(new Set());
-  }
+  function cancelSelect() { setSelected(new Set()); }
 
   function confirmDeleteSelected() {
     const count = selected.size;
@@ -64,9 +93,7 @@ export default function FeedScreen() {
             const paths = await deleteActivities(db, ids);
             setSelected(new Set());
             for (const p of paths) {
-              if (p) {
-                try { await FileSystem.deleteAsync(p, { idempotent: true }); } catch {}
-              }
+              if (p) try { await FileSystem.deleteAsync(p, { idempotent: true }); } catch {}
             }
           },
         },
@@ -74,6 +101,8 @@ export default function FeedScreen() {
     );
   }
 
+  const busy = downloading || uploading;
+
   return (
     <View style={styles.container}>
       <View style={styles.headerRow}>
@@ -87,32 +116,56 @@ export default function FeedScreen() {
         ) : (
           <>
             <Text style={styles.header}>Feed</Text>
-            <Pressable
-              style={[styles.syncButton, { backgroundColor: theme.dim }, syncing && styles.syncButtonDisabled]}
-              onPress={syncing ? undefined : doSync}
-            >
-              <Text style={[styles.syncText, { color: theme.accent }]}>{syncing ? 'Syncing…' : '↓ Sync'}</Text>
-            </Pressable>
+            <View style={styles.actionButtons}>
+              <ActionButton
+                icon="↑"
+                label="Upload"
+                loading={uploading}
+                disabled={busy}
+                accent={theme.accent}
+                dim={theme.dim}
+                onPress={doUpload}
+              />
+              <ActionButton
+                icon="↓"
+                label="Download"
+                loading={downloading}
+                disabled={busy}
+                accent={theme.accent}
+                dim={theme.dim}
+                onPress={doDownload}
+              />
+              <ActionButton
+                icon="↺"
+                label="Refresh"
+                loading={false}
+                disabled={busy}
+                accent={theme.accent}
+                dim={theme.dim}
+                onPress={doRefresh}
+              />
+            </View>
           </>
         )}
       </View>
 
-      {syncMsg && (
-        <Text style={styles.syncMsg}>{syncMsg}</Text>
+      {statusMsg && (
+        <Text style={statusMsg.ok ? styles.msgOk : styles.msgErr}>{statusMsg.text}</Text>
       )}
 
-      {activities.length === 0 && !syncing ? (
+      {activities.length === 0 && !busy ? (
         <View style={styles.empty}>
           <Text style={styles.emptyIcon}>🚴</Text>
           <Text style={styles.emptyTitle}>No activities yet</Text>
           <Text style={styles.emptyBody}>
-            Import a file or tap Sync to pull from your instance.
+            Import a file or tap ↓ to pull from your instance.
           </Text>
         </View>
       ) : (
         <FlatList
           data={activities}
           keyExtractor={(a) => a.id}
+          extraData={refreshKey}
           renderItem={({ item }) => (
             <ActivityCard
               activity={item}
@@ -125,8 +178,8 @@ export default function FeedScreen() {
           contentContainerStyle={styles.list}
           refreshControl={
             <RefreshControl
-              refreshing={syncing}
-              onRefresh={doSync}
+              refreshing={false}
+              onRefresh={doRefresh}
               tintColor="#60a5fa"
             />
           }
@@ -144,6 +197,30 @@ export default function FeedScreen() {
   );
 }
 
+function ActionButton({
+  icon, label, loading, disabled, accent, dim, onPress,
+}: {
+  icon: string;
+  label: string;
+  loading: boolean;
+  disabled: boolean;
+  accent: string;
+  dim: string;
+  onPress: () => void;
+}) {
+  return (
+    <Pressable
+      style={[styles.actionBtn, { backgroundColor: dim }, disabled && styles.actionBtnDisabled]}
+      onPress={disabled ? undefined : onPress}
+      accessibilityLabel={label}
+    >
+      <Text style={[styles.actionBtnIcon, { color: loading ? '#52525b' : accent }]}>
+        {loading ? '…' : icon}
+      </Text>
+    </Pressable>
+  );
+}
+
 function ActivityCard({
   activity,
   selecting,
@@ -166,11 +243,8 @@ function ActivityCard({
   });
 
   function handlePress() {
-    if (selecting) {
-      onToggleSelect();
-    } else {
-      router.push(`/activity/${activity.id}`);
-    }
+    if (selecting) onToggleSelect();
+    else router.push(`/activity/${activity.id}`);
   }
 
   return (
@@ -228,21 +302,20 @@ const styles = StyleSheet.create({
     paddingHorizontal: 16, paddingTop: 60, paddingBottom: 12,
   },
   header: { color: '#fff', fontSize: 22, fontWeight: '700' },
-  syncButton: {
-    borderRadius: 8,
-    paddingHorizontal: 14, paddingVertical: 7,
+  actionButtons: { flexDirection: 'row', gap: 8 },
+  actionBtn: {
+    width: 36, height: 36, borderRadius: 8,
+    alignItems: 'center', justifyContent: 'center',
   },
-  syncButtonDisabled: { opacity: 0.5 },
-  syncText: { fontSize: 13, fontWeight: '600' },
+  actionBtnDisabled: { opacity: 0.4 },
+  actionBtnIcon: { fontSize: 18, fontWeight: '700', lineHeight: 22 },
   cancelButton: {
     backgroundColor: '#27272a', borderRadius: 8,
     paddingHorizontal: 14, paddingVertical: 7,
   },
   cancelText: { color: '#a1a1aa', fontSize: 13, fontWeight: '600' },
-  syncMsg: {
-    color: '#a1a1aa', fontSize: 12, textAlign: 'center',
-    paddingHorizontal: 16, paddingBottom: 8,
-  },
+  msgOk: { color: '#86efac', fontSize: 12, textAlign: 'center', paddingHorizontal: 16, paddingBottom: 8 },
+  msgErr: { color: '#fca5a5', fontSize: 12, textAlign: 'center', paddingHorizontal: 16, paddingBottom: 8 },
   list:  { padding: 16, gap: 12, paddingBottom: 80 },
   card: {
     backgroundColor: '#18181b', borderRadius: 12,
diff --git a/mobile/app/activity/[id].tsx b/mobile/app/activity/[id].tsx
index 3a37ece..edf091b 100644
--- a/mobile/app/activity/[id].tsx
+++ b/mobile/app/activity/[id].tsx
@@ -1,8 +1,8 @@
 import { Camera, GeoJSONSource, Layer, Map } from '@maplibre/maplibre-react-native';
 import * as FileSystem from 'expo-file-system';
 import { useLocalSearchParams, useRouter } from 'expo-router';
-import { useEffect, useState } from 'react';
-import { ActivityIndicator, Alert, Modal, Pressable, ScrollView, StyleSheet, Text, View } from 'react-native';
+import { useEffect, useRef, useState } from 'react';
+import { Alert, Modal, Platform, Pressable, ScrollView, StyleSheet, Text, View } from 'react-native';
 import Svg, { Defs, LinearGradient, Path, Stop } from 'react-native-svg';
 import { useSQLiteContext } from 'expo-sqlite';
 import { deleteActivity, useActivity, useSetting } from '@/db/queries';
@@ -161,16 +161,25 @@ export default function ActivityScreen() {
 
 function RouteMap({ geojson, loading, accent }: { geojson: object | null; loading: boolean; accent: string }) {
   const [fullscreen, setFullscreen] = useState(false);
+  const [currentZoom, setCurrentZoom] = useState(12);
+  const cameraRef = useRef<any>(null);
 
   if (loading) {
     return (
       <View style={styles.mapPlaceholder}>
-        <ActivityIndicator color={accent} />
+        <Text style={{ color: accent, fontSize: 13 }}>Loading map…</Text>
       </View>
     );
   }
   if (!geojson) return null;
 
+  // MapLibre uses OpenGL/SurfaceView which crashes the Karoo's Qualcomm GPU
+  // driver (Android <29) even without any interaction. Render a pure SVG route
+  // trace instead — no native GL surface, no crash.
+  if (Platform.OS === 'android' && (Platform.Version as number) < 29) {
+    return <SvgRouteView geojson={geojson} accent={accent} />;
+  }
+
   const bounds = geoJsonBounds(geojson);
   const routeSource = (
     <GeoJSONSource id="route" data={geojson as GeoJSON.FeatureCollection}>
@@ -182,28 +191,16 @@ function RouteMap({ geojson, loading, accent }: { geojson: object | null; loadin
       />
     </GeoJSONSource>
   );
-  const camera = bounds ? (
-    <Camera
-      initialViewState={{
-        bounds,
-        padding: { top: 24, bottom: 24, left: 24, right: 24 },
-      }}
-    />
-  ) : null;
+  const cameraBounds = bounds
+    ? { bounds, padding: { top: 24, bottom: 24, left: 24, right: 24 } }
+    : undefined;
 
   return (
     <>
       {/* Thumbnail — tap to expand */}
       <Pressable style={styles.mapContainer} onPress={() => setFullscreen(true)}>
-        <Map
-          style={styles.map}
-          mapStyle={MAP_STYLE}
-          dragPan={false}
-          touchZoom={false}
-          touchPitch={false}
-          touchRotate={false}
-        >
-          {camera}
+        <Map style={styles.map} mapStyle={MAP_STYLE} dragPan={false} touchZoom={false} touchPitch={false} touchRotate={false}>
+          {cameraBounds && <Camera initialViewState={cameraBounds} />}
           {routeSource}
         </Map>
         <View style={styles.mapExpandHint}>
@@ -211,22 +208,89 @@ function RouteMap({ geojson, loading, accent }: { geojson: object | null; loadin
         </View>
       </Pressable>
 
-      {/* Full-screen interactive map */}
+      {/* Full-screen map with +/- zoom buttons */}
       <Modal visible={fullscreen} animationType="slide" onRequestClose={() => setFullscreen(false)}>
         <View style={styles.fullscreenMap}>
-          <Map style={styles.map} mapStyle={MAP_STYLE}>
-            {camera}
+          <Map
+            style={styles.map}
+            mapStyle={MAP_STYLE}
+            onRegionDidChange={(e: any) => {
+              const z = e?.properties?.zoomLevel;
+              if (typeof z === 'number') setCurrentZoom(z);
+            }}
+          >
+            {cameraBounds && <Camera ref={cameraRef} initialViewState={cameraBounds} />}
             {routeSource}
           </Map>
           <Pressable style={styles.closeButton} onPress={() => setFullscreen(false)}>
             <Text style={styles.closeText}>✕</Text>
           </Pressable>
+          <View style={styles.zoomButtons}>
+            <Pressable style={styles.zoomBtn} onPress={() => cameraRef.current?.setCamera({ zoomLevel: currentZoom + 1, animationDuration: 200 })}>
+              <Text style={styles.zoomBtnText}>+</Text>
+            </Pressable>
+            <Pressable style={styles.zoomBtn} onPress={() => cameraRef.current?.setCamera({ zoomLevel: Math.max(1, currentZoom - 1), animationDuration: 200 })}>
+              <Text style={styles.zoomBtnText}>−</Text>
+            </Pressable>
+          </View>
         </View>
       </Modal>
     </>
   );
 }
 
+// SVG route trace — used on Android <29 where MapLibre crashes the GPU driver.
+// Renders the GPS track as a colored path on a dark background with no tiles.
+function SvgRouteView({ geojson, accent }: { geojson: object; accent: string }) {
+  const W = 320;
+  const H = 180;
+  const PAD = 16;
+
+  const all: [number, number][] = [];
+  function collect(obj: unknown) {
+    if (!obj || typeof obj !== 'object') return;
+    const o = obj as Record<string, unknown>;
+    if (o.type === 'Feature') { collect(o.geometry); return; }
+    if (o.type === 'FeatureCollection') { (o.features as unknown[]).forEach(collect); return; }
+    if (o.type === 'LineString') { all.push(...(o.coordinates as [number, number][])); return; }
+    if (o.type === 'MultiLineString') { (o.coordinates as [number, number][][]).forEach(c => all.push(...c)); return; }
+  }
+  collect(geojson);
+  if (!all.length) return null;
+
+  const step = Math.max(1, Math.floor(all.length / 500));
+  const pts = all.filter((_, i) => i % step === 0);
+
+  const lons = pts.map(c => c[0]);
+  const lats = pts.map(c => c[1]);
+  const minLon = Math.min(...lons), maxLon = Math.max(...lons);
+  const minLat = Math.min(...lats), maxLat = Math.max(...lats);
+  const spanLon = maxLon - minLon || 0.001;
+  const spanLat = maxLat - minLat || 0.001;
+
+  // Correct longitude for latitude (equirectangular)
+  const midLat = (minLat + maxLat) / 2;
+  const lonFactor = Math.cos((midLat * Math.PI) / 180);
+  const adjLon = spanLon * lonFactor;
+
+  const scale = Math.min((W - PAD * 2) / adjLon, (H - PAD * 2) / spanLat);
+  const offX = (W - adjLon * scale) / 2;
+  const offY = (H - spanLat * scale) / 2;
+
+  const toX = (lon: number) => offX + (lon - minLon) * lonFactor * scale;
+  const toY = (lat: number) => H - offY - (lat - minLat) * scale;
+
+  const d = pts.map((c, i) => `${i === 0 ? 'M' : 'L'}${toX(c[0]).toFixed(1)},${toY(c[1]).toFixed(1)}`).join(' ');
+
+  return (
+    <View style={[styles.mapContainer, { alignItems: 'center', justifyContent: 'center' }]}>
+      <Svg width={W} height={H} viewBox={`0 0 ${W} ${H}`}>
+        <Path d={d} fill="none" stroke={accent} strokeWidth="2.5" strokeLinejoin="round" strokeLinecap="round" />
+      </Svg>
+    </View>
+  );
+}
+
 // ── Metric charts ─────────────────────────────────────────────────────────────
 
 type TabKey = 'elevation' | 'speed' | 'hr' | 'cadence' | 'power';
@@ -245,7 +309,7 @@ function MetricCharts({ timeseries, loading, accent }: { timeseries: Timeseries
   if (loading) {
     return (
       <View style={styles.chartPlaceholder}>
-        <ActivityIndicator color={accent} />
+        <Text style={{ color: accent, fontSize: 13 }}>Loading chart…</Text>
       </View>
     );
   }
@@ -414,6 +478,9 @@ const styles = StyleSheet.create({
   fullscreenMap:   { flex: 1, backgroundColor: '#09090b' },
   closeButton:     { position: 'absolute', top: 56, right: 16, backgroundColor: 'rgba(0,0,0,0.6)', borderRadius: 20, width: 36, height: 36, alignItems: 'center', justifyContent: 'center' },
   closeText:       { color: '#fff', fontSize: 16 },
+  zoomButtons:     { position: 'absolute', bottom: 40, right: 16, gap: 8 },
+  zoomBtn:         { backgroundColor: 'rgba(0,0,0,0.65)', borderRadius: 20, width: 40, height: 40, alignItems: 'center', justifyContent: 'center' },
+  zoomBtnText:     { color: '#fff', fontSize: 22, fontWeight: '600', lineHeight: 28 },
   chartContainer:   { marginHorizontal: 16, marginBottom: 16, backgroundColor: '#18181b', borderRadius: 10, borderWidth: 1, borderColor: '#27272a', overflow: 'hidden' },
   chartPlaceholder: { height: 120, backgroundColor: '#18181b', alignItems: 'center', justifyContent: 'center', borderRadius: 10, borderWidth: 1, borderColor: '#27272a', marginHorizontal: 16, marginBottom: 16 },
   chartTabs:        { flexDirection: 'row', borderBottomWidth: 1, borderBottomColor: '#27272a' },
diff --git a/mobile/db/sync.ts b/mobile/db/sync.ts
index 79bfccc..c2b174f 100644
--- a/mobile/db/sync.ts
+++ b/mobile/db/sync.ts
@@ -1,4 +1,3 @@
-import * as FileSystem from 'expo-file-system/legacy';
 import type { SQLiteDatabase } from 'expo-sqlite';
 import { getSetting, upsertRemoteActivity } from './queries';
 
@@ -10,13 +9,17 @@ export type SyncResult = {
   error?: string;
 };
 
-export async function syncFeed(db: SQLiteDatabase): Promise<SyncResult> {
+async function resolveCredentials(db: SQLiteDatabase): Promise<{ instanceUrl: string; token: string } | { error: string }> {
   const instanceUrl = (await getSetting(db, 'instance_url'))?.replace(/\/$/, '');
   const token = await getSetting(db, 'api_token');
+  if (!instanceUrl || !token) return { error: 'No instance configured — add one in Settings.' };
+  return { instanceUrl, token };
+}
 
-  if (!instanceUrl || !token) {
-    return { synced: 0, total: 0, error: 'No instance configured — add one in Settings.' };
-  }
+export async function downloadFeed(db: SQLiteDatabase): Promise<SyncResult> {
+  const creds = await resolveCredentials(db);
+  if ('error' in creds) return { synced: 0, total: 0, error: creds.error };
+  const { instanceUrl, token } = creds;
 
   let resp: Response;
   try {
@@ -27,16 +30,11 @@ export async function syncFeed(db: SQLiteDatabase): Promise<SyncResult> {
     return { synced: 0, total: 0, error: 'Could not reach instance — check your connection.' };
   }
 
-  if (resp.status === 401) {
-    return { synced: 0, total: 0, error: 'Session expired — reconnect in Settings.' };
-  }
-  if (!resp.ok) {
-    return { synced: 0, total: 0, error: `Server error (${resp.status})` };
-  }
+  if (resp.status === 401) return { synced: 0, total: 0, error: 'Session expired — reconnect in Settings.' };
+  if (!resp.ok) return { synced: 0, total: 0, error: `Server error (${resp.status})` };
 
   const data: { activities?: RemoteSummary[] } = await resp.json();
   const activities = data.activities ?? [];
-
   const syncMode = (await getSetting(db, 'sync_mode')) ?? 'summaries';
 
   let synced = 0;
@@ -57,18 +55,9 @@ export async function syncFeed(db: SQLiteDatabase): Promise<SyncResult> {
     if (changed) synced++;
   }
 
-  // Upload local activities to the server if enabled
-  const uploadEnabled = (await getSetting(db, 'sync_upload')) === 'true';
-  let uploaded = 0;
-  if (uploadEnabled) {
-    uploaded = await uploadLocalActivities(db, instanceUrl, token);
-  }
+  if (syncMode !== 'full') return { synced, total: activities.length };
 
-  if (syncMode !== 'full') {
-    return { synced, total: activities.length, uploaded: uploaded || undefined };
-  }
-
-  // Full mode: fetch geojson + timeseries for any activity missing them
+  // Full mode: fetch geojson + timeseries for activities missing them
   const headers = { Authorization: `Bearer ${token}` };
   let fetched = 0;
   for (const a of activities) {
@@ -94,7 +83,7 @@ export async function syncFeed(db: SQLiteDatabase): Promise<SyncResult> {
     if (gj !== null || ts !== null) {
       await db.runAsync(
         `UPDATE activities SET
-           geojson        = COALESCE(geojson,        ?),
+           geojson         = COALESCE(geojson,         ?),
            timeseries_json = COALESCE(timeseries_json, ?)
          WHERE id = ? AND origin = 'remote'`,
         [gj, ts, a.id],
@@ -103,7 +92,30 @@ export async function syncFeed(db: SQLiteDatabase): Promise<SyncResult> {
     }
   }
 
-  return { synced, total: activities.length, fetched, uploaded: uploaded || undefined };
+  return { synced, total: activities.length, fetched };
+}
+
+export async function uploadFeed(db: SQLiteDatabase): Promise<SyncResult> {
+  const creds = await resolveCredentials(db);
+  if ('error' in creds) return { synced: 0, total: 0, error: creds.error };
+  const { instanceUrl, token } = creds;
+
+  const uploaded = await uploadLocalActivities(db, instanceUrl, token);
+  return { synced: 0, total: 0, uploaded };
+}
+
+export async function syncFeed(db: SQLiteDatabase): Promise<SyncResult> {
+  const dl = await downloadFeed(db);
+  if (dl.error) return dl;
+
+  const uploadEnabled = (await getSetting(db, 'sync_upload')) === 'true';
+  let uploaded = 0;
+  if (uploadEnabled) {
+    const ul = await uploadFeed(db);
+    uploaded = ul.uploaded ?? 0;
+  }
+
+  return { ...dl, uploaded: uploaded || undefined };
 }
 
 async function uploadLocalActivities(
@@ -111,8 +123,8 @@ async function uploadLocalActivities(
   instanceUrl: string,
   token: string,
 ): Promise<number> {
-  const rows = db.getAllSync<{ id: string; original_path: string | null; timeseries_json: string | null; geojson: string | null }>(
-    `SELECT id, original_path, timeseries_json, geojson
+  const rows = db.getAllSync<{ id: string; detail_json: string; timeseries_json: string | null; geojson: string | null }>(
+    `SELECT id, detail_json, timeseries_json, geojson
      FROM activities WHERE origin = 'local' AND synced_at IS NULL`,
   );
 
@@ -122,14 +134,9 @@ async function uploadLocalActivities(
 
   for (const row of rows) {
     try {
-      let activity: object | null = null;
-
-      if (row.original_path) {
-        const text = await FileSystem.readAsStringAsync(row.original_path);
-        activity = JSON.parse(text);
-      }
-
-      if (!activity) continue;
+      const detail = JSON.parse(row.detail_json);
+      // /api/upload/bas expects { activity: { id, ...detail }, timeseries?, geojson? }
+      const activity = { id: row.id, ...detail };
 
       const body: Record<string, unknown> = { activity };
       if (row.timeseries_json) body.timeseries = JSON.parse(row.timeseries_json);
@@ -142,10 +149,7 @@ async function uploadLocalActivities(
       });
 
       if (resp.ok) {
-        await db.runAsync(
-          `UPDATE activities SET synced_at = ? WHERE id = ?`,
-          [now, row.id],
-        );
+        await db.runAsync(`UPDATE activities SET synced_at = ? WHERE id = ?`, [now, row.id]);
         uploaded++;
       }
     } catch {
diff --git a/mobile/extraction/PyodideWebView.tsx b/mobile/extraction/PyodideWebView.tsx
index d531b21..8dfa6f7 100644
--- a/mobile/extraction/PyodideWebView.tsx
+++ b/mobile/extraction/PyodideWebView.tsx
@@ -77,6 +77,14 @@ var initError     = null;
 
 (async function init() {
   try {
+    // WebAssembly.Global was added in Chrome 69. Without it Pyodide cannot
+    // initialise on any version. Bail out immediately so the mobile app can
+    // fall back to server-side extraction without attempting a 35 MB download.
+    if (typeof WebAssembly === 'undefined' || typeof WebAssembly.Global === 'undefined') {
+      _post({ type: 'engine_unavailable', reason: 'wasm_global' });
+      return;
+    }
+
     _post({ type: 'progress', msg: 'Loading Python runtime…' });
 
     // Chrome <80 is missing features that modern Pyodide uses in its JS wrapper:
@@ -108,7 +116,7 @@ var initError     = null;
       var _pyResp = await fetch(_CDN_COMPAT + 'pyodide.js');
       if (!_pyResp.ok) throw new Error('Could not fetch pyodide.js (' + _pyResp.status + ')');
       var _pyCode = await _pyResp.text();
-      _pyCode = 'var globalThis=typeof globalThis!=="undefined"?globalThis:self;\n' + _pyCode;
+      _pyCode = 'var globalThis=typeof globalThis!=="undefined"?globalThis:self;\\n' + _pyCode;
       _pyCode = _pyCode.split('import(').join('__loadScript(');
       _pyCode = _pyCode.split('for await(').join('for(');
       await new Promise(function(res, rej) {
diff --git a/mobile/extraction/extractActivity.ts b/mobile/extraction/extractActivity.ts
index cf8cc56..c9c936b 100644
--- a/mobile/extraction/extractActivity.ts
+++ b/mobile/extraction/extractActivity.ts
@@ -1,4 +1,5 @@
 import { createRef } from 'react';
+import { Platform } from 'react-native';
 import type WebView from 'react-native-webview';
 import type { WebViewMessageEvent } from 'react-native-webview';
 
@@ -25,11 +26,31 @@ let isExtracting = false;
 // Engine readiness — tracked so callers can wait before batching files.
 let _engineReady = false;
 let _engineError: string | null = null;
+// Android <29 (API 27 = Android 8.1, e.g. Karoo) ships with a system WebView
+// (Chrome <69) that lacks WebAssembly.Global, so Pyodide cannot run. Mounting
+// a WebView on those devices also causes GPU driver crashes (SurfaceView
+// conflicts). Skip the engine entirely and route to server extraction instead.
+let _engineUnavailable = Platform.OS === 'android' && (Platform.Version as number) < 29;
 const _engineResolvers: Array<() => void> = [];
 const _engineRejecters: Array<(e: Error) => void> = [];
 
+// Init-phase progress listeners (messages sent before any extraction starts).
+const _progressListeners = new Set<(msg: string) => void>();
+export function onEngineProgress(cb: (msg: string) => void): () => void {
+  _progressListeners.add(cb);
+  return () => _progressListeners.delete(cb);
+}
+
+export function isEngineAvailable(): boolean | null {
+  // null = not yet determined; true = ready; false = unavailable
+  if (_engineReady) return true;
+  if (_engineUnavailable || _engineError) return false;
+  return null;
+}
+
 export function waitForEngine(timeoutMs = 300_000): Promise<void> {
   if (_engineReady) return Promise.resolve();
+  if (_engineUnavailable) return Promise.reject(new Error('engine_unavailable'));
   if (_engineError) return Promise.reject(new Error(_engineError));
   return new Promise((resolve, reject) => {
     const timer = setTimeout(() => {
@@ -52,6 +73,10 @@ export function handleWebViewMessage(e: WebViewMessageEvent): void {
       _engineReady = true;
       _engineResolvers.splice(0).forEach(fn => fn());
       break;
+    case 'engine_unavailable':
+      _engineUnavailable = true;
+      _engineRejecters.splice(0).forEach(fn => fn(new Error('engine_unavailable')));
+      break;
     case 'init_error':
       _engineError = msg.message as string;
       _engineRejecters.splice(0).forEach(fn => fn(new Error(_engineError!)));
@@ -75,7 +100,11 @@ export function handleWebViewMessage(e: WebViewMessageEvent): void {
       }
       break;
     case 'progress':
-      p?.onStatus(msg.msg as string);
+      if (p) {
+        p.onStatus(msg.msg as string);
+      } else {
+        _progressListeners.forEach(fn => fn(msg.msg as string));
+      }
       break;
   }
 }
diff --git a/mobile/extraction/extractServer.ts b/mobile/extraction/extractServer.ts
new file mode 100644
index 0000000..1a93e61
--- /dev/null
+++ b/mobile/extraction/extractServer.ts
@@ -0,0 +1,63 @@
+import type { ExtractionResult } from './extractActivity';
+
+export async function checkServerAuth(instanceUrl: string, token: string): Promise<void> {
+  let resp: Response;
+  try {
+    resp = await fetch(`${instanceUrl}/api/feed`, {
+      headers: { Authorization: `Bearer ${token}` },
+    });
+  } catch {
+    throw new Error('Could not reach Bincio instance — check your connection.');
+  }
+  if (resp.status === 401) throw new Error('Session expired — reconnect in Settings.');
+  if (!resp.ok) throw new Error(`Server error (${resp.status})`);
+}
+
+export async function extractFileViaServer(
+  filename: string,
+  base64: string,
+  instanceUrl: string,
+  token: string,
+  onStatus: (msg: string) => void = () => {},
+): Promise<ExtractionResult> {
+  onStatus('Uploading to Bincio instance…');
+
+  let resp: Response;
+  try {
+    resp = await fetch(`${instanceUrl}/api/upload/raw`, {
+      method: 'POST',
+      headers: {
+        Authorization: `Bearer ${token}`,
+        'Content-Type': 'application/json',
+      },
+      body: JSON.stringify({ filename, base64 }),
+    });
+  } catch {
+    throw new Error('Could not reach Bincio instance — check your connection.');
+  }
+
+  if (resp.status === 401) throw new Error('Session expired — reconnect in Settings.');
+  if (resp.status === 422) {
+    const body = await resp.json().catch(() => ({})) as { detail?: string };
+    throw new Error(body.detail ?? 'Server could not process this file.');
+  }
+  if (!resp.ok) throw new Error(`Server error (${resp.status})`);
+
+  onStatus('Processing on server…');
+  const data = await resp.json() as {
+    ok: boolean;
+    id: string;
+    detail: object;
+    timeseries: object | null;
+    geojson: object | null;
+    source_hash: string;
+  };
+
+  return {
+    id: data.id,
+    detail: data.detail,
+    timeseries: data.timeseries,
+    geojson: data.geojson,
+    sourceHash: data.source_hash,
+  };
+}
diff --git a/scripts/dev_test.py b/scripts/dev_test.py
index 2ed6f01..dc5d236 100755
--- a/scripts/dev_test.py
+++ b/scripts/dev_test.py
@@ -18,6 +18,8 @@ URL:          http://localhost:4321
 """
 
 import argparse
+import platform
+import resource
 import shutil
 import subprocess
 import sys
@@ -163,6 +165,18 @@ def start_dev(mobile: bool = False) -> None:
 
 # ── main ──────────────────────────────────────────────────────────────────────
 
+def raise_open_file_limit() -> None:
+    # Astro's file watcher opens many handles; macOS defaults to 256, which
+    # causes EMFILE errors under a large project tree.
+    if platform.system() != "Darwin":
+        return
+    target = 65536
+    soft, hard = resource.getrlimit(resource.RLIMIT_NOFILE)
+    if soft < target:
+        resource.setrlimit(resource.RLIMIT_NOFILE, (min(target, hard), hard))
+        ok(f"open-file limit raised to {min(target, hard)}")
+
+
 def main() -> None:
     parser = argparse.ArgumentParser(description=__doc__,
                                      formatter_class=argparse.RawDescriptionHelpFormatter)
@@ -171,6 +185,8 @@ def main() -> None:
     parser.add_argument("--mobile", action="store_true", help="Bind API to 0.0.0.0 for local mobile testing")
     args = parser.parse_args()
 
+    raise_open_file_limit()
+
     print(f"\033[1mbincio dev test\033[0m  →  {DATA_DIR}")
 
     if args.fresh and DATA_DIR.exists():