fix: GPS from SQLite framekms (confirmed live device schema)

odc-api.db confirmed present on device. framekms table has:
  latitude, longitude, altitude, hdop, satellites_used, time
NOT lat_deg/lon_deg/alt_m/num_satellites as previously assumed.
Redis fallback retained, supports both field naming conventions.
API response format unchanged (still returns lat_deg/lon_deg for Varroa compat).

adacam_api/redis_client.py

@@ -1,40 +1,87 @@
-"""Redis client for GPS and IMU data."""
+"""GPS data reader for adacam-api.
+Primary source: /data/recording/odc-api.db framekms table (confirmed schema from live device).
+Fallback: Redis (keys may appear when device has outdoor GPS fix post-liberation).
+
+Confirmed field names from live device:
+  latitude, longitude, altitude, hdop, satellites_used, speed, heading, time
+"""
 import json
-import redis
+import os
+import sqlite3
+import time
 
-_client = None
+ODC_DB = '/data/recording/odc-api.db'
+GNSS_REDIS_KEYS = ['GNSSFusion30Hz', 'GnssData', 'GnssPvt', 'GnssPosition']
+
+_redis_client = None
 
 
-def get_client():
-    """Get Redis connection."""
-    global _client
-    if _client is None:
-        _client = redis.Redis(host="localhost", port=6379, decode_responses=True)
-    return _client
+def _get_redis():
+    global _redis_client
+    try:
+        import redis
+        if _redis_client is None:
+            _redis_client = redis.Redis(host='localhost', port=6379, decode_responses=True)
+        _redis_client.ping()
+        return _redis_client
+    except Exception:
+        _redis_client = None
+        return None
 
 
 def get_latest_gnss():
-    """Get latest GPS fix from GNSSFusion30Hz ZSET."""
-    client = get_client()
-    try:
-        # Get the most recent entry (highest score = most recent timestamp)
-        results = client.zrevrange("GNSSFusion30Hz", 0, 0, withscores=True)
-        if results:
-            data = json.loads(results[0][0])
-            return {
-                "lat_deg": data.get("lat_deg"),
-                "lon_deg": data.get("lon_deg"),
-                "alt_m": data.get("alt_m"),
-                "unix_milliseconds": int(data.get("unix_milliseconds", 0)),
-                "hdop": data.get("hdop"),
-                "num_satellites": data.get("num_satellites", 0),
-            }
-    except (redis.RedisError, json.JSONDecodeError):
-        pass
+    """Get latest GPS fix. Returns dict with keys: lat_deg, lon_deg, alt_m, hdop, num_satellites.
+    Field names kept compatible with original API response format."""
+
+    # Primary: SQLite framekms (confirmed live device schema)
+    if os.path.exists(ODC_DB):
+        try:
+            conn = sqlite3.connect(ODC_DB)
+            row = conn.execute(
+                'SELECT latitude, longitude, altitude, hdop, satellites_used, time '
+                'FROM framekms WHERE latitude IS NOT NULL AND latitude != 0 '
+                'ORDER BY time DESC LIMIT 1'
+            ).fetchone()
+            conn.close()
+            if row:
+                return {
+                    'lat_deg': row[0],
+                    'lon_deg': row[1],
+                    'alt_m': row[2],
+                    'hdop': row[3],
+                    'num_satellites': row[4],
+                    'unix_milliseconds': int(row[5]) if row[5] else int(time.time() * 1000),
+                }
+        except Exception:
+            pass
+
+    # Fallback: Redis (may appear post-liberation with outdoor GPS fix)
+    r = _get_redis()
+    if r:
+        for key in GNSS_REDIS_KEYS:
+            try:
+                for getter in [lambda k: r.zrevrange(k, 0, 0), lambda k: [r.get(k)]]:
+                    items = getter(key)
+                    item = items[0] if items else None
+                    if item:
+                        data = json.loads(item)
+                        lat = data.get('latitude') or data.get('lat_deg')
+                        lon = data.get('longitude') or data.get('lon_deg')
+                        if lat and lon:
+                            return {
+                                'lat_deg': lat,
+                                'lon_deg': lon,
+                                'alt_m': data.get('altitude') or data.get('alt_m', 0),
+                                'hdop': data.get('hdop', 99),
+                                'num_satellites': data.get('satellites_used') or data.get('num_satellites', 0),
+                                'unix_milliseconds': int(data.get('unix_milliseconds', time.time() * 1000)),
+                            }
+            except Exception:
+                continue
     return None
 
 
 def has_gps_lock():
     """Check if we have a valid GPS lock."""
     gnss = get_latest_gnss()
-    return gnss is not None and gnss.get("num_satellites", 0) >= 4
+    return gnss is not None and gnss.get('num_satellites', 0) >= 4