feat/#28 (#29)

Co-authored-by: Sayan Datta <sayan@Sayans-MacBook-Air.local>
Reviewed-on: #29

backend/api/routes_mobile_edge.py

@@ -610,26 +610,49 @@ async def session_heartbeat(
     pool = _pool(request)
     import json
     async with pool.acquire() as conn:
-        row = await conn.fetchrow(
+        existing_session_id = await conn.fetchval(
             """
-            INSERT INTO surface_sessions (tenant_id, user_id, surface_type, app_version, metadata)
-            VALUES ($1, $2, $3, $4, $5::jsonb)
-            ON CONFLICT DO NOTHING
-            RETURNING session_id
+            SELECT session_id
+            FROM surface_sessions
+            WHERE tenant_id=$1 AND user_id=$2 AND surface_type=$3
+              AND ended_at IS NULL
+              AND last_active_at > NOW() - INTERVAL '30 minutes'
+            ORDER BY last_active_at DESC
+            LIMIT 1
             """,
-            user.role, user.user_id, body.surface_type, body.app_version,
-            json.dumps(body.metadata),
+            user.role, user.user_id, body.surface_type,
         )
-        # Update last_active + screen_sequence for existing session (within 30 min)
-        if body.screen and row is None:
+
+        if existing_session_id:
             await conn.execute(
                 """
                 UPDATE surface_sessions
                 SET last_active_at=NOW(),
-                    screen_sequence = array_append(screen_sequence, $1)
-                WHERE tenant_id=$2 AND user_id=$3 AND surface_type=$4
-                  AND last_active_at > NOW() - INTERVAL '30 minutes'
+                    app_version=$1,
+                    metadata=$2::jsonb,
+                    screen_sequence = CASE
+                        WHEN $3::text IS NULL THEN screen_sequence
+                        ELSE array_append(screen_sequence, $3::text)
+                    END
+                WHERE session_id=$4
                 """,
-                body.screen, user.role, user.user_id, body.surface_type,
+                body.app_version, json.dumps(body.metadata), body.screen, existing_session_id,
+            )
+        else:
+            await conn.execute(
+                """
+                INSERT INTO surface_sessions (
+                    tenant_id, user_id, surface_type, app_version, metadata, screen_sequence
+                )
+                VALUES (
+                    $1, $2, $3, $4, $5::jsonb,
+                    CASE
+                        WHEN $6::text IS NULL THEN '{}'::text[]
+                        ELSE ARRAY[$6::text]
+                    END
+                )
+                """,
+                user.role, user.user_id, body.surface_type, body.app_version,
+                json.dumps(body.metadata), body.screen,
             )
     return {"status": "ok", "timestamp": _now()}