feat(l1): APScheduler hourly cleanup job for abandoned L1 sessions

flip_stale_sessions flips L1WalkSession.status from 'active' to
'abandoned' for rows where last_step_at is older than 24h. Preserves the
row for audit; removes it from the L1 dashboard's 'Resume in progress'
widget. Runs hourly via APScheduler with max_instances=1 (Lesson 1).
Uses the admin session factory (no RLS context at startup).

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

backend/app/main.py

@@ -221,6 +221,18 @@ async def lifespan(app: FastAPI):
         max_instances=1,
     )
 
+    # L1 walk session cleanup: flip stale active sessions to 'abandoned' (hourly)
+    from app.services.l1_session_cleanup import run_cleanup_job as l1_cleanup_run
+    scheduler.add_job(
+        l1_cleanup_run,
+        trigger="interval",
+        hours=1,
+        id="l1_session_cleanup",
+        replace_existing=True,
+        max_instances=1,
+        args=[async_session_maker],
+    )
+
     # Auto-seed trees in background on PR environments
     seed_task = None
     if settings.SEED_ON_DEPLOY:

backend/app/services/l1_session_cleanup.py

@@ -0,0 +1,49 @@
+"""Hourly cleanup job: flip stale active L1WalkSessions to 'abandoned'.
+
+Sessions with status='active' and last_step_at older than 24h are considered
+abandoned (L1 closed the browser, customer hung up, etc.). Flipping them
+removes them from the "Resume in progress" widget while preserving the row
+for audit/reporting.
+
+Run via APScheduler interval job, max_instances=1 (Lesson 1).
+"""
+import logging
+from datetime import datetime, timedelta, timezone
+
+from sqlalchemy import update
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.models.l1_walk_session import L1WalkSession
+
+
+logger = logging.getLogger(__name__)
+
+
+async def flip_stale_sessions(db: AsyncSession) -> int:
+    """Flip active sessions to 'abandoned' if last_step_at < now - 24h.
+
+    Returns the number of sessions flipped.
+    """
+    cutoff = datetime.now(timezone.utc) - timedelta(hours=24)
+    stmt = (
+        update(L1WalkSession)
+        .where(L1WalkSession.status == "active")
+        .where(L1WalkSession.last_step_at < cutoff)
+        .values(status="abandoned")
+    )
+    result = await db.execute(stmt)
+    await db.commit()
+    return result.rowcount or 0
+
+
+async def run_cleanup_job(session_factory) -> None:
+    """APScheduler entry point. Uses the admin session factory (no RLS context)."""
+    async with session_factory() as db:
+        try:
+            count = await flip_stale_sessions(db)
+            if count > 0:
+                logger.info(
+                    "l1_session_cleanup: flipped %d sessions to abandoned", count
+                )
+        except Exception:
+            logger.exception("l1_session_cleanup: error during run")