dispatcher : fix spin loop quand pas de worker dispo (sleep 30s)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

scripts/dispatcher.py

@@ -293,12 +293,13 @@ def run_one_stitch(stitch: sqlite3.Row):
                           finished_at=_now_iso())
 
 
-def run_one(job: sqlite3.Row):
+def run_one(job: sqlite3.Row) -> bool:
+    """Returns True if a worker was picked and work started."""
     job_id = job["id"]
     estimated = estimate_vram_mib(job["frame_count"] or 400)
     worker = pick_worker(estimated)
     if not worker:
-        return
+        return False
     set_status(job_id, status="extracting", worker_host=worker["host"], started_at=_now_iso())
     try:
         frames_dir = do_extract(job, worker)
@@ -311,6 +312,7 @@ def run_one(job: sqlite3.Row):
         _maybe_create_per_auv_stitch(job_id)
     except Exception as e:
         set_status(job_id, status="error", error=str(e)[:2000], finished_at=_now_iso())
+    return True
 
 
 def pop_queued() -> sqlite3.Row | None:
@@ -333,7 +335,9 @@ def main():
         job = pop_queued()
         if job:
             print(f"→ job #{job['id']} ({job['auv']}/{job['gopro_serial']}/{job['segment_label']})")
-            run_one(job)
+            if not run_one(job):
+                print("  ↳ pas de worker dispo, retry dans 30s")
+                time.sleep(30)
             continue
         stitch = pop_queued_stitch()
         if stitch: