dispatcher — window_size adaptatif + skip video courtes <8min

window_size selon len effectif (frame_count / stride):
  <= 320 -> 16/2   (petit overhead)
  <= 3000 -> 32/8
  > 3000 -> 64/16  (moins de windows sur longues sequences)

Skip auto si video_duration_s < COSMA_QC_MIN_VIDEO_S (default 480s = 8min):
  segments trop courts ne contiennent pas de plongee exploitable.
  Reco user: videos < 8 min sont inutiles pour la reconstruction.

scripts/dispatcher.py

@@ -349,6 +349,12 @@ def do_extract(job: sqlite3.Row, worker: dict) -> str:
     # Persist the measured video duration so the dashboard shows real length (segment_label
     # from ingest is only the timestamp of the first MP4 and lies when a segment spans multiple).
     set_status(job["id"], video_duration_s=total_duration_s)
+    # Skip segments that are too short to contain a meaningful dive.
+    min_video_s = int(os.environ.get("COSMA_QC_MIN_VIDEO_S", "480"))  # 8 min default
+    if total_duration_s < min_video_s:
+        print(f"  ↳ job #{job['id']}: video too short ({int(total_duration_s)}s < {min_video_s}s) — marking skipped")
+        set_status(job["id"], status="skipped", error=f"too short: {int(total_duration_s)}s of video")
+        raise RuntimeError("skipped_short")
     # Drop the hors-eau prefix AND suffix before reconstruction — AUV is out-of-water at both ends.
     head, tail, remaining = trim_above_water_prefix(worker, frames_dir)
     if head or tail:
@@ -382,12 +388,21 @@ def do_reconstruct(job: sqlite3.Row, worker: dict, frames_dir: str) -> tuple[str
     # demo.py starts a viser web server after saving the PLY and never exits.
     # Wrap it: launch in bg, wait for "PLY saved" marker in the log, kill, exit 0.
     # Match on the unique job frames_dir to identify our demo.py among all children/threads.
+    # Adapt window size to sequence length (lingbot-map README recommendation): bigger windows
+    # reduce overhead on long sequences. Effective frame count = frame_count / stride.
+    eff = frame_count // max(1, stride) if frame_count else 0
+    if eff > 3000:
+        window_size, overlap_size = 64, 16
+    elif eff > 320:
+        window_size, overlap_size = 32, 8
+    else:
+        window_size, overlap_size = 16, 2
     marker = shlex.quote(frames_dir)
     cmd = (
         f"cd {shlex.quote(worker['lingbot_path'])} && source .venv/bin/activate && "
         f"setsid python3 demo.py --model_path {shlex.quote(ckpt)} "
         f"--image_folder {shlex.quote(frames_dir)} --port {port} "
-        f"--stride {stride} --use_sdpa --mode windowed --window_size 16 --overlap_size 2 --offload_to_cpu "
+        f"--stride {stride} --use_sdpa --mode windowed --window_size {window_size} --overlap_size {overlap_size} --offload_to_cpu "
         f"--save_ply {shlex.quote(ply_path)} > {log} 2>&1 & "
         f"DEMO_PID=$!; "
         f"for i in $(seq 1 3600); do "