diff --git a/data/metadata/barrier_opening.csv b/data/metadata/barrier_opening.csv
index f1e2123..a83ae77 100644
--- a/data/metadata/barrier_opening.csv
+++ b/data/metadata/barrier_opening.csv
@@ -1,6 +1,7 @@
 machine_name,session_date,session_time,opening_s,trim_first_s,notes
-ETHOSCOPE_076,2025-07-15,16-03-10,52,0,hand-annotated 2025-07-15 batch
-ETHOSCOPE_076,2025-07-15,16-31-34,94,69,first ~66s misframed (arena partly out of frame)
-ETHOSCOPE_145,2025-07-15,16-03-27,42,0,hand-annotated 2025-07-15 batch
-ETHOSCOPE_145,2025-07-15,16-31-41,89,69,first ~60s misframed (arena partly out of frame)
-ETHOSCOPE_268,2025-07-15,16-32-05,75,0,hand-annotated 2025-07-15 batch
+ETHOSCOPE_076,2025-07-15,16-03-10,52.0,0,hand-annotated 2025-07-15 batch
+ETHOSCOPE_076,2025-07-15,16-31-34,94.0,69,first ~66s misframed (arena partly out of frame)
+ETHOSCOPE_145,2025-07-15,16-03-27,42.0,0,hand-annotated 2025-07-15 batch
+ETHOSCOPE_145,2025-07-15,16-31-41,89.0,69,first ~60s misframed (arena partly out of frame)
+ETHOSCOPE_268,2025-07-15,16-32-05,75.0,0,hand-annotated 2025-07-15 batch
+ETHOSCOPE_076,2024-10-21,11-07-54,346.8,0,
diff --git a/scripts/barrier_picker_app/Dockerfile b/scripts/barrier_picker_app/Dockerfile
new file mode 100644
index 0000000..35081fb
--- /dev/null
+++ b/scripts/barrier_picker_app/Dockerfile
@@ -0,0 +1,16 @@
+FROM python:3.12-slim
+
+WORKDIR /app
+
+# Reason: keep the image small — we only need pandas + fastapi + uvicorn.
+COPY requirements.txt .
+RUN pip install --no-cache-dir -r requirements.txt
+
+COPY app.py .
+COPY static/ ./static/
+
+ENV HOST=0.0.0.0 PORT=8000
+
+EXPOSE 8000
+
+CMD ["python", "app.py"]
diff --git a/scripts/barrier_picker_app/README.md b/scripts/barrier_picker_app/README.md
new file mode 100644
index 0000000..2b0614f
--- /dev/null
+++ b/scripts/barrier_picker_app/README.md
@@ -0,0 +1,70 @@
+# Cupido — web-based barrier-opening picker
+
+A small FastAPI + HTML5-video app for annotating the barrier-opening
+moment in each tracked recording. Lives in its own Docker container so
+it can run on the lab server without polluting any existing
+environment.
+
+## What it does
+
+For every video referenced by `all_video_info_merged.tsv` that has a
+tracking DB on disk and isn't yet in `barrier_opening.csv`, it serves
+a `<video>` element pre-loaded with that mp4. The analyst plays /
+scrubs / pauses at the moment the barrier opens, then clicks one of:
+
+| button | meaning | written to `bad_rois` |
+|---|---|---|
+| **All barriers open** | every ROI (1..6) is usable post-opening | _empty_ |
+| **Upper barriers open** | only the top row opens (ROIs 1, 3, 5) | `2,4,6` |
+| **Lower barriers open** | only the bottom row opens (ROIs 2, 4, 6) | `1,3,5` |
+
+Plus a **Skip** (advance without saving) and **Unusable** (write
+`opening_s = NaN`).
+
+## Keyboard shortcuts
+
+- <kbd>Space</kbd> — play / pause
+- <kbd>←</kbd> / <kbd>→</kbd> — ±5 s
+- <kbd>Shift</kbd>+arrows — ±1 s
+- <kbd>Ctrl</kbd>+arrows — ±0.1 s
+- <kbd>,</kbd> / <kbd>.</kbd> — ±1 frame
+- <kbd>1</kbd> / <kbd>2</kbd> / <kbd>3</kbd> — All / Upper / Lower
+- <kbd>s</kbd> — skip ; <kbd>u</kbd> — unusable
+
+## Run locally (docker compose)
+
+```bash
+cd scripts/barrier_picker_app
+docker compose up --build
+```
+
+Then browse to http://localhost:8000/.
+
+The container mounts:
+- `/mnt/data/projects/cupido` (data volume, read-only)
+- `/mnt/ethoscope_data/videos` (source mp4s, read-only)
+- `data/metadata/` from the repo (read-write — for persisting
+  `barrier_opening.csv`)
+
+Adjust paths in `docker-compose.yml` if your layout differs.
+
+## Run without Docker (development)
+
+```bash
+cd scripts/barrier_picker_app
+pip install -r requirements.txt
+python app.py     # serves on http://localhost:8000
+```
+
+By default it expects:
+- merged TSV at `/mnt/data/projects/cupido/all_video_info_merged.tsv`
+- inventory at `/cupido/data/metadata/video_inventory.csv`
+- writes to `/cupido/data/metadata/barrier_opening.csv`
+
+Override via environment variables:
+```bash
+CUPIDO_DATA_VOLUME=/path/to/data \
+CUPIDO_INVENTORY_CSV=$(pwd)/../../data/metadata/video_inventory.csv \
+CUPIDO_OUTPUT_CSV=$(pwd)/../../data/metadata/barrier_opening.csv \
+python app.py
+```
diff --git a/scripts/barrier_picker_app/app.py b/scripts/barrier_picker_app/app.py
new file mode 100644
index 0000000..708af7d
--- /dev/null
+++ b/scripts/barrier_picker_app/app.py
@@ -0,0 +1,280 @@
+"""FastAPI server for the web-based barrier-opening picker.
+
+Browse to http://<host>:8000/ and you'll see a video player loaded with
+the next un-annotated video from the queue. Use the arrow keys to
+scrub (←/→ ±5 s, Shift+←/→ ±1 s, Ctrl+←/→ ±0.1 s), space to pause/play,
+or click the seekbar. When the barrier opens, click one of:
+
+    [All barriers open]    every ROI is usable post-opening
+    [Upper barriers open]  only ROIs 1,3,5 are usable
+    [Lower barriers open]  only ROIs 2,4,6 are usable
+
+The current playhead time is recorded as the barrier-opening moment;
+ROI inclusion is set accordingly. There is also a Skip and a Mark
+unusable button.
+
+The queue is built from the merged TSV plus the inventory: every
+unique (machine, date, time) that has both a tracking DB and an mp4
+on disk and is not yet in barrier_opening.csv. Submissions persist
+to barrier_opening.csv after every click — refresh-safe.
+
+Configuration (environment variables):
+    CUPIDO_DATA_VOLUME    /mnt/data/projects/cupido           (data volume)
+    CUPIDO_INVENTORY_CSV  /cupido/data/metadata/video_inventory.csv
+    CUPIDO_OUTPUT_CSV     /cupido/data/metadata/barrier_opening.csv
+"""
+
+from __future__ import annotations
+
+import os
+import re
+from dataclasses import dataclass
+from pathlib import Path
+
+import pandas as pd
+from fastapi import FastAPI, HTTPException, Request
+from fastapi.responses import FileResponse, HTMLResponse, JSONResponse, Response
+from fastapi.staticfiles import StaticFiles
+from pydantic import BaseModel
+
+# ─── Config ──────────────────────────────────────────────────────────────
+DATA_VOLUME = Path(os.environ.get("CUPIDO_DATA_VOLUME", "/mnt/data/projects/cupido"))
+INVENTORY_CSV = Path(os.environ.get(
+    "CUPIDO_INVENTORY_CSV", "/cupido/data/metadata/video_inventory.csv"
+))
+OUTPUT_CSV = Path(os.environ.get(
+    "CUPIDO_OUTPUT_CSV", "/cupido/data/metadata/barrier_opening.csv"
+))
+TSV_PATH = DATA_VOLUME / "all_video_info_merged.tsv"
+
+# Reason: the (date, time, machine_uuid) prefix encoded in every tracking
+# DB filename and every inventory mp4 filename.
+DB_NAME_RE = re.compile(
+    r"^(\d{4}-\d{2}-\d{2})_(\d{2}-\d{2}-\d{2})_([0-9a-f]{32})__"
+)
+
+OUT_COLS = ["machine_name", "session_date", "session_time",
+            "opening_s", "trim_first_s", "bad_rois", "notes"]
+
+# ROI numbering in the HD mating arena (verified via tracking_geometry):
+#   upper row = ROIs 1, 3, 5    (y ≈ 0.125)
+#   lower row = ROIs 2, 4, 6    (y ≈ 0.795)
+ROIS_UPPER = "1,3,5"
+ROIS_LOWER = "2,4,6"
+
+
+@dataclass(frozen=True)
+class QueueItem:
+    idx: int
+    machine_name: str
+    session_date: str
+    session_time: str
+    mp4_path: str
+    duration_s: float | None
+    done: bool
+
+
+# ─── Queue building ─────────────────────────────────────────────────────
+def _build_queue() -> list[QueueItem]:
+    """Build the ordered queue of pickable videos."""
+    if not TSV_PATH.exists():
+        raise RuntimeError(f"merged TSV not found at {TSV_PATH}")
+    if not INVENTORY_CSV.exists():
+        raise RuntimeError(f"inventory not found at {INVENTORY_CSV}")
+    tsv = pd.read_csv(TSV_PATH, sep="\t")
+    inv = pd.read_csv(INVENTORY_CSV)
+
+    inv_by_key: dict[tuple[str, str, str], dict] = {}
+    for r in inv.itertuples(index=False):
+        inv_by_key[(r.machine_name, r.session_date, r.session_time)] = {
+            "mp4_path": r.mp4_path,
+            "duration_s": float(r.duration_s) if pd.notna(r.duration_s) else None,
+        }
+
+    if OUTPUT_CSV.exists():
+        out = pd.read_csv(OUTPUT_CSV)
+        done_keys = set(zip(out["machine_name"],
+                            out["session_date"],
+                            out["session_time"]))
+    else:
+        done_keys = set()
+
+    seen: set[tuple[str, str, str]] = set()
+    items: list[QueueItem] = []
+    for col in ("training_db_path", "testing_db_path"):
+        for row in tsv.itertuples(index=False):
+            db = getattr(row, col)
+            if not isinstance(db, str) or not db:
+                continue
+            db_path = Path(db)
+            if not db_path.exists():
+                continue
+            m = DB_NAME_RE.match(db_path.name)
+            if not m:
+                continue
+            session_date, session_time = m.group(1), m.group(2)
+            key = (row.machine_name, session_date, session_time)
+            if key in seen:
+                continue
+            seen.add(key)
+            inv_row = inv_by_key.get(key)
+            if inv_row is None or not Path(inv_row["mp4_path"]).exists():
+                continue
+            items.append(QueueItem(
+                idx=len(items),
+                machine_name=row.machine_name,
+                session_date=session_date,
+                session_time=session_time,
+                mp4_path=inv_row["mp4_path"],
+                duration_s=inv_row["duration_s"],
+                done=key in done_keys,
+            ))
+    return items
+
+
+# ─── App ───────────────────────────────────────────────────────────────
+app = FastAPI(title="Cupido barrier-opening picker")
+
+STATIC_DIR = Path(__file__).parent / "static"
+app.mount("/static", StaticFiles(directory=STATIC_DIR), name="static")
+
+
+@app.get("/")
+async def index() -> FileResponse:
+    return FileResponse(STATIC_DIR / "index.html")
+
+
+@app.get("/api/queue")
+async def get_queue() -> JSONResponse:
+    queue = _build_queue()
+    return JSONResponse([
+        {
+            "idx": q.idx,
+            "machine_name": q.machine_name,
+            "session_date": q.session_date,
+            "session_time": q.session_time,
+            "duration_s": q.duration_s,
+            "done": q.done,
+        }
+        for q in queue
+    ])
+
+
+def _stream_video(file_path: Path, request: Request) -> Response:
+    """HTTP Range-aware video streaming."""
+    file_size = file_path.stat().st_size
+    range_header = request.headers.get("range")
+    if range_header is None:
+        return FileResponse(file_path, media_type="video/mp4",
+                            headers={"Accept-Ranges": "bytes"})
+    # Parse "bytes=START-END" (END optional)
+    m = re.match(r"bytes=(\d+)-(\d*)", range_header)
+    if not m:
+        raise HTTPException(status_code=416, detail="bad Range header")
+    start = int(m.group(1))
+    end = int(m.group(2)) if m.group(2) else file_size - 1
+    end = min(end, file_size - 1)
+    if start > end:
+        raise HTTPException(status_code=416, detail="range not satisfiable")
+    chunk_size = end - start + 1
+
+    def iterfile():
+        with open(file_path, "rb") as f:
+            f.seek(start)
+            remaining = chunk_size
+            while remaining > 0:
+                buf = f.read(min(64 * 1024, remaining))
+                if not buf:
+                    break
+                yield buf
+                remaining -= len(buf)
+
+    return Response(
+        content=b"".join(iterfile()),
+        status_code=206,
+        media_type="video/mp4",
+        headers={
+            "Content-Range": f"bytes {start}-{end}/{file_size}",
+            "Accept-Ranges": "bytes",
+            "Content-Length": str(chunk_size),
+        },
+    )
+
+
+@app.get("/api/video/{idx}")
+async def get_video(idx: int, request: Request) -> Response:
+    queue = _build_queue()
+    if not 0 <= idx < len(queue):
+        raise HTTPException(status_code=404, detail="idx out of range")
+    return _stream_video(Path(queue[idx].mp4_path), request)
+
+
+class Submission(BaseModel):
+    idx: int
+    time_s: float | None  # None when marking unusable
+    mode: str             # "all" | "upper" | "lower" | "unusable" | "skip"
+    notes: str = ""
+
+
+@app.post("/api/submit")
+async def submit(payload: Submission) -> dict:
+    queue = _build_queue()
+    if not 0 <= payload.idx < len(queue):
+        raise HTTPException(status_code=404, detail="idx out of range")
+    item = queue[payload.idx]
+
+    if payload.mode == "skip":
+        return {"status": "skipped"}
+
+    if payload.mode == "unusable":
+        row = {
+            "machine_name": item.machine_name,
+            "session_date": item.session_date,
+            "session_time": item.session_time,
+            "opening_s": float("nan"),
+            "trim_first_s": 0,
+            "bad_rois": "",
+            "notes": payload.notes or "unusable",
+        }
+    else:
+        if payload.time_s is None:
+            raise HTTPException(status_code=400, detail="time_s required")
+        bad_rois = {
+            "all": "",
+            "upper": ROIS_LOWER,   # upper-only opens → lower row is bad
+            "lower": ROIS_UPPER,   # lower-only opens → upper row is bad
+        }.get(payload.mode)
+        if bad_rois is None:
+            raise HTTPException(status_code=400, detail=f"unknown mode: {payload.mode}")
+        row = {
+            "machine_name": item.machine_name,
+            "session_date": item.session_date,
+            "session_time": item.session_time,
+            "opening_s": round(payload.time_s, 1),
+            "trim_first_s": 0,
+            "bad_rois": bad_rois,
+            "notes": payload.notes,
+        }
+
+    OUTPUT_CSV.parent.mkdir(parents=True, exist_ok=True)
+    if OUTPUT_CSV.exists():
+        out = pd.read_csv(OUTPUT_CSV)
+    else:
+        out = pd.DataFrame(columns=OUT_COLS)
+    for col in OUT_COLS:
+        if col not in out.columns:
+            out[col] = ""
+    # Replace any existing row for this key.
+    mask = ~((out["machine_name"] == row["machine_name"])
+             & (out["session_date"] == row["session_date"])
+             & (out["session_time"] == row["session_time"]))
+    out = pd.concat([out[mask], pd.DataFrame([row])], ignore_index=True)
+    out[OUT_COLS].to_csv(OUTPUT_CSV, index=False)
+    return {"status": "saved", "row": row}
+
+
+if __name__ == "__main__":
+    import uvicorn
+    host = os.environ.get("HOST", "0.0.0.0")
+    port = int(os.environ.get("PORT", "8000"))
+    uvicorn.run("app:app", host=host, port=port, reload=False)
diff --git a/scripts/barrier_picker_app/docker-compose.yml b/scripts/barrier_picker_app/docker-compose.yml
new file mode 100644
index 0000000..9c9a241
--- /dev/null
+++ b/scripts/barrier_picker_app/docker-compose.yml
@@ -0,0 +1,21 @@
+services:
+  picker:
+    build: .
+    image: cupido-barrier-picker
+    container_name: cupido-barrier-picker
+    ports:
+      - "8000:8000"
+    volumes:
+      # Project data volume (videos + tracking DBs + merged TSV) — read-only.
+      - /mnt/data/projects/cupido:/mnt/data/projects/cupido:ro
+      # Source video tree — mount at the same path the inventory references
+      # (so the mp4_path strings in video_inventory.csv resolve unchanged).
+      - /mnt/ethoscope_data/videos:/mnt/ethoscope_data/videos:ro
+      # Repo's data/metadata folder — mount read-write so the app can persist
+      # barrier_opening.csv. Adjust the host path to your local checkout.
+      - ../../data/metadata:/cupido/data/metadata:rw
+    environment:
+      CUPIDO_DATA_VOLUME: /mnt/data/projects/cupido
+      CUPIDO_INVENTORY_CSV: /cupido/data/metadata/video_inventory.csv
+      CUPIDO_OUTPUT_CSV: /cupido/data/metadata/barrier_opening.csv
+    restart: unless-stopped
diff --git a/scripts/barrier_picker_app/requirements.txt b/scripts/barrier_picker_app/requirements.txt
new file mode 100644
index 0000000..01de60d
--- /dev/null
+++ b/scripts/barrier_picker_app/requirements.txt
@@ -0,0 +1,4 @@
+fastapi>=0.110
+uvicorn[standard]>=0.27
+pandas>=2.0
+pydantic>=2.0
diff --git a/scripts/barrier_picker_app/static/index.html b/scripts/barrier_picker_app/static/index.html
new file mode 100644
index 0000000..a427335
--- /dev/null
+++ b/scripts/barrier_picker_app/static/index.html
@@ -0,0 +1,214 @@
+<!DOCTYPE html>
+<html lang="en">
+<head>
+  <meta charset="UTF-8" />
+  <title>Cupido — barrier-opening picker</title>
+  <style>
+    * { box-sizing: border-box; }
+    body { margin: 0; font-family: -apple-system, "Segoe UI", system-ui, sans-serif;
+           background: #1a1a1a; color: #e8e8e8; }
+    header { padding: 0.6rem 1rem; background: #111; border-bottom: 1px solid #333;
+             display: flex; align-items: center; gap: 1.5rem; }
+    h1 { margin: 0; font-size: 1rem; font-weight: 500; color: #ccc; }
+    #status { font-family: ui-monospace, "SF Mono", monospace; font-size: 0.85rem;
+              color: #9aa; }
+    #info { font-family: ui-monospace, monospace; font-size: 0.85rem; color: #cce; }
+    main { display: flex; flex-direction: column; align-items: center; padding: 1rem; }
+    video { width: 100%; max-width: 1400px; height: auto; background: #000;
+            border-radius: 4px; }
+    #controls { margin-top: 1rem; display: flex; gap: 1rem; flex-wrap: wrap;
+                justify-content: center; }
+    button { padding: 0.7rem 1.4rem; font-size: 0.95rem; border: 1px solid #444;
+             background: #2a2a2a; color: #eee; border-radius: 4px; cursor: pointer;
+             transition: all 80ms; }
+    button:hover { background: #383838; border-color: #666; }
+    button:active { transform: translateY(1px); }
+    button.primary { background: #2d5; color: #053; border-color: #1a4;
+                     font-weight: 600; }
+    button.primary:hover { background: #3e6; }
+    button.warn { background: #d84; color: #311; border-color: #b62; }
+    button.warn:hover { background: #ea5; }
+    button.muted { background: #2a2a2a; color: #888; }
+    .mute-divider { width: 1px; background: #333; margin: 0 0.3rem; }
+    #help { margin-top: 1rem; font-size: 0.8rem; color: #889; text-align: center;
+            font-family: ui-monospace, monospace; }
+    kbd { background: #222; border: 1px solid #444; border-radius: 3px;
+          padding: 0.1rem 0.4rem; font-size: 0.8rem; color: #ddd;
+          font-family: ui-monospace, monospace; }
+    #progress { font-size: 0.85rem; color: #889; margin-left: auto; }
+    #flash { position: fixed; top: 0.5rem; right: 0.5rem; padding: 0.5rem 1rem;
+             border-radius: 4px; opacity: 0; transition: opacity 200ms;
+             font-family: ui-monospace, monospace; font-size: 0.85rem; }
+    #flash.show { opacity: 1; }
+    #flash.ok { background: #2d5; color: #042; }
+    #flash.err { background: #d44; color: white; }
+  </style>
+</head>
+<body>
+  <header>
+    <h1>Cupido — barrier picker</h1>
+    <span id="info">loading…</span>
+    <span id="progress"></span>
+  </header>
+
+  <main>
+    <video id="player" controls preload="auto"></video>
+    <div id="controls">
+      <button class="primary" data-mode="all">All barriers open <kbd>1</kbd></button>
+      <button class="primary" data-mode="upper">Upper barrier opens <kbd>2</kbd></button>
+      <button class="primary" data-mode="lower">Lower barrier opens <kbd>3</kbd></button>
+      <span class="mute-divider"></span>
+      <button class="muted" data-mode="skip">Skip <kbd>s</kbd></button>
+      <button class="warn" data-mode="unusable">Unusable <kbd>u</kbd></button>
+      <span class="mute-divider"></span>
+      <button class="muted" id="prev">◀ Previous</button>
+      <button class="muted" id="next">Next ▶</button>
+    </div>
+    <div id="help">
+      <kbd>Space</kbd> play/pause &nbsp;·&nbsp;
+      <kbd>←</kbd> / <kbd>→</kbd> ±5 s &nbsp;·&nbsp;
+      <kbd>Shift</kbd>+arrows ±1 s &nbsp;·&nbsp;
+      <kbd>Ctrl</kbd>+arrows ±0.1 s &nbsp;·&nbsp;
+      <kbd>,</kbd> / <kbd>.</kbd> ±1 frame
+    </div>
+    <div id="flash"></div>
+  </main>
+
+  <script>
+    const player = document.getElementById('player');
+    const info   = document.getElementById('info');
+    const progress = document.getElementById('progress');
+    const flash  = document.getElementById('flash');
+
+    let queue = [];
+    let cursor = 0;
+
+    function showFlash(msg, kind = 'ok') {
+      flash.textContent = msg;
+      flash.className = 'show ' + kind;
+      setTimeout(() => { flash.className = ''; }, 1800);
+    }
+
+    function updateProgress() {
+      const done = queue.filter(q => q.done).length;
+      progress.textContent = `${done}/${queue.length} done`;
+    }
+
+    function loadCursor() {
+      if (queue.length === 0) {
+        info.textContent = 'queue empty';
+        return;
+      }
+      cursor = ((cursor % queue.length) + queue.length) % queue.length;
+      const item = queue[cursor];
+      info.textContent =
+        `[${cursor + 1}/${queue.length}] ${item.machine_name} ${item.session_date} ${item.session_time} ` +
+        (item.duration_s ? `(${(item.duration_s/60).toFixed(1)} min)` : '') +
+        (item.done ? ' — already done' : '');
+      player.src = `/api/video/${item.idx}`;
+      player.load();
+    }
+
+    async function fetchQueue() {
+      const resp = await fetch('/api/queue');
+      queue = await resp.json();
+      // Jump to first not-yet-done
+      const firstUndone = queue.findIndex(q => !q.done);
+      cursor = firstUndone === -1 ? 0 : firstUndone;
+      updateProgress();
+      loadCursor();
+    }
+
+    async function submit(mode) {
+      if (queue.length === 0) return;
+      const item = queue[cursor];
+      const payload = {
+        idx: item.idx,
+        time_s: (mode === 'skip' || mode === 'unusable') ? null : player.currentTime,
+        mode: mode,
+        notes: '',
+      };
+      try {
+        const resp = await fetch('/api/submit', {
+          method: 'POST',
+          headers: { 'Content-Type': 'application/json' },
+          body: JSON.stringify(payload),
+        });
+        if (!resp.ok) {
+          const err = await resp.json();
+          showFlash('error: ' + (err.detail || resp.status), 'err');
+          return;
+        }
+        const result = await resp.json();
+        if (result.status === 'saved') {
+          item.done = true;
+          updateProgress();
+          const t = result.row.opening_s;
+          const bad = result.row.bad_rois;
+          showFlash(
+            `saved ${item.machine_name} ${item.session_date} ${item.session_time}: ` +
+            (Number.isNaN(t) || t === null ? 'unusable' :
+              `${t.toFixed(1)}s${bad ? ' (bad ROIs: ' + bad + ')' : ''}`)
+          );
+        } else if (result.status === 'skipped') {
+          showFlash(`skipped ${item.machine_name} ${item.session_date} ${item.session_time}`);
+        }
+        cursor = (cursor + 1) % queue.length;
+        loadCursor();
+      } catch (e) {
+        showFlash('network error: ' + e.message, 'err');
+      }
+    }
+
+    // Button handlers
+    document.querySelectorAll('button[data-mode]').forEach(btn => {
+      btn.addEventListener('click', () => submit(btn.dataset.mode));
+    });
+    document.getElementById('prev').addEventListener('click', () => {
+      cursor = (cursor - 1 + queue.length) % queue.length;
+      loadCursor();
+    });
+    document.getElementById('next').addEventListener('click', () => {
+      cursor = (cursor + 1) % queue.length;
+      loadCursor();
+    });
+
+    // Keyboard shortcuts
+    document.addEventListener('keydown', (e) => {
+      if (e.target.tagName === 'INPUT' || e.target.tagName === 'TEXTAREA') return;
+      // Prevent the browser default (e.g. video focus side effects on space).
+      const stop = () => { e.preventDefault(); e.stopPropagation(); };
+      switch (e.key) {
+        case ' ':
+          stop();
+          if (player.paused) player.play(); else player.pause();
+          break;
+        case 'ArrowLeft':
+          stop();
+          player.currentTime -= e.ctrlKey ? 0.1 : (e.shiftKey ? 1 : 5);
+          break;
+        case 'ArrowRight':
+          stop();
+          player.currentTime += e.ctrlKey ? 0.1 : (e.shiftKey ? 1 : 5);
+          break;
+        case ',':
+          stop();
+          // Step back one frame (assume 25 fps if unknown)
+          player.currentTime -= 1 / 25;
+          break;
+        case '.':
+          stop();
+          player.currentTime += 1 / 25;
+          break;
+        case '1': stop(); submit('all'); break;
+        case '2': stop(); submit('upper'); break;
+        case '3': stop(); submit('lower'); break;
+        case 's': stop(); submit('skip'); break;
+        case 'u': stop(); submit('unusable'); break;
+      }
+    });
+
+    fetchQueue();
+  </script>
+</body>
+</html>