From 17711d829e9be98fe7426d35083e8a02bbce582c Mon Sep 17 00:00:00 2001
From: digital-garbage <133010426+digital-garbage@users.noreply.github.com>
Date: Thu, 11 Jun 2026 19:16:30 +0300
Subject: [PATCH] Fix fast scrub preview and multi-select plain concat export.

Coalesce playhead seeks during drag so rapid scrubbing stays stable, and
route multi-select export through trim-only hard-cut concat instead of Render Final.
---
 movie_editor/frontend/api.js      |   2 +
 movie_editor/frontend/player.js   | 190 +++++++++++++++++++++++++++---
 movie_editor/frontend/store.js    |  45 ++++---
 movie_editor/frontend/timeline.js |  11 +-
 movie_editor/server.py            | 103 ++++++++++++++++
 5 files changed, 317 insertions(+), 34 deletions(-)

diff --git a/movie_editor/frontend/api.js b/movie_editor/frontend/api.js
index 482fbfdb..79333382 100644
--- a/movie_editor/frontend/api.js
+++ b/movie_editor/frontend/api.js
@@ -113,6 +113,8 @@
     renderFinal: (id, clips) => j("POST", API(`/projects/${id}/render`), { clips }),
     renderFinalStatus: (id, jobId) => j("GET", API(`/projects/${id}/render/${encodeURIComponent(jobId)}`)),
     exportClip: (id, clip) => j("POST", API(`/projects/${id}/export-clip`), { clip }),
+    exportClipsCombined: (id, clips) => j("POST", API(`/projects/${id}/export-clips`), { clips }),
+    exportClipsStatus: (id, jobId) => j("GET", API(`/projects/${id}/export-clips/${encodeURIComponent(jobId)}`)),
     resultUrl: (id, m) =>
       API(`/projects/${id}/result?filename=${encodeURIComponent(m.filename)}`) +
       `&subfolder=${encodeURIComponent(m.subfolder || "")}&type=${encodeURIComponent(m.type || "output")}`,
diff --git a/movie_editor/frontend/player.js b/movie_editor/frontend/player.js
index e612a7cc..ad8ac59c 100644
--- a/movie_editor/frontend/player.js
+++ b/movie_editor/frontend/player.js
@@ -20,6 +20,14 @@
   let _active = null;        // visible <video>
   let _seekPending = null;   // offset to apply once the active video has metadata
   let _playPending = false;
+  let _seekRaf = null;       // coalesce rapid scrub seeks to one per frame
+  let _pendingSeekSec = null;
+  let _videoSeekTimer = null;
+  let _pendingVideoTarget = null;
+  let _pendingFxClip = null;
+  let _pendingFxOffset = 0;
+  let _seekToken = 0;
+  let _scrubDepth = 0;       // suppress render()-driven re-seek while dragging playhead
   const _insPool = new Map(); // track id -> <audio>
   let _insTracks = [];
 
@@ -42,6 +50,47 @@
   const _clipUrl = (clip) => clip.binUrl || (clip.media ? _urlFor(clip.media) : "");
   const _clampT = (v, t) => Math.max(0, Math.min(t, (v.duration || (t + 1)) - 0.02));
 
+  function _applyVideoTime(v, target, fast) {
+    const t = _clampT(v, target);
+    try {
+      if (fast && typeof v.fastSeek === "function") v.fastSeek(t);
+      else v.currentTime = t;
+    } catch (_) {
+      try { v.currentTime = t; } catch (_) {}
+    }
+  }
+
+  function _flushVideoSeek(force) {
+    if (_videoSeekTimer) {
+      clearTimeout(_videoSeekTimer);
+      _videoSeekTimer = null;
+    }
+    if (_pendingVideoTarget == null || !_active || !_pendingFxClip) return;
+    const v = _active;
+    const target = _pendingVideoTarget;
+    const clip = _pendingFxClip;
+    const offset = _pendingFxOffset;
+    _pendingVideoTarget = null;
+    _pendingFxClip = null;
+    _pendingFxOffset = 0;
+    const token = ++_seekToken;
+    if (v.readyState >= 1) {
+      _applyVideoTime(v, target, force !== true && !_playing);
+      if (token === _seekToken) _applyFx(clip, offset);
+    } else {
+      v._pmSeekPending = target;
+      _seekPending = target;
+    }
+  }
+
+  function _scheduleVideoSeek(target, clip, offset) {
+    _pendingVideoTarget = target;
+    _pendingFxClip = clip;
+    _pendingFxOffset = offset;
+    if (_videoSeekTimer) return;
+    _videoSeekTimer = setTimeout(() => _flushVideoSeek(false), _playing ? 0 : 24);
+  }
+
   function _segmentSourceBadge(sceneId) {
     if (!sceneId) return "";
     const sc = S.scene(sceneId);
@@ -284,9 +333,19 @@
     zoom.append(v);
     viewport.append(zoom);
     v.addEventListener("loadedmetadata", () => {
+      const pending = v._pmSeekPending != null ? v._pmSeekPending : (v === _active ? _seekPending : null);
+      if (pending != null) {
+        _applyVideoTime(v, pending, !_playing);
+        v._pmSeekPending = null;
+        if (v === _active) _seekPending = null;
+      }
       if (v !== _active) return;
-      if (_seekPending != null) { v.currentTime = _clampT(v, _seekPending); _seekPending = null; }
       if (_playPending) { _playPending = false; v.play().catch(() => {}); }
+      if (_currentClip) _applyFx(_currentClip, Math.max(0, _phSec - _currentClip.startSec));
+    });
+    v.addEventListener("seeked", () => {
+      if (v !== _active || !_currentClip || _playing) return;
+      _applyFx(_currentClip, Math.max(0, _phSec - _currentClip.startSec));
     });
     v.addEventListener("ended", () => { if (v === _active) _advance(); });
     stage.append(viewport); pool.set(url, v);
@@ -312,6 +371,10 @@
       v._pmFx?.viewport.remove();
     }
     pool.clear(); _active = null; _currentClip = null; _seekPending = null; _playPending = false;
+    _pendingSeekSec = null;
+    _scrubDepth = 0;
+    if (_seekRaf) { cancelAnimationFrame(_seekRaf); _seekRaf = null; }
+    _flushVideoSeek(true);
     _pauseInsAudio();
     for (const a of _insPool.values()) a.removeAttribute("src");
     _insPool.clear();
@@ -330,6 +393,11 @@
     if (v) {
       v.classList.add("active");
       v._pmFx?.viewport.classList.add("active");
+      if (v._pmSeekPending != null && v.readyState >= 1) {
+        _applyVideoTime(v, v._pmSeekPending, !_playing);
+        v._pmSeekPending = null;
+        _seekPending = null;
+      }
     }
   }
 
@@ -386,6 +454,26 @@
     if (v.volume !== nv) { try { v.volume = nv; } catch (_) {} }
   }
 
+  function _applyClipUi(clip) {
+    if (!clip || clip.pending) {
+      _showBadge("");
+      _showSlate(clip?.slate || "Not generated yet", clip?.slateSub);
+      return;
+    }
+    _showSlate("");
+    const badge = clip.ghost ? (clip.slate || "Removed — preview only")
+      : _segmentSourceBadge(clip.sceneId);
+    _showBadge(badge);
+    if (_badgeEl && badge.startsWith("Mixed")) _badgeEl.classList.add("mixed-mode");
+    else if (_badgeEl) _badgeEl.classList.remove("mixed-mode");
+  }
+
+  function _sameVideoUrl(a, b) {
+    if (!a || !b) return false;
+    const ua = _clipUrl(a), ub = _clipUrl(b);
+    return !!ua && ua === ub;
+  }
+
   // Show `clip` at `offset` seconds into the clip; play if requested. Seeks to the clip's
   // in-point + offset within the (preloaded) source video.
   function _goto(clip, offset, play) {
@@ -393,26 +481,24 @@
     if (clip.pending) {
       _currentClip = clip;
       _setActive(null);
-      _showBadge("");
-      _showSlate(clip.slate || "Not generated yet", clip.slateSub);
+      _applyClipUi(clip);
       if (play) _startTick();
       return;
     }
     if (!clip.media && !clip.binUrl) return;
     const v = _ensureVideo(_clipUrl(clip));
     _currentClip = clip; _setActive(v);
-    _showSlate("");
-    const badge = clip.ghost ? (clip.slate || "Removed — preview only")
-      : _segmentSourceBadge(clip.sceneId);
-    _showBadge(badge);
-    if (_badgeEl && badge.startsWith("Mixed")) _badgeEl.classList.add("mixed-mode");
-    else if (_badgeEl) _badgeEl.classList.remove("mixed-mode");
+    _applyClipUi(clip);
     const target = (clip.inSec || 0) + Math.max(0, offset);
     if (v.readyState >= 1) {
-      v.currentTime = _clampT(v, target);
+      _applyVideoTime(v, target, !play);
+      v._pmSeekPending = null;
+      _seekPending = null;
       if (play) { v.play().catch(() => {}); _startTick(); } else _playPending = false;
     } else {
-      _seekPending = target; _playPending = !!play;
+      v._pmSeekPending = target;
+      _seekPending = target;
+      _playPending = !!play;
       if (play) _startTick();
     }
     _applyFx(clip, Math.max(0, offset));
@@ -467,15 +553,73 @@
   }
 
   // ── transport actions ──────────────────────────────────────────────────────
-  function _seek(sec) {
+  function _seekNow(sec) {
     _phSec = Math.max(0, sec);
     const clip = _clipAt(_phSec);
-    if (clip) _goto(clip, _phSec - clip.startSec, false);
-    else { _currentClip = null; _setActive(null); _showSlate(""); _showBadge(""); }
+    if (!clip) {
+      _flushVideoSeek(true);
+      _currentClip = null;
+      _setActive(null);
+      _showSlate("");
+      _showBadge("");
+      _syncInsAudio();
+      _notifyPh();
+      return;
+    }
+    const offset = _phSec - clip.startSec;
+    const sameClip = _currentClip === clip
+      || (_currentClip && clip && _currentClip.sceneId === clip.sceneId && _sameVideoUrl(_currentClip, clip));
+    const sameVideo = !clip.pending && _active && _sameVideoUrl(_currentClip, clip)
+      && (clip.media || clip.binUrl);
+    if (sameVideo && _active.readyState >= 1) {
+      _currentClip = clip;
+      _applyClipUi(clip);
+      const target = (clip.inSec || 0) + Math.max(0, offset);
+      _scheduleVideoSeek(target, clip, offset);
+    } else if (!sameClip || clip.pending) {
+      _flushVideoSeek(true);
+      _goto(clip, offset, false);
+    } else if (!clip.pending && (clip.media || clip.binUrl)) {
+      const target = (clip.inSec || 0) + Math.max(0, offset);
+      const v = _active;
+      if (v && v.readyState >= 1) _scheduleVideoSeek(target, clip, offset);
+      else _goto(clip, offset, false);
+    }
     _syncInsAudio();
     _notifyPh();
   }
 
+  function _seek(sec) {
+    _pendingSeekSec = Math.max(0, sec);
+    if (_seekRaf) return;
+    _seekRaf = requestAnimationFrame(() => {
+      _seekRaf = null;
+      const s = _pendingSeekSec;
+      _pendingSeekSec = null;
+      if (s == null) return;
+      _seekNow(s);
+    });
+  }
+
+  function _flushSeek() {
+    if (_seekRaf) {
+      cancelAnimationFrame(_seekRaf);
+      _seekRaf = null;
+    }
+    if (_pendingSeekSec != null) {
+      const s = _pendingSeekSec;
+      _pendingSeekSec = null;
+      _seekNow(s);
+    }
+    _flushVideoSeek(true);
+  }
+
+  function _beginScrub() { _scrubDepth++; }
+  function _endScrub() {
+    _scrubDepth = Math.max(0, _scrubDepth - 1);
+    _flushSeek();
+  }
+
   function _play() {
     // At (or past) the end of the timeline → loop the playhead back to the start.
     if (_phSec >= (_totalSecCur || 0) - 0.05 || !_clipFrom(_phSec)) _phSec = 0;
@@ -514,6 +658,9 @@
   // ── public Player API (consumed by timeline.js + inspector) ──────────────
   window.Player = {
     seek: _seek,
+    flushSeek: _flushSeek,
+    beginScrub: _beginScrub,
+    endScrub: _endScrub,
     getPlayhead: () => _phSec,
     play: _play,
     pause: _pause,
@@ -681,7 +828,7 @@
     }).join("|");
     if (hash !== _lastSegHash) {
       _lastSegHash = hash;
-      if (!st.mediaPreviewId) {
+      if (!st.mediaPreviewId && _scrubDepth === 0) {
         const clip = _clipAt(_phSec);
         if (clip) _goto(clip, _phSec - clip.startSec, _playing);
         else if (_clips.length && !_active) _goto(_clips[0], 0, false);
@@ -692,6 +839,12 @@
     const gen = st.gen || { state: "idle", media: [] };
     _fpsCur = p?.frame_rate || 25;
 
+    // While scrubbing, keep the program monitor DOM stable (no clear/rebuild).
+    if (_scrubDepth > 0) {
+      _totalSecCur = S.previewTotalSec ? S.previewTotalSec() : 0;
+      return;
+    }
+
     clear(body);
 
     const previewAsset = st.mediaPreviewId
@@ -826,6 +979,7 @@
         // Drag-to-scrub on minibar
         chip.addEventListener("mousedown", (e) => {
           e.preventDefault();
+          _beginScrub();
           const scrub = (ev) => {
             const r = minibar.getBoundingClientRect();
             const frac = Math.max(0, Math.min(1, (ev.clientX - r.left) / r.width));
@@ -833,7 +987,11 @@
           };
           scrub(e);
           const move = (ev) => scrub(ev);
-          const up = () => { document.removeEventListener("mousemove", move); document.removeEventListener("mouseup", up); };
+          const up = () => {
+            document.removeEventListener("mousemove", move);
+            document.removeEventListener("mouseup", up);
+            _endScrub();
+          };
           document.addEventListener("mousemove", move);
           document.addEventListener("mouseup", up);
         });
diff --git a/movie_editor/frontend/store.js b/movie_editor/frontend/store.js
index 0ba7ec86..5a663be2 100644
--- a/movie_editor/frontend/store.js
+++ b/movie_editor/frontend/store.js
@@ -2071,22 +2071,22 @@
     });
   }
 
-  async function _pollRenderJob(jobId, clipCount) {
+  async function _pollFfmpegJob(statusFn, jobId, clipCount, busyLabel) {
     let transientStreak = 0;
     for (;;) {
       if (_interrupted) throw new Error("Interrupted.");
       try {
-        const st = await API.renderFinalStatus(state.project.id, jobId);
+        const st = await statusFn(jobId);
         transientStreak = 0;
         if (st.state === "done") return st;
-        if (st.state === "error") throw new Error(st.detail || "Render failed");
-        updateGenProgress({ msg: `Stitching ${clipCount} clip(s)…` });
+        if (st.state === "error") throw new Error(st.detail || `${busyLabel} failed`);
+        updateGenProgress({ msg: `${busyLabel} ${clipCount} clip(s)…` });
       } catch (e) {
         if (_isTransientTunnelError(e)) {
           transientStreak++;
           if (transientStreak < 120) {
             updateGenProgress({
-              msg: `Stitching ${clipCount} clip(s) · tunnel reconnect (${transientStreak})…`,
+              msg: `${busyLabel} ${clipCount} clip(s) · tunnel reconnect (${transientStreak})…`,
             });
             await _sleep(2000);
             continue;
@@ -2098,6 +2098,24 @@
     }
   }
 
+  async function _pollRenderJob(jobId, clipCount) {
+    return _pollFfmpegJob(
+      (id) => API.renderFinalStatus(state.project.id, id),
+      jobId,
+      clipCount,
+      "Stitching",
+    );
+  }
+
+  async function _pollExportClipsJob(jobId, clipCount) {
+    return _pollFfmpegJob(
+      (id) => API.exportClipsStatus(state.project.id, id),
+      jobId,
+      clipCount,
+      "Combining",
+    );
+  }
+
   // Toggle a pending Studio session reset — applied to the FIRST run of the next
   // generation. Clicking again disarms it (in case of a mis-click).
   let _resetSessionPending = false;
@@ -2289,13 +2307,11 @@
     return _renderClips().filter((c) => set.has(c.sceneId));
   }
 
-  function _renderPayloadFromClips(rc) {
+  function _plainExportClipsFromRenderClips(rc) {
     return rc.map((c) => ({
       filename: c.media?.filename, subfolder: c.media?.subfolder || "", type: c.media?.type || "output",
       bin_media_ref: c.bin_media_ref || "",
       in: +c.inSec.toFixed(3), dur: +c.durationSec.toFixed(3),
-      fx: c.fx, fps: c.fps, w: c.w, h: c.h, transition: c.transition, tdur: +(c.tdur || 0).toFixed(3),
-      volume: c.volume, scene_id: c.sceneId,
     }));
   }
 
@@ -2304,7 +2320,7 @@
     return `${proj}_${clipCount}clips_${_stamp()}.mp4`;
   }
 
-  // Trim one clip, or stitch multiple selected clips (same ffmpeg path as Render Final).
+  // Trim one clip, or hard-cut concat multiple selected clips (no effects/transitions).
   async function _stitchSelectedClips(saveableIds) {
     const rc = _renderClipsForSceneIds(saveableIds);
     if (!rc.length) return null;
@@ -2314,10 +2330,9 @@
       const out = await API.exportClip(state.project.id, spec.clip);
       return { media: out.media, clips: 1, exportName: spec.name };
     }
-    await flushSave();
-    const queued = await API.renderFinal(state.project.id, _renderPayloadFromClips(rc));
+    const queued = await API.exportClipsCombined(state.project.id, _plainExportClipsFromRenderClips(rc));
     const r = queued?.job_id
-      ? await _pollRenderJob(queued.job_id, rc.length)
+      ? await _pollExportClipsJob(queued.job_id, rc.length)
       : queued;
     return { ...r, exportName: _combinedSelectionFilename(rc.length) };
   }
@@ -2396,7 +2411,7 @@
     return !!(state.sceneRenders[sceneId]?.media);
   }
 
-  // Export selected clip(s): one file; multi-select is stitched with trim/effects/seams.
+  // Export selected clip(s): one file; multi-select is hard-cut concat with trim only.
   async function exportSelected() {
     if (!state.project) return;
     if (!_hasTimelineClipSelection()) { alert("Select a clip first."); return; }
@@ -2411,7 +2426,7 @@
       `${skipped} selected clip(s) have no render yet and will be skipped. Export ${saveableIds.length} clip(s)?`
     )) return;
     if (saveableIds.length > 1 && !confirm(
-      `Stitch ${saveableIds.length} selected clips into one file and export?\n\nPer-clip trim, effects, and transitions between selected clips are applied.`
+      `Combine ${saveableIds.length} selected clips into one file and export?\n\nTimeline trim is applied per clip. No effects, transitions, or extra audio — use Render Final for that.`
     )) return;
     const showProgress = saveableIds.length > 1;
     if (showProgress) {
@@ -2444,7 +2459,7 @@
       `${skipped} selected clip(s) have no render yet and will be skipped. Save ${saveableIds.length} clip(s) to Media bin?`
     )) return;
     if (saveableIds.length > 1 && !confirm(
-      `Stitch ${saveableIds.length} selected clips into one file and save to Media bin?\n\nPer-clip trim, effects, and transitions between selected clips are applied.`
+      `Combine ${saveableIds.length} selected clips into one file and save to Media bin?\n\nTimeline trim is applied per clip. No effects, transitions, or extra audio — use Render Final for that.`
     )) return;
     const showProgress = saveableIds.length > 1;
     if (showProgress) {
diff --git a/movie_editor/frontend/timeline.js b/movie_editor/frontend/timeline.js
index 8ea2d8c0..e0691d43 100644
--- a/movie_editor/frontend/timeline.js
+++ b/movie_editor/frontend/timeline.js
@@ -314,14 +314,14 @@
       ? "Select a clip first"
       : saveable
         ? (multi
-          ? `Stitch ${saveableN} selected clips into one file and export (trim, effects, seams)`
+          ? `Combine ${saveableN} selected clips into one file (trim only, hard cuts)`
           : "Save the selected clip's rendered video to disk (renders are temporary)")
         : "Generate the clip first, or select a video clip with media";
     const binTitle = !hasSel
       ? "Select a clip first"
       : saveable
         ? (multi
-          ? `Stitch ${saveableN} selected clips into one file and save to Media bin`
+          ? `Combine ${saveableN} selected clips into one file and save to Media bin (trim only)`
           : "Copy the selected clip into the Media bin - add it back as a plain video clip")
         : "Generate the clip first, or select a video clip with media";
     return { exportTitle, binTitle };
@@ -1318,6 +1318,7 @@
     // updates just the needle + timecode element on every mousemove).
     ruler.addEventListener("mousedown", (e) => {
       e.preventDefault();
+      window.Player?.beginScrub?.();
       const scrub = (ev) => {
         const r = ruler.getBoundingClientRect();
         const sec = Math.max(0, Math.min((ev.clientX - r.left) / pxPerSec, totalSec));
@@ -1325,7 +1326,11 @@
       };
       scrub(e);
       const move = (ev) => scrub(ev);
-      const up = () => { document.removeEventListener("mousemove", move); document.removeEventListener("mouseup", up); };
+      const up = () => {
+        document.removeEventListener("mousemove", move);
+        document.removeEventListener("mouseup", up);
+        window.Player?.endScrub?.();
+      };
       document.addEventListener("mousemove", move);
       document.addEventListener("mouseup", up);
     });
diff --git a/movie_editor/server.py b/movie_editor/server.py
index d6b32675..0b46b64a 100644
--- a/movie_editor/server.py
+++ b/movie_editor/server.py
@@ -583,6 +583,76 @@ class RenderJobError(Exception):
 
 
 _render_jobs: dict[str, dict] = {}
+_export_jobs: dict[str, dict] = {}
+
+
+def _ffmpeg_concat_clips_plain(clips: list) -> dict:
+    """Join trimmed clips with hard cuts only — no effects, transitions, or extra audio mix."""
+    import os
+    import shutil
+    import subprocess
+    import time as _time
+
+    if not clips:
+        raise RenderJobError("Nothing to export.")
+    ff = shutil.which("ffmpeg")
+    if not ff:
+        raise RenderJobError("ffmpeg not found on PATH — install it to export clips.")
+    try:
+        import folder_paths
+        tempdir = folder_paths.get_temp_directory()
+    except Exception as e:  # noqa: BLE001
+        raise RenderJobError(f"Output directory unavailable: {e}") from e
+
+    stamp = int(_time.time())
+    if len(clips) == 1:
+        out_name = f"funpack_export_{stamp}.mp4"
+        out_path = os.path.join(tempdir, out_name)
+        try:
+            src_path = _resolve_clip_src_path(clips[0])
+            _ffmpeg_trim_clip(src_path, out_path, clips[0].get("in"), clips[0].get("dur"))
+        except FileNotFoundError as e:
+            raise RenderJobError(str(e)) from e
+        except RuntimeError as e:
+            raise RenderJobError(str(e)) from e
+        return {
+            "media": {"filename": out_name, "subfolder": "", "type": "temp", "kind": "videos"},
+            "clips": 1,
+        }
+
+    seg_paths: list[str] = []
+    for i, c in enumerate(clips):
+        try:
+            src_path = _resolve_clip_src_path(c)
+            seg = os.path.join(tempdir, f"funpack_seg_{stamp}_{i}.mp4")
+            _ffmpeg_trim_clip(src_path, seg, c.get("in"), c.get("dur"))
+            seg_paths.append(seg)
+        except FileNotFoundError as e:
+            raise RenderJobError(str(e)) from e
+        except RuntimeError as e:
+            raise RenderJobError(str(e)) from e
+
+    out_name = f"funpack_export_{stamp}.mp4"
+    out_path = os.path.join(tempdir, out_name)
+    list_path = os.path.join(tempdir, f"funpack_concat_{stamp}.txt")
+    with open(list_path, "w", encoding="utf-8") as f:
+        for p in seg_paths:
+            esc = p.replace("'", "'\\''")
+            f.write(f"file '{esc}'\n")
+    cmd = [
+        ff, "-y", "-f", "concat", "-safe", "0", "-i", list_path,
+        "-c:v", "libx264", "-pix_fmt", "yuv420p",
+        "-c:a", "aac", "-b:a", "192k",
+        "-movflags", "+faststart", out_path,
+    ]
+    proc = subprocess.run(cmd, capture_output=True, text=True)
+    if proc.returncode != 0:
+        tail = (proc.stderr or "")[-1000:]
+        raise RenderJobError(f"ffmpeg concat failed: {tail}")
+    return {
+        "media": {"filename": out_name, "subfolder": "", "type": "temp", "kind": "videos"},
+        "clips": len(clips),
+    }
 
 
 def _ffmpeg_stitch_final(proj, clips: list) -> dict:
@@ -1307,6 +1377,39 @@ if web is not None and PromptServer is not None:
             "media": {"filename": out_name, "subfolder": "", "type": "temp", "kind": "videos"},
         })
 
+    import asyncio
+    import uuid as _uuid_export
+
+    async def _run_export_concat_job(job_id: str, clips: list) -> None:
+        _export_jobs[job_id] = {"state": "running"}
+        try:
+            result = await asyncio.to_thread(_ffmpeg_concat_clips_plain, clips)
+            _export_jobs[job_id] = {"state": "done", **result}
+        except RenderJobError as e:
+            _export_jobs[job_id] = {"state": "error", "detail": str(e)}
+        except Exception as e:  # noqa: BLE001
+            _export_jobs[job_id] = {"state": "error", "detail": f"Export failed: {e}"}
+
+    @routes.post(UI_PREFIX + "/api/projects/{pid}/export-clips")
+    async def _export_clips(req):
+        _project_or_404(req.match_info["pid"])
+        body = await req.json() if req.can_read_body else {}
+        clips = body.get("clips") or []
+        if not clips:
+            return web.json_response({"detail": "Nothing to export."}, status=400)
+        job_id = _uuid_export.uuid4().hex
+        _export_jobs[job_id] = {"state": "queued"}
+        asyncio.create_task(_run_export_concat_job(job_id, clips))
+        return web.json_response({"job_id": job_id})
+
+    @routes.get(UI_PREFIX + "/api/projects/{pid}/export-clips/{job_id}")
+    async def _export_clips_status(req):
+        _project_or_404(req.match_info["pid"])
+        job = _export_jobs.get(req.match_info["job_id"])
+        if not job:
+            return web.json_response({"detail": "Export job not found."}, status=404)
+        return web.json_response(job)
+
     # --- API: models / pluggable node slots ---
     @routes.get(UI_PREFIX + "/api/node-roles")
     async def _node_roles(_req):