Bind mp4-mode result download to its own session via rec id

recording_finalized now carries the fork's rec dir name over the ws;
/download_last requires ?rec=<dir> (validated, must exist under the
record dir). Drop the <record_dir>/.last cross-process marker — it was
a server-wide global that could serve one user's output to another
(and was readable by anyone via a bare GET). Client no longer falls
back to "latest recording" on finalize timeout; it reports failure.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

app.py

@@ -521,16 +521,14 @@ async def health():
 
 
 @app.get("/download_last")
-async def download_last():
-    # Port of the local server's endpoint; the finalized dir comes from the fork
-    # via the <record_dir>/.last marker (forks cannot set main-process state).
+async def download_last(rec: str = ""):
     if _RECORD_DIR is None:
         return JSONResponse({"error": "Recording is not enabled."}, status_code=404)
-    marker = Path(_RECORD_DIR) / ".last"
-    rec_dir = marker.read_text(encoding="utf-8").strip() if marker.is_file() else ""
-    if not rec_dir:
-        return JSONResponse({"error": "No downloadable result yet. Send an edit first."}, status_code=404)
-    base = Path(rec_dir)
+    if not re.fullmatch(r"\d+_\d+", rec):
+        return JSONResponse({"error": "Missing or invalid rec id."}, status_code=400)
+    base = Path(_RECORD_DIR) / rec
+    if not base.is_dir():
+        return JSONResponse({"error": "No such recording."}, status_code=404)
     segments = sorted(base.glob("output_*.mp4"))
     if not segments:
         return JSONResponse({"error": "Recording file has not been generated yet. Try again later."}, status_code=404)

static/index.html

@@ -2432,13 +2432,17 @@ function handleVideoEnded() {
   updateMetrics();
   if (ws && ws.readyState === WebSocket.OPEN && sessionGranted) {
     finalizeIsForResult = true;
+    lastRecId = null;
     updateUploadProgress();
     if (finalizeWatchdog) clearTimeout(finalizeWatchdog);
     finalizeWatchdog = setTimeout(() => {
       finalizeWatchdog = null;
       if (!finalizeIsForResult) return;
       finalizeIsForResult = false;
-      fetchAndShowResult();
+      stopResultSync();
+      if (outputWaitOverlay) outputWaitOverlay.style.display = "none";
+      showOutputIdle(true);
+      setSendBusy(false, "");
     }, 30000);
     try { ws.send(JSON.stringify({ type: "finalize_recording" })); }
     catch (err) {}
@@ -2488,7 +2492,7 @@ function setSourceSeg(src) {
   if (segM) segM.addEventListener("click", () => { document.getElementById("videoFile").click(); });
 }
 const downloadBubble = document.getElementById("downloadBubble");
-let downloadPending = false;
+let lastRecId = null;
 function showDownloadBubble(show) {
   if (!downloadBubble) return;
   if (show && !(SERVER_DEFAULTS && SERVER_DEFAULTS.record_enabled)) return;
@@ -2558,6 +2562,7 @@ function stopResultSync() {
 function clearResultVideo() {
   stopResultSync();
   finalizeIsForResult = false;
+  lastRecId = null;
   resultEpoch += 1;
   if (typeof showDownloadBubble === "function") showDownloadBubble(false);
   if (outputResult) {
@@ -2584,29 +2589,13 @@ function triggerBrowserDownload(url, filename) {
   a.click();
   a.remove();
 }
-async function fetchAndSaveRecording() {
-  if (resultBlobUrl) {
-    triggerBrowserDownload(resultBlobUrl, "joyomni_output.mp4");
-    return;
-  }
-  try {
-    const resp = await fetch("/download_last", { cache: "no-store" });
-    if (!resp.ok) {
-      let detail = "";
-      try { const j = await resp.json(); detail = j.error || ""; } catch (e) {}
-      return;
-    }
-    const blob = await resp.blob();
-    const url = URL.createObjectURL(blob);
-    triggerBrowserDownload(url, "joyomni_output.mp4");
-    setTimeout(() => { try { URL.revokeObjectURL(url); } catch (e) {} }, 60000);
-  } catch (err) {
-  }
+function fetchAndSaveRecording() {
+  if (resultBlobUrl) triggerBrowserDownload(resultBlobUrl, "joyomni_output.mp4");
 }
 async function fetchAndShowResult() {
   const myEpoch = resultEpoch;
   try {
-    const resp = await fetch("/download_last", { cache: "no-store" });
+    const resp = await fetch("/download_last?rec=" + encodeURIComponent(lastRecId), { cache: "no-store" });
     if (myEpoch !== resultEpoch) return;
     if (!resp.ok) {
       let detail = "";
@@ -2628,8 +2617,8 @@ async function fetchAndShowResult() {
 }
 function onRecordingFinalized(msg) {
   if (finalizeWatchdog) { clearTimeout(finalizeWatchdog); finalizeWatchdog = null; }
-  downloadPending = false;
-  if (msg && msg.ok === false) {
+  lastRecId = msg.rec || null;
+  if (!lastRecId) {
     finalizeIsForResult = false;
     stopResultSync();
     if (outputWaitOverlay) outputWaitOverlay.style.display = "none";

xvideo/serving/serve_joyomni_streaming.py

@@ -8,6 +8,7 @@ import json
 import math
 import os
 import queue
+import re
 import sys
 import tempfile
 import threading
@@ -619,8 +620,6 @@ def create_app(args: argparse.Namespace) -> FastAPI:
 
     app.state.session_gate = SessionGate()
 
-    app.state.last_recording_dir = None
-
     @app.get("/")
     def index() -> HTMLResponse:
         server_defaults = {
@@ -706,13 +705,14 @@ def create_app(args: argparse.Namespace) -> FastAPI:
         return JSONResponse({"ok": True, "elapsed": time.time() - started})
 
     @app.get("/download_last")
-    async def download_last() -> Response:
+    async def download_last(rec: str = "") -> Response:
         if args.record_dir is None:
             return JSONResponse({"error": "Recording is not enabled (--record-dir is unset)."}, status_code=404)
-        rec_dir = getattr(app.state, "last_recording_dir", None)
-        if not rec_dir:
-            return JSONResponse({"error": "No downloadable result yet. Send an edit first."}, status_code=404)
-        base = Path(rec_dir)
+        if not re.fullmatch(r"\d+_\d+", rec):
+            return JSONResponse({"error": "Missing or invalid rec id."}, status_code=400)
+        base = Path(args.record_dir) / rec
+        if not base.is_dir():
+            return JSONResponse({"error": "No such recording."}, status_code=404)
         segments = sorted(base.glob("output_*.mp4"))
         if not segments:
             return JSONResponse({"error": "Recording file has not been generated yet. Try again later."}, status_code=404)
@@ -1522,11 +1522,10 @@ def create_app(args: argparse.Namespace) -> FastAPI:
                         await _stop_output_task()
                         finalized = rec_base
                         await asyncio.to_thread(_stop_recorders)
-                        if finalized is not None:
-                            app.state.last_recording_dir = str(finalized)
                         await _send_json({
                             "type": "recording_finalized",
                             "ok": finalized is not None,
+                            "rec": finalized.name if finalized is not None else None,
                             "message": None if finalized is not None
                             else "No downloadable result yet. Send an edit first.",
                         })

xvideo/serving/zerogpu_engine.py

@@ -521,14 +521,8 @@ async def _session_loop(runtime, args, websocket: _QueueWebSocket) -> None:
                 await _stop_output()
                 finalized = rec_base
                 await asyncio.to_thread(_stop_recorders)
-                if finalized is not None:
-                    # Cross-process handoff: /download_last runs in the main web
-                    # process, which cannot see this fork's memory.
-                    try:
-                        (Path(args.record_dir) / ".last").write_text(str(finalized), encoding="utf-8")
-                    except Exception:  # noqa: BLE001
-                        pass
                 await _send_json({"type": "recording_finalized", "ok": finalized is not None,
+                                  "rec": finalized.name if finalized is not None else None,
                                   "message": None if finalized is not None
                                   else "No downloadable result yet. Send an edit first."})
             elif msg_type == "frame_meta":