Movie Editor: ComfyUI backend log viewer

Add a 'Log' button in the menubar (next to Saved) that opens a collapsible panel
streaming ComfyUI's real backend log. The bridge tees stdout/stderr into a ring buffer
(writes still pass through to the terminal; captures print + logging); /api/log returns
the tail. Panel polls every 1.5s while open, auto-scrolls (pauses if you scroll up),
with Copy. Far more informative than our wrapped error messages.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

movie_editor/backend/bridge.py

@@ -53,6 +53,65 @@ def parse_timeline_verbatim(prompt: str) -> dict:
     return split_timeline_verbatim(str(prompt or ""))
 
 
+# ── ComfyUI log capture ───────────────────────────────────────────────────────
+# Tee stdout/stderr into a ring buffer so the editor can show ComfyUI's real backend
+# log (writes still pass through to the terminal). Captures print() and logging.
+import collections as _collections
+import threading as _threading
+
+_LOG = _collections.deque(maxlen=5000)
+_LOG_LOCK = _threading.Lock()
+_log_installed = False
+
+
+class _Tee:
+    def __init__(self, orig):
+        self._orig = orig
+        self._buf = ""
+
+    def write(self, s):
+        try:
+            self._orig.write(s)
+        except Exception:
+            pass
+        try:
+            with _LOG_LOCK:
+                self._buf += s
+                while "\n" in self._buf:
+                    line, self._buf = self._buf.split("\n", 1)
+                    _LOG.append(line)
+        except Exception:
+            pass
+        return len(s) if isinstance(s, str) else 0
+
+    def flush(self):
+        try:
+            self._orig.flush()
+        except Exception:
+            pass
+
+    def __getattr__(self, name):
+        return getattr(self._orig, name)
+
+
+def install_log_capture():
+    global _log_installed
+    if _log_installed:
+        return
+    import sys
+    try:
+        sys.stdout = _Tee(sys.stdout)
+        sys.stderr = _Tee(sys.stderr)
+        _log_installed = True
+    except Exception:
+        pass
+
+
+def recent_log(limit: int = 500) -> list:
+    with _LOG_LOCK:
+        return list(_LOG)[-int(limit):]
+
+
 def rating_labels() -> dict:
     """FunPack Studio V2 rating labels (for the Scene rating dropdown)."""
     try:

movie_editor/frontend/api.js

@@ -80,6 +80,7 @@
     status: (id, promptId) => j("GET", API(`/projects/${id}/status/${promptId}`)),
     progress: () => j("GET", API("/progress")),
     ratingLabels: () => j("GET", API("/rating-labels")),
+    log: (limit) => j("GET", API("/log" + (limit ? `?limit=${limit}` : ""))),
     interrupt: () => j("POST", API("/interrupt")),
     renderFinal: (id, clips) => j("POST", API(`/projects/${id}/render`), { clips }),
     resultUrl: (id, m) =>

movie_editor/frontend/index.html

@@ -89,6 +89,7 @@
   <script src="models.js"></script>
   <script src="menubar.js"></script>
   <script src="mediabrowser.js"></script>
+  <script src="log.js"></script>
   <script src="player.js"></script>
   <script src="sampler_panel.js"></script>
   <script src="inspector.js"></script>

movie_editor/frontend/log.js

@@ -0,0 +1,45 @@
+// Menubar "Log" button + a collapsible panel showing ComfyUI's real backend log
+// (tee'd stdout/stderr from the server). Polls only while open.
+(function () {
+  const API = window.MovieEditorAPI;
+  const right = document.querySelector(".menubar-right");
+  if (!right) return;
+
+  const btn = document.createElement("button");
+  btn.className = "log-btn"; btn.textContent = "Log"; btn.title = "Show the ComfyUI backend log";
+  right.insertBefore(btn, right.firstChild);
+
+  const panel = document.createElement("div");
+  panel.className = "log-panel"; panel.hidden = true;
+  const head = document.createElement("div"); head.className = "log-head";
+  const title = document.createElement("span"); title.textContent = "ComfyUI log";
+  const actions = document.createElement("div"); actions.className = "log-actions";
+  head.append(title, actions);
+  const bodyEl = document.createElement("pre"); bodyEl.className = "log-body";
+  panel.append(head, bodyEl);
+  document.body.append(panel);
+
+  let timer = null, autoscroll = true;
+
+  async function refresh() {
+    try {
+      const r = await API.log(800);
+      bodyEl.textContent = (r.lines || []).join("\n");
+      if (autoscroll) bodyEl.scrollTop = bodyEl.scrollHeight;
+    } catch (e) {
+      bodyEl.textContent = "(log unavailable: " + e.message + ")";
+    }
+  }
+  bodyEl.addEventListener("scroll", () => {
+    autoscroll = bodyEl.scrollHeight - bodyEl.scrollTop - bodyEl.clientHeight < 40;
+  });
+
+  function open() { panel.hidden = false; btn.classList.add("active"); autoscroll = true; refresh(); timer = setInterval(refresh, 1500); }
+  function close() { panel.hidden = true; btn.classList.remove("active"); clearInterval(timer); timer = null; }
+  btn.onclick = () => (panel.hidden ? open() : close());
+
+  const copy = document.createElement("button"); copy.className = "btn ghost tiny"; copy.textContent = "Copy";
+  copy.onclick = () => { try { navigator.clipboard.writeText(bodyEl.textContent); copy.textContent = "Copied"; setTimeout(() => (copy.textContent = "Copy"), 1200); } catch (_) {} };
+  const x = document.createElement("button"); x.className = "btn ghost tiny"; x.textContent = "✕"; x.onclick = close;
+  actions.append(copy, x);
+})();

movie_editor/frontend/styles.css

@@ -108,6 +108,20 @@ button, input, select, textarea { font-family: inherit; color: var(--text); }
 .save-chip { border-color: transparent; color: var(--faint); }
 .save-chip.dirty { color: var(--amber); }
 
+/* backend log viewer */
+.log-btn { background: var(--ink-2); border: 1px solid var(--line); border-radius: 20px; color: var(--muted);
+  font-family: var(--font-mono); font-size: 11px; letter-spacing: .5px; padding: 3px 11px; cursor: pointer; }
+.log-btn:hover { color: var(--amber-2); background: var(--ink-3); }
+.log-btn.active { color: var(--amber-2); border-color: color-mix(in srgb, var(--amber) 45%, var(--line)); }
+.log-panel { position: fixed; z-index: 9000; right: 14px; top: 48px; width: min(720px, 88vw); height: min(420px, 60vh);
+  background: #0c0b09f2; border: 1px solid var(--line); border-radius: 10px; display: flex; flex-direction: column;
+  box-shadow: 0 16px 40px -12px #000; overflow: hidden; }
+.log-head { display: flex; align-items: center; justify-content: space-between; padding: 7px 10px; border-bottom: 1px solid var(--line);
+  font-family: var(--font-mono); font-size: 11px; letter-spacing: 1px; text-transform: uppercase; color: var(--amber); }
+.log-actions { display: flex; gap: 6px; }
+.log-body { flex: 1; margin: 0; padding: 8px 10px; overflow: auto; white-space: pre-wrap; word-break: break-word;
+  font-family: var(--font-mono); font-size: 11px; line-height: 1.45; color: var(--muted); background: #060606; }
+
 /* ───────────────────────── WORKSPACE GRID ───────────────────────── */
 .workspace { height: calc(100% - var(--menubar-h)); display: flex; flex-direction: column; }
 .row-main { flex: 1; display: flex; min-height: 0; }

movie_editor/server.py

@@ -188,6 +188,7 @@ def _serve_static(tail: str) -> "web.Response":
 if web is not None and PromptServer is not None:
     routes = PromptServer.instance.routes
     config.ensure_dirs()
+    bridge.install_log_capture()  # tee ComfyUI stdout/stderr for the Log viewer
 
     # --- API: projects ---
     @routes.get(UI_PREFIX + "/api/health")
@@ -522,6 +523,14 @@ if web is not None and PromptServer is not None:
     async def _progress(_req):
         return web.json_response(bridge.current_progress())
 
+    @routes.get(UI_PREFIX + "/api/log")
+    async def _log(req):
+        try:
+            limit = int(req.query.get("limit", "600"))
+        except (TypeError, ValueError):
+            limit = 600
+        return web.json_response({"lines": bridge.recent_log(limit)})
+
     @routes.post(UI_PREFIX + "/api/interrupt")
     async def _interrupt(_req):
         try: