diff --git a/movie_editor/backend/builder.py b/movie_editor/backend/builder.py
index 256c498c..44676c34 100644
--- a/movie_editor/backend/builder.py
+++ b/movie_editor/backend/builder.py
@@ -223,9 +223,16 @@ def build(object_info: dict, models_config: dict, params: dict, media: dict | No
     # the result must be written to the output dir so the editor can fetch it back
     # (the reference graph used preview-only save_output=False).
     graph["vhs"]["inputs"]["save_output"] = True
+    # split_by_transitions MUST be True — Studio defaults to False (single-scene mode)
+    # but the Movie Editor always builds multi-scene combined prompts.  Force it here
+    # BEFORE the user's studio_inputs override block so it cannot be accidentally
+    # overwritten to False via the sampler panel.
+    graph["studio"]["inputs"]["split_by_transitions"] = True
 
     # 2b. project-level widget overrides for the built-in FunPack nodes.
     for k, v in (params.get("studio_inputs") or {}).items():
+        if k == "split_by_transitions":
+            continue  # never allow overriding — multi-scene mode is mandatory
         if k not in graph["studio"]["inputs"] or not isinstance(graph["studio"]["inputs"][k], list):
             graph["studio"]["inputs"][k] = v
     for k, v in (params.get("sampler_inputs") or {}).items():
diff --git a/movie_editor/frontend/models.js b/movie_editor/frontend/models.js
index 5a071605..a27da420 100644
--- a/movie_editor/frontend/models.js
+++ b/movie_editor/frontend/models.js
@@ -269,27 +269,7 @@
         const cur = slot.input_sources[ci.name] || "";
         srcs.forEach((s) => { const o = el("option", null, s.label); o.value = s.value; if (s.value === cur) o.selected = true; sel.append(o); });
         if (cur && !srcs.some((s) => s.value === cur)) { const o = el("option", null, cur + " (missing)"); o.value = cur; o.selected = true; sel.append(o); }
-        sel.onchange = async () => {
-          slot.input_sources[ci.name] = sel.value;
-          // Auto-wire: if the user just assigned a non-auto source and this slot has
-          // exactly one output of the same type that is not yet wired, and there is
-          // exactly one pipeline destination for that type, wire it automatically.
-          if (sel.value && sel.value !== "") {
-            const matchOuts = (cand.outputs || []).filter((o) => o.type === ci.type);
-            if (matchOuts.length === 1) {
-              const outName = matchOuts[0].name;
-              const existing = wireTargets(slot.wires?.[outName]).filter(Boolean);
-              if (!existing.length) {
-                const dests = destinations(slot, ci.type).filter((d) => d.value);
-                if (dests.length === 1) {
-                  slot.wires = slot.wires || {};
-                  slot.wires[outName] = [dests[0].value];
-                }
-              }
-            }
-          }
-          await persist();
-        };
+        sel.onchange = async () => { slot.input_sources[ci.name] = sel.value; await persist(); };
         row.append(sel);
         sbox.append(row);
       });
diff --git a/movie_editor/frontend/store.js b/movie_editor/frontend/store.js
index 64d3850e..a835ca35 100644
--- a/movie_editor/frontend/store.js
+++ b/movie_editor/frontend/store.js
@@ -286,9 +286,13 @@
     pollTimer = setInterval(async () => {
       try {
         const s = await API.status(state.project.id, promptId);
-        if (s.state === "completed") {
+        if (s.state === "error") {
           clearInterval(pollTimer);
-          set({ gen: { state: "done", promptId, media: s.media, msg: s.media.length ? "" : "Completed (no media found)." } });
+          const msg = s.error ? `ComfyUI error: ${s.error}` : "Generation failed inside ComfyUI — check the ComfyUI terminal for details.";
+          set({ gen: { state: "error", promptId, media: [], msg } });
+        } else if (s.state === "completed") {
+          clearInterval(pollTimer);
+          set({ gen: { state: "done", promptId, media: s.media, msg: s.media.length ? "" : "Completed but no output media found — check ComfyUI terminal." } });
         } else {
           set({ gen: { ...state.gen, state: s.state, msg: `Generating… (${s.state})` } });
         }
diff --git a/movie_editor/server.py b/movie_editor/server.py
index 07ce6ea2..30094f2f 100644
--- a/movie_editor/server.py
+++ b/movie_editor/server.py
@@ -398,10 +398,22 @@ if web is not None and PromptServer is not None:
             raise web.HTTPBadGateway(reason=f"history unavailable: {e}")
         if prompt_id in hist:
             entry = hist[prompt_id]
+            raw_status = entry.get("status") or {}
+            media = _media_from_history(entry)
+            # Extract ComfyUI execution errors from history so the frontend can show them.
+            exec_error: Optional[str] = None
+            for _kind, payload in raw_status.get("messages") or []:
+                if _kind == "execution_error" and isinstance(payload, dict):
+                    node_type = payload.get("node_type", "unknown node")
+                    exc = payload.get("exception_message") or payload.get("traceback") or "unknown error"
+                    exec_error = f"{node_type}: {exc}"
+                    break
+            is_error = raw_status.get("status_str") == "error"
             return web.json_response({
-                "state": "completed",
-                "media": _media_from_history(entry),
-                "status": entry.get("status", {}),
+                "state": "error" if (is_error and not media) else "completed",
+                "media": media,
+                "error": exec_error,
+                "status": raw_status,
             })
         try:
             running = await bridge.is_running(prompt_id)