Fix completed runs not appearing in list + add purge-failed endpoint

- Update save_run_cache to also update actor_id, recipe, inputs on conflict
- Add logging for actor_id when saving runs to run_cache
- Add admin endpoint DELETE /runs/admin/purge-failed to delete all failed runs

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

sexp_effects/primitive_libs/streaming.py

@@ -55,9 +55,13 @@ class VideoSource:
             self._proc.kill()
             self._proc = None
 
+        # Check file exists before trying to open
+        if not self.path.exists():
+            raise FileNotFoundError(f"Video file not found: {self.path}")
+
         w, h = self._frame_size
         cmd = [
-            "ffmpeg", "-v", "quiet",
+            "ffmpeg", "-v", "error",  # Show errors instead of quiet
             "-ss", f"{seek_time:.3f}",
             "-i", str(self.path),
             "-f", "rawvideo", "-pix_fmt", "rgb24",
@@ -65,9 +69,18 @@ class VideoSource:
             "-r", str(self.fps),  # Output at specified fps
             "-"
         ]
-        self._proc = subprocess.Popen(cmd, stdout=subprocess.PIPE, stderr=subprocess.DEVNULL)
+        self._proc = subprocess.Popen(cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
         self._stream_time = seek_time
 
+        # Check if process started successfully by reading first bit of stderr
+        import select
+        import sys
+        readable, _, _ = select.select([self._proc.stderr], [], [], 0.5)
+        if readable:
+            err = self._proc.stderr.read(4096).decode('utf-8', errors='ignore')
+            if err:
+                print(f"ffmpeg error for {self.path.name}: {err}", file=sys.stderr)
+
     def _read_frame_from_stream(self) -> np.ndarray:
         """Read one frame from the stream."""
         w, h = self._frame_size
@@ -130,8 +143,12 @@ class VideoSource:
         frame = self._read_frame_from_stream()
         if frame is None:
             import sys
-            print(f"NULL FRAME {self.path.name}: t={t:.2f} seek={seek_time:.2f}", file=sys.stderr)
-            frame = np.zeros((h, w, 3), dtype=np.uint8)
+            # Check for ffmpeg errors
+            if self._proc and self._proc.stderr:
+                err = self._proc.stderr.read(4096).decode('utf-8', errors='ignore')
+                if err:
+                    raise RuntimeError(f"Failed to read video frame from {self.path.name}: {err}")
+            raise RuntimeError(f"Failed to read video frame from {self.path.name} at t={t:.2f} - file may be corrupted or inaccessible")
         else:
             self._stream_time += self._frame_time