the rest of the refactor

cht/session.py

@@ -0,0 +1,35 @@
+"""Session data loading — reads frame/transcript indexes, returns plain data."""
+
+import json
+import logging
+from pathlib import Path
+
+log = logging.getLogger(__name__)
+
+
+def load_frame_index(frames_dir: Path) -> list[dict]:
+    """Read frames/index.json and return list of {id, path, timestamp}.
+
+    Returns only entries where the image file exists on disk.
+    Paths are resolved relative to *frames_dir* if needed.
+    """
+    index_path = frames_dir / "index.json"
+    if not index_path.exists():
+        return []
+    try:
+        index = json.loads(index_path.read_text())
+    except (json.JSONDecodeError, IOError):
+        return []
+    result = []
+    for entry in index:
+        fpath = Path(entry["path"])
+        if not fpath.exists():
+            fpath = frames_dir / fpath.name
+        if not fpath.exists():
+            continue
+        result.append({
+            "id": entry["id"],
+            "path": fpath,
+            "timestamp": entry.get("timestamp", 0),
+        })
+    return result