gallery of photos in the activity page

bincio/render/merge.py

@@ -90,6 +90,22 @@ def merge_all(data_dir: Path) -> int:
         for md_path in sorted(edits_dir.glob("*.md")):
             sidecars[md_path.stem] = parse_sidecar(md_path)
 
+    # Collect image lists — activities with uploaded images get custom.images even
+    # if they have no sidecar text yet
+    image_lists: dict[str, list[str]] = {}
+    images_root = edits_dir / "images" if edits_dir.exists() else None
+    if images_root and images_root.exists():
+        for img_dir in sorted(images_root.iterdir()):
+            if img_dir.is_dir():
+                files = sorted(
+                    p.name for p in img_dir.iterdir()
+                    if p.is_file() and not p.name.startswith(".")
+                )
+                if files:
+                    image_lists[img_dir.name] = files
+
+    to_merge = set(sidecars) | set(image_lists)
+
     # Wipe and recreate _merged/activities/
     if merged_acts.exists():
         shutil.rmtree(merged_acts)
@@ -102,20 +118,23 @@ def merge_all(data_dir: Path) -> int:
                 continue
             dest = merged_acts / src.name
             activity_id = src.stem
-            if src.suffix == ".json" and activity_id in sidecars:
-                fm, body = sidecars[activity_id]
+            if src.suffix == ".json" and activity_id in to_merge:
                 detail = json.loads(src.read_text(encoding="utf-8"))
-                merged = apply_sidecar(detail, fm, body)
-                dest.write_text(json.dumps(merged, indent=2, ensure_ascii=False))
+                if activity_id in sidecars:
+                    fm, body = sidecars[activity_id]
+                    detail = apply_sidecar(detail, fm, body)
+                if activity_id in image_lists:
+                    detail["custom"] = dict(detail.get("custom") or {})
+                    detail["custom"]["images"] = image_lists[activity_id]
+                dest.write_text(json.dumps(detail, indent=2, ensure_ascii=False))
             else:
                 dest.symlink_to(src.resolve())
 
     # Mirror edits/images/ → _merged/activities/images/ so the site can serve them
-    edits_images = edits_dir / "images" if edits_dir.exists() else None
-    if edits_images and edits_images.exists():
+    if images_root and images_root.exists():
         merged_images = merged_acts / "images"
         merged_images.mkdir(exist_ok=True)
-        for img_dir in edits_images.iterdir():
+        for img_dir in images_root.iterdir():
             if img_dir.is_dir():
                 dest_img = merged_images / img_dir.name
                 if not dest_img.exists():