diff --git a/api/router.py b/api/router.py
index c5c6adb..5431202 100644
--- a/api/router.py
+++ b/api/router.py
@@ -223,12 +223,22 @@ async def open_file(body: dict, user: dict = Depends(current_user)):
         from urllib.parse import quote
         cfg = load_config()
         vault = cfg.get("obsidian", {}).get("vault", "").strip()
-        open_target = paths[0]
+        # If only the index was passed, also include sibling transkript/zusammenfassung
+        all_paths = list(paths)
+        for p in paths:
+            if p.endswith("-index.md"):
+                base = p[: -len("-index.md")]
+                for suffix in ("-transkript.md", "-zusammenfassung.md"):
+                    sibling = base + suffix
+                    if os.path.exists(sibling) and sibling not in all_paths:
+                        all_paths.append(sibling)
+
+        open_target = all_paths[0]
         if vault and os.path.isdir(vault):
-            for p in paths:
+            for p in all_paths:
                 dest = os.path.join(vault, os.path.basename(p))
                 shutil.copy2(p, dest)
-            open_target = os.path.join(vault, os.path.basename(paths[0]))
+            open_target = os.path.join(vault, os.path.basename(all_paths[0]))
         uri = f"obsidian://open?path={quote(open_target, safe='/')}"
         obsidian_bin = shutil.which("obsidian") or "/usr/bin/obsidian"
         subprocess.Popen([obsidian_bin, uri])