diff --git a/tests/inspect_one_note.py b/tests/inspect_one_note.py
new file mode 100644
index 0000000..e68aeb4
--- /dev/null
+++ b/tests/inspect_one_note.py
@@ -0,0 +1,70 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+"""
+tests/inspect_one_note.py
+Diagnose einer einzelnen Markdown-Datei (kein Upsert).
+Usage:
+  python3 tests/inspect_one_note.py --path ./test_vault/30_projects/project-demo.md
+"""
+from __future__ import annotations
+import os, sys, json, argparse
+
+PROJECT_ROOT = os.path.abspath(os.path.join(os.path.dirname(__file__), ".."))
+if PROJECT_ROOT not in sys.path:
+    sys.path.insert(0, PROJECT_ROOT)
+
+from app.core.parser import read_markdown, normalize_frontmatter, validate_required_frontmatter
+from app.core.chunker import assemble_chunks
+from app.core.chunk_payload import make_chunk_payloads
+try:
+    from app.core.derive_edges import build_edges_for_note
+except Exception:
+    from app.core.edges import build_edges_for_note  # type: ignore
+
+def main():
+    ap = argparse.ArgumentParser()
+    ap.add_argument("--path", required=True)
+    args = ap.parse_args()
+    p = os.path.abspath(args.path)
+
+    try:
+        parsed = read_markdown(p)
+        if parsed is None:
+            print(json.dumps({"path": p, "error": "read_markdown returned None"}))
+            return
+    except Exception as e:
+        print(json.dumps({"path": p, "error": f"read_markdown failed: {type(e).__name__}: {e}"}))
+        return
+
+    try:
+        fm = normalize_frontmatter(parsed.frontmatter)
+        validate_required_frontmatter(fm)
+    except Exception as e:
+        print(json.dumps({"path": p, "error": f"frontmatter invalid: {type(e).__name__}: {e}"}))
+        return
+
+    body = getattr(parsed, "body", "") or ""
+    chunks = assemble_chunks(fm["id"], body, fm.get("type", "concept"))
+    rel_for_payload = os.path.relpath(p, os.path.join(p, "..", ".."))
+    chunk_pls = make_chunk_payloads(fm, rel_for_payload, chunks, note_text=body)
+
+    edge_error = None
+    edges_count = 0
+    try:
+        edges = build_edges_for_note(fm["id"], chunk_pls, include_note_scope_refs=True)
+        edges_count = len(edges)
+    except Exception as e:
+        edge_error = f"{type(e).__name__}: {e}"
+
+    print(json.dumps({
+        "path": p,
+        "id": fm.get("id"),
+        "title": fm.get("title"),
+        "body_len": len(body),
+        "chunks": len(chunk_pls),
+        "edges": edges_count,
+        "edge_error": edge_error
+    }, ensure_ascii=False, indent=2))
+
+if __name__ == "__main__":
+    main()