diff --git a/generative/pipeline/vault_writer.py b/generative/pipeline/vault_writer.py
index 383d84b..30ea202 100644
--- a/generative/pipeline/vault_writer.py
+++ b/generative/pipeline/vault_writer.py
@@ -591,13 +591,17 @@ def render_merge_stub(note: AtomicNoteDraft, source_file: str,
     rel_existing = str(existing_path.relative_to(VAULT)).replace("\\", "/")
     existing_link = existing_path.stem
     flags_yaml = _yaml_list(["merge-pending"] + note.quality_flags)
+    # Geschwister von Befund D (#45): fail-closed source_status auch auf dem Merge-Pfad
+    # rendern — render_note tut es, render_merge_stub ließ es sonst still fallen, sodass
+    # eine create-Note mit unauflösbarer Quelle + Vault-Titel-Treffer das Flag verlor.
+    source_status_line = f"\nsource-status: {note.source_status}" if note.source_status else ""
 
     frontmatter = f"""---
 title: "MERGE: {title_esc}"
 type: merge-stub
 merge-target: "[[{existing_link}]]"
 merge-target-path: "{rel_existing}"
-source-file: "{source_file}"
+source-file: "{source_file}"{source_status_line}
 claude-generated: true
 quality-flags:
 {flags_yaml}
diff --git a/generative/tests/test_vault_writer.py b/generative/tests/test_vault_writer.py
index affc2c9..20e437c 100644
--- a/generative/tests/test_vault_writer.py
+++ b/generative/tests/test_vault_writer.py
@@ -9,7 +9,7 @@
 from unittest.mock import patch
 from pathlib import Path
 
-from generative.pipeline.vault_writer import convert_inline_to_footnotes, build_quellen_block
+from generative.pipeline.vault_writer import convert_inline_to_footnotes, build_quellen_block, render_merge_stub, VAULT
 from generative.schemas.atomic_note import AtomicNoteDraft, TextAnchor
 
 
@@ -235,5 +235,27 @@ def test_no_existing_concepts_is_noop(self):
         self.assertEqual(sibling.related, ["[[X]]"])
 
 
+class TestMergeStubSourceStatus(unittest.TestCase):
+    """Geschwister von Befund D ([[Ungelesenes-Pipeline-Signal]], Codex-Hunt 2026-06-23):
+    `render_merge_stub` ließ das fail-closed-Flag `source_status` fallen, das `render_note`
+    rendert (#45). Eine create-Note mit unauflösbarer Quelle, die zufällig einen Vault-
+    Title/Alias-Treffer hat, rendert als Merge-Stub und verlor das Flag still."""
+
+    def _stub(self, source_status=None):
+        note = AtomicNoteDraft(
+            title="Webinar-Wirksamkeit", body="Body", source_anchors=[], related=[],
+            tags=[], synthesis_confidence="high", action="create",
+            source_status=source_status,
+        )
+        return render_merge_stub(note, "Ebner 2019.pdf",
+                                 VAULT / "04-wissen" / "Webinar Bestehend.md")
+
+    def test_unresolved_source_status_rendered_on_stub(self):
+        self.assertIn("source-status: unresolved", self._stub("unresolved"))
+
+    def test_no_source_status_line_when_unset(self):
+        self.assertNotIn("source-status:", self._stub(None))
+
+
 if __name__ == "__main__":
     unittest.main()