fix: scope Door A's ownership scan to its own filename prefix

The §3 ownership scan globbed every *.md file regardless of which door
wrote it, then unconditionally unlinked whatever _is_ingest_owned agreed
to. Because _is_ingest_owned reads through the line-oriented parser that
flattens nested blocks (pinned in
test_two_nested_block_mappings_sharing_a_key_collide_in_the_scalar_parser),
a Door B/C file whose nested content happened to share a key name with
the ownership markers (generated, ingest_manifest) could get promoted to
top level and spoof ownership -- silently deleting content this door
never wrote.

Scoping the glob to ingest_prefix closes this by construction: a Door
B/C file is never even a candidate for the scan, regardless of what its
frontmatter parses to. Traced from a coordination tip from
portfolio-optimiser-claude about the same flattening mechanism hitting
their `type` field.

src/llm_ingestion_okf/materialize.py

@@ -457,10 +457,20 @@ def materialize_bundle(
     staged_names = {name for name, _ in staged}
 
     # §3 ownership scan (sorted for determinism): only files carrying the
-    # ingest stamp are ours to replace.
+    # ingest stamp are ours to replace. Globs by THIS door's prefix, not just
+    # the shared suffix: `_is_ingest_owned` reads through the line-oriented
+    # parser that flattens nested blocks (pinned in
+    # test_two_nested_block_mappings_sharing_a_key_collide_in_the_scalar_parser),
+    # so a Door B/C file whose nested content happens to share a key name
+    # with the ownership markers could otherwise spoof ownership here and get
+    # unlinked below — content this door never wrote. Scoping the glob to
+    # `ingest_prefix` closes that by construction: a Door B/C file is never
+    # even a candidate, regardless of what its frontmatter parses to.
     owned = {
         path.name
-        for path in sorted(bundle.glob(f"*{profile.paths.concept_suffix}"))
+        for path in sorted(
+            bundle.glob(f"{profile.paths.ingest_prefix}*{profile.paths.concept_suffix}")
+        )
         if path.name != profile.index.name
         and _is_ingest_owned(path, manifest_file.stem, profile=profile)
     }

tests/test_materialize.py

@@ -340,6 +340,37 @@ def test_replacement_leaves_another_manifests_stamped_file(file_setup: tuple[Pat
     assert (bundle / "ingest-orders.md").is_file()
 
 
+def test_a_door_c_import_survives_a_same_stem_materialize_run(
+    file_setup: tuple[Path, Path],
+) -> None:
+    # The §3 scan used to glob every `*.md` regardless of which door wrote it,
+    # then unconditionally unlink whatever `_is_ingest_owned` agreed to. The
+    # line-oriented parser has no indentation model (pinned in
+    # test_two_nested_block_mappings_sharing_a_key_collide_in_the_scalar_parser),
+    # so a nested block in an externally-imported concept that happens to
+    # share a key name with the ownership markers gets promoted to a
+    # top-level `generated`/`ingest_manifest` pair and can spoof ownership —
+    # deleting content this door never wrote and does not own.
+    manifest_path, bundle = file_setup
+    bundle.mkdir()
+    imported = bundle / "import-external.md"
+    imported.write_text(
+        "---\n"
+        "type: Concept\n"
+        "title: Imported Concept\n"
+        "provenance:\n"
+        "  generated: true\n"
+        "  ingest_manifest: manifest@deadbeef\n"
+        "---\n\nExternally imported body.\n",
+        encoding="utf-8",
+    )
+
+    materialize_bundle(manifest_path, bundle, INGESTED_AT)
+
+    assert imported.is_file()
+    assert (bundle / "ingest-orders.md").is_file()
+
+
 def test_second_manifest_does_not_delete_first_manifests_stamped_file(tmp_path: Path) -> None:
     # §10.2 per-manifest ownership: two manifests writing into ONE bundle each
     # own only the files whose stamp names them by stem. Running manifest B

tests/test_profile_threading.py

@@ -164,10 +164,11 @@ def test_profile_paths_and_index_name_reach_disk(file_setup: tuple[Path, Path])
 def test_second_synthetic_run_replaces_rather_than_colliding(
     file_setup: tuple[Path, Path],
 ) -> None:
-    """The §3 ownership scan globs `*{concept_suffix}` and excludes `index.name`.
-    Left on `DEFAULT`, the glob finds nothing under a renamed suffix, `owned` is
-    empty, and the gate refuses to overwrite the file this same code just wrote.
-    The index must also not gain a second link for the same target.
+    """The §3 ownership scan globs `{ingest_prefix}*{concept_suffix}` and
+    excludes `index.name`. Left on `DEFAULT`, the glob finds nothing under a
+    renamed prefix and suffix, `owned` is empty, and the gate refuses to
+    overwrite the file this same code just wrote. The index must also not
+    gain a second link for the same target.
     """
     manifest_path, bundle = file_setup
     materialize_bundle(manifest_path, bundle, INGESTED_AT, profile=_SYNTHETIC)