diff --git a/diffgraph/structural.py b/diffgraph/structural.py
index 5c00fa3..63fba74 100644
--- a/diffgraph/structural.py
+++ b/diffgraph/structural.py
@@ -1,8 +1,8 @@
 """Deterministic, local DiffGraph v2 extraction from exact Git snapshots.
 
-This first baseline intentionally supports Python only. Other languages remain in
-``files`` and produce scoped ``UNSUPPORTED_LANGUAGE`` warnings; no capability is
-inferred from a filename beyond that explicit boundary.
+This first baseline intentionally supports Python source and stub files only.
+Other languages remain in ``files`` and produce scoped ``UNSUPPORTED_LANGUAGE``
+warnings; no capability is inferred from a filename beyond that explicit boundary.
 """
 from __future__ import annotations
 
@@ -34,6 +34,7 @@
 
 ANALYZER = "diffgraph-python-tree-sitter"
 QUERY_VERSION = "python-structure-v2"
+PYTHON_SUFFIXES = frozenset({".py", ".pyi"})
 _PARSER_STATE = threading.local()
 
 # Resolver failures are part of the public artifact contract. Keep their
@@ -744,7 +745,7 @@ def _unsupported_language_warning(entry: SnapshotEntry, path: str) -> Dict[str,
     return _warning(
         "UNSUPPORTED_LANGUAGE",
         path,
-        "Deterministic extraction currently supports Python (.py) only; "
+        "Deterministic extraction currently supports Python (.py and .pyi) only; "
         "pre-change blob {}; post-change blob {}.".format(
             entry.old_oid or "absent", entry.new_oid or "absent",
         ),
@@ -947,7 +948,7 @@ def analyze_local_diff(
                 "python"
                 if not binary_sides
                 and not non_regular_modes
-                and Path(path).suffix.lower() == ".py"
+                and Path(path).suffix.lower() in PYTHON_SUFFIXES
                 else None
             ),
             "change_kind": _change_kind(entry.status, entry.old_oid, entry.new_oid),
diff --git a/tests/test_structural.py b/tests/test_structural.py
index 3e5490b..8b577d4 100644
--- a/tests/test_structural.py
+++ b/tests/test_structural.py
@@ -180,6 +180,26 @@ def test_pathspec_scope_is_not_widened(tmp_path):
     assert [item["path"] for item in artifact["files"]] == ["inside/a.py"]
 
 
+def test_python_stub_files_are_analyzed_with_tree_sitter_provenance(tmp_path):
+    """Typed Python stubs are part of the deterministic Python baseline."""
+    root = repo(tmp_path)
+    write(root, "api.pyi", "def load(value: str) -> int: ...\n")
+    commit(root)
+    write(root, "api.pyi", "def load(value: str, retries: int = 0) -> int: ...\n")
+
+    artifact = analyze_local_diff(str(root))
+
+    assert_valid(artifact)
+    assert artifact["files"][0]["language"] == "python"
+    assert artifact["metadata"]["files_analyzed"] == 1
+    assert artifact["metadata"]["warnings"] == []
+    symbol = artifact["symbols"][0]
+    assert (symbol["id"], symbol["name"], symbol["change_kind"]) == (
+        "sym::api.pyi::load", "load", "modified"
+    )
+    assert "parser=tree-sitter-language-pack@" in symbol["evidence"][0]["detail"]
+
+
 def test_unsupported_language_is_explicit_and_not_overclaimed(tmp_path):
     """Unsupported snapshots keep their explicit capability boundary and blobs."""
     root = repo(tmp_path)
@@ -194,7 +214,7 @@ def test_unsupported_language_is_explicit_and_not_overclaimed(tmp_path):
     assert artifact["metadata"]["files_skipped"] == 1
     assert artifact["metadata"]["warnings"][0]["code"] == "UNSUPPORTED_LANGUAGE"
     assert artifact["metadata"]["warnings"][0]["detail"] == (
-        "Deterministic extraction currently supports Python (.py) only; "
+        "Deterministic extraction currently supports Python (.py and .pyi) only; "
         "pre-change blob {}; post-change blob {}."
     ).format(old_oid, new_oid)
 
@@ -218,7 +238,7 @@ def test_unsupported_language_one_sided_blob_is_absent(tmp_path, change_kind):
     artifact = analyze_local_diff(str(root))
     assert_valid(artifact)
     assert artifact["metadata"]["warnings"][0]["detail"] == (
-        "Deterministic extraction currently supports Python (.py) only; "
+        "Deterministic extraction currently supports Python (.py and .pyi) only; "
         "pre-change blob {}; post-change blob {}."
     ).format(old_oid, new_oid)