Don't Path()-coerce FileSlice units in the extract entry points (#1397, #1399)

The 0.8.43 str-path coercion (#1386) ran Path(f) over every item in
extract_files_direct, but extract_corpus_parallel feeds it FileSlice units from
the oversized-doc slicing (#1369), and Path(FileSlice) raises TypeError -- so
semantic extraction of any Markdown file larger than _FILE_CHAR_CAP crashed.
Coerce only non-Path/non-FileSlice entries. The #1386 tests used small files, so
slicing never ran; added a regression test with a file that actually slices.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

graphify/llm.py

@@ -1306,9 +1306,11 @@ def extract_files_direct(
 
     Accepts ``str`` paths as well as ``Path``; string entries are coerced up
     front so downstream helpers (``_partition_semantic_files``, ``_read_files``,
-    ``_build_image_refs``) can rely on ``Path`` semantics (#1386).
+    ``_build_image_refs``) can rely on ``Path`` semantics (#1386). FileSlice units
+    (from extract_corpus_parallel's oversized-doc slicing, #1369) pass through
+    untouched — Path(FileSlice) would raise (#1397/#1399).
     """
-    files = [Path(f) for f in files]
+    files = [f if isinstance(f, (Path, FileSlice)) else Path(f) for f in files]
     if backend is None:
         backend = detect_backend()
         if backend is None:
@@ -1737,7 +1739,7 @@ def extract_corpus_parallel(
     Accepts ``str`` paths as well as ``Path``; string entries are coerced up
     front so packing/slicing helpers can rely on ``Path`` semantics (#1386).
     """
-    files = [Path(f) for f in files]
+    files = [f if isinstance(f, (Path, FileSlice)) else Path(f) for f in files]
     # Split oversized splittable documents into slices that cover the whole file
     # before packing, so content past _FILE_CHAR_CAP is extracted instead of
     # silently dropped (#1369). Files at/under the cap pass through unchanged.

tests/test_llm_backends.py

@@ -167,6 +167,26 @@ def test_extract_corpus_parallel_accepts_str_and_mixed_paths(tmp_path, monkeypat
             assert merged["failed_chunks"] == 0
 
 
+def test_corpus_parallel_oversized_markdown_does_not_crash_on_fileslice(tmp_path, monkeypatch):
+    # #1397/#1399 regression: a Markdown file large enough to be sliced into
+    # FileSlice units must not crash extract_files_direct's Path() coercion
+    # (#1386). The earlier str-path tests used tiny files, so slicing never ran.
+    from graphify.llm import _FILE_CHAR_CAP
+    _clear_backend_env(monkeypatch)
+    monkeypatch.setenv("GOOGLE_API_KEY", "google-key")
+    big = tmp_path / "big.md"
+    big.write_text(("# Section\n\n" + "lorem ipsum dolor sit amet " * 60 + "\n\n") * 30)
+    assert len(big.read_text()) > _FILE_CHAR_CAP  # guarantees slicing kicks in
+    result = {"nodes": [], "edges": [], "hyperedges": [], "input_tokens": 1, "output_tokens": 1}
+
+    with patch("graphify.llm._call_openai_compat", return_value=result):
+        # both a str path and a FileSlice unit must flow through without TypeError
+        merged = llm.extract_corpus_parallel(
+            [str(big)], backend="gemini", root=tmp_path, max_concurrency=1
+        )
+    assert merged["failed_chunks"] == 0  # no chunk raised Path(FileSlice) TypeError
+
+
 def test_str_path_entry_points_handle_edge_cases(tmp_path, monkeypatch):
     _clear_backend_env(monkeypatch)
     monkeypatch.setenv("GOOGLE_API_KEY", "google-key")