fix(extract): preserve cross-drive syntax warnings

Keep warning path formatting from aborting a recovered extraction. AI assistance: Codex drafted the change and the actual extraction regression.

Co-Authored-By: Codex <noreply@openai.com>
(cherry picked from commit 1e91fc2f1b)

graphify/extract.py

@@ -7824,7 +7824,12 @@ def extract(
         # #2520 Luau case). `multiline_error` is absent from pre-fix cached
         # results, so those fall back to the file-node-only arm.
         if len(_res.get("nodes", [])) <= 1 or _pe.get("multiline_error"):
-            _rel = os.path.relpath(str(_p), str(root)).replace("\\", "/")
+            try:
+                _rel = os.path.relpath(str(_p), str(root)).replace("\\", "/")
+            except ValueError:
+                # Included files may live on another Windows drive. A display
+                # warning must not discard the graph recovered by the parser.
+                _rel = _p.as_posix()
             # Symbols recovered from the file, excluding its own file node. This
             # is what separates the two cases the warning otherwise blurs: a file
             # that contributed nothing but its file node is a total loss, while

tests/test_partial_extraction_warning.py

@@ -13,6 +13,7 @@ region. Both rendered as "may be partially extracted".
 Part 1 of #2788 — the Astro frontmatter parse itself — is NOT addressed here;
 that belongs to the .svelte/.astro AST work in #2731.
 """
+import ntpath
 import re
 
 import pytest
@@ -66,6 +67,38 @@ def test_warning_still_reports_the_first_error_line(tmp_path, capsys):
     assert re.search(r"first error at line \d+", err), err
 
 
+def test_syntax_warning_survives_cross_drive_paths_without_changing_the_graph(
+    tmp_path, capsys, monkeypatch,
+):
+    """The real recovery parse must return its graph even if display relpath fails."""
+    import graphify.extract as ex
+
+    source = _partial_parse_fixture(tmp_path)
+    original = extract([source], root=tmp_path)
+    original_warning = capsys.readouterr().err
+    assert "may be partially extracted: broken.lua (" in original_warning
+    assert source.as_posix() not in original_warning
+    original_relpath = ex.os.path.relpath
+    cross_drive_calls = []
+
+    def cross_drive_relpath(path, start=None):
+        if str(path) == str(source) and str(start) == str(tmp_path):
+            cross_drive_calls.append((path, start))
+            return ntpath.relpath("D:/included/broken.lua", "C:/scan-root")
+        return original_relpath(path, start)
+
+    monkeypatch.setattr(ex.os.path, "relpath", cross_drive_relpath)
+    result = extract([source], root=tmp_path)
+    assert cross_drive_calls
+    assert result["nodes"] == original["nodes"]
+    assert result["edges"] == original["edges"]
+    warning = capsys.readouterr().err
+    assert "partially extracted" in warning
+    assert source.as_posix() in warning
+    assert re.search(r"first error at line \d+", warning)
+    assert "yielded no symbols" not in warning
+
+
 def test_a_clean_file_is_silent(tmp_path, capsys):
     f = tmp_path / "fine.py"
     f.write_text("def ok():\n    return 1\n", encoding="utf-8")