perf(extract): resolve and parse each path once in the id remap and call tie-break

extract()'s id remap called Path.resolve() on the same file paths once
per input, once per target_file-stamped edge and once per node: ~24k
calls for ~1k distinct paths on graphify's own repo. Resolve each
distinct path once per extract() call through a local memo; a hit
returns the same Path the call would, and a path that raises is never
stored.

_path_proximity_winner (the #1553 god-node tie-break) re-parsed every
candidate's parent directory with PurePosixPath on every ambiguous call
site (~227k Path objects per update on graphify's repo), although the
same candidate files come back for every site of a common name. Memoize
the parent-directory parts per path string; equal tuples are exactly
equal PurePosixPath parents, so every tier decides as before.

graphify's own repo (18,830 nodes), `graphify update --force`,
alternated: cold 28.1 -> 26.3 s, no-change update 24.8 -> 22.5 s and
20.9 -> 18.0 s. graph.json identical (all attributes) cold and warm;
old vs new tie-break identical on 200,000 random cases.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

graphify/extract.py

@@ -7993,10 +7993,24 @@ def extract(
     # stem_forms for those in-root files as well lets the edge remap and the
     # target_file-guided repoint pass fix them exactly as on a full scan.
     remap_paths: list[Path] = list(paths)
+    # The remap below resolves the same few hundred file paths once per input,
+    # once per stamped edge and once per node (tens of thousands of calls on a
+    # mid-size repo). Resolve each distinct path once; a hit returns the same
+    # Path the call would, and a path that raises is never stored.
+    _resolve_memo: dict[str, Path] = {}
+
+    def _resolved(p: "str | Path") -> Path:
+        key = str(p)
+        hit = _resolve_memo.get(key)
+        if hit is None:
+            hit = Path(p).resolve()
+            _resolve_memo[key] = hit
+        return hit
+
     _remap_seen: set[Path] = set()
     for _p in paths:
         try:
-            _remap_seen.add(_p.resolve())
+            _remap_seen.add(_resolved(_p))
         except (OSError, RuntimeError):
             pass
     for _e in all_edges:
@@ -8005,7 +8019,7 @@ def extract(
             continue
         _raw_tp = Path(_tf)
         try:
-            _tp = _raw_tp.resolve()
+            _tp = _resolved(_raw_tp)
         except (OSError, RuntimeError):
             continue
         if _tp in _remap_seen:
@@ -8076,7 +8090,7 @@ def extract(
             rel = path.relative_to(root)
         except ValueError:
             try:
-                rel = path.resolve().relative_to(root)
+                rel = _resolved(path).relative_to(root)
             except ValueError:
                 continue
         new_id = _file_node_id(rel)
@@ -8085,14 +8099,15 @@ def extract(
         # Also register the absolute-resolved form of the file-level id so
         # alias/workspace import targets (resolved via .resolve()) remap to
         # canonical instead of orphaning (#1529).
-        old_id_abs = _make_id(str(path.resolve()))
+        path_abs = _resolved(path)
+        old_id_abs = _make_id(str(path_abs))
         if old_id_abs != new_id:
             id_remap[old_id_abs] = new_id
         old_prefs: list[tuple[str, str]] = []
         old_pref = _file_node_id(path)
         if old_pref != new_id:
             old_prefs.append((old_pref, new_id))
-        old_pref_abs = _file_node_id(path.resolve())
+        old_pref_abs = _file_node_id(path_abs)
         if old_pref_abs != new_id and old_pref_abs != old_pref:
             old_prefs.append((old_pref_abs, new_id))
         # Bash entrypoint node ids append "__entry" to the file-level id
@@ -8111,10 +8126,10 @@ def extract(
             if _entry_old != _entry_new:
                 id_remap.setdefault(_entry_old, _entry_new)
         if old_prefs:
-            prefix_remap[path.resolve()] = old_prefs
+            prefix_remap[path_abs] = old_prefs
         # Absolute form first: it is the longest, so prefix decomposition can
         # try forms in order without a shorter form shadowing it.
-        stem_forms[path.resolve()] = (
+        stem_forms[path_abs] = (
             new_id, [old_pref_abs, old_pref, new_id]
         )
     if id_remap:
@@ -8166,7 +8181,7 @@ def extract(
             if n.get("type") == "package":
                 continue
             try:
-                entry = prefix_remap.get(Path(sf).resolve())
+                entry = prefix_remap.get(_resolved(sf))
             except Exception:
                 continue
             if entry is None:
@@ -8272,7 +8287,7 @@ def extract(
 
         def _decompose(target: str, tf: str) -> "tuple[str, str] | None":
             try:
-                forms = stem_forms.get(Path(tf).resolve())
+                forms = stem_forms.get(_resolved(tf))
             except (OSError, RuntimeError):
                 return None
             if not forms:

graphify/paths.py

@@ -16,6 +16,7 @@ flow) and every reader honours it.
 
 from __future__ import annotations
 
+import functools
 import json
 import os
 import re
@@ -253,6 +254,18 @@ def _is_test_path(path: str) -> bool:
     return False
 
 
+@functools.lru_cache(maxsize=65536)
+def _parent_parts(source_file: str) -> tuple[str, ...]:
+    """Segments of ``source_file``'s parent directory, POSIX-normalized.
+
+    `_path_proximity_winner` compares every candidate's directory against the
+    call site's, and an ambiguous name (``run``, ``get``) brings the same
+    candidate files back on every call site, so the parse is memoized. Equal
+    tuples here mean equal ``PurePosixPath(...).parent`` values.
+    """
+    return PurePosixPath(source_file.replace("\\", "/")).parent.parts
+
+
 def _path_proximity_winner(call_site_file: str, candidate_files: dict[str, str]) -> str | None:
     """Pick the candidate whose source file is closest to the call site.
 
@@ -270,7 +283,7 @@ def _path_proximity_winner(call_site_file: str, candidate_files: dict[str, str])
     if not call_site_file:
         return None
     call_norm = str(call_site_file).replace("\\", "/")
-    call_dir = PurePosixPath(call_norm).parent
+    call_parts = _parent_parts(call_norm)
 
     # Tier 1: exact same file.
     same_file = [cid for cid, f in candidate_files.items()
@@ -282,7 +295,7 @@ def _path_proximity_winner(call_site_file: str, candidate_files: dict[str, str])
 
     # Tier 2: same directory.
     same_dir = [cid for cid, f in candidate_files.items()
-                if PurePosixPath(str(f).replace("\\", "/")).parent == call_dir]
+                if _parent_parts(str(f)) == call_parts]
     if len(same_dir) == 1:
         return same_dir[0]
     if len(same_dir) > 1:
@@ -290,10 +303,8 @@ def _path_proximity_winner(call_site_file: str, candidate_files: dict[str, str])
 
     # Tier 3: longest common path-prefix, computed over path segments. The
     # winner must be a strict unique maximum, else we bail (guard holds).
-    call_parts = call_dir.parts
-
     def _common_prefix_len(f: str) -> int:
-        parts = PurePosixPath(str(f).replace("\\", "/")).parent.parts
+        parts = _parent_parts(str(f))
         n = 0
         for a, b in zip(call_parts, parts):
             if a != b:

tests/test_extract_path_memo.py

@@ -0,0 +1,67 @@
+"""extract()'s id remap and the call tie-break parse each distinct path once.
+
+The remap resolved the same file paths once per input, once per stamped edge
+and once per node, and `_path_proximity_winner` re-parsed every candidate's
+directory on every ambiguous call site. Both now memoize; answers are unchanged.
+"""
+from __future__ import annotations
+
+import sys
+from pathlib import Path, PurePosixPath
+
+import pytest
+
+from graphify import paths as paths_mod
+from graphify.extract import extract
+
+
+def _corpus(root: Path) -> list[Path]:
+    (root / "pkg").mkdir(parents=True)
+    files = []
+    for i in range(4):
+        body = "".join(f"def f{i}_{j}():\n    return f{i}_{j + 1}()\n\n\n" for j in range(40))
+        body += "".join(f"from pkg.m{k} import f{k}_0\n" for k in range(4) if k != i)
+        p = root / "pkg" / f"m{i}.py"
+        p.write_text(body, encoding="utf-8")
+        files.append(p)
+    (root / "pkg" / "__init__.py").write_text("", encoding="utf-8")
+    return files + [root / "pkg" / "__init__.py"]
+
+
+def test_extract_resolves_each_distinct_path_once(tmp_path: Path, monkeypatch):
+    files = _corpus(tmp_path / "proj")
+    calls: list[str] = []
+    real_resolve = Path.resolve
+    remap_frames = {"extract", "_decompose", "_resolved"}  # the id-remap code in extract()
+
+    def counting_resolve(self, *args, **kwargs):
+        if sys._getframe(1).f_code.co_name in remap_frames:
+            calls.append(str(self))
+        return real_resolve(self, *args, **kwargs)
+
+    monkeypatch.setattr(Path, "resolve", counting_resolve)
+    result = extract(files, root=tmp_path / "proj", cache_root=tmp_path / "cache", parallel=False)
+    assert len(result["nodes"]) > 160  # every function became a node, so the per-node remap ran
+    # Without the memo the remap resolved once per node and per stamped edge
+    # (~200 calls here); with it, once per distinct path.
+    assert len(calls) == len(set(calls)), f"{len(calls)} remap resolve calls for {len(set(calls))} paths"
+
+
+@pytest.mark.parametrize(
+    "site, candidates, expected",
+    [
+        ("pkg/a/x.py", {"1": "pkg/a/y.py", "2": "pkg/b/y.py"}, "1"),            # same dir
+        ("pkg\\a\\x.py", {"1": "pkg/a/y.py", "2": "pkg/b/y.py"}, "1"),          # backslashes
+        ("pkg/a/b/x.py", {"1": "pkg/a/y.py", "2": "other/y.py"}, "1"),          # longest prefix
+        ("pkg/a/x.py", {"1": "pkg/b/y.py", "2": "pkg/c/y.py"}, None),           # tied prefix
+        ("x.py", {"1": "y.py", "2": "z/y.py"}, "1"),                            # root-level file
+        ("pkg/a/x.py", {"1": "pkg/a/x.py", "2": "pkg/a/y.py"}, "1"),            # same file
+    ],
+)
+def test_proximity_winner_matches_a_fresh_parse(site, candidates, expected):
+    paths_mod._parent_parts.cache_clear()
+    assert paths_mod._path_proximity_winner(site, candidates) == expected
+    # second call is served from the memo and must agree
+    assert paths_mod._path_proximity_winner(site, candidates) == expected
+    for f in candidates.values():
+        assert paths_mod._parent_parts(f) == PurePosixPath(f.replace("\\", "/")).parent.parts