Make code_tutor OSError fingerprint test Python-version-robust

test_codebase_fingerprint_stat_oserror_raises passed on 3.14 but failed
on CI's 3.11: there Path.is_file() itself calls stat() and re-raises an
OSError without a recognized errno, so the injected error escaped before
the loop reached the guarded path.stat() call. Force is_file() True for
the target (without calling stat) so the explicit fingerprint-time stat()
deterministically raises and hits the except OSError branch on every
Python version. Verified passing on 3.11.11 and 3.14.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017RRCdR4D8SaVrN2xraMQxM

docs/superpowers/evidence/code-tutor-test-version-fix-2026-07-11.json

@@ -0,0 +1,30 @@
+{
+  "intent": "Fix a Python-version-fragile code_tutor test so testsAndMisc CI (Python 3.11) passes: the codebase_fingerprint OSError-branch test passed on 3.14 but failed on 3.11.",
+  "scope": [
+    "python_pkg/code_tutor/tests/test_analyzer.py",
+    "Non-goal: any change to _analyzer.py source (behavior unchanged)."
+  ],
+  "changes": [
+    "test_codebase_fingerprint_stat_oserror_raises now patches Path.is_file to return True for the target file (without calling stat) in addition to patching Path.stat to raise, so the loop deterministically reaches the guarded path.stat() call and hits the `except OSError` branch on every Python version.",
+    "Root cause: on 3.11/3.12 Path.is_file() calls stat() and re-raises OSErrors without a recognized errno, so the injected error escaped before the guarded stat() was reached; on 3.14 is_file() uses os.path.isfile and did not."
+  ],
+  "verification": [
+    {
+      "command": "python3.11 -m pytest test_codebase_fingerprint_stat_oserror_raises -o addopts=''",
+      "result": "pass",
+      "evidence": "1 passed on 3.11.11 (the CI version that previously failed)"
+    },
+    {
+      "command": "python -m pytest test_analyzer.py::...stat_oserror_raises --cov=python_pkg.code_tutor._analyzer",
+      "result": "pass",
+      "evidence": "1 passed on 3.14; _analyzer.py lines 386-387 (except OSError branch) covered"
+    }
+  ],
+  "risks": [
+    "Patching is_file globally could mask a real is_file bug, but the mock delegates to the real is_file for all non-target paths."
+  ],
+  "rollback": [
+    "git revert the commit; the prior test still covers the branch on 3.14 only.",
+    "After rollback, re-run on 3.11 to confirm the flake returns."
+  ]
+}

python_pkg/code_tutor/tests/test_analyzer.py

@@ -422,12 +422,15 @@ def test_code_item_defaults() -> None:
 def test_codebase_fingerprint_stat_oserror_raises(tmp_path: Path) -> None:
     """Skip a file whose ``stat`` raises ``OSError`` (except branch).
 
-    On this Python ``Path.is_file`` uses ``os.path.isfile`` rather than
-    ``Path.stat``, so a stat that always fails for the source file reaches
-    the ``except OSError`` handler that drops the unreadable entry.
+    ``is_file()`` is forced True for the target so the loop reaches the
+    explicit ``path.stat()`` at fingerprint time; that stat then raises and
+    the ``except OSError`` handler drops the unreadable entry.  Patching both
+    keeps this deterministic across Python versions (on some, ``is_file``
+    itself calls ``stat`` and would otherwise re-raise before line reached).
     """
     (tmp_path / "source.py").write_text("x = 1", encoding="utf-8")
     real_stat = Path.stat
+    real_is_file = Path.is_file
 
     def failing_stat(self: Path, **kwargs: object) -> object:
         """Raise for the target file, delegate to the real stat otherwise."""
@@ -436,7 +439,14 @@ def test_codebase_fingerprint_stat_oserror_raises(tmp_path: Path) -> None:
             raise OSError(msg)
         return real_stat(self, **kwargs)
 
-    with patch.object(Path, "stat", failing_stat):
+    def always_file(self: Path) -> bool:
+        """Report the target as a regular file without calling stat."""
+        return str(self).endswith("source.py") or real_is_file(self)
+
+    with (
+        patch.object(Path, "stat", failing_stat),
+        patch.object(Path, "is_file", always_file),
+    ):
         result = codebase_fingerprint(tmp_path)
 
     assert len(result) == 16