fix(guard,#17371): kernel drift -- language_info.version compare au niveau major.minor (option 1)

scripts/notebook_tools/check_kernel_drift.py

@@ -7,8 +7,11 @@
 classes observed:
 
   - Kernel change: ``metadata.kernelspec.name`` or
-    ``metadata.language_info.version`` differs (Python 3.11 -> 3.13).
-    Outputs may format ``repr(np.float64(0.9999999999999999))`` instead
+    ``metadata.language_info.version`` differs at major.minor level
+    (Python 3.11 -> 3.13). Patch-only drift (3.13.3 -> 3.13.15) is NOT
+    flagged: the venv patch evolves under the canonical interpreter and
+    never changes repr() semantics (#17371). Outputs may format
+    ``repr(np.float64(0.9999999999999999))`` instead
     of ``[1.0, 1.0, ...]`` even when the cell computes the same values.
   - Float format drift: NumPy 1.x prints ``[1.0, 1.0, 1.0]``; NumPy 2.x
     prints ``[1.0, 0.9999999999999999, 1.0]``. The values are within
@@ -171,13 +174,40 @@ def kernel_info(nb):
     }
 
 
+def _version_prefix(version):
+    """Truncate a language version to its major.minor components (#17371).
+
+    Patch-level drift (3.13.3 -> 3.13.15) is systemic: the project venv
+    evolves under the lane's canonical interpreter, so any fresh
+    re-execution of a notebook whose base stamp is older drifts on the
+    patch component alone (measured 2026-09-22 on #16858: base 3.13.3,
+    venv 3.13.15, 10/10 cells, 0 error). A patch bump does not change
+    repr() semantics; a kernel swap or a major/minor change does. Versions
+    with fewer than two components ("", "3") are returned verbatim. A JSON
+    ``"version": null`` (valid nbformat, which the ``.get("version", "")``
+    default does not cover) is read as the empty version rather than
+    crashing: the guard must emit a finding, never a traceback.
+    """
+    text = str(version or "")
+    parts = text.split(".")
+    return ".".join(parts[:2]) if len(parts) >= 2 else text
+
+
 def diff_kernel(base_info, head_info):
-    """Return a list of human-readable kernel-version drift strings."""
+    """Return a list of human-readable kernel-version drift strings.
+
+    #17371: ``language_info.version`` is compared at major.minor level —
+    patch-only drift is not a kernel regression. The full versions are
+    still shown in the message for diagnosis.
+    """
     diffs = []
-    if base_info["language_version"] != head_info["language_version"]:
+    base_ver = _version_prefix(base_info["language_version"])
+    head_ver = _version_prefix(head_info["language_version"])
+    if base_ver != head_ver:
         diffs.append(
             f"language_info.version: {base_info['language_version']!r} -> "
-            f"{head_info['language_version']!r}"
+            f"{head_info['language_version']!r} "
+            f"(major.minor {base_ver} -> {head_ver})"
         )
     if base_info["kernelspec_name"] != head_info["kernelspec_name"]:
         diffs.append(

scripts/notebook_tools/tests/test_check_kernel_drift.py

@@ -78,6 +78,77 @@ def test_diff_kernel_both_change():
     assert len(diffs) == 1
 
 
+# --- #17371: patch-level language_info.version drift is not a regression ---
+
+
+def test_version_prefix_shapes():
+    assert ckd._version_prefix("3.13.3") == "3.13"
+    assert ckd._version_prefix("3.13.15") == "3.13"
+    assert ckd._version_prefix("3.13.15rc1") == "3.13"
+    assert ckd._version_prefix("3.13") == "3.13"
+    assert ckd._version_prefix("3") == "3"
+    assert ckd._version_prefix("") == ""
+
+
+def test_version_prefix_null_version_does_not_crash():
+    # `"version": null` is valid nbformat: the `.get("version", "")`
+    # extraction default only covers a MISSING key, so the helper received
+    # None and raised AttributeError -- a traceback where the pre-fix
+    # comparison emitted a degraded but handled drift (NanoClaw, 2026-09-22).
+    assert ckd._version_prefix(None) == ""
+
+
+def test_diff_kernel_null_version_vs_version_flagged():
+    a = {"language_version": None, "kernelspec_name": "python3"}
+    b = {"language_version": "3.13.3", "kernelspec_name": "python3"}
+    diffs = ckd.diff_kernel(a, b)
+    assert len(diffs) == 1
+    assert "language_info.version" in diffs[0]
+    assert "None" in diffs[0] and "3.13.3" in diffs[0]
+
+
+def test_diff_kernel_null_version_on_both_sides_not_flagged():
+    a = {"language_version": None, "kernelspec_name": "python3"}
+    b = {"language_version": None, "kernelspec_name": "python3"}
+    assert ckd.diff_kernel(a, b) == []
+
+
+def test_diff_kernel_patch_level_drift_not_flagged():
+    # Measured on #16858: base stamp 3.13.3, fresh re-exec under the
+    # project venv 3.13.15 -- same kernel, same repr() semantics.
+    a = {"language_version": "3.13.3", "kernelspec_name": "python3"}
+    b = {"language_version": "3.13.15", "kernelspec_name": "python3"}
+    assert ckd.diff_kernel(a, b) == []
+
+
+def test_diff_kernel_patch_drift_with_rc_suffix_not_flagged():
+    a = {"language_version": "3.13.3", "kernelspec_name": "python3"}
+    b = {"language_version": "3.13.15rc1", "kernelspec_name": "python3"}
+    assert ckd.diff_kernel(a, b) == []
+
+
+def test_diff_kernel_minor_change_still_flagged():
+    a = {"language_version": "3.11.16", "kernelspec_name": "python3"}
+    b = {"language_version": "3.13.15", "kernelspec_name": "python3"}
+    diffs = ckd.diff_kernel(a, b)
+    assert len(diffs) == 1
+    assert "3.11.16" in diffs[0] and "3.13.15" in diffs[0]
+    assert "3.11 -> 3.13" in diffs[0]
+
+
+def test_diff_kernel_major_change_still_flagged():
+    a = {"language_version": "2.7.18", "kernelspec_name": "python3"}
+    b = {"language_version": "3.13.15", "kernelspec_name": "python3"}
+    diffs = ckd.diff_kernel(a, b)
+    assert len(diffs) == 1
+
+
+def test_diff_kernel_empty_vs_full_version_flagged():
+    a = {"language_version": "", "kernelspec_name": "python3"}
+    b = {"language_version": "3.13.15", "kernelspec_name": "python3"}
+    assert len(ckd.diff_kernel(a, b)) == 1
+
+
 def test_float_signatures_matches_array_shape():
     nb = _nb("python3", "3.13.3",
              ["n=5: distances = [1.0, 0.9999999999999999, 1.0, 1.0, 1.0]\n"])