@@ -0,0 +1,77 @@
+r"""W-RE-PARSER-DEOPT-DETACH sentinel — re._parser JIT correctness
+regression discovered via pythia #128 #2 perf seam (generalist
+2026-04-24 22:05Z; supervisor-opened workstream 22:06:56Z).
+
+Workload: re.compile() of patterns containing named groups, hammered
+across the auto-compile threshold so re._parser:Tokenizer.__next + sibling
+parser methods get JIT-compiled by cinderjit.auto().
+
+Observed at HEAD a45aa5b69c (push 50, x86_64 release):
+- After ~1000 iterations the JIT auto-compiles re._parser internals.
+- Subsequent re.compile() calls either:
+  (a) raise AttributeError: 'SubPattern' object has no attribute 'state'
+      (re/_compiler.py:761 reading p.state.groupdict)
+  (b) SIGSEGV (exit code 139)
+- Without JIT (no JIT_ENABLE=1): clean PASS through 2000+ iterations.
+
+Reduction: even a single pattern r'(?P<int>\d+)' is sufficient to
+trigger the crash; diverse-pattern corpus also reproduces.
+
+JIT trace messages preceding the failure (cinderjit.auto() context):
+  Deopt backoff: Tokenizer.__next reached 1000 guard failures, suppressing
+  detaching JIT from Tokenizer.__next
+  Deopt backoff: Tokenizer.match reached 1000 guard failures, suppressing
+  detaching JIT from Tokenizer.match
+  Skipping compilation of re._parser:SubPattern.__init__
+    (all STORE_ATTRs generic, no specialised LOAD_ATTRs)
+  Deopt backoff: SubPattern.__getitem__ reached 1000 guard failures
+  Deopt backoff: SubPattern.getwidth reached 1000 guard failures
+  Skipping compilation of re._parser:State.__init__
+    (all STORE_ATTRs generic, no specialised LOAD_ATTRs)
+
+Two failure modes (AttributeError vs SIGSEGV) suggest UAF / corrupted
+attribute storage post-deopt-detach rather than a missing __init__ run
+(theologian 22:06:38Z structural read).
+
+W-RE-PARSER-DEOPT-DETACH workstream open per supervisor 22:06:56Z;
+investigation pending. cinderx_dev oracle deferred until devgpu004
+SSH-2FA infra restored.
+
+This test is currently SKIPPED — uncomment the workload to reproduce
+the SIGSEGV / AttributeError. It exists as a sentinel: when
+W-RE-PARSER-DEOPT-DETACH is fixed, un-skip and add as regression
+gate.
+"""
+
+import unittest
+
+
+class TestREParserJITCrash(unittest.TestCase):
+    def setUp(self):
+        try:
+            import _cinderx  # noqa: F401
+            import cinderjit
+            self.cinderjit = cinderjit
+            cinderjit.auto()
+        except ImportError:
+            self.skipTest("cinderjit not available")
+
+    @unittest.skip(
+        "W-RE-PARSER-DEOPT-DETACH sentinel — uncomment to reproduce "
+        "AttributeError/SIGSEGV; un-skip when bug is fixed (sentinel "
+        "preserved per W-A4-mid sentinel precedent)."
+    )
+    def test_named_group_compile_repeated(self):
+        """Reduced repro: single named-group pattern, hammered past
+        the auto-compile threshold so re._parser:Tokenizer.__next +
+        SubPattern.__getitem__ + .getwidth all hit deopt-backoff +
+        detach. Subsequent re.compile() either crashes or raises
+        AttributeError on SubPattern.state."""
+        import re
+        for _ in range(2000):
+            re.compile(r'(?P<int>\d+)')
+            re.purge()
+
+
+if __name__ == '__main__':
+    unittest.main()