fix(5.4): add cannot/can't negation patterns (R3 finding)

GPT-5.4 R3 found 'cannot confirm' and 'can't confirm' bypassed negation.
Added \bcannot\b and \bcan'?t\b to negative keyword regex.
3 new tests: cannot_confirm, cant_confirm, cant_proceed_no_apostrophe.

47 confirmation tests; 1,517 total pass, 127 skipped.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: Brian Krafft

openspace/skill_engine/evolution/confirmation.py

@@ -154,14 +154,16 @@ def parse_confirmation(response: str) -> bool:
     # confirm/reject/skip use stem-style matching so that common
     # LLM variants like "confirmed", "rejected", "skipping" still
     # parse correctly.
-    # Negation words (not/never/don't) catch "do not confirm" patterns.
+    # Negation words catch "do not confirm", "cannot confirm", "can't proceed".
     _wb = re.search  # shorthand
     if (
         any(w in response for w in ('"proceed": false', "proceed: false"))
         or _wb(r"\bno\b", response)
         or _wb(r"\bnot\b", response)
         or _wb(r"\bnever\b", response)
         or _wb(r"\bdon'?t\b", response)
+        or _wb(r"\bcannot\b", response)
+        or _wb(r"\bcan'?t\b", response)
         or _wb(r"\breject\w*\b", response)
         or _wb(r"\bskip\w*\b", response)
     ):

tests/test_evolution_confirmation.py

@@ -126,6 +126,18 @@ def test_dont_proceed(self):
         """'don't proceed' — contraction negation."""
         assert parse_confirmation("don't proceed with this change") is False
 
+    def test_cannot_confirm(self):
+        """'cannot confirm' — 'cannot' is a negation keyword."""
+        assert parse_confirmation("cannot confirm this evolution") is False
+
+    def test_cant_confirm(self):
+        """'can't confirm' — contraction of cannot."""
+        assert parse_confirmation("can't confirm this change") is False
+
+    def test_cant_proceed_no_apostrophe(self):
+        """'cant proceed' — informal spelling without apostrophe."""
+        assert parse_confirmation("cant proceed with evolution") is False
+
     def test_negation_with_json_example(self):
         """Negation in prose even with JSON example should fail-safe."""
         assert parse_confirmation('do not proceed. Example JSON: {"proceed": true}') is False