Handle negated pain mentions in injury keyword detection

"about my calves, nothing hurts" matched the "hurts" keyword, forced
pain_or_injury to "yes", and the muscle word "calves" then synthesized
a phantom gastrocnemius pain issue. Strip negated injury mentions
("no pain", "nothing hurts", "doesn't hurt", "pain free") before the
keyword check; positive mentions elsewhere in the text still force
"yes" ("no pain except my knee hurts").

tests/test_parser.py

@@ -629,6 +629,40 @@ class ParserTest(unittest.TestCase):
         self.assertIn("event=parser_validated_json", output)
         self.assertIn("event=parser_normalized_json", output)
 
+    def test_negated_pain_mentions_do_not_force_injury(self):
+        for text in (
+            "about my calves, nothing hurts",
+            "60 minutes, slept great, feeling strong, no pain",
+            "shoulder doesn't hurt anymore",
+            "pain free today",
+        ):
+            parsed = ParsedCheckIn(
+                check_in=CheckIn(raw_text=text, pain_or_injury="no")
+            )
+
+            normalized = normalize_parsed_check_in(parsed)
+
+            self.assertEqual(
+                normalized.check_in.pain_or_injury, "no", msg=repr(text)
+            )
+            self.assertEqual(normalized.check_in.pain_issues, [], msg=repr(text))
+
+    def test_positive_pain_mentions_still_force_injury(self):
+        for text in (
+            "my tricep aches a bit",
+            "no pain except my knee hurts",
+            "left shoulder hurts but back doesn't hurt",
+        ):
+            parsed = ParsedCheckIn(
+                check_in=CheckIn(raw_text=text, pain_or_injury="no")
+            )
+
+            normalized = normalize_parsed_check_in(parsed)
+
+            self.assertEqual(
+                normalized.check_in.pain_or_injury, "yes", msg=repr(text)
+            )
+
     def test_parse_model_response_drops_training_actions(self):
         response = json.dumps(
             {

training_coach/parser.py

@@ -331,8 +331,25 @@ def _infer_sleep_quality_from_text(text: str):
     return None
 
 
+# Negation word followed within a few words by an injury keyword, e.g.
+# "no pain", "nothing hurts", "doesn't hurt", "never injured".
+_NEGATED_INJURY_PATTERN = re.compile(
+    r"\b(?:no|not|nothing|never|without|zero|don'?t|doesn'?t|isn'?t|aren'?t)\b"
+    r"(?:\W+\w+){0,3}?\W*"
+    r"\b(?:ache|aches|aching|hurt|hurts|hurting|injur\w*|pain\w*|"
+    r"sore\w*|strain\w*|pull\w*|tear\w*|tore|torn)\b",
+    re.IGNORECASE,
+)
+_PAIN_FREE_PATTERN = re.compile(r"\bpain[- ]?free\b", re.IGNORECASE)
+
+
+def _strip_negated_injury_mentions(text: str) -> str:
+    text = _NEGATED_INJURY_PATTERN.sub(" ", text)
+    return _PAIN_FREE_PATTERN.sub(" ", text)
+
+
 def _mentions_injury(text: str) -> bool:
-    return _contains_keyword(text, INJURY_KEYWORDS)
+    return _contains_keyword(_strip_negated_injury_mentions(text), INJURY_KEYWORDS)
 
 
 def _known_check_in_fields(check_in: CheckIn) -> set[str]: