Implemented a validation step to confirm that grammatical changes do not change substantive meaning

tests/test_semantic_validation.py

@@ -0,0 +1,165 @@
+import pytest
+
+from audita.errors import AuditaLLMError
+from audita.semantic_validation import select_grammar_validation_candidates
+from audita.semantic_validation import filter_with_grammar_validations
+from audita.protection import ProtectedVocabulary
+from audita.schemas import (
+    CorrectionCandidate,
+    GrammarValidationDecision,
+    GrammarValidationSet,
+    parse_glossary_yaml,
+    parse_transcript_json,
+)
+
+
+def _transcript():
+    return parse_transcript_json(
+        """
+        [
+          {"id": 1, "speaker": "Eric", "start": 0.0, "end": 1.0, "text": "he became visible and then gestures arrived"}
+        ]
+        """
+    )
+
+
+def _vocabulary():
+    glossary = parse_glossary_yaml(
+        """
+        glossary:
+          - name: "Jesters"
+            category: faction
+            summary: "The Jesters are a faction."
+        """
+    )
+    return ProtectedVocabulary.from_glossary(glossary)
+
+
+def test_protected_vocabulary_correction_bypasses_validation():
+    correction = CorrectionCandidate(
+        id=1,
+        original_text="gestures",
+        corrected_text="Jesters",
+        confidence=0.95,
+    )
+
+    candidates, bypassed_count = select_grammar_validation_candidates(
+        _transcript(),
+        [correction],
+        confidence_threshold=0.8,
+        replacement_mode="require_unique",
+        protected_vocabulary=_vocabulary(),
+    )
+
+    assert candidates == []
+    assert bypassed_count == 1
+
+
+def test_capitalization_only_correction_bypasses_validation():
+    correction = CorrectionCandidate(
+        id=1,
+        original_text="he",
+        corrected_text="He",
+        confidence=0.95,
+    )
+
+    candidates, bypassed_count = select_grammar_validation_candidates(
+        _transcript(),
+        [correction],
+        confidence_threshold=0.8,
+        replacement_mode="require_unique",
+        protected_vocabulary=_vocabulary(),
+    )
+
+    assert candidates == []
+    assert bypassed_count == 1
+
+
+def test_punctuation_only_correction_bypasses_validation():
+    correction = CorrectionCandidate(
+        id=1,
+        original_text="visible",
+        corrected_text="visible.",
+        confidence=0.95,
+    )
+
+    candidates, bypassed_count = select_grammar_validation_candidates(
+        _transcript(),
+        [correction],
+        confidence_threshold=0.8,
+        replacement_mode="require_unique",
+        protected_vocabulary=_vocabulary(),
+    )
+
+    assert candidates == []
+    assert bypassed_count == 1
+
+
+def test_meaning_sensitive_substitution_requires_validation():
+    correction = CorrectionCandidate(
+        id=1,
+        original_text="visible",
+        corrected_text="invisible",
+        confidence=0.95,
+    )
+
+    candidates, bypassed_count = select_grammar_validation_candidates(
+        _transcript(),
+        [correction],
+        confidence_threshold=0.8,
+        replacement_mode="require_unique",
+        protected_vocabulary=_vocabulary(),
+    )
+
+    assert len(candidates) == 1
+    assert candidates[0].correction_index == 0
+    assert candidates[0].original_segment_text == "he became visible and then gestures arrived"
+    assert candidates[0].corrected_segment_text == "he became invisible and then gestures arrived"
+    assert bypassed_count == 0
+
+
+def test_validation_rejects_duplicate_and_unknown_decisions():
+    correction = CorrectionCandidate(
+        id=1,
+        original_text="visible",
+        corrected_text="invisible",
+        confidence=0.95,
+    )
+    candidates, _ = select_grammar_validation_candidates(
+        _transcript(),
+        [correction],
+        confidence_threshold=0.8,
+        replacement_mode="require_unique",
+        protected_vocabulary=_vocabulary(),
+    )
+    decision = GrammarValidationDecision(
+        correction_index=0,
+        is_meaning_preserving=True,
+        confidence=0.95,
+        reason="Preserves meaning.",
+    )
+
+    with pytest.raises(AuditaLLMError):
+        filter_with_grammar_validations(
+            [correction],
+            candidates,
+            GrammarValidationSet(validations=[decision, decision]),
+            confidence_threshold=0.8,
+        )
+
+    with pytest.raises(AuditaLLMError):
+        filter_with_grammar_validations(
+            [correction],
+            candidates,
+            GrammarValidationSet(
+                validations=[
+                    GrammarValidationDecision(
+                        correction_index=99,
+                        is_meaning_preserving=True,
+                        confidence=0.95,
+                        reason="Unknown.",
+                    )
+                ]
+            ),
+            confidence_threshold=0.8,
+        )