[QA] ✅ VERIFICATION PASSED All 66 edge case tests pass successfully. Comprehensive coverage verified: - 17 metrics edge cases (WER/CER with empty, unicode, very long strings) - 13 audio format edge cases (corrupted headers, random bytes, empty data) - 11 schema edge cases (boundary values, unicode, temperature limits) - 12 API endpoint edge cases (malformed JSON, invalid types, wrong methods) - 6 TTS text edge cases (single char, emojis, mixed languages) - 2 error response format tests - 3 stress tests (1000+ operations without crashes) Full test suite: 489/489 tests pass (154s runtime) Edge case tests: 66/66 tests pass (1.3s runtime) No crashes, errors, or security issues detected. Implementation is production-ready. QA report: /tmp/qa-LCA-20.md

## Implementation Complete Added comprehensive edge case tests in `tests/test_edge_cases.py` with 66 new tests covering: ### Metrics Edge Cases (17 tests) - None-like strings, numeric strings, single words - Unicode normalization, very long strings, repeated words - Special characters only, whitespace variations - Empty strings for WER/CER, single characters - RoundtripResult boundary values - Text normalization edge cases ### Audio Format Edge Cases (13 tests) - Empty/short bytes, random bytes - Corrupted WAV headers, partial magic bytes - None filename, missing extension, unknown extension ### Schema Edge Cases (11 tests) - Speed boundaries (0.25, 4.0) - Input length boundaries (4096, 4097 chars) - Unicode/newline/tab input - Temperature boundaries (0.0, 1.0) - Empty transcription response - Optional verbose fields ### API Endpoint Edge Cases (12 tests) - Empty JSON, null values, wrong types - Extra unknown fields, empty filename - Invalid temperatures, health endpoint - Non-existent endpoint, wrong HTTP method - Malformed JSON ### TTS Text Edge Cases (6 tests) - Single character, numbers only, special chars - Emojis, mixed languages, very long words ### Stress Tests (3 tests) - Many WER calculations (1000x) - Growing string lengths - Many format detections (1000x) ## Test Results All 66 new tests pass, and total test suite (489 tests) passes with no crashes. ## Files Changed - tests/test_edge_cases.py (new, 650 lines) ## Verification Ran pytest tests/test_edge_cases.py -v - all 66 tests pass Ran pytest tests/ -v - all 489 tests pass