- Implement per-ticker commits to ensure atomic operations per data source
- Add rollback on exception to prevent partial data corruption
- Add _safe_float() and _safe_int() helper methods for defensive type conversion
- Validate column count after DataFrame reset to catch schema issues early
- Skip records with missing essential values (close price) with debug logging
- Remove final db.commit() since commits now happen per ticker in the loop
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>