Quality cleanup refactoring

Made-with: Cursor

_docs/04_refactoring/01-quality-cleanup/execution_log.md

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+# Execution Log
+
+**Run**: 01-quality-cleanup
+**Date**: 2026-04-13
+
+## Summary
+
+| Metric | Value |
+|--------|-------|
+| Total tasks | 3 |
+| Batches | 2 |
+| Total changes | 10 (C01–C10) |
+| Files modified | 7 |
+| Tests before | 18 passed |
+| Tests after | 18 passed |
+
+## Batches
+
+### Batch 4: Crypto + Thread Safety (parallel)
+- **Tasks**: 06_refactor_crypto_uploads, 07_refactor_thread_safety
+- **Verdict**: PASS
+- **Report**: `_docs/03_implementation/batch_04_report.md`
+
+### Batch 5: Cleanup (sequential, depended on batch 4)
+- **Tasks**: 08_refactor_cleanup
+- **Verdict**: PASS
+- **Report**: `_docs/03_implementation/batch_05_report.md`
+
+## Files Modified
+
+| File | Changes |
+|------|---------|
+| security.pyx | C03: Library PKCS7 unpadder |
+| binary_split.py | C04: Streaming PKCS7 unpadder |
+| api_client.pyx | C09: CDN upload check, C10: error propagation, C07: dead methods removed |
+| api_client.pxd | C07: dead declarations removed |
+| main.py | C01: thread-safe singleton, C02: unlock state holder, C06: log os.remove |
+| constants.pyx | C05: LOG_DIR env var, C08: dead constants removed, dead import removed |
+| constants.pxd | C08: dead declarations removed |
+
+## Blocked / Failed
+
+None.
+
+## Tracker Status
+
+Jira not authenticated — task statuses not updated. Pending transitions:
+- 06_refactor_crypto_uploads → Done
+- 07_refactor_thread_safety → Done
+- 08_refactor_cleanup → Done