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Release Notes — v0.4.9

Release Date: 2026-05-13

TaipanStack v0.4.9 achieves the ultimate quality milestone: 100% REAL branch coverage across the entire core without any artificial gaps or bypasses. This release also focuses on critical security hardening for error handling and logging, eliminates concurrency deadlocks in the circuit breaker, and introduces daily micro-chaos testing for state integrity.

🛡️ Security

  • Fix (Medium) — Error Handling Information Leakage: Remedied a vulnerability where internal error state could leak sensitive information during unhandled exception propagation (PR #739).
  • Fix (Medium) — Nested Redaction: Resolved an issue in logging utilities where sensitive data inside nested dictionaries was not properly redacted (PR #730).
  • Hardening — Recursive Redaction: Implemented a more robust, recursive redaction algorithm for complex data structures to ensure PII and secrets are never logged (Commit 84dc56f1).
  • Hardening — Rate Limiter Resilience: Hardened rate_limit.py against type mutation and NaN propagation via enhanced chaos testing (PR #731).

🌊 Resilience

  • Deadlock Elimination: Eliminated a potential lock deadlock vector in the CircuitBreaker concurrency model, significantly improving stability in high-throughput environments (PR #726).
  • Retry Context Integrity: Hardened the Retrier context manager to handle potential type mutations during attempt tracking (PR #719).
  • Chaos Testing Expansion: Introduced daily micro-chaos tests specifically targeting CircuitBreaker and Retry state transitions to prevent silent corruption (PR #714, #711, #710).

⚡ Refactoring & Performance

  • Codebase Sanitization: Removed unused sanitizers, types, and legacy benchmark suites to reduce repository bloat and streamline dependencies (PR #736, #725).
  • Complexity Refactor: Significantly reduced cyclomatic complexity in RetryConfig, HealthPinger, and various core security sanitizers to improve maintainability (PR #728, #717, #713).
  • Dependency Audit: Conducted a comprehensive DevSecOps audit of CI/CD pipelines, enforcing strict performance degradation limits (PR #727, #720, #712).

✅ QA & Testing

  • 100% Genuine Branch Coverage: Achieved true 100% code coverage by eliminating all remaining pragma: no cover bypasses and validating every edge case (PR #738, #724).
  • 1,333 Passing Tests: The test suite now encompasses 1,333 passing tests, fully verified across all supported Python versions (3.11–3.14).
  • Infrastructure Standardization: Synchronized test counts and metadata across all documentation portals to ensure transparency (PR #729, #721).

📚 Documentation

  • Release Synchronization: Synchronized project version and release notes across all documentation portals.
  • Jules Fixes: Integrated various documentation improvements and clarifications (PR #734).