GHCP - Run: Ex15 Resilience Sweep

[DWSPalmer]

Title: GHCP - Run: Ex15 Resilience Sweep

Summary

• Hardened mutation flows in samples/book-app-project/books.py with rollback-on-persist-failure behavior
• Added failure-path tests for mark_as_read and remove_book rollback semantics
• Added run-level resilience sweep notes in ai-track-docs/run-resilience-sweep.md

Evidence

• Validation command:
  • cd samples/book-app-project
  • . .venv/bin/activate
  • python -m pytest tests/test_books.py -q
• Key output:
  • 17 passed in 0.16s

Risk and Rollback

• Risk: low
• Rollback: revert commit a938143

Track

• Level: Run
• Exercise: Ex15