# Challenging Fullstack + Multi-file Benchmark Set (2026-02-26)

Purpose:
- Expose deterministic-tool failures in cross-layer API changes and transactional multi-file edits.

Catalog:
- `datasets/project_benchmarks/challenging_fullstack_multifile_2026-02-26.jsonl`

Challenge classes:
- full-stack API contract evolution
- multi-file transactional refactor
- security policy propagation
- schema migration + rollback
- feature-flag rollout choreography
- SLO-budget-preserving refactors