design: multi-file apply semantics (partial success vs fail-fast)

[omsherikar]

Summary

RefactronPipeline.apply processes each file independently: some files may apply fixes while others are blocked. Backup session is created once, but there is no single orchestration policy (transactional batch vs best-effort) documented for users or for rollback UX.

Suggested direction

• Define supported behavior: e.g. best-effort (current) vs --fail-fast stop on first blocked file.
• Ensure backup_session_id and rollback story matches partial applies (document which files are included in backup).
• Optionally add session summary: files_attempted, files_succeeded, files_failed.

Acceptance

• README or docstring for pipeline behavior; tests for fail-fast if implemented.
• No silent data loss: blocked files always recorded in blocked_fixes.

Code

• refactron/core/pipeline.py — apply
• refactron/cli/run.py