[luuuc]

Summary

Two defects found while running the shipped binary end-to-end: brain init scaffolds a directory git cannot carry faithfully, and the layer classifier misfiles decisions and lessons.

Changes

init — git hygiene

• Writes .brain/.gitignore covering *.lock. Lock files (effectiveness/.lock, trust/trust.yml.lock) are flock targets holding no memory, so committing one shipped another machine's runtime state to everyone who clones.
• Writes a .gitkeep in each layer directory. git carries files, not directories, so every empty layer vanished on the way through a commit and created facts/ was a promise git silently broke.
• ensureConfig generalises to ensureFile, keeping the O_EXCL write so a second init never clobbers a file you edited.

engine — classification

• "We chose Go over Rust for the CLI" filed as a fact. The only decision signal for that verb was "chose to", but the object of a choice is usually the thing chosen. Broadened to "chose ", plus "picked " and "went with".
• "Never run migrations without a backup" filed as a correction. It is a lesson. Corrections now key on overriding the tool's behaviour ("stop ", "override", "don't flag", "do not suggest"); bare prohibitions fall through to lessons.

Architecture Highlights

Corrections and lessons have opposite lifetimes: a lesson retires after a clean streak, a correction is permanent and immutable (.doc/definition/03-data-model.md). Filing a lesson as a correction creates a rule that can never be forgotten — the failure brAIn exists to avoid — so an ambiguous prohibition now resolves to the layer that can retire.

Neither .gitignore nor .gitkeep is load-bearing: every write path already creates its own parent, and commands work fine against a .brain/ missing its empty directories. This only makes a committed .brain/ match the one init reports creating.

Test Plan

• .gitignore covers both lock names, verified through a real git add -A — lock files unstaged, memory files staged
• Every layer directory has something staged after a commit, so a clone keeps the tree
• A second init leaves an edited .gitignore alone
• The two real-world misfires assert their corrected layers; the five prescriptive-rule cases moved from correction to lesson
• make ci passes (build + test + lint, 0 issues)
• Manual end-to-end: init → three remember calls land in decisions/, lessons/, corrections/