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Lesson Ledger

The lesson ledger preserves lessons that should influence future implementation and review.

Lessons are reusable when they name a failure pattern, an evidence source, and a future behavior change.

Repeated mistakes are expensive. Lessons make review memory visible before future tasks start.

  • Generated lessons
  • Review summaries
  • Source task history
  • Harness docs

Phase 1 exposed lessons around CRLF-sensitive tests, generated-summary self-reference, PII sentinel behavior, explicit harness contracts, and agent coordination.

Lessons should be promoted from observation to accepted rule only when they are backed by task or review evidence.

  • Repeated failure patterns
  • Testing lessons
  • Code review lessons
  • Agent coordination lessons
  • Safe source and export boundaries
  • Whether a lesson is still relevant after Phase 2 architecture changes
  • Whether future tests cover the failure mode
  • Whether a lesson should become a standard harness rule

Use docs/history-templates/lesson-record.template.md for individual lesson records.