mementomori-co

Lesson Learned — Development skill for Claude Code

Development community

Write a post-mortem of a mistake into lessons/.

How to install Lesson Learned

Installs to ~/.claude/commands/mementomori-co-maker-mastery-lesson-learned.md

Terminal

mkdir -p ~/.claude/commands && curl -fsSL https://raw.githubusercontent.com/mementomori-co/maker-mastery/HEAD/.claude/commands/lesson-learned.md -o ~/.claude/commands/mementomori-co-maker-mastery-lesson-learned.md

Restart Claude Code, or start a new session, for it to be picked up.

What Lesson Learned does

description: Write a post-mortem of a mistake into lessons/

Create lessons\YYYY-MM-DD-.md as a table: what happened | root cause | rule now, plus where that rule now lives (CLAUDE.md, an agent, a skill, a checklist or a tool). Use today's date from the PC clock. Keep it free of personal details: no names, accounts, addresses or private project names. If a new rule is needed, propose the exact CLAUDE.md line and add it.

Alternatives in Development

Pre Mortem — Run pre-mortem risk analysis on PRDs and launch plans 7.8k ★
Evolving Agents — A director agent that learns how your team works: it plans by walking your CLAUDE.md and memory as linked stat 453 ★
Check Setup.En — Top-level alias — see lesson/check-setup.en.md for the full body 347 ★