Lesson Learned

This takes your recent git changes and extracts the actual software engineering principle at work. You ask "what's the lesson here?" after merging a feature branch or finishing a refactor, and it diffs your commits, reads the messages, and mirrors back the pattern you just demonstrated. It references a principles catalog to name what you did (separation of concerns, defensive copying, whatever), then connects it to the specific files you changed. The format is tight: what happened in the code, the principle at work, why it matters, and a takeaway for next time. It's reflective, not prescriptive. If your changes are trivial, it'll say so instead of inventing lessons. Good for teams that want to turn everyday work into shared learning without the overhead of retrospectives.

skills.sh installs: 3K
GitHub stars: 2.7K
last updated: Aug 21, 2026

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Install

$ npx -y skills add softaworks/agent-toolkit --skill lesson-learned --agent claude-code

Installs into .claude/skills of the current project.

Files

Lesson Learned

Extract specific, grounded software engineering lessons from actual code changes. Not a lecture -- a mirror. Show the user what their code already demonstrates.

Before You Begin

Load the principles reference first.

Read references/se-principles.md to have the principle catalog available
Optionally read references/anti-patterns.md if you suspect the changes include areas for improvement
Determine the scope of analysis (see Phase 1)

Do not proceed until you've loaded at least se-principles.md.

Phase 1: Determine Scope

Ask the user or infer from context what to analyze.

Scope	Git Commands	When to Use
Feature branch	`git log main..HEAD --oneline` + `git diff main...HEAD`	User is on a non-main branch (default)
Last N commits	`git log --oneline -N` + `git diff HEAD~N..HEAD`	User specifies a range, or on main (default N=5)
Specific commit	`git show <sha>`	User references a specific commit
Working changes	`git diff` + `git diff --cached`	User says "what about these changes?" before committing