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.

1. Read references/se-principles.md to have the principle catalog available
2. Optionally read references/anti-patterns.md if you suspect the changes include areas for improvement
3. 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

Default behavior:

• If on a feature branch: analyze branch commits vs main
• If on main: analyze the last 5 commits
• If the user provides a different scope, use that

Phase 2: Gather Changes

1. Run git log with the determined scope to get the commit list and messages
2. Run git diff for the full diff of the scope
3. If the diff is large (>500 lines), use git diff --stat first, then selectively read the top 3-5 most-changed files
4. Read commit messages carefully -- they contain intent that raw diffs miss
5. Only read changed files. Do not read the entire repo.

Phase 3: Analyze

Identify the dominant pattern -- the single most instructive thing about these changes.