dotnet-learn-from-fix

name	dotnet:learn-from-fix
description	Extract durable lessons from a just-finished fix — propose CLAUDE.md rule, Iron Law addition, or Solution doc. Use after resolving a surprising/repeatable bug.
argument-hint	<optional: specific fix to learn from>
effort	low

learn-from-fix

Convert a debugging win into institutional memory. Runs after a fix lands so the same bug doesn't reappear.

When to Use

• Just fixed something surprising or non-obvious
• Fix involved a pattern the user would hit again
• Correction of Claude's approach ("don't do X, do Y")
• Discovery of a library/framework gotcha

Skip for trivial fixes (typos, obvious off-by-ones).

Flow

1. Summarize what broke and why in ≤3 sentences
2. Classify the lesson:
   • CLAUDE.md rule — instruction to Claude for future sessions
   • Iron Law candidate — universal enough to become rule #35+
   • Solution doc — concrete problem → fix pattern worth storing
   • Skill reference update — existing pattern file needs a new section
3. Draft the artifact (rule text, solution doc, reference diff)
4. Ask user to confirm before writing

Classification Rubric

Lesson type	Example
CLAUDE.md rule	"Claude should check for sibling files before fixing a bug in a named variant"
Iron Law	"Never use float for money" (this is how Iron Laws get born)
Solution doc	"Adding a NOT NULL column to a large table" → two-phase migration
Reference update	"Add EF .AsSplitQuery() note when .Include count ≥ 3"

Iron Law Candidacy Check

Before promoting to Iron Law (#35+), confirm:

• Applies across ≥3 .NET project types (not blazor-specific)
• Violation is grep-able (programmatic verifier possible)
• Non-compliance has concrete consequences (data loss, security, perf cliff)
• Can be stated in ≤2 sentences

If any fail, demote to CLAUDE.md rule or reference update.

Output

One of:

1. CLAUDE.md patch — diff against the behavioral-instructions section
2. Solution doc — .claude/solutions/{category}/{slug}.md (uses /dotnet:compound format)
3. Skill reference update — diff against plugins/dotnet/skills/<name>/references/*.md
4. Iron Law proposal — drafted rule, with verifier grep pattern, submitted to CLAUDE.md + inject-iron-laws.sh

Integration

/dotnet:work (bug fixed)
        ↓
/dotnet:learn-from-fix → rule / solution / Iron Law candidate
        ↓
/dotnet:compound (if solution doc type)

References

• ${CLAUDE_SKILL_DIR}/references/iron-law-criteria.md — full rubric with examples of accepted/rejected candidates
• ${CLAUDE_SKILL_DIR}/references/rule-writing.md — how to write CLAUDE.md rules: actionable, negated form ("do NOT X — instead Y")
• ${CLAUDE_SKILL_DIR}/references/solution-vs-rule.md — decision tree for classification

Anti-patterns

• Promoting every fix to Iron Law — bar is high
• Writing vague rules ("be more careful") — must be actionable
• Writing rules that duplicate existing Iron Laws
• Not including a verifier (grep pattern) for new Iron Laws