/blueprint:derive-rules

Extract project decisions from git commit history and codify them as Claude rules. Newer commits override older decisions when conflicts exist.

Use case

Derive implicit project patterns from git history to establish consistent AI-assisted development guidelines.

Usage

:

/blueprint:derive-rules [--since DATE] [--scope SCOPE]

When to Use This Skill

Use this skill when...

Use alternative when...

Want to extract implicit decisions from git history

Creating rules from requirements (use PRDs instead)

Project has significant commit history

New project with little history

Establishing project coding standards

Quick manual rule creation

Context

Git repository: !

git rev-parse --git-dir

Blueprint initialized: !

find docs/blueprint -maxdepth 1 -name 'manifest.json' -type f

Total commits: !

git rev-list --count HEAD

Conventional commits %: !

git log --format="%s"

Existing rules: !

find .claude/rules -name "*.md" -type f

Parameters

Parse

$ARGUMENTS

:

--since DATE

Analyze commits from specific date (e.g.,

--since 2024-01-01

)

--scope SCOPE

Focus on specific area (e.g.,

--scope api

,

--scope testing

)

Execution

Execute the complete git-to-rules derivation workflow:

Step 1: Verify prerequisites

If not a git repository → Error: "This directory is not a git repository"

If Blueprint not initialized → Suggest

/blueprint:init

first

If few commits (< 20) → Warn: "Limited commit history; derived rules may be incomplete"

Step 2: Analyze git history quality

Calculate total commits in scope

Calculate conventional commits percentage

Report quality: Higher % = higher confidence in extracted rules

Parse

--since

and

--scope

flags to determine analysis range

Step 3: Extract decision-bearing commits

Use parallel agents to analyze git history efficiently (see

REFERENCE.md

):

Agent 1

Analyze

refactor:

commits for code style patterns

Agent 2

Analyze

fix:

commits for repeated issue types

Agent 3

Analyze

feat!:

and

BREAKING CHANGE:

commits for architecture decisions

Agent 4

Analyze

chore:

and

build:

commits for tooling decisions

Consolidate findings by domain (code-style, testing, api-design, etc.), chronologically (newest first), and by frequency (most common wins).

Step 4: Resolve conflicts

When multiple commits address the same topic:

Detect conflicts using pattern matching:

git log --format="%H|%ai|%s" | grep "{topic}"

Apply resolution strategy:

Newer overrides older

Latest decision wins
Higher frequency wins: If 5 commits say X and 1 says Y, X wins Breaking changes override : feat!: trumps regular commits Mark overridden decisions as "superseded" with reference to newer decision Confirm significant decisions with user via AskUserQuestion Step 5: Generate rules in .claude/rules/ For each decision, generate rule file using template from REFERENCE.md : Extract source commit, date, type Determine confidence level (High/Medium/Low based on commit frequency and clarity) Generate actionable rule statement Include code examples from commit diffs Reference any superseded earlier decisions Add paths frontmatter when the rule is naturally scoped to specific file types (see REFERENCE.md for suggested patterns per category) Generate separate rule files by category (see REFERENCE.md ): code-style.md , testing-standards.md , api-conventions.md , error-handling.md , dependencies.md , security-practices.md Path-scope rules where appropriate — e.g., testing-standards.md scoped to test files reduces context noise when working on non-test code. Step 6: Handle conflicts with existing rules Check for conflicts with existing rules in .claude/rules/ : If conflicts found → Ask user: Git-derived overrides existing rule, or keep existing? Apply user choice: Update, merge, or keep separate Document conflict resolution in rule file Step 7: Update task registry Update the task registry entry in docs/blueprint/manifest.json : jq --arg now " $( date -u +%Y-%m-%dT%H:%M:%SZ ) " \ --arg sha " $( git rev-parse HEAD 2

/dev/null ) " \ --argjson processed " ${COMMITS_ANALYZED :- 0} " \ --argjson created " ${RULES_DERIVED :- 0} " \ '.task_registry["derive-rules"].last_completed_at = $now | .task_registry["derive-rules"].last_result = "success" | .task_registry["derive-rules"].context.commits_analyzed_up_to = $sha | .task_registry["derive-rules"].stats.runs_total = ((.task_registry["derive-rules"].stats.runs_total // 0) + 1) | .task_registry["derive-rules"].stats.items_processed = $processed | .task_registry["derive-rules"].stats.items_created = $created' \ docs/blueprint/manifest.json

tmp.json && mv tmp.json docs/blueprint/manifest.json Step 8: Update manifest and report Update docs/blueprint/manifest.json with derived rules metadata: timestamp, commits analyzed, rules generated, source commits Generate completion report showing: Commits analyzed (count and date range) Conventional commits percentage Rules generated by category Confidence scores per rule Any conflicts resolved Prompt user for next action: Review rules, execute derived development workflow, or done Agentic Optimizations Context Command Check git status git rev-parse --git-dir 2>/dev/null && echo "YES" || echo "NO" Count total commits git rev-list --count HEAD 2>/dev/null || echo "0" Conventional commits % git log --format="%s" | grep -c "^(feat|fix|refactor)" || echo 0 Extract decision commits git log --format="%H|%s|%b" | grep -E "(always|never|must|prefer)" Fast derivation Use parallel agents (Explore) for multi-domain analysis For git analysis patterns, rule templates, conflict resolution, and detailed procedures, see REFERENCE.md .

blueprint-derive-rules

安装