Extract Rules

Extract Rules

Analyzes existing codebase to identify what Claude would get wrong without project-specific guidance, extracting coding rules and domain knowledge as structured markdown documentation for AI agents.

Usage

/extract-rules                      # Extract rules from codebase (initial)
/extract-rules --update             # Re-scan and add new patterns (preserve existing)
/extract-rules --restructure        # Re-analyze, reorganize structure, merge existing rules
/extract-rules --from-conversation              # Extract from current session (latest)
/extract-rules --from-conversation <session-id> # Extract from a specific session
/extract-rules --from-pr 123                   # PR in current repo
/extract-rules --from-pr owner/repo#123        # PR in another repo (URL form also accepted)
/extract-rules --from-pr 100..110              # PR range (current repo)
/extract-rules --from-pr owner/repo#100..110   # PR range (another repo)
/extract-rules --compact                       # Compact all over-threshold rules files (output_dir/**/*.md)
/extract-rules --compact path/to/file.md ...   # Compact specific files (caller passes explicit paths)
/extract-rules --realign                       # Re-judge every rule file under output_dir against current criteria
/extract-rules --realign path/to/file.md ...   # Re-judge only the named files
/extract-rules --apply-conversation-candidates <path>  # Apply pre-scanned rule candidates (Step C5 only; orchestrator sub-skill)
# Multiple specs allowed (space-separated) → cross-analysis detects org-wide principles

Change-origin flags: extract-rules scopes a change-based extraction only from a conversation session (--from-conversation) or a PR (--from-pr) — it has no diff-base / commit-sha origin argument. A --base-commit <sha> (or similar diff-range) argument belongs to diff-scoped reviewer skills, not here; passing one is unsupported. Use --from-conversation / --from-pr for change-based extraction, or no flag for a full-codebase scan.

Configuration

Settings file: extract-rules.local.md (YAML frontmatter only, no markdown body)

• Project-level: .claude/extract-rules.local.md (takes precedence)
• User-level: ~/.claude/extract-rules.local.md

---
target_dirs:
  - .
exclude_dirs:
  - .git
  - .claude
exclude_patterns:
  - "*.generated.ts"
output_dir: .claude/rules
examples_output_dir: .claude/rules-extras
staging_output_dir: .claude/rules-staging
language: ja
split_output: true
resolve_references: true
compaction_threshold: 40000
min_cluster_size: 3
---

Output Structure

Three output directories are involved: output_dir for rule files (.md / .local.md), examples_output_dir for .examples.md files, and staging_output_dir for staged 1st-observation project-level patterns from incremental modes. The paths: frontmatter on rule files is preserved as a human-facing category-scope hint — its loader-side semantics is not empirically verified, and the actual auto-load boundary is determined by directory placement only.

Default (split_output: true):

.claude/rules/                     # output_dir (inside auto-load scope)
├── languages/
│   ├── typescript.md              # Principles only (portable)
│   └── typescript.local.md        # Project-specific patterns only
├── frameworks/
│   ├── react.md                   # Principles only (portable)
│   └── react.local.md             # Project-specific patterns only
└── project.md                     # Always single file (no split)

.claude/rules-extras/              # examples_output_dir (outside auto-load scope)
├── languages/
│   └── typescript.examples.md     # Examples for both
├── frameworks/
│   └── react.examples.md          # Examples for both
└── project.examples.md            # Examples

.claude/rules-staging/             # staging_output_dir (outside auto-load scope)
└── project.staging.local.md       # 1st-observation project-level candidates (incremental modes only)

Principles (portable across projects) and Project-specific patterns (local) are separated by default.

Hybrid mode (split_output: false):

.claude/rules/                     # output_dir (inside auto-load scope)
├── languages/
│   └── typescript.md              # Principles + Project-specific patterns
├── frameworks/
│   └── react.md                   # Principles + Project-specific patterns
└── project.md                     # Domain, architecture, conventions

.claude/rules-extras/              # examples_output_dir (outside auto-load scope)
├── languages/
│   └── typescript.examples.md     # Examples
├── frameworks/
│   └── react.examples.md          # Examples
└── project.examples.md            # Examples

.claude/rules-staging/             # staging_output_dir (outside auto-load scope)
└── project.staging.local.md       # 1st-observation project-level candidates (incremental modes only)

Layered frameworks (Rails, Django, Spring, etc.): When a framework has distinct architectural layers, generate layer-specific files:

• <framework>.md — Cross-layer rules (no paths: or broad scope)
• <framework>-<layer>.md — Layer-specific rules with scoped paths: (e.g., app/models/**)
• In split mode, both cross-layer and layer-specific files get .local.md counterparts

Integration libraries (Inertia, Pundit, Devise, Turbo, etc.): When integration libraries are detected alongside a layered framework:

• integrations/<framework>-<integration>.md — Integration-specific rules
• Separated from layer files into dedicated integrations/ directory
• In split mode, integration files also get .local.md counterparts

Format switching: Run --restructure after changing split_output setting to switch between split and hybrid formats.

Dispatch authorization

This skill's procedure dispatches subagents, so invoking the skill is the request to use that mechanism: an ambient instruction allowing subagent dispatch only when the user asked for it — a permission-shaped restriction — is already satisfied by this invocation. Do not ask the user to re-confirm the dispatch, and do not silently substitute inline execution for a dispatch this procedure specifies. Only two things justify that substitution: technical availability (the dispatch tool is not present and callable on the current tool surface), and an explicit contract term from the caller bounding this skill to its own thread. A permission-shaped restriction is neither.

Processing Flow

Mode Detection

Check arguments to determine mode:

• No arguments → Full Extraction Mode (Step 1-7)
• --update → Update Mode (Step U1-U6)
• --restructure → Restructure Mode (Step R1-R5)
• --from-conversation [session-id] → Conversation Extraction Mode (Step C1-C5)
• --compact [<paths>] → Compaction Mode (Step CP1-CP5)
• --realign [<paths>] → Realign Mode (Step RA1-RA5)
• --from-pr <number|owner/repo#number|range> [...] → PR Review Extraction Mode (Step P1-P5)
• --apply-conversation-candidates <path> → Conversation Candidate Apply Mode (Step A1-A2)

Full Extraction Mode

Step 1: Load Settings

Search for extract-rules.local.md:

1. Project-level: .claude/extract-rules.local.md
2. User-level: ~/.claude/extract-rules.local.md

Priority:

• If both exist, use project-level only
• If only one exists, use that file
• If neither exists, use default settings

Extract settings (target_dirs, exclude_dirs, exclude_patterns, output_dir, examples_output_dir, staging_output_dir, language, split_output, resolve_references, compaction_threshold) from the config file. See Configuration section above for defaults.

language resolution: skill config → Claude Code settings (~/.claude/settings.json language field) → default ja

Step 2: Detect Project Type

Detect project language and framework:

1. Detect languages by config files (package.json, tsconfig.json, pyproject.toml, go.mod, Cargo.toml, Gemfile, pom.xml, etc.) and file extensions (.ts/.tsx, .py, .go, .rb, etc.)

2. Detect frameworks by their config files (e.g., next.config.*, playwright.config.*) and dependencies in package manifests.

3. Detect architectural layers (for layered frameworks): If a framework has distinct layers with separate directories (e.g., Rails: app/models/, app/controllers/; Django: models.py, views.py), detect them for layer-specific rule files. Only split when corresponding directories actually exist.

4. Detect integration libraries (for layered frameworks): Read references/integration-criteria.md for detection rules and classification criteria.

Output: List of detected languages, frameworks, architectural layers, and integration libraries

Step 3: Collect Sample Files

Collect target files for analysis:

1. Get git-tracked files using git ls-files (respects .gitignore). If not a git repo, fall back to Glob with manual exclusions from settings.
2. Filter by target_dirs, exclude_dirs, exclude_patterns, and detected language extensions
3. Sample 10-15 files per category, distributed across directories for representative coverage. Large projects (100+): prioritize directory diversity. Small projects (<10): analyze all files.

Step 4: Analyze by Category

Read references/extraction-criteria.md before proceeding to understand the classification criteria. The core question for every pattern is: "Would Claude produce something different without knowing this?" — extract only what fills the gap between Claude's general knowledge and this project's actual conventions.

For each detected language, framework, and integration library:

1. Use Grep/Read to collect relevant code patterns

1.5. Separate integration-specific patterns (for layered frameworks with integrations): See references/integration-criteria.md "Pattern routing" section.

2. Classify each pattern (see references/extraction-criteria.md):

   • General style choice (uses only language built-ins) → Abstract principle + hints
   • Project-defined symbol (types, functions, hooks defined in project) → Include concrete example

3. For general style patterns:

   • Group related patterns (e.g., "prefer const", "avoid mutations", "use spread" → Immutability)
   • Formulate as principle with parenthetical implementation hints (2-4 keywords)

4. For project-specific patterns:

   • Extract only the minimal signature (type definition, function signature, or API combination)
   • Format as one line: signature - brief context (2-5 words)
   • Avoid multi-line code blocks

5. Apply AI judgment to determine which patterns meet the extraction criteria (see references/extraction-criteria.md)

Determine appropriate detection methods based on language and project structure.

Step 5: Analyze Documentation and Existing Rules

Also analyze non-code documentation:

• README.md
• CONTRIBUTING.md
• PR templates
• Existing CLAUDE.md

Extract explicit coding rules and guidelines from these documents.

Deduplication check: Read any files under .claude/rules/ to build a set of already-documented rules. Rules extracted in Step 4 that overlap with these existing rules should be skipped. Note: CLAUDE.md is NOT a deduplication source — rules should exist in .claude/rules/ even if also mentioned in CLAUDE.md. This check applies to all modes (Full Extraction, Update, Conversation, Conversation Candidate Apply, PR Review).

Step 6: Generate Output

Read references/security.md before generating output to ensure sensitive information is not included.

1. Check if output_dir exists

   • If exists: Error "Output directory already exists. Use --restructure to reorganize, --update to add new patterns, or delete the directory manually to start fresh."
   • If not exists: Create output_dir. Also create examples_output_dir if it differs from output_dir and does not exist yet (when both resolve to the same path the single directory created above is reused).

2. Generate rule files per category. Rule files (<name>.md and <name>.local.md) are written under output_dir; <name>.examples.md files are written under examples_output_dir.

   • languages/<lang>.md for language-specific rules (under output_dir)
   • frameworks/<framework>.md for framework-specific rules (under output_dir)
   • project.md for project-specific rules (under output_dir)
   • Layered frameworks: <framework>.md (cross-layer) + <framework>-<layer>.md per detected layer with scoped paths:
   • Integration libraries: See references/integration-criteria.md "Output structure" section.

   By default (split_output: true): Generate 3 files per category (except project which gets 2):

   • <output_dir>/<name>.md — ## Principles only (portable), with paths: frontmatter
   • <output_dir>/<name>.local.md — ## Project-specific patterns only (local), with the same paths: frontmatter as its <name>.md counterpart
   • <examples_output_dir>/<name>.examples.md — Examples for both
   • Layer-specific and regular files each define their own paths: independently (applies to both .md and .local.md). Cross-layer files (<framework>.md / <framework>.local.md) use no paths: or broad scope.
   • Skip generating a file if it would be empty. Skipped files are omitted from the Step 7 report.

   When split_output: false: Generate single hybrid file per category under output_dir, and the matching <name>.examples.md under examples_output_dir.

Rule file format (hybrid example):

---
paths:
  - "**/*.ts"
  - "**/*.tsx"
---
# TypeScript Rules

## Principles

- FP only (no classes, pure functions, composition over inheritance)
- Strict null handling (no non-null assertions, explicit narrowing required)
- Barrel exports required (re-export from index.ts per directory)

## Project-specific patterns

- `RefOrNull<T extends { id: string }> = T | { id: null }` - nullable relationships
- `pathFor(page) + url()` - Page Object navigation pair
- `useAuthClient()` returns `{ user, login, logout }` - auth hook interface

## Examples

When in doubt: ../../rules-extras/languages/typescript.examples.md

(The path above assumes default settings — output_dir: .claude/rules and examples_output_dir: .claude/rules-extras. See references/examples-format.md § Reference Section in Rule Files for the relative-path computation under non-default settings.)

Format guidelines:

For Principles section:

• Each principle: Principle name (hint1, hint2, hint3)
• Principle name: noun phrase naming the philosophy (e.g., "Immutability" not "Use const")
• Hints: 2-4 keywords per principle, describing implementation techniques observed in the project
• Only for general style choices (language built-ins)

For Project-specific patterns section:

• One line per pattern: `signature` - brief context
• Use inline code for signatures, not code blocks
• Keep context to 2-5 words
• Only include the minimal signature: type name, function signature with return type, or API combination
• Example of minimal: useAuth() → { user, login, logout } (not full implementation)

For a prose rule — a project-level rule stating a working convention rather than naming a symbol — see references/extraction-criteria.md § What a Rule Is Made Of.

For .examples.md files: Read references/examples-format.md for file structure, Good/Bad contrast guidelines, and the reference section format. Each rule file with a corresponding .examples.md must end with a ## Examples reference section (see the reference for format). ### titles must match the corresponding rule name exactly — do not translate or rephrase.

paths patterns by category:

• TypeScript: **/*.ts, **/*.tsx
• Python: **/*.py
• React: **/*.tsx, **/*.jsx
• Integration libraries: scope paths: to layers where the integration is used (e.g., Inertia in controllers: app/controllers/**)
• (project.md: no paths frontmatter = applies to all files)

Step 6.5: Security Self-Check

After generating all rule files, verify no sensitive information was included:

1. Grep generated/updated files for patterns that may indicate secrets:
   • Long hex strings: [0-9a-fA-F]{20,}
   • Base64-like strings: [A-Za-z0-9+/=]{40,}
   • Keyword-adjacent literals: (key|token|secret|password|credential)\s*[:=]\s*["'][^"']+
   • Internal URLs: (internal|staging|localhost:[0-9]+)
2. If found, redact with placeholders (e.g., API_KEY_REDACTED) and warn the user

Note: This check applies to all modes that generate or update rule files (Full Extraction, Update, Restructure, Conversation Extraction, Conversation Candidate Apply, Realign). Also check .examples.md files.

Step 7: Report Summary

Display analysis summary. See references/report-templates.md for format.

Update Mode

When --update is specified, re-scan the codebase and add new patterns while preserving existing rules.

Staging awareness: Update Mode reads the staging file under staging_output_dir (when present) and promotes any staged project-level patterns that re-match against fresh code observations to canonical (<output_dir>/project.md, the single hybrid file for project-level patterns), removing them from staging. Update Mode does not write new entries to staging — un-matched new patterns from this run land directly in canonical. See references/conversation-mode.md § Mode interaction summary for the full per-mode staging behavior.

Operational note: After a dependency's major-version bump, run --update so the Step U3 staleness check flags removed symbols. The check only scans inline `symbol` in .local.md's ## Project-specific patterns — .examples.md is not auto-scanned, so manually review it for the affected framework(s).

Step U1: Load Settings and Check Prerequisites

1. Load settings from extract-rules.local.md (same as Step 1 in Full Extraction Mode)

2. Check if output directory exists (default: .claude/rules/)

   • If not exists: Error "Run /extract-rules first to initialize rule files."
   • If split_output: true and hybrid files exist (.md files containing both ## Principles and ## Project-specific patterns): warn that hybrid files were found — recommend running --restructure to migrate to split format
   • If split_output: false and .local.md files exist: warn that orphaned .local.md files were found — recommend deleting orphaned files manually or running --restructure

3. Load existing rule files to understand current rules (load <output_dir>/<name>.md, <output_dir>/<name>.local.md, and <examples_output_dir>/<name>.examples.md when split). When examples_output_dir does not yet exist (e.g. legacy projects where examples were co-located under output_dir), fall back to loading <output_dir>/<name>.examples.md. Additionally load <staging_output_dir>/project.staging.local.md if present — this file is required for the Step U4 staging-match branch. Skip silently if the staging file does not yet exist.

Step U2: Re-scan Codebase

Execute Step 2-5 from Full Extraction Mode:

• Detect project type
• Collect sample files
• Analyze by category
• Analyze documentation

Step U3: Staleness Check

Before adding new rules, check existing project-specific patterns for staleness:

1. Collect patterns from ## Project-specific patterns sections:
   • When split_output: true: from .local.md files
   • When split_output: false: from ## Project-specific patterns sections in .md files
2. For each pattern that has an inline code signature (`symbol`), verify the symbol still exists in the codebase using Grep
   • Skip patterns without searchable symbols (e.g., principles, anti-patterns like "No default exports")
   • For combination patterns (e.g., `pathFor() + url()`), check each symbol individually
3. Patterns whose symbols can no longer be found → Flag as potentially stale in the Step U6 report
4. Do NOT auto-delete stale rules — only report them for user review

Step U4: Compare and Merge

For each extracted principle/pattern:

1. Check if already exists: Compare with existing rules (check both shared and local files if split_output: true). Evaluate the branches below in order, first match wins:

   • Exact match → Skip
   • Similar but different → Keep both (let user review)
   • Cross-format duplicate check: A project-specific pattern may have been promoted to a Principle by merge-rules. Check if the pattern's description semantically matches an existing principle name in the corresponding .md file (use AI judgment: case-insensitive, synonyms). For example, `useAuth() → { user, login, logout }` - auth hook interface is a duplicate of Auth hook interface (useAuth) in ## Principles. Skip patterns that already exist as Principles.
   • Staging match (project-level patterns only): if the pattern matches an entry in <staging_output_dir>/project.staging.local.md per the staging-match criterion (see references/conversation-mode.md § Step C5's "staging-match criterion" paragraph), schedule a promote — append to <output_dir>/project.md (the single hybrid file for project-level patterns) in Step U5, then delete the matched entry from staging in Step U5 (move-atomicity: canonical-first, staging-delete-second). Update Mode does not write new staging entries; un-matched project-level patterns land directly in canonical.
   • New → Add

2. Preserve manual edits: Do not modify existing rules

Step U5: Append New Rules

1. New category detected (e.g., new framework/language): Create new rule files following Step 6 format. Report as "New" in Step U6.
2. Append new principles to ## Principles section
3. Append new project-specific patterns to ## Project-specific patterns section
4. When split_output: true: Principles go to <output_dir>/<name>.md, patterns go to <output_dir>/<name>.local.md. Create missing files with proper frontmatter.
5. For <output_dir>/project.md: always append to the single file
6. Maintain file structure and formatting
7. Update .examples.md: Resolve the target path via examples_output_dir (<examples_output_dir>/<name>.examples.md). Create the file (and any missing parent directories under examples_output_dir) when absent. Follow the common generation procedure in references/examples-format.md to add examples for each new rule. Promotes from staging (item 8) count as canonical writes and get an entry too.
8. Promote staging matches (project-level patterns flagged in Step U4 as staging matches): append each to <output_dir>/project.md (the single hybrid file for project-level patterns, per item 5) and, after verifying the canonical write, Edit <staging_output_dir>/project.staging.local.md to remove the corresponding bullet. If the staging-delete Edit fails because the bullet is no longer uniquely matchable, leave the duplicate — the next session's canonical-match skip resolves it. Update Mode does not write new staging entries.

Step U5.5: Security Self-Check

Run Security Self-Check (same as Step 6.5) on new/updated files, including the staging file if any staging-delete edits landed in Step U5 (the staging file was rewritten by the staging-delete Edit).

Step U6: Report Changes

Report what was added per file. Also report any stale rules found in Step U3. Include canonical_skip_count and promoted_count (Update Mode never increments staged_count). See references/report-templates.md for format.

Restructure Mode

When --restructure is specified, re-analyze the codebase to determine the optimal file structure, then merge existing rule content into the new structure. Use this when the project has evolved (new frameworks, architectural changes) or when split_output settings change. After updating the extract-rules skill itself, which mode you need depends on what changed: --restructure when the file layout should change, --realign when the extraction criteria did (§ Realign Mode).

Note: Restructure Mode does NOT run the Step U3 staleness check — use --update first so stale symbols are flagged for manual review (see the Update Mode operational note for the post-major-version-bump workflow).

Step R1: Load Settings and Snapshot Existing Rules

1. Load settings (same as Step 1 in Full Extraction Mode)
2. Check output_dir exists → Error if not: "Run /extract-rules first to initialize rule files."
3. Read and parse all existing rule files: <output_dir>/**/<name>.md and <output_dir>/**/<name>.local.md (rule files), plus <examples_output_dir>/**/<name>.examples.md (examples files). When examples_output_dir differs from output_dir, also scan <output_dir>/**/<name>.examples.md to pick up legacy co-located examples written by older runs; treat such legacy files as candidates to migrate during Step R4.

Step R2: Re-analyze Codebase

Execute Step 2-5 from Full Extraction Mode to determine the ideal file structure.

Step R2.5: Resolve File References

Skip this step if resolve_references is false. Default is true.

Scan existing rule content (loaded in R1) for file references (Markdown links, text references like "See <path>", @path references), resolve them, extract rules from referenced files, and merge into the R1 snapshot. Rules from references are treated as existing rules (take priority on conflict in R4). See references/resolve-references.md for detailed processing steps.

Step R3: Show Restructure Plan and Confirm

Compare old and new file structures, display planned changes (Keep/New/Remove per file), and wait for user confirmation before proceeding. If references were resolved in R2.5, include the number of rules extracted from referenced files in the plan display.

Step R4: Merge and Write

1. Fresh extraction results as base, route existing rules (including rules extracted from resolved references) to appropriate new files by category/scope/layer/integration
2. Existing rules take priority on conflict (respect manual edits, conversation-extracted rules, and reference-extracted rules)
3. Unmatched rules → project.md as fallback; preserve custom sections in the most relevant file
4. Apply split_output setting (handle hybrid ↔ split transitions), deduplicate
5. Write new files first, then remove old files no longer in the new structure
6. Handle .examples.md: Write .examples.md files to <examples_output_dir>/<name>.examples.md, following the same structure changes as rule files. When R1 picked up legacy <output_dir>/<name>.examples.md files (co-located with rule files from older runs), move them to the new location under examples_output_dir and remove the legacy copies after the new file is written. Generate new .examples.md for categories that didn't have one (see references/examples-format.md).

Step R4.5: Security Self-Check

Run Security Self-Check (same as Step 6.5) on all generated files.

Step R5: Report Summary

Report structural changes, content merge summary, unmatched rules, and reference resolution results. See references/report-templates.md for format.

Conversation Extraction Mode

When --from-conversation is specified, extract rules from the full conversation history stored in session .jsonl files. The heavy processing (jsonl parsing, analysis, rule writing) is delegated to a subagent.

Step C1: Prepare and Locate Session File (main agent)

1. Load settings from extract-rules.local.md (same as Step 1 in Full Extraction Mode)

2. Check if output directory exists (default: .claude/rules/)

   • If not exists: Error "Run /extract-rules first to initialize rule files."

3. Locate the session file:

   1. Get the current working directory (pwd)
   2. Encode the path: replace / and . with - (leading - is kept)
      • Example: /Users/alice/src/github.com/acme/widget → -Users-alice-src-github-com-acme-widget
   3. Session files are stored at: ~/.claude/projects/<encoded-path>/<session-id>.jsonl

4. Select the target session:

   • If a <session-id> argument is provided: use ~/.claude/projects/<encoded-path>/<session-id>.jsonl
   • If no argument: use the most recently modified .jsonl file in the directory (by ls -t)
     • Note: This is a heuristic — if multiple Claude Code instances are running concurrently, the latest file may not be the current session.
   • Verify the file exists. Inform the user which session file was selected.

Step C2: Delegate to Subagent (main agent)

Spawn a subagent using the Agent tool. The subagent performs all heavy processing (C3–C5) and returns a summary of what was added. Read references/conversation-mode.md for the full subagent instructions (Steps C3–C5).

Include in the agent prompt:

• This skill's absolute directory path (where SKILL.md resides — needed to run bundled scripts)
• Session file absolute path
• output_dir, examples_output_dir, and staging_output_dir paths, plus split_output / language settings (the subagent must write rule files under output_dir, .examples.md files under examples_output_dir, and staging entries under staging_output_dir)
• canonical_files: list of existing rule file paths for canonical-match deduplication — include both rule files under output_dir and .examples.md files under examples_output_dir
• staging_files: list of existing staging file paths for staging-match detection — include the project-level staging file under staging_output_dir (gating is scoped to project-level patterns)
• The subagent instructions from references/conversation-mode.md

After the subagent completes, report the results to the user.

Conversation Candidate Apply Mode

When --apply-conversation-candidates <path> is specified, run only Step C5 (dedup / route / write / promote / .examples.md / Security Self-Check) against a pre-scanned rule-candidate block, skipping the jsonl parsing and analysis (C3/C4).

The input candidate file conforms to references/conversation-mode.md § Rule-candidate contract. This mode runs entirely in the main agent (no subagent spawn).

Step A1: Load Settings and Read Candidates (main agent)

1. Load settings from extract-rules.local.md (same as Step 1 in Full Extraction Mode).
2. Check the output directory exists (default .claude/rules/); if not, Error "Run /extract-rules first to initialize rule files."
3. Read the candidate file at <path> and validate it against references/conversation-mode.md § Rule-candidate contract: each ### Candidate <N> carries the required fields, Type / Category hold enum values, and the trailing Candidates: <N> count matches the number of parsed ### Candidate blocks. On an empty file, a parse failure, a count mismatch, or any candidate that omits a field its Type / Category discriminators mark required-non-empty (per the contract's Fields section — e.g. a Type: pattern candidate with an empty Signature), stop with a fail-loud diagnostic naming the path and the validation failure — do not silently proceed with a partial candidate set.

Step A2: Apply via Step C5 (main agent)

Execute references/conversation-mode.md § Step C5 with the Step A1 candidate list standing in for C4's in-context extracted items, running directly in the main agent (no subagent — see the mode intro above). Step C5 item 1 resolves canonical_files / staging_files from settings directly (no prompt boundary). Step C5 then performs dedup / routing / staging append+promote / .examples.md generation (mined from the codebase per references/examples-format.md) / Security Self-Check, and returns its counter summary. Report to the user using the references/report-templates.md § Conversation Extraction Mode (Step C4) template, reused as-is (its ### Promoted from staging / ### Newly staged / ### No changes subsections apply unchanged) — no new template section is added.

Compaction Mode

When --compact is specified, compact over-threshold rules files (thresholds: § Configuration).

Read references/compaction-procedure.md for the full processing steps (CP1-CP5); re-read it when a Step CP reference no longer resolves in context. Key flow:

1. Load settings; resolve targets
2. Per-file Pattern A loop: dispatch, parse, apply, converge
3. Security Self-Check with revert
4. Fenced JSON summary
5. § Sub-skill caller directive

Realign Mode

When --realign [<path> ...] is specified, re-judge rules already written against the current extraction criteria, then drop, split, or trim the ones that no longer meet them (§ Restructure Mode's intro says which of the two modes a given change calls for). Named paths judge only those files; no paths judges every rule file under output_dir.

Against --compact, which also shrinks a rule file: one invariant divides them — --compact preserves the set of norms a file states, merging near-duplicates and dropping an entry only where another already subsumes it, while --realign can take a norm away outright. When both apply to one file, realign first.

Read references/realign-mode.md for the full processing steps (RA1-RA5). Key flow:

1. Load settings; check output_dir exists (same as Step C1's output-directory-existence check); resolve the targets from the named paths, or by discovery under output_dir when none were named
2. Dispatch one analysis subagent per target file, parse its fenced JSON verdict, and count each non-keep rule's referrers
3. USER APPROVAL GATE — present the verdicts; nothing is written until it resolves
4. Apply the accepted edits and follow through on the affected .examples.md entries
5. Security Self-Check on every file written, then report per references/report-templates.md § Realign Mode

PR Review Extraction Mode

When --from-pr is specified, extract rules from PR review comments (human comments only). Single or multiple PRs can be specified. Numbers and URLs can be mixed. Cross-repository PRs are allowed.

Read references/pr-review-mode.md for the full processing steps (P1-P5). Key flow:

1. Check prerequisites (gh CLI authentication)
2. Parse all PR arguments, validate each PR exists
3. Fetch review comments from GitHub API (3 endpoints per PR), filter bot comments
4. Extract principles and patterns (same criteria as references/extraction-criteria.md)
5. Multiple PRs: Cross-PR frequency analysis — general best practices that are repeatedly pointed out across different PRs are promoted as organizational emphasis (reframed with specific application context, not just restated)
6. Append to existing rule files and update .examples.md (same as Step C5)

Sub-skill caller directive

When invoked as a sub-skill (i.e. via Skill(extract-rules) from an orchestrator), the fenced JSON verdict block this skill emits in --compact mode is the structured return value of the skill's procedure — it is not a deliverable to the user, and emitting it does not terminate the orchestrator's turn. The same agent that ran this skill must immediately issue the next tool call dictated by the orchestrator's flow (an orchestrator that surfaces a per-callee guidance bullet names the specific next action there). Do not insert a prose summary, an acknowledgment, or a "shall I proceed?" sentence between the JSON verdict and the next tool call. Only one fenced JSON block — the verdict block — appears in the response, so callers can locate it unambiguously. The skill's own procedure is over; the orchestrator's procedure continues without pause.

This directive applies specifically to --compact mode. Other modes (Full Extraction, Update, Restructure, Conversation, Conversation Candidate Apply, Realign, PR Review) produce prose reports rather than fenced JSON verdicts and are not subject to this contract.

Stop hook structural conflict (caller-side note)

If a ~/.claude/stop-hook-git-check.sh style Stop hook is registered, it may fire mid-dispatch with uncommitted-change feedback. This is a known structural conflict between non-interactive orchestrator flows and per-turn hooks. Treat each fire as spurious: ignore the prose and continue the prescribed flow; per-file flow runs that complete the orchestrator's sub-step boundaries are the canonical completion signal.