Check — Change Verification + Rule Evolution

Analyze git diff against .hoyeon/rules/ to catch missed cascading changes, then propose rule updates when new unmatched patterns are detected.

Prerequisite: The project must have a .hoyeon/rules/ directory containing rule files with YAML frontmatter. If .hoyeon/rules/ does not exist, guide the user to create it: mkdir -p .hoyeon/rules, then help them write their first rule file following ${baseDir}/references/rules-authoring.md.

Two-phase structure:

• Phase 1 (always): Validate changes — produce PASS/WARN results
• Phase 2 (conditional): Propose rule updates — only when unmatched patterns exist

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Phase 1: Change Validation

1. Collect Changed Files

# Gather committed + uncommitted changes
git diff --name-only HEAD~1..HEAD
git diff --name-only --cached
git diff --name-only

Deduplicate and store as CHANGED_FILES.

2. Build Rule Graph and Match

Read YAML frontmatter from all .hoyeon/rules/*.md files to construct the rule graph. Refer to references/rules-authoring.md ("Structure" section) for the frontmatter schema.

Matching order:

1. Glob-match each file in CHANGED_FILES against every rule's triggers patterns
2. Follow depends_on edges from matched rules to pull in related rules (1-depth only)
3. Finalize the active rule set
4. Store unmatched files separately as UNMATCHED_FILES (used in Phase 2)

Note: Meta documents (e.g., RULES.md) are excluded from matching.

3. Parallel Subagent Verification

Spawn one subagent per active rule using the Agent tool (subagent_type="general-purpose") and run them in parallel.

Pass each subagent:

• The CHANGED_FILES list
• The rule file's body (checklist content)
• The actual diff of changed files (git diff)

Each subagent:

1. Applies checklist items against CHANGED_FILES
2. Identifies cases where a file was changed but related files were not
3. Reads the actual diff for WARN items to determine if the omission is genuine
4. Returns results classified as PASS / WARN / Not Applicable

4. Aggregate and Output Results

Collect all subagent results and output them grouped by category: domain rules first, then concern rules, then pipeline rules.

## Phase 1: Verification Results

### PASS (N items)
#### domain
- [billing] schema.ts changed -> migration file created
#### concern
- [infra] .env changed -> terraform synced
#### pipeline
- [api-codegen] swagger changed -> types regenerated

### WARN (N items)
#### concern
- [ux] en.json changed -> ko.json not updated

### Not Applicable (N items)
- [docs] no docs/ changes

5. Execute agents/commands

If active rules have agents or commands fields:

• agents: Run automatically via the Agent tool for additional verification. Merge any WARNs from agent results into the Phase 1 WARN list.
• commands: Present the commands to the user for manual execution (e.g., pnpm generate:api).

6. Process WARNs

For each WARN item:

1. Read the changed code to determine whether a change is actually needed
2. Distinguish between intentional omissions and accidental misses
3. For genuine misses, specify exactly which file and section needs modification

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Phase 2: Rule Update Proposals (Conditional)

Phase 2 trigger conditions — Execute Phase 2 if ANY of the following is true:

1. UNMATCHED_FILES contains at least one meaningful source file (.ts, .tsx, .json, .yaml, .tf, etc.) — exclude meta files (.md, lock files, etc.)
2. Any WARN from Phase 1 indicates a rule gap (not a rule violation)

Skip condition: If UNMATCHED_FILES is empty AND no WARNs indicate rule gaps, skip Phase 2 and proceed directly to follow-up actions (step 9).

Distinguishing rule gaps from rule violations: If a WARN was caused by violating an existing checklist item, it is a rule violation (handled in Phase 1). If no checklist item exists anywhere that could have caught the WARN in advance, it is a rule gap — this triggers Phase 2.

7. Analyze Patterns and Cross-Reference Rules

Analyze UNMATCHED_FILES and Phase 1 WARN results to identify:

• Uncovered change patterns — file changes not matched by any rule's triggers
• Near-miss cascading changes — duplicate logic across multiple locations where only some were updated
• Newly discovered sync points — relationships where changing one location requires updating another

Read references/rules-authoring.md for authoring guidelines, then classify findings:

• Existing rule needs new items — propose the rule file and specific items to add
• New rule file needed — entirely new pattern not covered by any existing rule; include the category field (domain | concern | pipeline)

8. Output Rule Update Proposals

## Phase 2: Rule Update Proposals

1. [subscriptions.md] Add sync check for URL detection functions across 3 apps
   - Reason: isSubstackUrl() duplicated in 3 locations, only 2 updated
2. [New file: webhook.md] Add sync check for webhook event changes
   - category: domain
   - Reason: new domain with no existing rule coverage

Confirm each proposal with AskUserQuestion:

• "Add" — Apply the item to the rule file
• "Edit & Add" — Adjust the content before adding
• "Skip" — Unnecessary, skip this item

Apply approved items to the corresponding rule files. For new rule files, create them with frontmatter (category and triggers are required).

After adding or modifying rules, verify that the frontmatter triggers patterns correctly match the intended files.

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9. Follow-Up Actions

Consolidate WARNs from Phase 1 and rule updates from Phase 2 into a follow-up change list.

If one or more WARN items exist, present the list and use AskUserQuestion to ask the user:

• "Fix All" — Automatically fix all WARN items
• "Select" — Choose specific items to fix (multiSelect)
• "Ignore & Proceed" — Treat as intentional omissions, finish without changes

When "Fix All" or "Select" is chosen, apply the fixes in order and display the updated results.

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Additional Resources

Reference Files

• ${baseDir}/references/rules-authoring.md — Rule authoring principles, frontmatter schema, category classification, and abstraction-level guidelines. Consult when creating or updating rules.