refactor: remove custom rules feature

[let-sunny]

Summary

• Remove custom rules feature (--custom-rules) entirely
• Keep config overrides (--config) for adjusting scores, severity, and thresholds

Why

Built-in rules should be complete and well-calibrated. Custom rules added complexity (loader, schema, diversity denominator issues) without clear value — if a check is worth having, it should be a built-in rule maintained by the project.

This also resolves the diversity scoring issue flagged in #111 where custom rules weren't included in TOTAL_SCORE_PER_CATEGORY.

What's removed

• src/core/rules/custom/ directory (loader, schema, index) — -1,465 lines
• examples/custom-rules.json
• --custom-rules option from CLI, MCP server, docs
• Custom rules section from docs/REFERENCE.md
• Custom rules guide from canicode docs rules

What's kept

• --config option for rule score/severity/threshold overrides
• config-loader.ts moved from custom/ to rules/ (cleaner location)

Test plan

• 662 tests pass
• Type check clean
• --config still works (config-loader moved, not deleted)

🤖 Generated with Claude Code

Summary by CodeRabbit

Release Notes

• Removed Features
  • Removed custom rules functionality and the --custom-rules CLI option from analyze and list-rules commands.
  • Removed custom rules documentation, reference guides, and example files.
  • Simplified configuration options to use --config exclusively for rule customization.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: ASSERTIVE

Plan: Pro

Run ID: 71abc8db-ad27-4cd5-a84d-a26468e79a18

📥 Commits

Reviewing files that changed from the base of the PR and between a53ea35 and 97ae2b7.

📒 Files selected for processing (15)

• CLAUDE.md
• README.md
• docs/REFERENCE.md
• examples/custom-rules.json
• src/cli/commands/analyze.ts
• src/cli/commands/list-rules.ts
• src/cli/docs.ts
• src/cli/index.ts
• src/core/rules/config-loader.test.ts
• src/core/rules/config-loader.ts
• src/core/rules/custom/custom-rule-loader.test.ts
• src/core/rules/custom/custom-rule-loader.ts
• src/core/rules/custom/custom-rule-schema.ts
• src/core/rules/custom/index.ts
• src/mcp/server.ts

💤 Files with no reviewable changes (8)

• README.md
• src/cli/docs.ts
• docs/REFERENCE.md
• src/core/rules/custom/custom-rule-schema.ts
• examples/custom-rules.json
• src/core/rules/custom/custom-rule-loader.test.ts
• src/core/rules/custom/index.ts
• src/core/rules/custom/custom-rule-loader.ts

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📝 Walkthrough

Walkthrough

This PR completely removes custom rules functionality from the codebase. It deletes the custom rule loader, schema definitions, and test suite; removes the --custom-rules CLI option from multiple commands; and eliminates all related documentation from CLAUDE.md, README.md, and REFERENCE.md. The MCP server is updated accordingly.

Changes

Cohort / File(s)	Summary
Documentation Removal CLAUDE.md, README.md, docs/REFERENCE.md	Removed all references to --custom-rules option and comprehensive custom rules guidance, including schema definitions, match-condition examples, and rule JSON samples.
Custom Rules Implementation Deletion src/core/rules/custom/custom-rule-loader.ts, src/core/rules/custom/custom-rule-schema.ts, src/core/rules/custom/custom-rule-loader.test.ts, src/core/rules/custom/index.ts	Deleted entire custom rule loading logic, JSON schema validation, comprehensive test suite (876 lines), and re-export surface for custom rules functionality.
CLI Command Updates src/cli/commands/analyze.ts, src/cli/commands/list-rules.ts	Removed --custom-rules CLI option and associated config merging logic that dynamically loaded and registered custom rules during execution.
CLI Help & Docs Interface src/cli/index.ts, src/cli/docs.ts	Removed --custom-rules from help text customization section and deleted printDocsRules() function with routing support for custom rules documentation topic.
MCP Server & Import Updates src/mcp/server.ts, src/core/rules/config-loader.ts	Removed customRulesPath parameter from analyze tool schema; updated imports to remove custom-rule-loader references and correct config-loader paths.
Examples examples/custom-rules.json	Removed example custom rules JSON file containing icon-not-component and large-frame-no-auto-layout rule definitions.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Possibly related PRs

• refactor: split CLI index.ts into per-command modules (#47) #59: Both PRs modify the same CLI modules (analyze.ts, list-rules.ts, docs.ts, index.ts), but in opposite directions—this PR removes custom-rules support while #59 adds it.
• feat: enrich --json output for AI agent consumption #96: Both PRs modify src/cli/commands/analyze.ts and affect the analyze command implementation.
• refactor: replace module-level mutable state with per-analysis RuleContext state #56: Both PRs touch src/core/rules/custom/custom-rule-loader.test.ts—this PR deletes it entirely while #56 modifies it.

Poem

🐰 Farewell, custom rules, you've served us well,
Now simplified paths have much more to tell,
No schemas to juggle, no loaders to parse,
The CLI runs cleaner—a hop, skip, and... smart! ✨

🚥 Pre-merge checks | ✅ 2

✅ Passed checks (2 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'refactor: remove custom rules feature' directly and clearly summarizes the main objective of the changeset—removing the custom rules feature across the codebase.

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✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch refactor/remove-custom-rules

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