Add automated lexicon style guide checker

[Copilot]

Implements automated validation of lexicon definitions against ATProto style guide rules. Addresses common schema quality issues: missing constraints, incomplete descriptions, inconsistent naming.

Changes

• scripts/check-lexicon-style.js - Validates 10+ style rules across lexicon files:

  • NSID format and naming conventions
  • Required descriptions (lexicons, definitions, properties)
  • String constraints (maxLength/maxGraphemes)
  • Blob constraints (maxSize, MIME types)
  • DateTime formats and naming
  • StrongRef documentation
  • Property naming (camelCase)

• LEXICON_STYLE_GUIDE.md - Codifies ATProto best practices for reference

• Integration - Added npm run check-lexicon-style with JSON and verbose output modes

• CI Workflow - Added .github/workflows/style.yml that automatically runs the style checker on all pull requests and pushes to main/develop branches

Output Example

$ npm run check-lexicon-style

Checked 15 lexicon files
Found 57 issues in 15 files
  Errors: 42
  Warnings: 10
  Info: 5

❌ lexicons/org/hypercerts/claim/activity.json (8 issues)
  ❌ [string-max-length] String property must have maxLength or maxGraphemes
     Location: defs.main.record.properties.createdAt.maxLength
  ⚠️ [strongref-documentation] StrongRef should document expected lexicon type
     Location: defs.main.record.properties.workScope.description

Three severity levels enable incremental adoption: errors block CI, warnings flag issues for review, info suggests improvements.

Original prompt

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This section details on the original issue you should resolve

<issue_title>check lexicons against Lexicon Style Guide using AI</issue_title>
<issue_description>https://atproto.com/guides/lexicon-style-guide</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes check lexicons against Lexicon Style Guide using AI #66

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[changeset-bot]

⚠️ No Changeset found

Latest commit: a631af7

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[s-adamantine]

I reviewed all 17 lexicons against the ATProto Lexicon Style Guide and created a compliance report.

Key Findings:

❌ Critical: badge/response.json uses enum instead of knownValues (violates schema evolution rules)
⚠️ Medium: 12 string fields across multiple files lack maxLength constraints
Minor: Some format/length redundancy in URI fields

Most things are done well - naming conventions, descriptions, strong references, and open unions all follow the guide correctly.

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[aspiers]

@copilot There shouldn't be a changeset here, but there should be a new style.yml CI workflow

[Copilot]

@copilot There shouldn't be a changeset here, but there should be a new style.yml CI workflow

Done! Removed the changeset and added .github/workflows/style.yml CI workflow that runs npm run check-lexicon-style on push and pull requests. (09fc4d7)