Add JSR package validation hook

[drernie]

Summary

Add deno-jsr-check built-in hook to validate JSR package metadata and structure before publishing, catching common issues early.

Motivation

Publishing to JSR requires:

• Specific deno.json structure
• Valid exports configuration
• Proper versioning
• README and documentation
• License information

Catching these issues in a pre-push hook saves time and prevents publishing failures.

Proposed Solution

hooks:
  pre-push:
    - id: jsr-validate
      run: deno-jsr-check
      config:
        checkExports: true
        checkVersion: true
        checkReadme: true
        checkLicense: true
        checkDocs: true

Implementation

Built-in hook that validates:

1. Exports field: Ensure deno.json has valid exports

// Check that all export paths exist
const config = JSON.parse(await Deno.readTextFile("deno.json"));
for (const [name, path] of Object.entries(config.exports)) {
  if (!await exists(path)) {
    violations.push(`Export "${name}" points to non-existent ${path}`);
  }
}

2. Version format: Validate semver in package.json/deno.json

const version = config.version;
if (!version.match(/^\d+\.\d+\.\d+$/)) {
  violations.push(`Invalid version format: ${version}`);
}

3. README: Ensure README.md exists and has content
4. License: Check for LICENSE file
5. Documentation: Verify JSDoc on public exports
6. Package name: Validate format (@scope/name)

Configuration Options

• checkExports: Validate exports field (default: true)
• checkVersion: Validate version format (default: true)
• checkReadme: Require README.md (default: true)
• checkLicense: Require LICENSE file (default: true)
• checkDocs: Validate JSDoc comments (default: false)
• minReadmeLength: Minimum README length in chars (default: 100)

Example Validations

Missing export:

❌ JSR validation failed:
  - Export "./install" points to non-existent src/install.ts

Invalid version:

❌ JSR validation failed:
  - Invalid version format: "1.0" (expected semver like "1.0.0")

Missing README:

❌ JSR validation failed:
  - README.md not found (required for JSR publishing)

Benefits

• ✅ Catch publishing issues before push
• ✅ Ensure JSR package quality
• ✅ Ecosystem play - Help grow JSR adoption
• ✅ Unique to Deno - JSR-specific validation
• ✅ Save time vs failed publishes

Use Cases

Library authors:

hooks:
  pre-push:
    - id: jsr-ready
      run: deno-jsr-check
      config:
        checkExports: true
        checkVersion: true
        checkReadme: true
        checkLicense: true
        checkDocs: true  # Ensure public APIs documented

Quick projects:

hooks:
  pre-push:
    - id: jsr-basic
      run: deno-jsr-check
      config:
        checkExports: true
        checkVersion: true

Files to Modify

• src/executor.ts - Add denoJsrCheck built-in hook
• Create src/jsr-validator.ts - JSR validation logic

Priority

LOW - High marketing value for JSR ecosystem, but niche use case. Good for "Phase 2" features.