Claude Marketplace Tools

A web-compatible VS Code extension that validates Claude Code plugin marketplaces in the browser (github.dev / vscode.dev) and on desktop.

It surfaces problems as editor diagnostics (squiggles + Problems panel), running inside github.dev's WebWorker extension host (no Node APIs). See CLAUDE.md for design & roadmap.

What it validates

Frontmatter (SKILL.md, agents/*.md, commands/*.md) — via in-process diagnostics over a declarative field engine:

• Required vs recommended (per the docs, by file type): a SKILL.md description is recommended (a Warning if missing — Claude falls back to the first body paragraph); agents require name + description (an Error); commands may omit frontmatter entirely.
• Enum values are checked against the docs, e.g. model (sonnet/opus/haiku/fable/inherit or a claude-* id), effort (low/medium/high/xhigh/max), shell (bash/powershell), context (fork), agent permissionMode / color / memory / isolation.
• Types (booleans, lists, maps), kebab-case names, length caps, and unknown fields (warned — Claude Code ignores unrecognized keys).

JSON config (.claude-plugin/plugin.json, .claude-plugin/marketplace.json, .claude/settings.json + settings.local.json, .claude/keybindings.json) — via the official SchemaStore schemas wired through contributes.jsonValidation, giving field validation, enum completions, hover descriptions, and (for manifests) the discriminated source variants (github / url / git-subdir / npm / relative path). These need no activation — the built-in JSON language service applies them, and the hosted schemas track upstream automatically.

Architecture

• src/diagnostics.ts — shared Problem shape (code, message, severity, span).
• src/frontmatter.ts — tolerant --- … --- parsing (eemeli/yaml) with node ranges.
• src/fieldSpec.ts — the generic, data-driven field-validation engine.
• schemas/{skill,agent,command}.fields.json — the frontmatter rules as plain JSON (edit these when the docs change); src/specs/*.ts load them via load.ts, with the lone open-ended model check in patterns.ts.
• src/validateSkill.ts / validateAgent.ts / validateCommand.ts — pure per-type entry points (no vscode import); the test seam.
• src/hover.ts — pure hover lookup; renders a field's docs from the same specs.
• src/extension.ts — thin vscode adapter: scans, keeps results live via document events + FileSystemWatchers, registers the hover provider, maps offsets/severity to Diagnostics.
• package.json contributes.jsonValidation — points the JSON config files (plugin.json, marketplace.json, .claude/settings.json + settings.local.json, .claude/keybindings.json) at their official claude-code-* schemas on schemastore.org (no local copies to maintain). Frontmatter rule data lives under schemas/*.fields.json, bundled into the web worker at build time.
• esbuild.js — single WebWorker bundle, vscode external → dist/web/extension.js.

Develop & test

See TESTING.md for full step-by-step verification.

npm install
npm run compile-web        # build the bundle
npm run open-in-browser    # launch test-web against fixtures/sample-marketplace
npm run package            # build a shareable .vsix