Claude Mods are Claude Code plugins whose behaviour lives in a function-hooks module: one register(on, options) entry that hooks the engine's events as functions ($, e, next). Reference: https://github.com/anthropics/claude-code/tree/main/mods

Early access. Mods load in Claude Code >= 2.1.259 with CLAUDE_CODE_ENABLE_FUNCTION_HOOKS=1; the $ API may change between releases.

Layout in this repo

Each mod is a complete plugin directory, exactly Anthropic's mods/ layout:

{category}/{name}/
  .claude-plugin/plugin.json   name, version, description, author, license, userConfig, types
  hooks/hooks.json             { "description", "modules": ["./register.ts"] }
  hooks/**                     the hooks-modules: any number of .ts/.tsx files, relative imports
  types/*.d.ts                 optional: the contract of a noun the mod adds to $
  tests/**                     optional: claude plugin test (or the mod's own runner)
  README.md                    what the site shows; everything else is browsable beside it

npx claude-code-templates --mod {category}/{name} downloads the directory and writes it verbatim to .claude/skills/{name}/, which Claude Code auto-loads as {name}@skills-dir. Third-party mods (e.g. games/cc-arcade) are vendored as-is with their LICENSE and attribution in plugin.json.

Options

A mod's options are declared as userConfig in .claude-plugin/plugin.json (the engine reads options only from the manifest). Field types are string | number | boolean | directory | file (title is required; options makes a picker; sensitive goes to secure storage). There is no array type, so list options take a comma-separated string. Values are read from user settings (~/.claude/settings.json), --settings <file> or managed settings, never from project settings:

{ "pluginConfigs": { "npm-to-pnpm-rewriter": { "options": { "manager": "yarn" } } } }

types/claude-code.d.ts is Anthropic's declaration file as /plugin-types writes it (the first line names the Claude Code version). Regenerate it from a current Claude Code rather than editing it.

Typecheck

cd cli-tool/components/mods && npx -y typescript@5 tsc -p tsconfig.json

The root tsconfig.json covers every mod's hooks/ and types/ (strict, without noUncheckedIndexedAccess, so third-party code typechecks). Every module must import its types from 'claude-code' only, spell $ as $.noun.event(...) at the call site (never pass $ to a helper), treat e as frozen, and return { deny } / { result } / next(e) as the event's result type demands. After installing, claude plugin validate <dir> lists what the module hooks and calls; claude plugin test <dir> runs its tests.