Add first-class Grok Build harness support

Emit .grok skills, agents, and PostToolUse/Stop hooks; wire the CLI
installer and downloads; fix the plugin install path to #plugin; and
document Grok in HARNESSES.md and README.

AI assistance: written with Grok Build.

scripts/build.js

@@ -462,11 +462,15 @@ This folder contains skills for all supported tools:
   .codex/     -> Codex custom agents (Codex skills use .agents/)
   .agents/    -> Codex CLI
   .github/    -> GitHub Copilot
+  .grok/      -> Grok Build
   .kiro/      -> Kiro
   .opencode/  -> OpenCode
   .pi/        -> Pi
   .trae-cn/   -> Trae China
   .trae/      -> Trae International
+  .rovodev/   -> Rovo Dev
+  .vibe/      -> Mistral Vibe
+  .qoder/     -> Qoder
 
 To install, copy the relevant folder(s) into your project root.
 For Codex, repo and user skill installs come from .agents/skills.
@@ -590,18 +594,21 @@ async function build() {
 
     console.log(`📋 Synced skills to: ${syncConfigs.map(p => p.configDir).join(', ')}`);
 
-    // Build the Claude Code plugin subtree at ./plugin/.
-    // The Claude Code marketplace is configured with `source: "./plugin"`, so
-    // the plugin cache only copies this slim directory (~0.3 MB) instead of
-    // the entire monorepo (~291 MB on the previous "./" source). The harness
-    // dirs above stay where they are because `npx skills add pbakaus/impeccable`
-    // reads them directly from the GitHub repo at install time.
+    // Build the shared plugin subtree at ./plugin/.
+    // Claude Code marketplace is configured with `source: "./plugin"`, so the
+    // plugin cache only copies this slim directory (~0.3 MB) instead of the
+    // entire monorepo. Grok Build installs the same subtree via
+    // `grok plugin install pbakaus/impeccable#plugin --trust` (or the
+    // marketplace source). The harness dirs above stay where they are because
+    // `npx skills add pbakaus/impeccable` reads them from the GitHub repo.
     const pluginRoot = path.join(ROOT_DIR, 'plugin');
     const pluginManifestDir = path.join(pluginRoot, '.claude-plugin');
+    const grokPluginManifestDir = path.join(pluginRoot, '.grok-plugin');
     const pluginSkillsDir = path.join(pluginRoot, 'skills');
     const pluginAgentsDir = path.join(pluginRoot, 'agents');
     const pluginHooksDir = path.join(pluginRoot, 'hooks');
     if (fs.existsSync(pluginManifestDir)) fs.rmSync(pluginManifestDir, { recursive: true });
+    if (fs.existsSync(grokPluginManifestDir)) fs.rmSync(grokPluginManifestDir, { recursive: true });
     if (fs.existsSync(pluginSkillsDir)) fs.rmSync(pluginSkillsDir, { recursive: true });
     if (fs.existsSync(pluginAgentsDir)) fs.rmSync(pluginAgentsDir, { recursive: true });
     if (fs.existsSync(pluginHooksDir)) fs.rmSync(pluginHooksDir, { recursive: true });
@@ -636,6 +643,26 @@ async function build() {
       JSON.stringify(pluginManifest, null, 2) + '\n',
     );
 
+    // Native Grok plugin manifest. Grok also reads `.claude-plugin/`; dual
+    // manifests keep both marketplaces and `grok plugin validate` happy when
+    // Claude compat is disabled.
+    // https://docs.x.ai/build/features/skills-plugins-marketplaces
+    const grokPluginManifest = {
+      name: pluginManifest.name,
+      version: pluginManifest.version,
+      description: pluginManifest.description,
+      author: pluginManifest.author,
+      homepage: pluginManifest.homepage,
+      repository: pluginManifest.repository,
+      license: pluginManifest.license || 'MIT',
+      keywords: ['design', 'frontend', 'ui', 'ux', 'skills', 'hooks'],
+    };
+    fs.mkdirSync(grokPluginManifestDir, { recursive: true });
+    fs.writeFileSync(
+      path.join(grokPluginManifestDir, 'plugin.json'),
+      JSON.stringify(grokPluginManifest, null, 2) + '\n',
+    );
+
     const claudeSkillsSrc = path.join(DIST_DIR, 'claude-code', '.claude', 'skills', 'impeccable');
     if (fs.existsSync(claudeSkillsSrc)) {
       fs.mkdirSync(pluginSkillsDir, { recursive: true });
@@ -646,17 +673,18 @@ async function build() {
       copyDirSync(claudeAgentsSrc, pluginAgentsDir);
     }
 
-    // Ship the design detector as a plugin-packaged hook. Claude Code
-    // auto-discovers `hooks/hooks.json` at the plugin root, so marketplace /
-    // `/plugin install` users get the PostToolUse hook without it being merged
-    // into their project `.claude/settings.json` (that path is the CLI's job).
+    // Ship the design detector as a plugin-packaged hook. Claude Code and
+    // Grok Build both auto-discover `hooks/hooks.json` at the plugin root
+    // (Grok aliases CLAUDE_PLUGIN_ROOT → GROK_PLUGIN_ROOT), so marketplace /
+    // plugin-install users get PostToolUse + Stop without merging into project
+    // settings (that path remains the CLI's job for project-scoped installs).
     fs.mkdirSync(pluginHooksDir, { recursive: true });
     fs.writeFileSync(
       path.join(pluginHooksDir, 'hooks.json'),
       JSON.stringify(buildClaudePluginHooksManifest(), null, 2) + '\n',
     );
 
-    console.log('📦 Built Claude Code plugin subtree at ./plugin/');
+    console.log('📦 Built Claude Code / Grok Build plugin subtree at ./plugin/');
   } else {
     console.log('📋 Skipped root harness and plugin sync (--skip-root-sync)');
   }

scripts/lib/transformers/hooks.js

@@ -7,9 +7,12 @@
  *      - Claude Code: `.claude/settings.json`   (${CLAUDE_PROJECT_DIR}-relative)
  *      - Codex:       `.codex/hooks.json`
  *      - Cursor:      `.cursor/hooks.json`
+ *      - Grok Build:  `.grok/hooks/impeccable.json`
  *
  * 2. Claude Code plugin package (the marketplace / `/plugin install` path):
  *      - `plugin/hooks/hooks.json`              (${CLAUDE_PLUGIN_ROOT}-relative)
+ *        Also consumed by Grok Build via Claude Code plugin compatibility
+ *        (`CLAUDE_PLUGIN_ROOT` is aliased to `GROK_PLUGIN_ROOT`).
  *
  * 3. OpenAI plugin package:
  *      - `hooks/hooks.json`                     (${PLUGIN_ROOT}-relative)
@@ -49,6 +52,9 @@ const CODEX_PLUGIN_HOOK = '${PLUGIN_ROOT}/skills/impeccable/scripts/hook.mjs';
 const CODEX_PROJECT_HOOK = '.agents/skills/impeccable/scripts/hook.mjs';
 const CURSOR_BEFORE_EDIT_SCRIPT = '.cursor/skills/impeccable/scripts/hook-before-edit.mjs';
 const GITHUB_PROJECT_HOOK = '$(git rev-parse --show-toplevel)/.github/skills/impeccable/scripts/hook.mjs';
+// Grok project hooks are relative to the git/workspace root. Claude tool names
+// in the matcher (Edit|Write|MultiEdit) alias to Grok's search_replace family.
+const GROK_PROJECT_HOOK = '.grok/skills/impeccable/scripts/hook.mjs';
 
 export function buildClaudeSettingsManifest() {
   return {
@@ -185,6 +191,32 @@ export function buildGitHubHooksManifest() {
   };
 }
 
+// Grok Build discovers project hooks from `.grok/hooks/*.json` and requires
+// folder trust (`/hooks-trust` or `--trust`) before they run. Event schema is
+// Claude-compatible (PostToolUse / Stop / PreToolUse); Claude tool names in
+// matchers are aliased to Grok tools (Edit|Write|MultiEdit → search_replace).
+// https://docs.x.ai/build/features/hooks
+export function buildGrokHooksManifest() {
+  return {
+    hooks: {
+      PostToolUse: [
+        {
+          matcher: 'Edit|Write|MultiEdit',
+          hooks: [
+            {
+              type: 'command',
+              command: `node "${GROK_PROJECT_HOOK}"`,
+              timeout: TIMEOUT_SECONDS,
+              statusMessage: STATUS_MESSAGE,
+            },
+          ],
+        },
+      ],
+      Stop: [stopEntry(`node "${GROK_PROJECT_HOOK}"`)],
+    },
+  };
+}
+
 export function hooksJsonFor(provider) {
   switch (provider) {
     case 'claude':
@@ -195,6 +227,8 @@ export function hooksJsonFor(provider) {
       return buildCursorHooksManifest();
     case 'github':
       return buildGitHubHooksManifest();
+    case 'grok':
+      return buildGrokHooksManifest();
     default:
       return null;
   }

scripts/lib/transformers/index.js

@@ -16,5 +16,6 @@ export const transformPi = createTransformer(PROVIDERS.pi);
 export const transformQoder = createTransformer(PROVIDERS.qoder);
 export const transformRovoDev = createTransformer(PROVIDERS['rovo-dev']);
 export const transformVibe = createTransformer(PROVIDERS.vibe);
+export const transformGrok = createTransformer(PROVIDERS.grok);
 
 export { createTransformer, PROVIDERS };

scripts/lib/transformers/providers.js

@@ -129,4 +129,21 @@ export const PROVIDERS = {
     displayName: 'Mistral Vibe',
     frontmatterFields: ['user-invocable', 'license', 'compatibility', 'metadata', 'allowed-tools'],
   },
+  grok: {
+    provider: 'grok',
+    providerTags: ['grok'],
+    configDir: '.grok',
+    displayName: 'Grok Build',
+    // Grok's skill frontmatter matches the Agent Skills spec plus Claude-style
+    // extensions (user-invocable, argument-hint, allowed-tools, model, effort).
+    // See https://docs.x.ai/build/features/skills-plugins-marketplaces and
+    // ~/.grok/docs/user-guide/08-skills.md.
+    frontmatterFields: ['user-invocable', 'argument-hint', 'license', 'compatibility', 'metadata', 'allowed-tools'],
+    // Project/user agents are markdown with YAML frontmatter (Claude-compatible).
+    agentFormat: 'claude-md',
+    emitHooks: 'grok',
+    // Grok discovers project hooks from `.grok/hooks/*.json` (not a single
+    // settings.json). Claude tool-name matchers alias to Grok tools.
+    hooksManifestRel: 'hooks/impeccable.json',
+  },
 };

scripts/lib/utils.js

@@ -633,6 +633,12 @@ export const PROVIDER_PLACEHOLDERS = {
     config_file: 'AGENTS.md',
     ask_instruction: 'ask the user directly to clarify what you cannot infer.',
     command_prefix: '/'
+  },
+  'grok': {
+    model: 'Grok',
+    config_file: 'AGENTS.md',
+    ask_instruction: 'STOP and call the AskUserQuestion tool to clarify.',
+    command_prefix: '/'
   }
 };
 
@@ -644,6 +650,7 @@ export const PROVIDER_BLOCK_TAGS = new Set([
   'cursor',
   'gemini',
   'github',
+  'grok',
   'kiro',
   'opencode',
   'pi',