feat(cli): support skill discovery for Open Plugins

- Updated skillLoader to support discovery in skills/ subdirectories
- Implemented convention-based skill discovery for Open Plugins
- Enforced namespacing for plugin skills (plugin:skill-name)
- Refactored skill resolution into resolvePluginSkills for better maintainability
- Added comprehensive tests for Open Plugin skill discovery

Fixes https://github.com/google-gemini/maintainers-gemini-cli/issues/1592

packages/cli/src/config/open-plugin-discovery.test.ts

@@ -129,11 +129,10 @@ describe('ExtensionManager - Open Plugin Support', () => {
     expect(plugin?.description).toBe(`Uses root: ${pluginDir}`);
   });
 
-  it('should NOT load skills or context files for Open Plugins in v1', async () => {
+  it('should load skills for Open Plugins', async () => {
     const pluginDir = path.join(userExtensionsDir, 'feature-plugin');
-    const hiddenDir = path.join(pluginDir, '.plugin');
-    fs.mkdirSync(hiddenDir, { recursive: true });
-    const skillsDir = path.join(pluginDir, 'skills', 'test');
+    fs.mkdirSync(pluginDir, { recursive: true });
+    const skillsDir = path.join(pluginDir, 'skills', 'test-skill');
     fs.mkdirSync(skillsDir, { recursive: true });
 
     fs.writeFileSync(
@@ -147,20 +146,19 @@ describe('ExtensionManager - Open Plugin Support', () => {
     fs.writeFileSync(
       path.join(skillsDir, 'SKILL.md'),
       `---
-  name: test-skill
-  description: "Test"
-  ---
-  Body`,
+name: my-skill
+description: "Test description"
+---
+Body`,
     );
 
-    fs.writeFileSync(path.join(pluginDir, 'GEMINI.md'), '# Context');
-
     const extensions = await extensionManager.loadExtensions();
     const plugin = extensions.find((ext) => ext.name === 'feature-plugin');
 
     expect(plugin).toBeDefined();
-    expect(plugin?.skills).toBeUndefined();
-    expect(plugin?.contextFiles).toEqual([]);
+    expect(plugin?.skills).toBeDefined();
+    expect(plugin?.skills?.[0].name).toBe('feature-plugin:my-skill');
+    expect(plugin?.skills?.[0].extensionName).toBe('feature-plugin');
   });
 
   it('should prioritize gemini-extension.json over plugin.json', async () => {

packages/cli/src/config/plugin.ts

@@ -7,9 +7,10 @@
 import * as fs from 'node:fs';
 import * as path from 'node:path';
 import { z } from 'zod';
-import type {
-  ExtensionInstallMetadata,
-  GeminiCLIExtension,
+import {
+  loadSkillsFromDir,
+  type ExtensionInstallMetadata,
+  type GeminiCLIExtension,
 } from '@google/gemini-cli-core';
 import {
   EXTENSIONS_CONFIG_FILENAME,
@@ -156,7 +157,6 @@ export async function loadOpenPluginConfig(
 
 /**
  * Creates a GeminiCLIExtension from an Open Plugin directory.
- * v1: Does not enable skills, mcp servers, context files, or settings.
  */
 export async function createOpenPlugin(
   pluginDir: string,
@@ -173,6 +173,20 @@ export async function createOpenPlugin(
     workspaceDir,
   );
 
+  const hydrationContext = {
+    extensionPath: pluginDir,
+    PLUGIN_ROOT: pluginDir,
+    workspacePath: workspaceDir,
+    '/': path.sep,
+    pathSeparator: path.sep,
+  };
+
+  const skills = await resolvePluginSkills(
+    pluginDir,
+    config.name,
+    hydrationContext,
+  );
+
   return {
     name: config.name,
     version: config.version,
@@ -193,8 +207,30 @@ export async function createOpenPlugin(
     excludeTools: undefined,
     settings: undefined,
     resolvedSettings: undefined,
-    skills: undefined,
+    skills,
     agents: undefined,
     themes: undefined,
   };
 }
+
+/**
+ * Discovers and namespaces skills for an Open Plugin.
+ */
+async function resolvePluginSkills(
+  pluginDir: string,
+  pluginName: string,
+  hydrationContext: Record<string, string>,
+): Promise<GeminiCLIExtension['skills']> {
+  const skillsDir = path.join(pluginDir, 'skills');
+  const discoveredSkills = await loadSkillsFromDir(skillsDir);
+
+  if (discoveredSkills.length === 0) {
+    return undefined;
+  }
+
+  return discoveredSkills.map((skill) => ({
+    ...recursivelyHydrateStrings(skill, hydrationContext),
+    name: `${pluginName}:${skill.name}`,
+    extensionName: pluginName,
+  }));
+}

packages/cli/src/services/SlashCommandResolver.test.ts

@@ -218,6 +218,19 @@ describe('SlashCommandResolver', () => {
       expect(names).toContain('google-workspace:chat1');
     });
 
+    it('should NOT double-prefix when a skill name is already prefixed', () => {
+      const skill = {
+        ...createMockCommand('google-workspace:chat', CommandKind.SKILL),
+        extensionName: 'google-workspace',
+      };
+
+      const { finalCommands } = SlashCommandResolver.resolve([skill]);
+
+      const names = finalCommands.map((c) => c.name);
+      expect(names).toContain('google-workspace:chat');
+      expect(names).not.toContain('google-workspace:google-workspace:chat');
+    });
+
     it('should NOT prefix skills with "skill" when extension name is missing', () => {
       const builtin = createMockCommand('chat', CommandKind.BUILT_IN);
       const skill = createMockCommand('chat', CommandKind.SKILL);

packages/cli/src/services/SlashCommandResolver.ts

@@ -173,7 +173,15 @@ export class SlashCommandResolver {
     const isExtensionPrefix =
       kind === CommandKind.SKILL || kind === CommandKind.EXTENSION_FILE;
     const separator = isExtensionPrefix ? ':' : '.';
-    const base = prefix ? `${prefix}${separator}${name}` : name;
+
+    // Check if it's already correctly prefixed
+    const alreadyPrefixed = prefix && name.startsWith(`${prefix}${separator}`);
+    const base = alreadyPrefixed
+      ? name
+      : prefix
+        ? `${prefix}${separator}${name}`
+        : name;
+
     let renamedName = base;
     let suffix = 1;