Load extension settings for hooks, agents, skills (#17245)

packages/cli/src/config/extension-manager-hydration.test.ts

@@ -0,0 +1,318 @@
+/**
+ * @license
+ * Copyright 2026 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { describe, it, expect, vi, beforeEach, afterEach } from 'vitest';
+import * as fs from 'node:fs';
+import * as path from 'node:path';
+import * as os from 'node:os';
+import { ExtensionManager } from './extension-manager.js';
+import { debugLogger, coreEvents } from '@google/gemini-cli-core';
+import { createTestMergedSettings } from './settings.js';
+import { createExtension } from '../test-utils/createExtension.js';
+import { EXTENSIONS_DIRECTORY_NAME } from './extensions/variables.js';
+
+const mockHomedir = vi.hoisted(() => vi.fn(() => '/tmp/mock-home'));
+
+vi.mock('node:os', async (importOriginal) => {
+  const actual = await importOriginal<typeof import('node:os')>();
+  return {
+    ...actual,
+    homedir: mockHomedir,
+  };
+});
+
+// Mock @google/gemini-cli-core
+vi.mock('@google/gemini-cli-core', async (importOriginal) => {
+  const actual =
+    await importOriginal<typeof import('@google/gemini-cli-core')>();
+  return {
+    ...actual,
+    homedir: mockHomedir,
+    // Use actual implementations for loading skills and agents to test hydration
+    loadAgentsFromDirectory: actual.loadAgentsFromDirectory,
+    loadSkillsFromDir: actual.loadSkillsFromDir,
+  };
+});
+
+describe('ExtensionManager hydration', () => {
+  let extensionManager: ExtensionManager;
+  let tempDir: string;
+  let extensionsDir: string;
+
+  beforeEach(() => {
+    vi.clearAllMocks();
+    vi.spyOn(coreEvents, 'emitFeedback');
+    vi.spyOn(debugLogger, 'debug').mockImplementation(() => {});
+
+    tempDir = fs.mkdtempSync(path.join(os.tmpdir(), 'gemini-test-'));
+    mockHomedir.mockReturnValue(tempDir);
+
+    // Create the extensions directory that ExtensionManager expects
+    extensionsDir = path.join(tempDir, '.gemini', EXTENSIONS_DIRECTORY_NAME);
+    fs.mkdirSync(extensionsDir, { recursive: true });
+
+    extensionManager = new ExtensionManager({
+      settings: createTestMergedSettings({
+        telemetry: { enabled: false },
+        experimental: { extensionConfig: true },
+      }),
+      requestConsent: vi.fn().mockResolvedValue(true),
+      requestSetting: vi.fn(),
+      workspaceDir: tempDir,
+    });
+  });
+
+  afterEach(() => {
+    try {
+      fs.rmSync(tempDir, { recursive: true, force: true });
+    } catch {
+      // ignore
+    }
+  });
+
+  it('should hydrate skill body with extension settings', async () => {
+    const sourceDir = path.join(tempDir, 'source-ext-skill');
+    const extensionName = 'skill-hydration-ext';
+    createExtension({
+      extensionsDir: sourceDir,
+      name: extensionName,
+      version: '1.0.0',
+      settings: [
+        {
+          name: 'API Key',
+          description: 'API Key',
+          envVar: 'MY_API_KEY',
+        },
+      ],
+      installMetadata: {
+        type: 'local',
+        source: path.join(sourceDir, extensionName),
+      },
+    });
+    const extensionPath = path.join(sourceDir, extensionName);
+
+    // Create skill with variable
+    const skillsDir = path.join(extensionPath, 'skills');
+    const skillSubdir = path.join(skillsDir, 'my-skill');
+    fs.mkdirSync(skillSubdir, { recursive: true });
+    fs.writeFileSync(
+      path.join(skillSubdir, 'SKILL.md'),
+      `---
+name: my-skill
+description: test
+---
+Use key: \${MY_API_KEY}
+`,
+    );
+
+    await extensionManager.loadExtensions();
+
+    extensionManager.setRequestSetting(async (setting) => {
+      if (setting.envVar === 'MY_API_KEY') return 'secret-123';
+      return '';
+    });
+
+    const extension = await extensionManager.installOrUpdateExtension({
+      type: 'local',
+      source: extensionPath,
+    });
+
+    expect(extension.skills).toHaveLength(1);
+    expect(extension.skills![0].body).toContain('Use key: secret-123');
+  });
+
+  it('should hydrate agent system prompt with extension settings', async () => {
+    const sourceDir = path.join(tempDir, 'source-ext-agent');
+    const extensionName = 'agent-hydration-ext';
+    createExtension({
+      extensionsDir: sourceDir,
+      name: extensionName,
+      version: '1.0.0',
+      settings: [
+        {
+          name: 'Model Name',
+          description: 'Model',
+          envVar: 'MODEL_NAME',
+        },
+      ],
+      installMetadata: {
+        type: 'local',
+        source: path.join(sourceDir, extensionName),
+      },
+    });
+    const extensionPath = path.join(sourceDir, extensionName);
+
+    // Create agent with variable
+    const agentsDir = path.join(extensionPath, 'agents');
+    fs.mkdirSync(agentsDir, { recursive: true });
+    fs.writeFileSync(
+      path.join(agentsDir, 'my-agent.md'),
+      `---
+name: my-agent
+description: test
+---
+System using model: \${MODEL_NAME}
+`,
+    );
+
+    await extensionManager.loadExtensions();
+
+    extensionManager.setRequestSetting(async (setting) => {
+      if (setting.envVar === 'MODEL_NAME') return 'gemini-pro';
+      return '';
+    });
+
+    const extension = await extensionManager.installOrUpdateExtension({
+      type: 'local',
+      source: extensionPath,
+    });
+
+    expect(extension.agents).toHaveLength(1);
+    const agent = extension.agents![0];
+    if (agent.kind === 'local') {
+      expect(agent.promptConfig.systemPrompt).toContain(
+        'System using model: gemini-pro',
+      );
+    } else {
+      throw new Error('Expected local agent');
+    }
+  });
+
+  it('should hydrate hooks with extension settings', async () => {
+    const sourceDir = path.join(tempDir, 'source-ext-hooks');
+    const extensionName = 'hooks-hydration-ext';
+    createExtension({
+      extensionsDir: sourceDir,
+      name: extensionName,
+      version: '1.0.0',
+      settings: [
+        {
+          name: 'Hook Command',
+          description: 'Cmd',
+          envVar: 'HOOK_CMD',
+        },
+      ],
+      installMetadata: {
+        type: 'local',
+        source: path.join(sourceDir, extensionName),
+      },
+    });
+    const extensionPath = path.join(sourceDir, extensionName);
+
+    const hooksDir = path.join(extensionPath, 'hooks');
+    fs.mkdirSync(hooksDir, { recursive: true });
+    fs.writeFileSync(
+      path.join(hooksDir, 'hooks.json'),
+      JSON.stringify({
+        hooks: {
+          BeforeTool: [
+            {
+              hooks: [
+                {
+                  type: 'command',
+                  command: 'echo $HOOK_CMD',
+                },
+              ],
+            },
+          ],
+        },
+      }),
+    );
+
+    // Enable hooks in settings
+    extensionManager = new ExtensionManager({
+      settings: createTestMergedSettings({
+        telemetry: { enabled: false },
+        experimental: { extensionConfig: true },
+        tools: { enableHooks: true },
+        hooksConfig: { enabled: true },
+      }),
+      requestConsent: vi.fn().mockResolvedValue(true),
+      requestSetting: vi.fn(),
+      workspaceDir: tempDir,
+    });
+
+    await extensionManager.loadExtensions();
+
+    extensionManager.setRequestSetting(async (setting) => {
+      if (setting.envVar === 'HOOK_CMD') return 'hello-world';
+      return '';
+    });
+
+    const extension = await extensionManager.installOrUpdateExtension({
+      type: 'local',
+      source: extensionPath,
+    });
+
+    expect(extension.hooks).toBeDefined();
+    expect(extension.hooks?.BeforeTool).toHaveLength(1);
+    expect(extension.hooks?.BeforeTool![0].hooks[0].env?.['HOOK_CMD']).toBe(
+      'hello-world',
+    );
+  });
+
+  it('should pick up new settings after restartExtension', async () => {
+    const sourceDir = path.join(tempDir, 'source-ext-restart');
+    const extensionName = 'restart-hydration-ext';
+    createExtension({
+      extensionsDir: sourceDir,
+      name: extensionName,
+      version: '1.0.0',
+      settings: [
+        {
+          name: 'Value',
+          description: 'Val',
+          envVar: 'MY_VALUE',
+        },
+      ],
+      installMetadata: {
+        type: 'local',
+        source: path.join(sourceDir, extensionName),
+      },
+    });
+    const extensionPath = path.join(sourceDir, extensionName);
+
+    const skillsDir = path.join(extensionPath, 'skills');
+    const skillSubdir = path.join(skillsDir, 'my-skill');
+    fs.mkdirSync(skillSubdir, { recursive: true });
+    fs.writeFileSync(
+      path.join(skillSubdir, 'SKILL.md'),
+      '---\nname: my-skill\ndescription: test\n---\nValue is: ${MY_VALUE}',
+    );
+
+    await extensionManager.loadExtensions();
+
+    // Initial setting
+    extensionManager.setRequestSetting(async () => 'first');
+    const extension = await extensionManager.installOrUpdateExtension({
+      type: 'local',
+      source: extensionPath,
+    });
+    expect(extension.skills![0].body).toContain('Value is: first');
+
+    const { updateSetting, ExtensionSettingScope } = await import(
+      './extensions/extensionSettings.js'
+    );
+    const extensionConfig =
+      await extensionManager.loadExtensionConfig(extensionPath);
+
+    const mockRequestSetting = vi.fn().mockResolvedValue('second');
+    await updateSetting(
+      extensionConfig,
+      extension.id,
+      'MY_VALUE',
+      mockRequestSetting,
+      ExtensionSettingScope.USER,
+    );
+
+    await extensionManager.restartExtension(extension);
+
+    const reloadedExtension = extensionManager
+      .getExtensions()
+      .find((e) => e.name === extensionName)!;
+    expect(reloadedExtension.skills![0].body).toContain('Value is: second');
+  });
+});

packages/cli/src/config/extension-manager.ts

@@ -57,6 +57,7 @@ import {
   INSTALL_METADATA_FILENAME,
   recursivelyHydrateStrings,
   type JsonObject,
+  type VariableContext,
 } from './extensions/variables.js';
 import {
   getEnvContents,
@@ -538,12 +539,14 @@ Would you like to attempt to install via "git clone" instead?`,
           extensionId,
           ExtensionSettingScope.USER,
         );
-        workspaceSettings = await getScopedEnvContents(
+        if (isWorkspaceTrusted(this.settings).isTrusted) {
-          config,
+          workspaceSettings = await getScopedEnvContents(
-          extensionId,
+            config,
-          ExtensionSettingScope.WORKSPACE,
+            extensionId,
-          this.workspaceDir,
+            ExtensionSettingScope.WORKSPACE,
-        );
+            this.workspaceDir,
+          );
+        }
       }
 
       const customEnv = { ...userSettings, ...workspaceSettings };
@@ -612,24 +615,63 @@ Would you like to attempt to install via "git clone" instead?`,
         )
         .filter((contextFilePath) => fs.existsSync(contextFilePath));
 
+      const hydrationContext: VariableContext = {
+        extensionPath: effectiveExtensionPath,
+        workspacePath: this.workspaceDir,
+        '/': path.sep,
+        pathSeparator: path.sep,
+        ...customEnv,
+      };
+
       let hooks: { [K in HookEventName]?: HookDefinition[] } | undefined;
       if (
         this.settings.tools.enableHooks &&
         this.settings.hooksConfig.enabled
       ) {
-        hooks = await this.loadExtensionHooks(effectiveExtensionPath, {
+        hooks = await this.loadExtensionHooks(
-          extensionPath: effectiveExtensionPath,
+          effectiveExtensionPath,
-          workspacePath: this.workspaceDir,
+          hydrationContext,
-        });
+        );
       }
 
-      const skills = await loadSkillsFromDir(
+      // Hydrate hooks with extension settings as environment variables
+      if (hooks && config.settings) {
+        const hookEnv: Record<string, string> = {};
+        for (const setting of config.settings) {
+          const value = customEnv[setting.envVar];
+          if (value !== undefined) {
+            hookEnv[setting.envVar] = value;
+          }
+        }
+
+        if (Object.keys(hookEnv).length > 0) {
+          for (const eventName of Object.keys(hooks)) {
+            const eventHooks = hooks[eventName as HookEventName];
+            if (eventHooks) {
+              for (const definition of eventHooks) {
+                for (const hook of definition.hooks) {
+                  // Merge existing env with new env vars, giving extension settings precedence.
+                  hook.env = { ...hook.env, ...hookEnv };
+                }
+              }
+            }
+          }
+        }
+      }
+
+      let skills = await loadSkillsFromDir(
         path.join(effectiveExtensionPath, 'skills'),
       );
+      skills = skills.map((skill) =>
+        recursivelyHydrateStrings(skill, hydrationContext),
+      );
 
       const agentLoadResult = await loadAgentsFromDirectory(
         path.join(effectiveExtensionPath, 'agents'),
       );
+      agentLoadResult.agents = agentLoadResult.agents.map((agent) =>
+        recursivelyHydrateStrings(agent, hydrationContext),
+      );
 
       // Log errors but don't fail the entire extension load
       for (const error of agentLoadResult.errors) {
@@ -671,6 +713,14 @@ Would you like to attempt to install via "git clone" instead?`,
     }
   }
 
+  override async restartExtension(
+    extension: GeminiCLIExtension,
+  ): Promise<void> {
+    const extensionDir = extension.path;
+    await this.unloadExtension(extension);
+    await this.loadExtension(extensionDir);
+  }
+
   /**
    * Removes `extension` from the list of extensions and stops it if
    * appropriate.
@@ -720,7 +770,7 @@ Would you like to attempt to install via "git clone" instead?`,
 
   private async loadExtensionHooks(
     extensionDir: string,
-    context: { extensionPath: string; workspacePath: string },
+    context: VariableContext,
   ): Promise<{ [K in HookEventName]?: HookDefinition[] } | undefined> {
     const hooksFilePath = path.join(extensionDir, 'hooks', 'hooks.json');
 

packages/cli/src/config/extensions/variables.ts

@@ -24,7 +24,7 @@ export type JsonValue =
   | JsonArray;
 
 export type VariableContext = {
-  [key in keyof typeof VARIABLE_SCHEMA]?: string;
+  [key: string]: string | undefined;
 };
 
 export function validateVariables(
@@ -33,7 +33,7 @@ export function validateVariables(
 ) {
   for (const key in schema) {
     const definition = schema[key];
-    if (definition.required && !variables[key as keyof VariableContext]) {
+    if (definition.required && !variables[key]) {
       throw new Error(`Missing required variable: ${key}`);
     }
   }
@@ -43,30 +43,33 @@ export function hydrateString(str: string, context: VariableContext): string {
   validateVariables(context, VARIABLE_SCHEMA);
   const regex = /\${(.*?)}/g;
   return str.replace(regex, (match, key) =>
-    context[key as keyof VariableContext] == null
+    context[key] == null ? match : context[key],
-      ? match
-      : (context[key as keyof VariableContext] as string),
   );
 }
 
-export function recursivelyHydrateStrings(
+export function recursivelyHydrateStrings<T>(
-  obj: JsonValue,
+  obj: T,
   values: VariableContext,
-): JsonValue {
+): T {
   if (typeof obj === 'string') {
-    return hydrateString(obj, values);
+    return hydrateString(obj, values) as unknown as T;
   }
   if (Array.isArray(obj)) {
-    return obj.map((item) => recursivelyHydrateStrings(item, values));
+    return obj.map((item) =>
+      recursivelyHydrateStrings(item, values),
+    ) as unknown as T;
   }
   if (typeof obj === 'object' && obj !== null) {
-    const newObj: JsonObject = {};
+    const newObj: Record<string, unknown> = {};
     for (const key in obj) {
       if (Object.prototype.hasOwnProperty.call(obj, key)) {
-        newObj[key] = recursivelyHydrateStrings(obj[key], values);
+        newObj[key] = recursivelyHydrateStrings(
+          (obj as Record<string, unknown>)[key],
+          values,
+        );
       }
     }
-    return newObj;
+    return newObj as T;
   }
   return obj;
 }

packages/core/src/hooks/hookRunner.ts

@@ -267,6 +267,7 @@ export class HookRunner {
         ...sanitizeEnvironment(process.env, this.config.sanitizationConfig),
         GEMINI_PROJECT_DIR: input.cwd,
         CLAUDE_PROJECT_DIR: input.cwd, // For compatibility
+        ...hookConfig.env,
       };
 
       const child = spawn(

packages/core/src/hooks/types.ts

@@ -59,6 +59,7 @@ export interface CommandHookConfig {
   description?: string;
   timeout?: number;
   source?: ConfigSource;
+  env?: Record<string, string>;
 }
 
 export type HookConfig = CommandHookConfig;