feat(cli): add support for the ${extensionPath} variable in extension TOML commands (#22681)

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

@@ -895,6 +895,66 @@ describe('FileCommandLoader', () => {
       expect(command.extensionName).toBe('my-test-ext');
       expect(command.extensionId).toBe(extensionId);
     });
+
+    it('correctly injects ${extensionPath} into extension commands', async () => {
+      const extensionDir = path.join(
+        process.cwd(),
+        GEMINI_DIR,
+        'extensions',
+        'path-test-ext',
+      );
+
+      mock({
+        [extensionDir]: {
+          'gemini-extension.json': JSON.stringify({
+            name: 'path-test-ext',
+            version: '1.0.0',
+          }),
+          commands: {
+            'path-cmd.toml': 'prompt = "Path: ${extensionPath}/templates"',
+          },
+        },
+      });
+
+      const mockConfig = {
+        getProjectRoot: vi.fn(() => process.cwd()),
+        getExtensions: vi.fn(() => [
+          {
+            name: 'path-test-ext',
+            version: '1.0.0',
+            isActive: true,
+            path: extensionDir,
+          },
+        ]),
+        getFolderTrust: vi.fn(() => false),
+        isTrustedFolder: vi.fn(() => false),
+      } as unknown as Config;
+      const loader = new FileCommandLoader(mockConfig);
+      const commands = await loader.loadCommands(signal);
+
+      expect(commands).toHaveLength(1);
+      const command = commands[0];
+      expect(command.name).toBe('path-cmd');
+
+      const result = await command.action?.(
+        createMockCommandContext({
+          invocation: {
+            raw: '/path-cmd',
+            name: 'path-cmd',
+            args: '',
+          },
+        }),
+        '',
+      );
+
+      if (result?.type === 'submit_prompt') {
+        expect(result.content).toEqual([
+          { text: `Path: ${extensionDir}/templates` },
+        ]);
+      } else {
+        assert.fail('Incorrect action type');
+      }
+    });
   });
 
   describe('Argument Handling Integration (via ShellProcessor)', () => {

packages/cli/src/services/FileCommandLoader.ts

@@ -39,6 +39,7 @@ interface CommandDirectory {
   kind: CommandKind;
   extensionName?: string;
   extensionId?: string;
+  extensionPath?: string;
 }
 
 /**
@@ -114,6 +115,7 @@ export class FileCommandLoader implements ICommandLoader {
             dirInfo.kind,
             dirInfo.extensionName,
             dirInfo.extensionId,
+            dirInfo.extensionPath,
           ),
         );
 
@@ -175,6 +177,7 @@ export class FileCommandLoader implements ICommandLoader {
         kind: CommandKind.EXTENSION_FILE,
         extensionName: ext.name,
         extensionId: ext.id,
+        extensionPath: ext.path,
       }));
 
       dirs.push(...extensionCommandDirs);
@@ -197,6 +200,7 @@ export class FileCommandLoader implements ICommandLoader {
     kind: CommandKind,
     extensionName?: string,
     extensionId?: string,
+    extensionPath?: string,
   ): Promise<SlashCommand | null> {
     let fileContent: string;
     try {
@@ -235,6 +239,14 @@ export class FileCommandLoader implements ICommandLoader {
 
     const validDef = validationResult.data;
 
+    // Hydrate extensionPath if this is an extension command
+    if (extensionPath) {
+      validDef.prompt = validDef.prompt.replace(
+        /\$\{extensionPath\}/g,
+        () => extensionPath,
+      );
+    }
+
     const relativePathWithExt = path.relative(baseDir, filePath);
     const relativePath = relativePathWithExt.substring(
       0,