fix: error when creating agent directories

Adds a check to avoid file system errors when creating directories like `.gemini`.

Author: crisbeto

runner/codegen/claude-code-runner.ts

@@ -4,7 +4,7 @@ import {
   LlmRunner,
 } from './llm-runner.js';
 import {join} from 'path';
-import {mkdirSync} from 'fs';
+import {existsSync, mkdirSync} from 'fs';
 import {writeFile} from 'fs/promises';
 import {BaseCliAgentRunner} from './base-cli-agent-runner.js';
 
@@ -48,7 +48,9 @@ export class ClaudeCodeRunner extends BaseCliAgentRunner implements LlmRunner {
     const instructionFilePath = join(context.directory, 'CLAUDE.md');
     const settingsDir = join(context.directory, '.claude');
 
-    mkdirSync(settingsDir);
+    if (!existsSync(settingsDir)) {
+      mkdirSync(settingsDir);
+    }
 
     await Promise.all([
       writeFile(join(settingsDir, 'settings.json'), this.getSettingsJsonFile(options.context)),

runner/codegen/codex-runner.ts

@@ -1,6 +1,6 @@
 import {LocalLlmGenerateFilesRequestOptions, LlmRunner} from './llm-runner.js';
 import {join} from 'path';
-import {mkdirSync} from 'fs';
+import {existsSync, mkdirSync} from 'fs';
 import {writeFile} from 'fs/promises';
 import {BaseCliAgentRunner} from './base-cli-agent-runner.js';
 
@@ -39,7 +39,9 @@ export class CodexRunner extends BaseCliAgentRunner implements LlmRunner {
     const instructionFilePath = join(context.directory, 'AGENTS.md');
     const settingsDir = join(context.directory, '.codex');
 
-    mkdirSync(settingsDir);
+    if (!existsSync(settingsDir)) {
+      mkdirSync(settingsDir);
+    }
 
     await Promise.all([
       writeFile(join(settingsDir, 'config.toml'), this.getSettingsFile()),

runner/codegen/gemini-cli-runner.ts

@@ -1,6 +1,6 @@
 import {LocalLlmGenerateFilesRequestOptions, LlmRunner} from './llm-runner.js';
 import {join} from 'path';
-import {mkdirSync} from 'fs';
+import {existsSync, mkdirSync} from 'fs';
 import {writeFile} from 'fs/promises';
 import {BaseCliAgentRunner} from './base-cli-agent-runner.js';
 
@@ -36,7 +36,9 @@ export class GeminiCliRunner extends BaseCliAgentRunner implements LlmRunner {
     const instructionFilePath = join(context.directory, 'GEMINI.md');
     const settingsDir = join(context.directory, '.gemini');
 
-    mkdirSync(settingsDir);
+    if (!existsSync(settingsDir)) {
+      mkdirSync(settingsDir);
+    }
 
     const commonIgnorePatterns = super.getCommonIgnorePatterns();
     const ignoreFileContent = [