[codex] fix prompt delivery and select backends per sub-task

electron/ipc/agents.ts

@@ -1,10 +1,11 @@
 import { execFile } from 'child_process';
 import { promisify } from 'util';
 import path from 'path';
+import type { AgentBackend } from '../mcp/agent-backends.js';
 
 const execFileAsync = promisify(execFile);
 
-interface AgentDef {
+export interface AgentDef {
   id: string;
   name: string;
   command: string;
@@ -99,6 +100,13 @@ export function getSkipPermissionsArgs(command: string): string[] {
   return agent ? [...agent.skip_permissions_args] : [];
 }
 
+export function getAgentByBackend(backend: AgentBackend): AgentDef {
+  const id = backend === 'claude' ? 'claude-code' : backend;
+  const agent = DEFAULT_AGENTS.find((candidate) => candidate.id === id);
+  if (!agent) throw new Error(`Missing built-in agent definition for backend: ${backend}`);
+  return { ...agent, args: [...agent.args] };
+}
+
 export async function listAgents(): Promise<AgentDef[]> {
   const now = Date.now();
   if (cachedAgents && now - cacheTime < AGENT_CACHE_TTL) {

electron/ipc/git.ts

@@ -775,7 +775,10 @@ export async function createWorktree(
 
   ensureClaudeSandboxFiles(worktreePath, repoRoot);
   ensureSandboxExcludes(worktreePath);
-  ensureSymlinkExcludes(worktreePath, createdSymlinks);
+  // `.claude` is a real directory, but missing entries are copied from the
+  // main worktree and required sandbox placeholders are created locally. Ignore
+  // only untracked contents; tracked `.claude` changes remain visible to Git.
+  ensureSymlinkExcludes(worktreePath, [...createdSymlinks, '.claude']);
 
   return { path: worktreePath, branch: branchName };
 }

electron/mcp/agent-backends.ts

@@ -0,0 +1,14 @@
+export const AGENT_BACKENDS = [
+  'claude',
+  'codex',
+  'gemini',
+  'opencode',
+  'copilot',
+  'antigravity',
+] as const;
+
+export type AgentBackend = (typeof AGENT_BACKENDS)[number];
+
+export function isAgentBackend(value: unknown): value is AgentBackend {
+  return typeof value === 'string' && AGENT_BACKENDS.some((backend) => backend === value);
+}

electron/mcp/agent-frame-fixtures.ts

@@ -17,6 +17,15 @@ export const READY_AGENT_FRAME_FIXTURES: AgentFrameFixture[] = [
       'opus · /Users/brooksc/git/parallel-code/.worktrees/task-023-10-loading-states · ctx:24k/200k',
     ].join('\n'),
   },
+  {
+    name: 'Claude empty prompt with rotating suggestion',
+    frame: [
+      '─'.repeat(80),
+      '❯ Try "how does <filepath> work?"',
+      '─'.repeat(80),
+      '⏵⏵ bypass permissions on (shift+tab to cycle) · ← for agents',
+    ].join('\r'),
+  },
   {
     name: 'Claude empty insert mode at fresh prompt',
     frame: [
@@ -44,6 +53,11 @@ export const READY_AGENT_FRAME_FIXTURES: AgentFrameFixture[] = [
       'gpt-5.5 default · /Users/brooksc/git/parallel-code/.worktrees/task-028-unit-tests',
     ].join('\n'),
   },
+  {
+    name: 'Codex prompt with redraw-damaged escape sequences',
+    frame:
+      '13;15H s qg se q MCP server q q›Summarize recent commitsgpt-5.5 medium · ~/repo/.worktrees/task/example q',
+  },
   {
     name: 'Gemini typed-message prompt',
     frame: [

electron/mcp/client.ts

@@ -52,6 +52,7 @@ export class MCPClient {
     coordinatorTaskId?: string;
     skipPermissions?: boolean;
     baseBranch?: string;
+    backend?: string;
   }): Promise<ApiTaskDetail> {
     return this.request<ApiTaskDetail>('POST', '/api/tasks', opts);
   }

electron/mcp/coordinator.test.ts

@@ -106,7 +106,7 @@ vi.mock('./prompt-detect.js', () => ({
       .slice(-1000)
       .split(/\r\n?|\n/)
       .some((line) =>
-        /(?:^|\s)[❯›]\s*$|^\s*--\s*INSERT\s*--\s*$|^\s*>\s*(?:Type your message|$)/i.test(
+        /(?:^|\s)[❯›]\s*$|^\s*❯\s*Try\s+["“]|(?:^|\s|q)›[^\r\n›]*?gpt-[\w.-]+\s+\w+\s+·\s+~?\/|^\s*--\s*INSERT\s*--\s*$|^\s*>\s*(?:Type your message|$)/i.test(
           line.trim(),
         ),
       );
@@ -131,7 +131,7 @@ vi.mock('./prompt-detect.js', () => ({
     return tail
       .split(/\r\n?|\n/)
       .some((line) =>
-        /(?:^|\s)[❯›]\s*$|^\s*--\s*INSERT\s*--\s*$|^\s*>\s*(?:Type your message|$)/i.test(
+        /(?:^|\s)[❯›]\s*$|^\s*❯\s*Try\s+["“]|(?:^|\s|q)›[^\r\n›]*?gpt-[\w.-]+\s+\w+\s+·\s+~?\/|^\s*--\s*INSERT\s*--\s*$|^\s*>\s*(?:Type your message|$)/i.test(
           line.trim(),
         ),
       );
@@ -181,7 +181,7 @@ vi.mock('../log.js', () => ({
 
 // Import after mocks
 const { Coordinator } = await import('./coordinator.js');
-const { removePreambleBlock } = await import('./preamble.js');
+const { normalizePreambleFileContent, removePreambleBlock } = await import('./preamble.js');
 
 // --- helpers ---
 function getExitHandler(): (agentId: string, data: unknown) => void {
@@ -1987,6 +1987,45 @@ describe('Coordinator sub-agent spawn settings', () => {
     );
   });
 
+  it('uses the requested backend instead of the coordinator command', async () => {
+    coordinator.setCoordinatorSpawnDefaults('coord-1', 'claude', ['--model', 'opus']);
+    await coordinator.createTask({
+      name: 'test',
+      prompt: 'do',
+      coordinatorTaskId: 'coord-1',
+      backend: 'codex',
+    });
+    expect(mockSpawnAgent).toHaveBeenCalledWith(
+      expect.anything(),
+      expect.objectContaining({ command: 'codex', args: expect.not.arrayContaining(['opus']) }),
+    );
+  });
+
+  it('maps the antigravity backend to the agy command', async () => {
+    await coordinator.createTask({
+      name: 'test',
+      prompt: 'do',
+      coordinatorTaskId: 'coord-1',
+      backend: 'antigravity',
+    });
+    expect(mockSpawnAgent).toHaveBeenCalledWith(
+      expect.anything(),
+      expect.objectContaining({ command: 'agy' }),
+    );
+  });
+
+  it('rejects unsupported backends before creating a worktree', async () => {
+    await expect(
+      coordinator.createTask({
+        name: 'test',
+        prompt: 'do',
+        coordinatorTaskId: 'coord-1',
+        backend: 'unknown',
+      }),
+    ).rejects.toThrow('Unsupported agent backend');
+    expect(mockCreateBackendTask).not.toHaveBeenCalled();
+  });
+
   it('inherits coordinator base args (e.g. --model)', async () => {
     coordinator.setCoordinatorSpawnDefaults('coord-1', 'claude', ['--model', 'claude-opus-4-7']);
     await coordinator.createTask({ name: 'test', prompt: 'do', coordinatorTaskId: 'coord-1' });
@@ -5601,6 +5640,24 @@ describe('Coordinator removePreambleBlock', () => {
   });
 });
 
+describe('normalizePreambleFileContent', () => {
+  const BLOCK = '<sub-task-mode>\nrules\n</sub-task-mode>';
+
+  it('normalizes a committed AGENTS.md preamble on both sides of landing comparisons', () => {
+    expect(normalizePreambleFileContent('AGENTS.md', BLOCK)).toBe('');
+    expect(normalizePreambleFileContent('AGENTS.md', `${BLOCK}\n\n# User change`)).toBe(
+      '# User change',
+    );
+  });
+
+  it('normalizes injected Claude settings while preserving user settings', () => {
+    const content = JSON.stringify({ model: 'opus', systemPrompt: BLOCK });
+    expect(normalizePreambleFileContent('.claude/settings.local.json', content)).toBe(
+      JSON.stringify({ model: 'opus' }, null, 2),
+    );
+  });
+});
+
 // ─── getTaskDiff — preamble-bearing files (#34) ───────────────────────────────
 
 describe('Coordinator getTaskDiff — preamble-bearing files', () => {

electron/mcp/coordinator.ts

@@ -30,7 +30,8 @@ import {
 const execAsync = promisify(execFile);
 import type { BrowserWindow } from 'electron';
 import { createTask as createBackendTask, deleteTask } from '../ipc/tasks.js';
-import { getSkipPermissionsArgs } from '../ipc/agents.js';
+import { getAgentByBackend, getSkipPermissionsArgs } from '../ipc/agents.js';
+import { isAgentBackend } from './agent-backends.js';
 import {
   spawnAgent,
   writeToAgent,
@@ -792,6 +793,7 @@ export class Coordinator {
     agentArgs?: string[];
     skipPermissions?: boolean;
     baseBranch?: string;
+    backend?: string;
   }): Promise<CoordinatedTask> {
     const coordinatorId =
       opts.coordinatorTaskId !== REST_COORDINATOR_SENTINEL
@@ -820,6 +822,16 @@ export class Coordinator {
     if (baseBranch !== undefined) {
       validateBranchName(baseBranch, 'baseBranch');
     }
+    const backend = opts.backend;
+    if (backend && !isAgentBackend(backend)) {
+      throw new Error(`Unsupported agent backend: ${backend}`);
+    }
+    const requestedAgent =
+      backend && isAgentBackend(backend) ? getAgentByBackend(backend) : undefined;
+    const selectedAgentCommand =
+      requestedAgent?.command ?? opts.agentCommand ?? coordinatorState.spawnDefaults.command;
+    const selectedAgentArgs =
+      requestedAgent?.args ?? opts.agentArgs ?? coordinatorState.spawnDefaults.args;
 
     // Create worktree + branch via existing backend
     const result = await createBackendTask(
@@ -878,7 +890,7 @@ export class Coordinator {
     // Spawn the agent process
     if (!this.win) throw new Error('No window set on coordinator');
 
-    const agentCmd = (opts.agentCommand ?? coordinatorState.spawnDefaults.command).toLowerCase();
+    const agentCmd = selectedAgentCommand.toLowerCase();
     const preamble = `<sub-task-mode>\nThese rules override all skills and hooks:\n- When your work is complete, commit your changes and call the \`land_self\` MCP tool with the verification checks you ran. A successful \`land_self\` call is the finish line — do NOT call \`signal_done\` afterward, use finishing-a-development-branch, or offer merge/PR options.\n- Use \`signal_done\` only if the coordinator explicitly asks for manual review instead of self-landing.\n- Asking questions is fine when requirements are unclear or an action is risky.\n</sub-task-mode>`;
     // Declared here so the catch block can restore preamble files on failure.
     let preambleFilePath: string | undefined;
@@ -986,8 +998,8 @@ export class Coordinator {
         task.mcpConfigPath = configPath;
       }
 
-      const agentCommand = opts.agentCommand ?? coordinatorState.spawnDefaults.command;
-      const agentArgs = opts.agentArgs ?? coordinatorState.spawnDefaults.args;
+      const agentCommand = selectedAgentCommand;
+      const agentArgs = selectedAgentArgs;
       const baseArgs = [
         ...agentArgs,
         ...(coordinatorState.propagateSkipPermissions ? getSkipPermissionsArgs(agentCommand) : []),

electron/mcp/mcp-tool-list.test.ts

@@ -71,6 +71,18 @@ describe('selectTools — role-based tool list', () => {
     expect(properties?.prompt?.type).toBe('string');
   });
 
+  it('create_task exposes the supported agent backends', () => {
+    const createTask = COORDINATOR_TOOLS.find((tool) => tool.name === 'create_task');
+    const properties = createTask?.inputSchema.properties as
+      | Record<string, { type?: string; enum?: string[] }>
+      | undefined;
+    expect(properties?.backend).toEqual({
+      type: 'string',
+      enum: ['claude', 'codex', 'gemini', 'opencode', 'copilot', 'antigravity'],
+      description: expect.stringContaining('Defaults to the coordinator backend'),
+    });
+  });
+
   it('send_prompt requires a prompt', () => {
     const sendPrompt = COORDINATOR_TOOLS.find((tool) => tool.name === 'send_prompt');
     expect(sendPrompt?.inputSchema.required).toContain('prompt');

electron/mcp/mcp-tool-list.ts

@@ -68,6 +68,12 @@ export const COORDINATOR_TOOLS: ToolDef[] = [
           description:
             'Git branch to base the worktree on. Defaults to the coordinator task branch. Only set this when deliberately overriding that default.',
         },
+        backend: {
+          type: 'string',
+          enum: ['claude', 'codex', 'gemini', 'opencode', 'copilot', 'antigravity'],
+          description:
+            'AI agent backend for this task. Defaults to the coordinator backend when omitted.',
+        },
       },
       required: ['name', 'prompt'],
     },

electron/mcp/preamble.ts

@@ -36,6 +36,25 @@ export function removePreambleBlock(content: string): string {
   return `${before}\n\n${after}`;
 }
 
+export function normalizePreambleFileContent(
+  filename: string,
+  content: string,
+  removePreamble: (value: string) => string = removePreambleBlock,
+): string | null {
+  if (filename !== '.claude/settings.local.json') return removePreamble(content);
+  try {
+    const settings = JSON.parse(content) as Record<string, unknown>;
+    if (typeof settings.systemPrompt === 'string') {
+      const stripped = removePreamble(settings.systemPrompt);
+      if (stripped.trim()) settings.systemPrompt = stripped;
+      else delete settings.systemPrompt;
+    }
+    return Object.keys(settings).length === 0 ? '' : JSON.stringify(settings, null, 2);
+  } catch {
+    return null;
+  }
+}
+
 /** Return the set of filenames (relative to worktreePath) that contain a preamble block. */
 export async function detectPreambleFiles(worktreePath: string): Promise<Set<string>> {
   const result = new Set<string>();
@@ -91,43 +110,28 @@ export async function buildNormalizedPreambleFileDiff(
     return '';
   }
 
-  let normalizedContent: string;
-  if (filename === '.claude/settings.local.json') {
-    try {
-      const s = JSON.parse(worktreeContent) as Record<string, unknown>;
-      if (typeof s.systemPrompt === 'string') {
-        const stripped = removePreamble(s.systemPrompt);
-        if (stripped.trim()) {
-          s.systemPrompt = stripped;
-        } else {
-          delete s.systemPrompt;
-        }
-      }
-      normalizedContent = Object.keys(s).length === 0 ? '' : JSON.stringify(s, null, 2);
-    } catch {
-      return '';
-    }
-  } else {
-    normalizedContent = removePreamble(worktreeContent);
-  }
+  const normalizedContent = normalizePreambleFileContent(filename, worktreeContent, removePreamble);
+  if (normalizedContent === null) return '';
 
   let baseContent = '';
   try {
-    const { stdout } = await execAsync('git', ['show', `${baseSha}:${filename}`], {
+    const result = await execAsync('git', ['show', `${baseSha}:${filename}`], {
       cwd: worktreePath,
     });
-    baseContent = stdout;
+    const stdout = typeof result === 'string' ? result : result.stdout;
+    baseContent = typeof stdout === 'string' ? stdout : '';
   } catch {
     baseContent = '';
   }
 
-  if (normalizedContent === baseContent) return '';
+  const normalizedBaseContent = normalizePreambleFileContent(filename, baseContent, removePreamble);
+  if (normalizedBaseContent === null || normalizedContent === normalizedBaseContent) return '';
 
   const id = randomUUID();
   const tmpBase = join(os.tmpdir(), `parallel-code-base-${id}`);
   const tmpNorm = join(os.tmpdir(), `parallel-code-norm-${id}`);
   try {
-    writeFileSync(tmpBase, baseContent);
+    writeFileSync(tmpBase, normalizedBaseContent);
     writeFileSync(tmpNorm, normalizedContent);
     let diffOut = '';
     try {

electron/mcp/prompt-detect.ts

@@ -31,8 +31,13 @@ export const PROMPT_PATTERNS: RegExp[] = [
  */
 export const AGENT_READY_TAIL_PATTERNS: RegExp[] = [
   /^\s*❯\s*$/, // Claude Code
+  /^\s*❯\s*Try\s+["“]/i, // Claude Code empty prompt with rotating suggestion
   /^\s*--\s*INSERT\s*--(?:$|\s|[^\w].*$)/i, // Claude Code vim-style input mode
   /^\s*›\s*$/, // Codex CLI
+  // Codex redraws can lose CSI escape introducers when output chunks split an
+  // escape sequence. stripAnsi then leaves `q` separators and cursor-position
+  // fragments, collapsing the input placeholder and footer onto one line.
+  /(?:^|\s|q)›[^\r\n›]*?gpt-[\w.-]+\s+\w+\s+·\s+~?\//i,
   /^\s*>\s*(?:Type your message|$)/i, // Gemini CLI
 ];