feat(cli): add -C / --cd <dir> to set the working directory (Codex parity)

apps/cli/src/cli.ts

@@ -35,6 +35,22 @@ async function main(): Promise<number> {
     return 2;
   }
 
+  // -C / --cd <dir>: change the working directory before anything resolves cwd
+  // (Codex parity). Done here — after --help/--version short-circuit but before
+  // every subcommand/REPL/headless path that reads process.cwd() — so a single
+  // chdir covers them all. Validate eagerly so a bad path fails fast (exit 2)
+  // instead of surfacing as a confusing error deep in the agent.
+  if (args.cwd !== undefined) {
+    try {
+      process.chdir(args.cwd);
+    } catch (err) {
+      process.stderr.write(
+        `Cannot change to --cd directory "${args.cwd}": ${(err as Error).message}\n`,
+      );
+      return 2;
+    }
+  }
+
   if (args.doctor) {
     return doctor();
   }

apps/cli/src/parse-args.test.ts

@@ -24,6 +24,15 @@ describe('parseArgs', () => {
     expect(parseArgs(['upgrade']).upgrade).toBe(true);
   });
 
+  it('-C / --cd <dir> sets working directory', () => {
+    expect(parseArgs(['-C', '/work/dir']).cwd).toBe('/work/dir');
+    expect(parseArgs(['--cd', '/another']).cwd).toBe('/another');
+  });
+  it('cwd is undefined without -C/--cd', () => {
+    expect(parseArgs([]).cwd).toBeUndefined();
+    expect(parseArgs(['--mode', 'plan']).cwd).toBeUndefined();
+  });
+
   it('-p "prompt"', () => {
     expect(parseArgs(['-p', 'do the thing']).prompt).toBe('do the thing');
     expect(parseArgs(['--print', 'foo']).prompt).toBe('foo');

apps/cli/src/parse-args.ts

@@ -27,6 +27,9 @@ export interface ParsedArgs {
   maxTurns?: number;
   bare: boolean;
 
+  /** `-C` / `--cd <dir>`: chdir to this directory before running (Codex parity). */
+  cwd?: string;
+
   // System prompt overrides
   systemPrompt?: string;
   appendSystemPrompt?: string;
@@ -181,6 +184,9 @@ export function parseArgs(argv: string[]): ParsedArgs {
       case a === '--bare':
         out.bare = true;
         break;
+      case a === '-C' || a === '--cd':
+        out.cwd = next();
+        break;
       case a === '--system-prompt':
         out.systemPrompt = next();
         break;
@@ -287,6 +293,9 @@ MODE
   --permission-mode <name>              Alias for --mode (Claude Code parity)
   --bare                                No plugins / MCP / skills — just kernel + tools
 
+WORKING DIRECTORY
+  -C, --cd <dir>                        Change to <dir> before running (default: current dir)
+
 MODEL & EFFORT
   --model <id>                          deepseek-chat | deepseek-reasoner
   --effort <tier>                       low | medium | high | xhigh | max