feat: create parent directories when creating new files. (#552)

apply_patch doesn't create parent directories when creating a new file
leading to confusion and flailing by the agent. This will create parent
directories automatically when absent.

---------

Co-authored-by: Thibault Sottiaux <tibo@openai.com>

codex-cli/tests/exec-apply-patch.test.ts

@@ -0,0 +1,44 @@
+import { execApplyPatch } from "../src/utils/agent/exec.js";
+import fs from "fs";
+import os from "os";
+import path from "path";
+import { test, expect } from "vitest";
+
+/**
+ * This test verifies that `execApplyPatch()` is able to add a new file whose
+ * parent directory does not yet exist. Prior to the fix, the call would throw
+ * because `fs.writeFileSync()` could not create intermediate directories. The
+ * test creates an isolated temporary directory to avoid polluting the project
+ * workspace.
+ */
+test("execApplyPatch creates missing directories when adding a file", () => {
+  const tmpDir = fs.mkdtempSync(path.join(os.tmpdir(), "apply-patch-test-"));
+
+  // Ensure we start from a clean slate.
+  const nestedFileRel = path.join("foo", "bar", "baz.txt");
+  const nestedFileAbs = path.join(tmpDir, nestedFileRel);
+  expect(fs.existsSync(nestedFileAbs)).toBe(false);
+
+  const patch = `*** Begin Patch\n*** Add File: ${nestedFileRel}\n+hello new world\n*** End Patch`;
+
+  // Run execApplyPatch() with cwd switched to tmpDir so that the relative
+  // path in the patch is resolved inside the temporary location.
+  const prevCwd = process.cwd();
+  try {
+    process.chdir(tmpDir);
+
+    const result = execApplyPatch(patch);
+    expect(result.exitCode).toBe(0);
+    expect(result.stderr).toBe("");
+  } finally {
+    process.chdir(prevCwd);
+  }
+
+  // The file (and its parent directories) should have been created with the
+  // expected contents.
+  const fileContents = fs.readFileSync(nestedFileAbs, "utf8");
+  expect(fileContents).toBe("hello new world");
+
+  // Cleanup to keep tmpdir tidy.
+  fs.rmSync(tmpDir, { recursive: true, force: true });
+});