diff --git a/plugins/codex/scripts/lib/process.mjs b/plugins/codex/scripts/lib/process.mjs
index dd8fc3751..78bb9a20e 100644
--- a/plugins/codex/scripts/lib/process.mjs
+++ b/plugins/codex/scripts/lib/process.mjs
@@ -1,13 +1,16 @@
 import { spawnSync } from "node:child_process";
 import process from "node:process";
 
+// Git metadata can exceed Node's 1 MiB spawnSync default. Keep a generous explicit bound.
+const DEFAULT_MAX_BUFFER = 256 * 1024 * 1024;
+
 export function runCommand(command, args = [], options = {}) {
   const result = spawnSync(command, args, {
     cwd: options.cwd,
     env: options.env,
     encoding: "utf8",
     input: options.input,
-    maxBuffer: options.maxBuffer,
+    maxBuffer: options.maxBuffer ?? DEFAULT_MAX_BUFFER,
     stdio: options.stdio ?? "pipe",
     shell: options.shell ?? (process.platform === "win32" ? (process.env.SHELL || true) : false),
     windowsHide: true
diff --git a/tests/process.test.mjs b/tests/process.test.mjs
index 80e0715b0..13e70ecf0 100644
--- a/tests/process.test.mjs
+++ b/tests/process.test.mjs
@@ -1,7 +1,29 @@
 import test from "node:test";
 import assert from "node:assert/strict";
 
-import { terminateProcessTree } from "../plugins/codex/scripts/lib/process.mjs";
+import { runCommand, terminateProcessTree } from "../plugins/codex/scripts/lib/process.mjs";
+
+test("runCommand allows output larger than Node's default maxBuffer", () => {
+  const outputBytes = 2 * 1024 * 1024;
+  const result = runCommand(process.execPath, [
+    "-e",
+    `process.stdout.write("x".repeat(${outputBytes}))`
+  ], { shell: false });
+
+  assert.equal(result.error, null);
+  assert.equal(result.status, 0);
+  assert.equal(Buffer.byteLength(result.stdout), outputBytes);
+});
+
+test("runCommand preserves an explicit maxBuffer override", () => {
+  const result = runCommand(
+    process.execPath,
+    ["-e", `process.stdout.write("x".repeat(${2 * 1024}))`],
+    { maxBuffer: 1024, shell: false }
+  );
+
+  assert.equal(result.error?.code, "ENOBUFS");
+});
 
 test("terminateProcessTree uses taskkill on Windows", () => {
   let captured = null;
@@ -53,3 +75,18 @@ test("terminateProcessTree treats missing Windows processes as already stopped",
   assert.equal(outcome.result.status, 128);
   assert.match(outcome.result.stdout, /not found/i);
 });
+
+
+for (const [stream, character] of [["stdout", "é"], ["stderr", "😀"]]) {
+  test(`runCommand retains large Unicode ${stream} output`, () => {
+    const text = character.repeat(600_000);
+    const result = runCommand(process.execPath, [
+      "-e",
+      `process.${stream}.write(${JSON.stringify(character)}.repeat(600000))`
+    ], { shell: false });
+    assert.equal(result.status, 0);
+    assert.equal(result.error, null);
+    assert.equal(result[stream], text);
+    assert.equal(Buffer.byteLength(result[stream]), Buffer.byteLength(text));
+  });
+}