EAGAIN crash in hook scripts: readFileSync(0) fails when stdin is non-blocking

Description

Both stop-review-gate-hook.mjs and session-lifecycle-hook.mjs crash intermittently with:

Error: EAGAIN: resource temporarily unavailable, read
    at Object.readFileSync (node:fs:449:20)
    at readHookInput (file:///.claude/plugins/marketplaces/openai-codex/plugins/codex/scripts/stop-review-gate-hook.mjs:22:18)

Root Cause

readHookInput() uses fs.readFileSync(0, "utf8") to read stdin. When Claude Code invokes hooks with stdin as a pipe in non-blocking mode, the kernel returns EAGAIN instead of blocking. Node.js synchronous APIs don't retry — they throw.

// Both scripts, line 22-23
function readHookInput() {
  const raw = fs.readFileSync(0, "utf8").trim();  // throws EAGAIN
  if (!raw) { return {}; }
  return JSON.parse(raw);
}

Reproduction

Happens intermittently across Claude Code sessions on macOS (Darwin 25.3.0, Node.js v20.19.6). More frequent when multiple hooks fire in quick succession.

Suggested Fix

Catch EAGAIN and treat as empty input:

function readHookInput() {
  try {
    const raw = fs.readFileSync(0, "utf8").trim();
    if (!raw) return {};
    return JSON.parse(raw);
  } catch (e) {
    if (e.code === 'EAGAIN') return {};
    throw e;
  }
}

Both stop-review-gate-hook.mjs and session-lifecycle-hook.mjs need the same fix.

Environment

• macOS Darwin 25.3.0
• Node.js v20.19.6
• Plugin version: 1.0.2 (commit 8e403f9)
• Claude Code v2.1.90

Start with readHookInput() in stop-review-gate-hook.mjs and session-lifecycle-hook.mjs, where both scripts call fs.readFileSync(0, "utf8"). Reproduce or inspect the EAGAIN path on the documented macOS and Node.js environment. Done means EAGAIN produces empty input in both hooks while other errors still propagate.