diff --git a/plugins/codex/scripts/session-lifecycle-hook.mjs b/plugins/codex/scripts/session-lifecycle-hook.mjs
index 9655eae..7942c36 100644
--- a/plugins/codex/scripts/session-lifecycle-hook.mjs
+++ b/plugins/codex/scripts/session-lifecycle-hook.mjs
@@ -20,11 +20,42 @@ export const SESSION_ID_ENV = "CODEX_COMPANION_SESSION_ID";
 const PLUGIN_DATA_ENV = "CLAUDE_PLUGIN_DATA";
 
 function readHookInput() {
-  const raw = fs.readFileSync(0, "utf8").trim();
-  if (!raw) {
-    return {};
+  // Claude Code may invoke hooks with stdin as a non-blocking pipe, which
+  // causes read() to throw EAGAIN before EOF. We read stdin in chunks,
+  // accumulating across EAGAIN retries so partial reads are not lost.
+  // See: https://github.com/openai/codex-plugin-cc/issues/120
+  const MAX_RETRIES = 20;
+  const RETRY_DELAY_MS = 10;
+  const sleepBuf = new Int32Array(new SharedArrayBuffer(4));
+  const chunks = [];
+  const buf = Buffer.alloc(65536);
+  let eagainCount = 0;
+
+  for (;;) {
+    let n;
+    try {
+      n = fs.readSync(0, buf, 0, buf.length, null);
+    } catch (err) {
+      if (err.code !== "EAGAIN") {
+        throw err;
+      }
+      if (eagainCount >= MAX_RETRIES) {
+        // Gracefully degrade: session_id won't be set in CLAUDE_ENV_FILE,
+        // but the hook succeeds instead of surfacing a startup error.
+        return {};
+      }
+      eagainCount++;
+      Atomics.wait(sleepBuf, 0, 0, RETRY_DELAY_MS);
+      continue;
+    }
+    if (n === 0) {
+      break; // EOF
+    }
+    chunks.push(Buffer.from(buf.subarray(0, n)));
   }
-  return JSON.parse(raw);
+
+  const raw = Buffer.concat(chunks).toString("utf8").trim();
+  return raw ? JSON.parse(raw) : {};
 }
 
 function shellEscape(value) {
diff --git a/plugins/codex/scripts/stop-review-gate-hook.mjs b/plugins/codex/scripts/stop-review-gate-hook.mjs
index c22edbd..4196d6e 100644
--- a/plugins/codex/scripts/stop-review-gate-hook.mjs
+++ b/plugins/codex/scripts/stop-review-gate-hook.mjs
@@ -19,11 +19,40 @@ const ROOT_DIR = path.resolve(SCRIPT_DIR, "..");
 const STOP_REVIEW_TASK_MARKER = "Run a stop-gate review of the previous Claude turn.";
 
 function readHookInput() {
-  const raw = fs.readFileSync(0, "utf8").trim();
-  if (!raw) {
-    return {};
+  // Claude Code may invoke hooks with stdin as a non-blocking pipe, which
+  // causes read() to throw EAGAIN before EOF. We read stdin in chunks,
+  // accumulating across EAGAIN retries so partial reads are not lost.
+  // See: https://github.com/openai/codex-plugin-cc/issues/120
+  const MAX_RETRIES = 20;
+  const RETRY_DELAY_MS = 10;
+  const sleepBuf = new Int32Array(new SharedArrayBuffer(4));
+  const chunks = [];
+  const buf = Buffer.alloc(65536);
+  let eagainCount = 0;
+
+  for (;;) {
+    let n;
+    try {
+      n = fs.readSync(0, buf, 0, buf.length, null);
+    } catch (err) {
+      if (err.code !== "EAGAIN") {
+        throw err;
+      }
+      if (eagainCount >= MAX_RETRIES) {
+        return {};
+      }
+      eagainCount++;
+      Atomics.wait(sleepBuf, 0, 0, RETRY_DELAY_MS);
+      continue;
+    }
+    if (n === 0) {
+      break; // EOF
+    }
+    chunks.push(Buffer.from(buf.subarray(0, n)));
   }
-  return JSON.parse(raw);
+
+  const raw = Buffer.concat(chunks).toString("utf8").trim();
+  return raw ? JSON.parse(raw) : {};
 }
 
 function emitDecision(payload) {