diff --git a/scripts/hooks/session-end-marker.js b/scripts/hooks/session-end-marker.js
index 54918410..c635a93d 100755
--- a/scripts/hooks/session-end-marker.js
+++ b/scripts/hooks/session-end-marker.js
@@ -1,15 +1,29 @@
 #!/usr/bin/env node
 'use strict';
 
-const MAX_STDIN = 1024 * 1024;
-let raw = '';
-process.stdin.setEncoding('utf8');
-process.stdin.on('data', chunk => {
-  if (raw.length < MAX_STDIN) {
-    const remaining = MAX_STDIN - raw.length;
-    raw += chunk.substring(0, remaining);
-  }
-});
-process.stdin.on('end', () => {
-  process.stdout.write(raw);
-});
+/**
+ * Session end marker hook - outputs stdin to stdout unchanged.
+ * Exports run() for in-process execution (avoids spawnSync issues on Windows).
+ */
+
+function run(rawInput) {
+  return rawInput || '';
+}
+
+// Legacy CLI execution (when run directly)
+if (require.main === module) {
+  const MAX_STDIN = 1024 * 1024;
+  let raw = '';
+  process.stdin.setEncoding('utf8');
+  process.stdin.on('data', chunk => {
+    if (raw.length < MAX_STDIN) {
+      const remaining = MAX_STDIN - raw.length;
+      raw += chunk.substring(0, remaining);
+    }
+  });
+  process.stdin.on('end', () => {
+    process.stdout.write(raw);
+  });
+}
+
+module.exports = { run };