fix: harden startup and schema repair contracts

Reliability patch covering startup path resolution, install marker compatibility, export CLI request contracts, schema repair safety, hard-stop retry-loop handling, and the PR babysit status helper.

plugin/scripts/version-check.js

@@ -32,6 +32,24 @@ function emitUpgradeHint(message) {
   }
 }
 
+const LEGACY_VERSION_MARKER_RE =
+  /^v?\d+\.\d+\.\d+(?:-[0-9A-Za-z.-]+)?(?:\+[0-9A-Za-z.-]+)?$/;
+
+function readInstallMarkerVersion(markerPath) {
+  const content = readFileSync(markerPath, 'utf-8');
+  try {
+    const marker = JSON.parse(content);
+    return marker && typeof marker === 'object' && typeof marker.version === 'string'
+      ? marker.version
+      : null;
+  } catch {
+    const legacyVersion = content.trim();
+    return LEGACY_VERSION_MARKER_RE.test(legacyVersion)
+      ? legacyVersion.replace(/^v/i, '')
+      : null;
+  }
+}
+
 try {
   const pkg = JSON.parse(readFileSync(join(ROOT, 'package.json'), 'utf-8'));
   const markerPath = join(ROOT, '.install-version');
@@ -39,8 +57,10 @@ try {
     emitUpgradeHint('claude-mem: runtime not yet set up - run: npx claude-mem@latest install');
     process.exit(0);
   }
-  const marker = JSON.parse(readFileSync(markerPath, 'utf-8'));
-  if (marker.version !== pkg.version) {
+  const markerVersion = readInstallMarkerVersion(markerPath);
+  if (!markerVersion) {
+    emitUpgradeHint('claude-mem: install marker unreadable - run: npx claude-mem@latest install');
+  } else if (markerVersion !== pkg.version) {
     emitUpgradeHint(`claude-mem: upgraded to v${pkg.version} - run: npx claude-mem@latest install`);
   }
 } catch {