diff --git a/open-sse/handlers/chatCore.ts b/open-sse/handlers/chatCore.ts
index 98ffd4cdaa..aef0ac63e2 100644
--- a/open-sse/handlers/chatCore.ts
+++ b/open-sse/handlers/chatCore.ts
@@ -1526,6 +1526,7 @@ export async function handleChatCore({
   let tokensCompressed: number | null = null;
   body = injectSystemPrompt(body);
   // ── Plugin onRequest hook ──
+  // Dynamic import cached by Node.js after first call — minimal overhead
   try {
     const { runOnRequest } = await import("@/lib/plugins/index");
     const pluginCtx = {
@@ -1560,7 +1561,7 @@ export async function handleChatCore({
       };
     }
     if (pluginResult?.ctx && "body" in pluginResult.ctx) {
-      body = (pluginResult.ctx as Record<string, unknown>).body;
+      body = (pluginResult.ctx as unknown as Record<string, unknown>).body;
     }
   } catch (pluginErr) {
     log?.debug?.(
diff --git a/src/app/api/plugins/[name]/config/route.ts b/src/app/api/plugins/[name]/config/route.ts
index f0861d5aa8..120f3ea6b4 100644
--- a/src/app/api/plugins/[name]/config/route.ts
+++ b/src/app/api/plugins/[name]/config/route.ts
@@ -60,6 +60,35 @@ export async function PUT(request: NextRequest, { params }: { params: Promise<{
     );
   }
 
+  // Validate config values against configSchema if defined
+  const configSchema = JSON.parse(plugin.configSchema || "{}");
+  if (Object.keys(configSchema).length > 0) {
+    for (const [key, value] of Object.entries(parsed.data.config)) {
+      const field = configSchema[key];
+      if (!field) continue; // Allow extra keys
+      if (field.type === "number" && typeof value === "number") {
+        if (field.min !== undefined && value < field.min) {
+          return NextResponse.json(
+            { error: `Config '${key}' must be >= ${field.min}` },
+            { status: 400, headers: CORS_HEADERS }
+          );
+        }
+        if (field.max !== undefined && value > field.max) {
+          return NextResponse.json(
+            { error: `Config '${key}' must be <= ${field.max}` },
+            { status: 400, headers: CORS_HEADERS }
+          );
+        }
+      }
+      if (field.type === "select" && field.enum && !field.enum.includes(String(value))) {
+        return NextResponse.json(
+          { error: `Config '${key}' must be one of: ${field.enum.join(", ")}` },
+          { status: 400, headers: CORS_HEADERS }
+        );
+      }
+    }
+  }
+
   updatePluginConfig(name, parsed.data.config);
 
   return NextResponse.json(
diff --git a/src/lib/db/plugins.ts b/src/lib/db/plugins.ts
index 41ed7f24c9..e13aee1e42 100644
--- a/src/lib/db/plugins.ts
+++ b/src/lib/db/plugins.ts
@@ -118,7 +118,11 @@ export function insertPlugin(input: PluginCreateInput): PluginRow {
   );
 
   log.info("plugin.inserted", { id: input.id, name: input.name });
-  return getPluginByName(input.name)!;
+  const plugin = getPluginByName(input.name);
+  if (!plugin) {
+    throw new Error(`Failed to retrieve plugin '${input.name}' after insertion`);
+  }
+  return plugin;
 }
 
 export function getPluginById(id: string): PluginRow | null {
diff --git a/src/lib/plugins/loader.ts b/src/lib/plugins/loader.ts
index e686b3a3d4..432282316c 100644
--- a/src/lib/plugins/loader.ts
+++ b/src/lib/plugins/loader.ts
@@ -98,19 +98,18 @@ export async function loadPlugin(
   const moduleObj = { exports: moduleExports };
   sandbox.module = moduleObj;
   sandbox.exports = moduleExports;
+  const allowedModules: Record<string, unknown> = {};
+  if (permissions.includes("network")) {
+    allowedModules.crypto = require("crypto");
+  }
   sandbox.require = (id: string) => {
-    // Only allow specific safe modules
-    const allowed: Record<string, unknown> = {};
-    if (id === "crypto") {
-      allowed.crypto = require("crypto");
-    }
-    if (allowed[id]) return allowed[id];
+    if (id in allowedModules) return allowedModules[id];
     throw new Error(`Module '${id}' is not allowed in plugin sandbox`);
   };
 
   try {
     // Wrap source in a function to capture exports
-    const wrapped = `(async function(module, exports, require) { ${source} })(module, exports, require);`;
+    const wrapped = `(async function(module, exports, require) {\n${source}\n})(module, exports, require);`;
     vm.runInContext(wrapped, context, {
       filename: entryPoint,
       timeout: 10000, // 10s init timeout
diff --git a/src/lib/plugins/manager.ts b/src/lib/plugins/manager.ts
index b2609b57bb..94d74a7487 100644
--- a/src/lib/plugins/manager.ts
+++ b/src/lib/plugins/manager.ts
@@ -48,7 +48,36 @@ class PluginManager {
    * Copies to plugin dir, validates manifest, registers in DB.
    */
   async install(sourceDir: string): Promise<PluginRow> {
-    const { plugins, errors } = await scanPluginDir(sourceDir);
+    // Check if sourceDir itself contains plugin.json (direct plugin dir)
+    const { safeValidateManifest } = await import("./manifest");
+    const { readFile: readFileFs } = await import("fs/promises");
+    let directPlugin: {
+      name: string;
+      manifest: any;
+      pluginDir: string;
+      entryPoint: string;
+    } | null = null;
+
+    try {
+      const manifestPath = join(sourceDir, "plugin.json");
+      const raw = await readFileFs(manifestPath, "utf-8");
+      const parsed = JSON.parse(raw);
+      const result = safeValidateManifest(parsed);
+      if (result.success) {
+        const entryPoint = join(sourceDir, result.data.main);
+        directPlugin = {
+          name: result.data.name,
+          manifest: result.data,
+          pluginDir: sourceDir,
+          entryPoint,
+        };
+      }
+    } catch {}
+
+    const { plugins, errors } = directPlugin
+      ? { plugins: [directPlugin], errors: [] }
+      : await scanPluginDir(sourceDir);
+
     if (plugins.length === 0) {
       throw new Error(
         `No valid plugin found in ${sourceDir}: ${errors.map((e) => e.error).join(", ")}`
@@ -110,7 +139,12 @@ class PluginManager {
     if (row.status === "active") return;
 
     const manifest = JSON.parse(row.manifest) as PluginManifestWithDefaults;
+
+    // Path traversal guard: entry point must stay within plugin directory
     const entryPoint = join(row.pluginDir, manifest.main);
+    if (!entryPoint.startsWith(row.pluginDir)) {
+      throw new Error(`Plugin '${name}' entry point escapes plugin directory`);
+    }
 
     try {
       const loaded = await loadPlugin(entryPoint, manifest);