diff --git a/electron/build/installer-recovery.nsh b/electron/build/installer-recovery.nsh
index accbede9..a1c95020 100644
--- a/electron/build/installer-recovery.nsh
+++ b/electron/build/installer-recovery.nsh
@@ -54,6 +54,30 @@
   Sleep 1500
 !macroend
 
+!macro customInstall
+  ; ---- Defender prewarm: scan the heavy binaries while user is still watching the installer, not on first launch ----
+  ;
+  ; Right after extraction we spawn OpenSwarm.exe --prewarm, which loads
+  ; python.exe and node.exe just enough to trigger Windows Defender's
+  ; on-execute scan against them. Defender then has a cached verdict by
+  ; the time the user double-clicks the app, dropping cold-start by
+  ; 3-7 seconds on default-Defender Windows installs.
+  ;
+  ; --prewarm in main.js: no windows, no single-instance lock, no
+  ; backend spawn, no UI side effects. Touches binaries via
+  ; execFileSync('--version') and process.exit(0). 15s internal timeout
+  ; per binary; outer nsExec call adds no further bound, so worst case
+  ; this adds ~30-45s to install on a truly pathological machine.
+  ; Standard machines: 3-8s.
+  ;
+  ; Failure here is silent and non-fatal. If --prewarm itself errors,
+  ; the install still completes; user just pays the cold-start tax on
+  ; first launch, same as before this macro existed.
+
+  nsExec::Exec '"$INSTDIR\OpenSwarm.exe" --prewarm'
+  Pop $0  ; discard exit code; prewarm is best-effort
+!macroend
+
 !macro customRemoveFiles
   ; ---- Layer B: bulk-delete heavy dirs with REBOOTOK fallback ----
   ;
diff --git a/electron/main.js b/electron/main.js
index 3ed6e598..16a73b2a 100644
--- a/electron/main.js
+++ b/electron/main.js
@@ -9,6 +9,22 @@ const getPort = require('get-port');
 const http = require('http');
 const affiliateTracking = require('./affiliateTracking');
 
+// Defender warmup: NSIS runs us with --prewarm right after install so Windows scans the bundled binaries while the user is already watching the installer instead of staring at a slow first launch.
+if (process.argv.includes('--prewarm') && process.platform === 'win32') {
+  const touchExe = (rel) => {
+    const full = path.join(process.resourcesPath, rel);
+    try {
+      if (fs.existsSync(full)) {
+        execFileSync(full, ['--version'], { timeout: 15000, stdio: 'ignore', windowsHide: true });
+      }
+    } catch (_) {}
+  };
+  touchExe(path.join('python-env', 'python.exe'));
+  touchExe(path.join('node', 'x64', 'node.exe'));
+  touchExe(path.join('node', 'arm64', 'node.exe'));
+  process.exit(0);
+}
+
 // Prevent duplicate instances. Without this, double-clicking the app icon
 // (or macOS auto-launch + manual launch overlapping) spawns two independent
 // processes — each with its own backend on a different port — resulting in
diff --git a/electron/package-lock.json b/electron/package-lock.json
index c6c40ee7..ff8ca8a1 100644
--- a/electron/package-lock.json
+++ b/electron/package-lock.json
@@ -1,12 +1,12 @@
 {
   "name": "openswarm",
-  "version": "1.1.40",
+  "version": "1.1.41-exp.1",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "openswarm",
-      "version": "1.1.40",
+      "version": "1.1.41-exp.1",
       "hasInstallScript": true,
       "dependencies": {
         "electron-updater": "^6.3.0",
diff --git a/electron/package.json b/electron/package.json
index 42e6146b..6cb0a4df 100644
--- a/electron/package.json
+++ b/electron/package.json
@@ -1,6 +1,6 @@
 {
   "name": "openswarm",
-  "version": "1.1.40",
+  "version": "1.1.41-exp.1",
   "description": "OpenSwarm — AI Agent Orchestrator",
   "main": "main.js",
   "scripts": {