diff --git a/apps/desktop/scripts/dev-renderer-warmup.mjs b/apps/desktop/scripts/dev-renderer-warmup.mjs
new file mode 100644
index 0000000000..d4bcfcf6c2
--- /dev/null
+++ b/apps/desktop/scripts/dev-renderer-warmup.mjs
@@ -0,0 +1,36 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+/**
+ * Resolve the renderer entry before Electron starts. This lets Vite finish
+ * dependency optimization and prevents a first navigation from combining
+ * modules from two optimizer generations.
+ */
+export async function warmupDevRenderer(server, entry = '/main.tsx') {
+  const environment = server.environments?.client;
+  if (environment?.warmupRequest && environment?.waitForRequestsIdle) {
+    await environment.warmupRequest(entry);
+    await environment.waitForRequestsIdle();
+    return;
+  }
+
+  // Vite 7 and earlier expose the same operation on the server. Keep this
+  // fallback for local installs that have not moved to per-environment APIs.
+  await server.warmupRequest(entry);
+}
diff --git a/apps/desktop/scripts/dev-renderer-warmup.test.mjs b/apps/desktop/scripts/dev-renderer-warmup.test.mjs
new file mode 100644
index 0000000000..cf97003ad4
--- /dev/null
+++ b/apps/desktop/scripts/dev-renderer-warmup.test.mjs
@@ -0,0 +1,50 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+import assert from 'node:assert/strict';
+import test from 'node:test';
+import { warmupDevRenderer } from './dev-renderer-warmup.mjs';
+
+test('warms the client environment and waits for its imports to settle', async () => {
+  const calls = [];
+  const server = {
+    environments: {
+      client: {
+        async warmupRequest(url) { calls.push(`warmup:${url}`); },
+        async waitForRequestsIdle() { calls.push('idle'); },
+      },
+    },
+    async warmupRequest() { throw new Error('legacy server API should not be used'); },
+  };
+
+  await warmupDevRenderer(server);
+
+  assert.deepEqual(calls, ['warmup:/main.tsx', 'idle']);
+});
+
+test('falls back to the server warmup API for older Vite versions', async () => {
+  const calls = [];
+  const server = {
+    async warmupRequest(url) { calls.push(url); },
+  };
+
+  await warmupDevRenderer(server, '/legacy.tsx');
+
+  assert.deepEqual(calls, ['/legacy.tsx']);
+});
diff --git a/apps/desktop/scripts/dev.mjs b/apps/desktop/scripts/dev.mjs
index 56e7ec7e31..304f7090c0 100644
--- a/apps/desktop/scripts/dev.mjs
+++ b/apps/desktop/scripts/dev.mjs
@@ -47,6 +47,7 @@ import {
   handleDevelopmentLaunchOutcome,
   waitForDevelopmentLaunchVerdict,
 } from './dev-app-runtime.mjs';
+import { warmupDevRenderer } from './dev-renderer-warmup.mjs';
 
 const DESKTOP_DIR = resolve(fileURLToPath(new URL('..', import.meta.url)));
 const REPO_ROOT    = resolve(DESKTOP_DIR, '..', '..');
@@ -151,6 +152,7 @@ process.chdir(DESKTOP_DIR);
 log('vite', 'starting dev server...');
 const server = await createServer();
 await server.listen();
+await warmupDevRenderer(server);
 server.printUrls();
 
 const devUrl = server.resolvedUrls?.local?.[0]?.replace(/\/$/, '');
diff --git a/apps/desktop/src/main/__tests__/main-renderer-loader.test.ts b/apps/desktop/src/main/__tests__/main-renderer-loader.test.ts
new file mode 100644
index 0000000000..79ba648a31
--- /dev/null
+++ b/apps/desktop/src/main/__tests__/main-renderer-loader.test.ts
@@ -0,0 +1,46 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+import assert from 'node:assert/strict';
+import test from 'node:test';
+import { clearDevRendererCache, type MainRendererCacheOwner } from '../main-renderer-loader.js';
+
+test('clears the renderer session cache only for a Vite development entry', async () => {
+  let clearCount = 0;
+  const owner: MainRendererCacheOwner = {
+    webContents: {
+      session: {
+        async clearCache() { clearCount += 1; },
+      },
+    },
+  };
+
+  await clearDevRendererCache(owner, {
+    filePath: '/app/dist-renderer/index.html',
+    url: 'http://127.0.0.1:5173',
+    useDevServer: true,
+  });
+  await clearDevRendererCache(owner, {
+    filePath: '/app/dist-renderer/index.html',
+    url: 'file:///app/dist-renderer/index.html',
+    useDevServer: false,
+  });
+
+  assert.equal(clearCount, 1);
+});
diff --git a/apps/desktop/src/main/main-renderer-loader.ts b/apps/desktop/src/main/main-renderer-loader.ts
index 5b97a43564..fa1bc4450d 100644
--- a/apps/desktop/src/main/main-renderer-loader.ts
+++ b/apps/desktop/src/main/main-renderer-loader.ts
@@ -31,6 +31,21 @@ export interface MainRendererEntry {
   readonly useDevServer: boolean;
 }
 
+export interface MainRendererCacheOwner {
+  webContents: {
+    session: {
+      clearCache(): Promise<void>;
+    };
+  };
+}
+
+export async function clearDevRendererCache(
+  mainWindow: MainRendererCacheOwner,
+  rendererEntry: MainRendererEntry,
+): Promise<void> {
+  if (rendererEntry.useDevServer) await mainWindow.webContents.session.clearCache();
+}
+
 export function resolveMainRendererEntry(
   mainModuleDirectory: string,
   viteDevServerUrl: string | undefined,
diff --git a/apps/desktop/src/main/main-window.ts b/apps/desktop/src/main/main-window.ts
index 9f8fbc1e84..e1bec8686a 100644
--- a/apps/desktop/src/main/main-window.ts
+++ b/apps/desktop/src/main/main-window.ts
@@ -28,7 +28,11 @@ import { BrowserViewController } from './browser/controller.js';
 import { BrowserViewManager } from './browser/view-manager.js';
 import type { E2eFixture } from './e2e-fixture.js';
 import { installMainWindowPermissionPolicy } from './main-window-permission-policy.js';
-import { loadMainRenderer, resolveMainRendererEntry } from './main-renderer-loader.js';
+import {
+  clearDevRendererCache,
+  loadMainRenderer,
+  resolveMainRendererEntry,
+} from './main-renderer-loader.js';
 import {
   type MainRendererFrameIdentity,
   observeMainRendererProcessGone,
@@ -522,6 +526,7 @@ export function createMainWindowController(deps: MainWindowControllerDeps): Main
       void writeSavedBounds(workspaceRoot, final);
     });
 
+    await clearDevRendererCache(mainWindow, rendererEntry);
     await loadMainRenderer(mainWindow, rendererEntry);
 
     // PR-SHOW-AFTER-FIRST-COMMIT: reveal fallback. Start this budget only once