diff --git a/cypress.config.ts b/cypress.config.ts
index 87e26ec521..cbe64083c9 100644
--- a/cypress.config.ts
+++ b/cypress.config.ts
@@ -1,25 +1,36 @@
 import { defineConfig } from 'cypress';
 import fkill from 'fkill';
 
-import { runChainlit } from './cypress/support/run';
+import { runChainlit, stopChainlit } from './cypress/support/run';
 
 export const CHAINLIT_APP_PORT = 8000;
 
+const signals = ['SIGTERM', 'SIGINT', 'SIGHUP', 'SIGBREAK'] as const;
+type ExitSignal = (typeof signals)[number];
+
+const signalMap: Record<ExitSignal, number> = {
+  SIGTERM: 15,
+  SIGINT: 2,
+  SIGHUP: 1,
+  SIGBREAK: 21
+};
+
 async function killChainlit() {
-  await fkill(`:${CHAINLIT_APP_PORT}`, {
-    force: true,
-    silent: true
-  });
-}
+  const stoppedTracked = await stopChainlit();
 
-['SIGTERM', 'SIGINT', 'SIGHUP', 'SIGBREAK'].forEach((signal) => {
-  process.on(signal, () => {
-    (async () => {
-      await killChainlit(); // Ensure Chainlit is killed on exit
+  if (!stoppedTracked) {
+    try {
+      await fkill(`:${CHAINLIT_APP_PORT}`, { force: true, silent: true });
+    } catch {
+      // best-effort cleanup only
+    }
+  }
+}
 
-      const signalMap = { SIGTERM: 15, SIGINT: 2, SIGHUP: 1, SIGBREAK: 21 };
-      process.exit(128 + (signalMap[signal] || 0));
-    })();
+signals.forEach((signal) => {
+  process.on(signal, async () => {
+    await killChainlit(); // Ensure Chainlit is killed on exit
+    process.exit(128 + signalMap[signal]);
   });
 });
 
@@ -36,7 +47,7 @@ export default defineConfig({
     experimentalInteractiveRunEvents: true,
     async setupNodeEvents(on, config) {
       await killChainlit(); // Fallback to ensure no previous instance is running
-      await runChainlit(); // Start Chainlit before running tests as Cypress require
+      await runChainlit(); // Start Chainlit before running tests as Cypress requires
 
       on('before:spec', async (spec) => {
         await killChainlit();
@@ -57,15 +68,10 @@ export default defineConfig({
           return null;
         },
         restartChainlit(spec: Cypress.Spec) {
-          return new Promise((resolve) => {
-            killChainlit().then(() => {
-              runChainlit(spec).then(() => {
-                setTimeout(() => {
-                  resolve(null);
-                }, 1000);
-              });
-            });
-          });
+          return killChainlit()
+            .then(() => runChainlit(spec))
+            .then(() => new Promise((r) => setTimeout(r, 1000)))
+            .then(() => null);
         }
       });
 
diff --git a/cypress/support/run.ts b/cypress/support/run.ts
index d05bea079b..9d9e3385dc 100644
--- a/cypress/support/run.ts
+++ b/cypress/support/run.ts
@@ -1,10 +1,65 @@
 import {
-  ChildProcessWithoutNullStreams,
-  SpawnOptionsWithoutStdio,
+  type ChildProcessWithoutNullStreams,
+  type SpawnOptionsWithoutStdio,
   spawn
-} from 'child_process';
-import { access } from 'fs/promises';
-import { dirname, join } from 'path';
+} from 'node:child_process';
+import { access } from 'node:fs/promises';
+import { dirname, join } from 'node:path';
+
+let currentChainlit: ChildProcessWithoutNullStreams | null = null;
+
+/**
+ * Kill a process tree on Windows using taskkill /T /F
+ */
+async function taskkillTree(pid: number): Promise<void> {
+  await new Promise<void>((resolve) => {
+    const p = spawn('taskkill', ['/PID', String(pid), '/T', '/F'], {
+      windowsHide: true,
+      stdio: 'ignore'
+    });
+
+    p.on('exit', () => resolve());
+    p.on('error', () => resolve()); // best-effort
+  });
+
+  // Give Windows time to release the port
+  await sleep(750);
+}
+
+function sleep(ms: number) {
+  return new Promise((r) => setTimeout(r, ms));
+}
+
+export async function stopChainlit(): Promise<boolean> {
+  const proc = currentChainlit;
+  if (!proc?.pid) return false;
+
+  const pid = proc.pid;
+
+  if (process.platform === 'win32') {
+    // Windows: kill entire process tree
+    await taskkillTree(pid);
+  } else {
+    // POSIX: kill process group (requires detached: true)
+    try {
+      process.kill(-pid, 'SIGTERM');
+    } catch {
+      // ignore
+    }
+
+    await sleep(1500);
+
+    try {
+      process.kill(-pid, 'SIGKILL');
+    } catch {
+      // ignore
+    }
+  }
+
+  currentChainlit = null;
+
+  return true;
+}
 
 export const runChainlit = async (
   spec: Cypress.Spec | null = null
@@ -12,24 +67,24 @@ export const runChainlit = async (
   const CHAILIT_DIR = join(process.cwd(), 'backend', 'chainlit');
   const SAMPLE_DIR = join(CHAILIT_DIR, 'sample');
 
-  return new Promise((resolve, reject) => {
-    const testDir = spec ? dirname(spec.absolute) : SAMPLE_DIR;
-    const entryPointFileName = spec
-      ? spec.name.startsWith('async')
-        ? 'main_async.py'
-        : spec.name.startsWith('sync')
-        ? 'main_sync.py'
-        : 'main.py'
-      : 'hello.py';
-
-    const entryPointPath = join(testDir, entryPointFileName);
-
-    if (!access(entryPointPath)) {
-      return reject(
-        new Error(`Entry point file does not exist: ${entryPointPath}`)
-      );
-    }
+  const testDir = spec ? dirname(spec.absolute) : SAMPLE_DIR;
+  const entryPointFileName = spec
+    ? spec.name.startsWith('async')
+      ? 'main_async.py'
+      : spec.name.startsWith('sync')
+      ? 'main_sync.py'
+      : 'main.py'
+    : 'hello.py';
 
+  const entryPointPath = join(testDir, entryPointFileName);
+
+  try {
+    await access(entryPointPath);
+  } catch {
+    throw new Error(`Entry point file does not exist: ${entryPointPath}`);
+  }
+
+  return new Promise((resolve, reject) => {
     const command = 'uv';
 
     const args = [
@@ -47,11 +102,14 @@ export const runChainlit = async (
       env: {
         ...process.env,
         CHAINLIT_APP_ROOT: testDir
-      }
+      },
+      detached: true
     };
 
     const chainlit = spawn(command, args, options);
 
+    currentChainlit = chainlit;
+
     chainlit.stdout.on('data', (data) => {
       const output = data.toString();
       if (output.includes('Your app is available at')) {
@@ -64,11 +122,11 @@ export const runChainlit = async (
     });
 
     chainlit.on('error', (error) => {
-      reject(error.message);
+      reject(error);
     });
 
-    chainlit.on('exit', function (code) {
-      reject('Chainlit process exited with code ' + code);
+    chainlit.on('exit', (code) => {
+      reject(new Error('Chainlit process exited with code ' + code));
     });
   });
 };