docs: Add full expandable examples and define FASTAPI_APP

Add copy-pasteable full examples using expandable CodeGroups for the
screenshot and agent data extraction sections. Define the missing
FASTAPI_APP constant in the step-by-step code blocks.

Author: beran-t

docs/use-cases/remote-browser.mdx

@@ -69,6 +69,26 @@ Deploy a web app inside an E2B sandbox, get a public URL, then use a Kernel brow
 ```typescript JavaScript & TypeScript
 import { Sandbox } from 'e2b'
 
+// A minimal FastAPI app with three routes to screenshot
+const FASTAPI_APP = `
+from fastapi import FastAPI
+from fastapi.responses import HTMLResponse
+
+app = FastAPI()
+
+@app.get("/")
+def home():
+    return HTMLResponse("<h1>Home</h1><p>Welcome to the app.</p>")
+
+@app.get("/about")
+def about():
+    return HTMLResponse("<h1>About</h1><p>About this app.</p>")
+
+@app.get("/dashboard")
+def dashboard():
+    return HTMLResponse("<h1>Dashboard</h1><p>Your dashboard.</p>")
+`
+
 const sandbox = await Sandbox.create('kernel-browser', {
   envs: { KERNEL_API_KEY: process.env.KERNEL_API_KEY! },
   timeoutMs: 300_000,
@@ -88,6 +108,26 @@ await sandbox.commands.run(
 import os
 from e2b import Sandbox
 
+# A minimal FastAPI app with three routes to screenshot
+FASTAPI_APP = """
+from fastapi import FastAPI
+from fastapi.responses import HTMLResponse
+
+app = FastAPI()
+
+@app.get("/")
+def home():
+    return HTMLResponse("<h1>Home</h1><p>Welcome to the app.</p>")
+
+@app.get("/about")
+def about():
+    return HTMLResponse("<h1>About</h1><p>About this app.</p>")
+
+@app.get("/dashboard")
+def dashboard():
+    return HTMLResponse("<h1>Dashboard</h1><p>Your dashboard.</p>")
+"""
+
 sandbox = Sandbox.create(
     "kernel-browser",
     envs={"KERNEL_API_KEY": os.environ["KERNEL_API_KEY"]},
@@ -186,6 +226,162 @@ sandbox.kill()
 </Step>
 </Steps>
 
+Full example:
+
+<CodeGroup>
+```typescript JavaScript & TypeScript expandable
+import { Sandbox } from 'e2b'
+
+// A minimal FastAPI app with three routes to screenshot
+const FASTAPI_APP = `
+from fastapi import FastAPI
+from fastapi.responses import HTMLResponse
+
+app = FastAPI()
+
+@app.get("/")
+def home():
+    return HTMLResponse("<h1>Home</h1><p>Welcome to the app.</p>")
+
+@app.get("/about")
+def about():
+    return HTMLResponse("<h1>About</h1><p>About this app.</p>")
+
+@app.get("/dashboard")
+def dashboard():
+    return HTMLResponse("<h1>Dashboard</h1><p>Your dashboard.</p>")
+`
+
+// 1. Create the sandbox and start the app
+const sandbox = await Sandbox.create('kernel-browser', {
+  envs: { KERNEL_API_KEY: process.env.KERNEL_API_KEY! },
+  timeoutMs: 300_000,
+})
+
+await sandbox.files.write('/home/user/app.py', FASTAPI_APP)
+await sandbox.commands.run(
+  'pip install fastapi uvicorn',
+  { timeoutMs: 60_000 },
+)
+await sandbox.commands.run(
+  'uvicorn app:app --host 0.0.0.0 --port 8000',
+  { background: true, cwd: '/home/user' },
+)
+
+// 2. Screenshot each route with a Kernel browser
+const host = sandbox.getHost(8000)
+const appUrl = `https://${host}`
+
+const BROWSE_SCRIPT = `
+import sys
+from kernel import Kernel
+from playwright.sync_api import sync_playwright
+
+app_url = "${appUrl}"
+routes = ["/", "/about", "/dashboard"]
+
+kernel = Kernel()
+kb = kernel.browsers.create()
+
+with sync_playwright() as pw:
+    browser = pw.chromium.connect_over_cdp(kb.cdp_ws_url)
+    page = browser.new_page()
+    page.set_viewport_size({"width": 1280, "height": 720})
+
+    for route in routes:
+        page.goto(f"{app_url}{route}", wait_until="networkidle")
+        name = "home" if route == "/" else route.strip("/")
+        page.screenshot(path=f"/home/user/{name}.png")
+        print(f"Captured {route}")
+
+    browser.close()
+`
+
+await sandbox.files.write('/home/user/browse.py', BROWSE_SCRIPT)
+const result = await sandbox.commands.run(
+  'python3 /home/user/browse.py',
+  { timeoutMs: 60_000 },
+)
+console.log(result.stdout)
+await sandbox.kill()
+```
+```python Python expandable
+import os
+from e2b import Sandbox
+
+# A minimal FastAPI app with three routes to screenshot
+FASTAPI_APP = """
+from fastapi import FastAPI
+from fastapi.responses import HTMLResponse
+
+app = FastAPI()
+
+@app.get("/")
+def home():
+    return HTMLResponse("<h1>Home</h1><p>Welcome to the app.</p>")
+
+@app.get("/about")
+def about():
+    return HTMLResponse("<h1>About</h1><p>About this app.</p>")
+
+@app.get("/dashboard")
+def dashboard():
+    return HTMLResponse("<h1>Dashboard</h1><p>Your dashboard.</p>")
+"""
+
+# 1. Create the sandbox and start the app
+sandbox = Sandbox.create(
+    "kernel-browser",
+    envs={"KERNEL_API_KEY": os.environ["KERNEL_API_KEY"]},
+    timeout=300,
+)
+
+sandbox.files.write("/home/user/app.py", FASTAPI_APP)
+sandbox.commands.run(
+    "pip install fastapi uvicorn",
+    timeout=60,
+)
+sandbox.commands.run(
+    "uvicorn app:app --host 0.0.0.0 --port 8000",
+    background=True,
+    cwd="/home/user",
+)
+
+# 2. Screenshot each route with a Kernel browser
+host = sandbox.get_host(8000)
+app_url = f"https://{host}"
+
+BROWSE_SCRIPT = f'''
+from kernel import Kernel
+from playwright.sync_api import sync_playwright
+
+app_url = "{app_url}"
+routes = ["/", "/about", "/dashboard"]
+
+kernel = Kernel()
+kb = kernel.browsers.create()
+
+with sync_playwright() as pw:
+    browser = pw.chromium.connect_over_cdp(kb.cdp_ws_url)
+    page = browser.new_page()
+    page.set_viewport_size({{"width": 1280, "height": 720}})
+
+    for route in routes:
+        page.goto(f"{{app_url}}{{route}}", wait_until="networkidle")
+        name = "home" if route == "/" else route.strip("/")
+        page.screenshot(path=f"/home/user/{{name}}.png")
+        print(f"Captured {{route}}")
+
+    browser.close()
+'''
+
+sandbox.files.write("/home/user/browse.py", BROWSE_SCRIPT)
+result = sandbox.commands.run("python3 /home/user/browse.py", timeout=60)
+print(result.stdout)
+sandbox.kill()
+```
+</CodeGroup>
+
 ---
 
 ## Agent data extraction
@@ -294,6 +490,94 @@ sandbox.kill()
 </Step>
 </Steps>
 
+Full example:
+
+<CodeGroup>
+```typescript JavaScript & TypeScript expandable
+import { Sandbox } from 'e2b'
+
+// 1. Create the sandbox with API keys
+const sandbox = await Sandbox.create('kernel-browser', {
+  envs: {
+    KERNEL_API_KEY: process.env.KERNEL_API_KEY!,
+    ANTHROPIC_API_KEY: process.env.ANTHROPIC_API_KEY!,
+  },
+  timeoutMs: 300_000,
+})
+
+// 2. Write and run the Browser Use agent
+const AGENT_SCRIPT = `
+import asyncio
+from kernel import Kernel
+from browser_use import Agent, Browser, ChatAnthropic
+
+async def main():
+    kernel = Kernel()
+    kb = kernel.browsers.create()
+    browser = Browser(cdp_url=kb.cdp_ws_url)
+
+    agent = Agent(
+        task="Go to https://news.ycombinator.com, find the top 5 stories, and return their titles and point counts as JSON",
+        llm=ChatAnthropic(model="claude-sonnet-4"),
+        browser=browser,
+    )
+    result = await agent.run()
+    print(result)
+
+asyncio.run(main())
+`
+
+await sandbox.files.write('/home/user/agent_task.py', AGENT_SCRIPT)
+const result = await sandbox.commands.run(
+  'python3 /home/user/agent_task.py',
+  { timeoutMs: 180_000 },
+)
+console.log(result.stdout)
+await sandbox.kill()
+```
+```python Python expandable
+import os
+from e2b import Sandbox
+
+# 1. Create the sandbox with API keys
+sandbox = Sandbox.create(
+    "kernel-browser",
+    envs={
+        "KERNEL_API_KEY": os.environ["KERNEL_API_KEY"],
+        "ANTHROPIC_API_KEY": os.environ["ANTHROPIC_API_KEY"],
+    },
+    timeout=300,
+)
+
+# 2. Write and run the Browser Use agent
+AGENT_SCRIPT = '''
+import asyncio
+from kernel import Kernel
+from browser_use import Agent, Browser, ChatAnthropic
+
+async def main():
+    kernel = Kernel()
+    kb = kernel.browsers.create()
+    browser = Browser(cdp_url=kb.cdp_ws_url)
+
+    agent = Agent(
+        task="Go to https://news.ycombinator.com, find the top 5 stories, and return their titles and point counts as JSON",
+        llm=ChatAnthropic(model="claude-sonnet-4"),
+        browser=browser,
+    )
+    result = await agent.run()
+    print(result)
+
+asyncio.run(main())
+'''
+
+sandbox.files.write("/home/user/agent_task.py", AGENT_SCRIPT)
+result = sandbox.commands.run("python3 /home/user/agent_task.py", timeout=180)
+print(result.stdout)
+sandbox.kill()
+```
+</CodeGroup>
+
 ---
 
 ## Live browser preview