diff --git a/pydantic_ai/models/__init__.py b/pydantic_ai/models/__init__.py
index 81ae41033..212c3f464 100644
--- a/pydantic_ai/models/__init__.py
+++ b/pydantic_ai/models/__init__.py
@@ -99,4 +99,4 @@ def cached_async_http_client() -> AsyncHTTPClient:
     described in [encode/httpx#2026](https://github.com/encode/httpx/pull/2026), but when experimenting or showing
     examples, it's very useful not to, this allows multiple Agents to use a single client.
     """
-    return AsyncHTTPClient()
+    return AsyncHTTPClient(timeout=30)
diff --git a/pydantic_ai/models/gemini.py b/pydantic_ai/models/gemini.py
index 638db390e..5ae51499a 100644
--- a/pydantic_ai/models/gemini.py
+++ b/pydantic_ai/models/gemini.py
@@ -346,14 +346,17 @@ class _GeminiResponse:
 
 @dataclass
 class _GeminiCandidates:
+    """See <https://ai.google.dev/api/generate-content#v1beta.Candidate>."""
+
     content: _GeminiContent
     finish_reason: Annotated[Literal['STOP'], Field(alias='finishReason')]
     """
-    See https://ai.google.dev/api/generate-content#FinishReason, lots of other values are possible,
+    See <https://ai.google.dev/api/generate-content#FinishReason>, lots of other values are possible,
     but let's wait until we see them and know what they mean to add them here.
     """
-    index: int
-    safety_ratings: Annotated[list[_GeminiSafetyRating], Field(alias='safetyRatings')]
+    avg_log_probs: Annotated[float, Field(alias='avgLogProbs')] | None = None
+    index: int | None = None
+    safety_ratings: Annotated[list[_GeminiSafetyRating], Field(alias='safetyRatings')] | None = None
 
 
 @dataclass
diff --git a/pydantic_ai_examples/README.md b/pydantic_ai_examples/README.md
index f2ac0974a..01ed2efc6 100644
--- a/pydantic_ai_examples/README.md
+++ b/pydantic_ai_examples/README.md
@@ -156,3 +156,23 @@ You can then ask the agent a question with:
 ```bash
 (uv run/python) -m pydantic_ai_examples.rag search "How do I configure logfire to work with FastAPI?"
 ```
+
+### `chat_app.py`
+
+(Demonstrates: reusing chat history, serializing messages)
+
+**TODO**: stream responses
+
+Simple chat app example build with FastAPI.
+
+This demonstrates storing chat history between requests and using it to give the model context for new responses.
+
+Most of the complex logic here is in `chat_app.html` which includes the page layout and JavaScript to handle the chat.
+
+Run the app with:
+
+```bash
+(uv run/python) -m pydantic_ai_examples.chat_app
+```
+
+Then open the app at [localhost:8000](http://localhost:8000).
diff --git a/pydantic_ai_examples/chat_app.html b/pydantic_ai_examples/chat_app.html
index 544f75fb6..25d8cf056 100644
--- a/pydantic_ai_examples/chat_app.html
+++ b/pydantic_ai_examples/chat_app.html
@@ -4,39 +4,10 @@
   <meta charset="UTF-8">
   <meta name="viewport" content="width=device-width, initial-scale=1.0">
   <title>Chat App</title>
+  <link href="https://cdn.jsdelivr.net/npm/bootstrap@5.3.3/dist/css/bootstrap.min.css" rel="stylesheet">
   <style>
     main {
-      font-family: Verdana, sans-serif;
       max-width: 600px;
-      margin: 40px auto;
-      border: 1px solid #ccc;
-      border-radius: 4px;
-      padding: 20px 30px;
-    }
-    input {
-      width: calc(100% - 22px);
-      padding: 10px;
-      margin-top: 10px;
-      border: 1px solid #ccc;
-      border-radius: 4px;
-      font-size: 1rem;
-    }
-    button {
-      margin: 10px 0 0 auto;
-      padding: 8px 15px;
-      background-color: #007bff;
-      color: white;
-      border: none;
-      border-radius: 4px;
-      display: block;
-    }
-    #conversation {
-      margin: 10px 5px;
-    }
-    #conversation div {
-      margin: 10px 0 0;
-      padding-top: 5px;
-      border-top: 1px solid #ccc;
     }
     #conversation .user::before {
       content: 'You asked: ';
@@ -48,48 +19,40 @@
       font-weight: bold;
       display: block;
     }
-    .center {
-      display: flex;
-      justify-content: center;
-    }
     #spinner {
       opacity: 0;
       transition: opacity 500ms ease-in;
       width: 30px;
       height: 30px;
-      border: 3px solid #444;
+      border: 3px solid #222;
       border-bottom-color: transparent;
       border-radius: 50%;
-      display: inline-block;
-      box-sizing: border-box;
       animation: rotation 1s linear infinite;
     }
-    #spinner.active {
-      opacity: 1;
-    }
     @keyframes rotation {
       0% { transform: rotate(0deg); }
       100% { transform: rotate(360deg); }
     }
-    #error {
-      display: none;
-      color: red;
+    #spinner.active {
+      opacity: 1;
     }
   </style>
 </head>
 <body>
-  <main id="main">
+  <main class="border rounded mx-auto my-5 p-4">
     <h1>Chat App</h1>
     <p>Ask me anything...</p>
-    <div id="conversation"></div>
-    <div class="center">
+    <div id="conversation" class="px-2"></div>
+    <div class="d-flex justify-content-center mb-3">
       <div id="spinner"></div>
     </div>
     <form method="post">
-      <input id="prompt-input" name="prompt"/>
-      <button>Send</button>
+      <input id="prompt-input" name="prompt" class="form-control"/>
+      <div class="d-flex justify-content-end">
+        <button class="btn btn-primary mt-2">Send</button>
+      </div>
     </form>
-    <div id="error">
+    <div id="error" class="d-none text-danger">
       Error occurred, check the console for more information.
     </div>
   </main>
@@ -103,7 +66,7 @@ <h1>Chat App</h1>
     const parent = document.getElementById('conversation');
     for (const message of messages) {
       let msgDiv = document.createElement('div');
-      msgDiv.classList.add(message.role);
+      msgDiv.classList.add('border-top', 'pt-2', message.role);
       msgDiv.innerHTML = marked.parse(message.content);
       parent.appendChild(msgDiv);
     }
@@ -111,7 +74,8 @@ <h1>Chat App</h1>
 
   function onError(error) {
     console.error(error);
-    document.getElementById('error').style.display = 'block';
+    document.getElementById('error').classList.remove('d-none');
+    document.getElementById('spinner').classList.remove('active');
   }
 
   async function fetchResponse(response) {
@@ -145,16 +109,18 @@ <h1>Chat App</h1>
     e.preventDefault();
     const spinner = document.getElementById('spinner');
     spinner.classList.add('active');
+    const body = new FormData(e.target);
 
     let input = document.getElementById('prompt-input')
     input.value = '';
     input.disabled = true;
 
-    const response = await fetch('/chat/', {method: 'POST', body: new FormData(e.target)});
+    const response = await fetch('/chat/', {method: 'POST', body});
     await fetchResponse(response);
     spinner.classList.remove('active');
   }
 
+  // call onSubmit when form is submitted (e.g. user clicks the send button or hits Enter)
   document.querySelector('form').addEventListener('submit', (e) => onSubmit(e).catch(onError));
 
   // load messages on page load
diff --git a/pydantic_ai_examples/chat_app.py b/pydantic_ai_examples/chat_app.py
index b8c69d955..9e2dfb107 100644
--- a/pydantic_ai_examples/chat_app.py
+++ b/pydantic_ai_examples/chat_app.py
@@ -1,3 +1,10 @@
+"""Simple chat app example build with FastAPI.
+
+Run with:
+
+    uv run -m pydantic_ai_examples.chat_app
+"""
+
 from collections.abc import Iterator
 from dataclasses import dataclass
 from pathlib import Path