workshop: add Chapter 1 preview stubs (weather tool)

- Add lib/ai/tools/get-weather.ts with TODO placeholder
- Add TODO comment in route.ts showing where to wire tools
- Provides clear starting point for Chapter 1 implementation

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: NiallJoeMaher

app/(chat)/api/chat/route.ts

@@ -171,6 +171,20 @@ export async function POST(request: Request) {
 
     const stream = createUIMessageStream({
       execute: ({ writer: dataStream }) => {
+        // TODO CHAPTER 1: Add tools to streamText
+        // Import the weather tool:
+        //   import { getWeather } from "@/lib/ai/tools/get-weather";
+        //
+        // Then add these options to streamText below:
+        //   stopWhen: stepCountIs(5),
+        //   experimental_activeTools:
+        //     selectedChatModel === "chat-model-reasoning" ? [] : ["getWeather"],
+        //   tools: {
+        //     getWeather,
+        //   },
+        //
+        // See CHAPTER-1.md for complete implementation details.
+
         const result = streamText({
           model: myProvider.languageModel(selectedChatModel),
           system: systemPrompt({ selectedChatModel, requestHints }),

lib/ai/tools/get-weather.ts

@@ -0,0 +1,51 @@
+import { tool } from "ai";
+import { z } from "zod";
+
+// TODO CHAPTER 1: Implement the weather tool
+//
+// This tool should:
+// 1. Accept a city name OR latitude/longitude coordinates
+// 2. Geocode the city to coordinates using Open-Meteo Geocoding API
+// 3. Fetch weather data from Open-Meteo Weather API
+// 4. Return temperature and weather data
+//
+// Key implementation steps:
+// - Create a geocodeCity() helper function
+// - Handle both city and coordinate inputs
+// - Return helpful error messages if geocoding fails
+//
+// See CHAPTER-1.md for the complete implementation.
+
+/**
+ * Weather Tool - Gets current weather for a location
+ *
+ * Accepts either:
+ * - city: A city name like "San Francisco" or "London"
+ * - latitude + longitude: Coordinates like 37.7749, -122.4194
+ */
+export const getWeather = tool({
+  description:
+    "Get the current weather at a location. You can provide either coordinates or a city name.",
+  inputSchema: z.object({
+    latitude: z.number().optional(),
+    longitude: z.number().optional(),
+    city: z
+      .string()
+      .describe("City name (e.g., 'San Francisco', 'New York', 'London')")
+      .optional(),
+  }),
+  execute: async () => {
+    // TODO: Implement in Chapter 1
+    // 1. If city provided, geocode it to lat/long
+    // 2. Fetch weather data from Open-Meteo API
+    // 3. Return the weather data
+
+    // Placeholder await to satisfy linter (remove when implementing)
+    await Promise.resolve();
+
+    return {
+      todo: "Implement weather tool in Chapter 1",
+      hint: "See CHAPTER-1.md for the complete implementation",
+    };
+  },
+});