Adds native Live Search support to xAI provider (#9537)

Co-authored-by: Christian Bromann <git@bromann.dev>

Author: pawel-twardziak

.changeset/ninety-paws-cough.md

@@ -0,0 +1,5 @@
+---
+"@langchain/xai": minor
+---
+
+Adds native Live Search support to xAI provider

libs/providers/langchain-xai/README.md

@@ -31,6 +31,156 @@ const message = new HumanMessage("What color is the sky?");
 const res = await model.invoke([message]);
 ```
 
+## Server Tool Calling (Live Search)
+
+xAI supports server-side tools that are executed by the API rather than requiring client-side execution. The `live_search` tool enables the model to search the web for real-time information.
+
+### Using the built-in live_search tool
+
+```typescript
+import { ChatXAI, tools } from "@langchain/xai";
+
+const model = new ChatXAI({
+  model: "grok-2-1212",
+});
+
+// Create the built-in live_search tool with optional parameters
+const searchTool = tools.xaiLiveSearch({
+  maxSearchResults: 5,
+  returnCitations: true,
+});
+
+// Bind the live_search tool to the model
+const modelWithSearch = model.bindTools([searchTool]);
+
+// The model will search the web for real-time information
+const result = await modelWithSearch.invoke(
+  "What happened in tech news today?"
+);
+console.log(result.content);
+```
+
+### Using searchParameters for more control
+
+```typescript
+import { ChatXAI } from "@langchain/xai";
+
+const model = new ChatXAI({
+  model: "grok-2-1212",
+  searchParameters: {
+    mode: "auto", // "auto" | "on" | "off"
+    max_search_results: 5,
+    from_date: "2024-01-01", // ISO date string
+    return_citations: true,
+  },
+});
+
+const result = await model.invoke("What are the latest AI developments?");
+```
+
+### Override search parameters per request
+
+```typescript
+const result = await model.invoke("Find recent news about SpaceX", {
+  searchParameters: {
+    mode: "on",
+    max_search_results: 10,
+    sources: [
+      {
+        type: "web",
+        allowed_websites: ["spacex.com", "nasa.gov"],
+      },
+    ],
+  },
+});
+```
+
+### Configuring data sources with `sources`
+
+You can configure which data sources Live Search should use via the `sources` field
+in `searchParameters`. Each entry corresponds to one of the sources described in the
+official xAI Live Search docs (`web`, `news`, `x`, `rss`).
+
+```typescript
+const result = await model.invoke(
+  "What are the latest updates from xAI and related news?",
+  {
+    searchParameters: {
+      mode: "on",
+      sources: [
+        {
+          type: "web",
+          // Only search on these websites
+          allowed_websites: ["x.ai"],
+        },
+        {
+          type: "news",
+          // Exclude specific news websites
+          excluded_websites: ["bbc.co.uk"],
+        },
+        {
+          type: "x",
+          // Focus on specific X handles
+          included_x_handles: ["xai"],
+        },
+      ],
+    },
+  }
+);
+```
+
+You can also use RSS feeds as a data source:
+
+```typescript
+const result = await model.invoke("Summarize the latest posts from this feed", {
+  searchParameters: {
+    mode: "on",
+    sources: [
+      {
+        type: "rss",
+        links: ["https://example.com/feed.rss"],
+      },
+    ],
+  },
+});
+```
+
+> Notes:
+>
+> - The `xaiLiveSearch` tool options use **camelCase** field names in TypeScript
+>   (for example `maxSearchResults`, `fromDate`, `returnCitations`,
+>   `allowedWebsites`, `excludedWebsites`, `includedXHandles`). These are
+>   automatically mapped to the underlying JSON API's `search_parameters`
+>   object, which uses `snake_case` field names as documented in the official
+>   xAI Live Search docs.
+
+### Combining live_search with custom tools
+
+```typescript
+import { ChatXAI, tools } from "@langchain/xai";
+
+const model = new ChatXAI({ model: "grok-2-1212" });
+
+const modelWithTools = model.bindTools([
+  tools.xaiLiveSearch(), // Built-in server tool
+  {
+    // Custom function tool
+    type: "function",
+    function: {
+      name: "get_stock_price",
+      description: "Get the current stock price",
+      parameters: {
+        type: "object",
+        properties: {
+          symbol: { type: "string" },
+        },
+        required: ["symbol"],
+      },
+    },
+  },
+]);
+```
+
 ## Development
 
 To develop the `@langchain/xai` package, you'll need to follow these instructions: