feat(langchain-anthropic): introduce ChatAnthropicInput type for improved constructor typing (#9588)

Signed-off-by: Yu Ishikawa <[email protected]>

Author: yu-iskw

.changeset/expose-chatanthropic-input-type.md

@@ -0,0 +1,7 @@
+---
+"@langchain/anthropic": minor
+---
+
+Expose `ChatAnthropicInput` type for improved type safety and user experience.
+
+This change introduces a new exported type `ChatAnthropicInput` which is an intersection of `AnthropicInput` and `BaseChatModelParams`. This allows LangChain users to define and pass ChatAnthropic configuration options with full type safety and IntelliSense.

libs/providers/langchain-anthropic/src/chat_models.ts

@@ -300,6 +300,11 @@ export interface AnthropicInput {
   betas?: AnthropicBeta[];
 }
 
+/**
+ * Input to ChatAnthropic class.
+ */
+export type ChatAnthropicInput = AnthropicInput & BaseChatModelParams;
+
 function extractToken(chunk: AIMessageChunk): string | undefined {
   if (typeof chunk.content === "string") {
     return chunk.content;
@@ -910,7 +915,7 @@ export class ChatAnthropicMessages<
    */
   createClient: (options: ClientOptions) => Anthropic;
 
-  constructor(fields?: AnthropicInput & BaseChatModelParams) {
+  constructor(fields?: ChatAnthropicInput) {
     super(fields ?? {});
 
     this.anthropicApiKey =