feat(ai): add shared contentText utility (#6840)

Co-authored-by: Armin Ronacher <armin.ronacher@active-4.com>

packages/ai/src/index.ts

@@ -41,6 +41,7 @@ export * from "./utils/event-stream.ts";
 export * from "./utils/json-parse.ts";
 export * from "./utils/overflow.ts";
 export * from "./utils/retry.ts";
+export { contentText } from "./utils/text.ts";
 export * from "./utils/typebox-helpers.ts";
 export { uuidv7 } from "./utils/uuid.ts";
 export * from "./utils/validation.ts";

packages/ai/src/utils/text.ts

@@ -0,0 +1,12 @@
+import type { ImageContent, TextContent, ThinkingContent, ToolCall } from "../types.ts";
+
+type Content = TextContent | ImageContent | ThinkingContent | ToolCall;
+
+/** Extract and join text from message content. */
+export function contentText(content: string | readonly Content[], separator = "\n"): string {
+	if (typeof content === "string") return content;
+	return content
+		.filter((block) => block.type === "text")
+		.map((block) => block.text)
+		.join(separator);
+}