Refactor LLM route-first provider API (#28523)

packages/llm/src/providers/google.ts

@@ -1,5 +1,6 @@
-import type { RouteModelInput } from "../route/client"
-import { Provider } from "../provider"
+import type { RouteDefaultsInput } from "../route/client"
+import { Auth } from "../route/auth"
+import type { ProviderAuthOption } from "../route/auth-options"
 import { ProviderID, type ModelID } from "../schema"
 import * as Gemini from "../protocols/gemini"
 
@@ -7,12 +8,28 @@ export const id = ProviderID.make("google")
 
 export const routes = [Gemini.route]
 
-export const model = (
-  id: string | ModelID,
-  options: Omit<RouteModelInput, "id" | "baseURL"> & { readonly baseURL?: string } = {},
-) => Gemini.model({ ...options, id })
+export type Config = RouteDefaultsInput & ProviderAuthOption<"optional"> & { readonly baseURL?: string }
 
-export const provider = Provider.make({
-  id,
-  model,
-})
+const auth = (options: ProviderAuthOption<"optional">) => {
+  if ("auth" in options && options.auth) return options.auth
+  return Auth.optional("apiKey" in options ? options.apiKey : undefined, "apiKey")
+    .orElse(Auth.config("GOOGLE_GENERATIVE_AI_API_KEY"))
+    .pipe(Auth.header("x-goog-api-key"))
+}
+
+const configuredRoute = (input: Config) => {
+  const { apiKey: _, auth: _auth, baseURL, ...rest } = input
+  return Gemini.route.with({ ...rest, endpoint: { baseURL }, auth: auth(input) })
+}
+
+export const configure = (input: Config = {}) => {
+  const route = configuredRoute(input)
+  return {
+    id,
+    model: (modelID: string | ModelID) => route.model({ id: modelID }),
+    configure,
+  }
+}
+
+export const provider = configure()
+export const model = provider.model