Pass sessionAffinity to workersai model

Include sessionAffinity when creating the workersai model in ChatAgent. The streamText call now invokes workersai with a second argument ({ sessionAffinity: this.sessionAffinity }) so requests can be routed with session affinity (sticky sessions), improving consistency for stateful or session-based interactions.

Author: threepointone

src/server.ts

@@ -68,7 +68,9 @@ export class ChatAgent extends AIChatAgent<Env> {
     const workersai = createWorkersAI({ binding: this.env.AI });
 
     const result = streamText({
-      model: workersai("@cf/moonshotai/kimi-k2.5"),
+      model: workersai("@cf/moonshotai/kimi-k2.5", {
+        sessionAffinity: this.sessionAffinity
+      }),
       system: `You are a helpful assistant that can understand images. You can check the weather, get the user's timezone, run calculations, and schedule tasks. When users share images, describe what you see and answer questions about them.
 
 ${getSchedulePrompt({ date: new Date() })}