fix(zen): emit cost chunk in client-facing format, not upstream format (#16817)

packages/console/app/src/routes/zen/util/provider/anthropic.ts

@@ -167,7 +167,6 @@ export const anthropicHelper: ProviderHelper = ({ reqModel, providerModel }) =>
           }
         },
         retrieve: () => usage,
-        buidlCostChunk: (cost: string) => `event: ping\ndata: ${JSON.stringify({ type: "ping", cost })}\n\n`,
       }
     },
     normalizeUsage: (usage: Usage) => ({

packages/console/app/src/routes/zen/util/provider/google.ts

@@ -56,7 +56,6 @@ export const googleHelper: ProviderHelper = ({ providerModel }) => ({
         usage = json.usageMetadata
       },
       retrieve: () => usage,
-      buidlCostChunk: (cost: string) => `data: ${JSON.stringify({ type: "ping", cost })}\n\n`,
     }
   },
   normalizeUsage: (usage: Usage) => {

packages/console/app/src/routes/zen/util/provider/openai-compatible.ts

@@ -54,7 +54,6 @@ export const oaCompatHelper: ProviderHelper = () => ({
         usage = json.usage
       },
       retrieve: () => usage,
-      buidlCostChunk: (cost: string) => `data: ${JSON.stringify({ choices: [], cost })}\n\n`,
     }
   },
   normalizeUsage: (usage: Usage) => {

packages/console/app/src/routes/zen/util/provider/openai.ts

@@ -44,7 +44,6 @@ export const openaiHelper: ProviderHelper = () => ({
         usage = json.response.usage
       },
       retrieve: () => usage,
-      buidlCostChunk: (cost: string) => `event: ping\ndata: ${JSON.stringify({ type: "ping", cost })}\n\n`,
     }
   },
   normalizeUsage: (usage: Usage) => {

packages/console/app/src/routes/zen/util/provider/provider.ts

@@ -43,7 +43,6 @@ export type ProviderHelper = (input: { reqModel: string; providerModel: string }
   createUsageParser: () => {
     parse: (chunk: string) => void
     retrieve: () => any
-    buidlCostChunk: (cost: string) => string
   }
   normalizeUsage: (usage: any) => UsageInfo
 }
@@ -162,6 +161,19 @@ export interface CommonChunk {
   }
 }
 
+export function buildCostChunk(format: ZenData.Format, cost: string): string {
+  switch (format) {
+    case "anthropic":
+      return `event: ping\ndata: ${JSON.stringify({ type: "ping", cost })}\n\n`
+    case "openai":
+      return `event: ping\ndata: ${JSON.stringify({ type: "ping", cost })}\n\n`
+    case "oa-compat":
+      return `data: ${JSON.stringify({ choices: [], cost })}\n\n`
+    default:
+      return `data: ${JSON.stringify({ type: "ping", cost })}\n\n`
+  }
+}
+
 export function createBodyConverter(from: ZenData.Format, to: ZenData.Format) {
   return (body: any): any => {
     if (from === to) return body