Agents: normalize WS usage aliases

src/agents/openai-ws-message-conversion.ts

@@ -10,6 +10,7 @@ import type {
 } from "./openai-ws-connection.js";
 import { normalizeToolParameterSchema } from "./pi-tools.schema.js";
 import { buildAssistantMessage, buildUsageWithNoCost } from "./stream-message-shared.js";
+import { normalizeUsage } from "./usage.js";
 
 type AnyMessage = Message & { role: string; content: unknown };
 type AssistantMessageWithPhase = AssistantMessage & { phase?: OpenAIResponsesAssistantPhase };
@@ -538,15 +539,16 @@ export function buildAssistantMessageFromResponse(
 
   const hasToolCalls = content.some((part) => part.type === "toolCall");
   const stopReason: StopReason = hasToolCalls ? "toolUse" : "stop";
+  const normalizedUsage = normalizeUsage(response.usage);
 
   const message = buildAssistantMessage({
     model: modelInfo,
     content,
     stopReason,
     usage: buildUsageWithNoCost({
-      input: response.usage?.input_tokens ?? 0,
-      output: response.usage?.output_tokens ?? 0,
-      totalTokens: response.usage?.total_tokens ?? 0,
+      input: normalizedUsage?.input ?? 0,
+      output: normalizedUsage?.output ?? 0,
+      totalTokens: normalizedUsage?.total ?? response.usage?.total_tokens ?? 0,
     }),
   });
 

src/agents/openai-ws-stream.test.ts

@@ -860,6 +860,20 @@ describe("buildAssistantMessageFromResponse", () => {
     expect(msg.usage.totalTokens).toBe(150);
   });
 
+  it("maps prompt_tokens and completion_tokens usage aliases", () => {
+    const response = makeResponseObject("resp_5b", "Hello");
+    (response as unknown as { usage?: Record<string, number> }).usage = {
+      prompt_tokens: 44,
+      completion_tokens: 11,
+      total_tokens: 55,
+    };
+
+    const msg = buildAssistantMessageFromResponse(response, modelInfo);
+    expect(msg.usage.input).toBe(44);
+    expect(msg.usage.output).toBe(11);
+    expect(msg.usage.totalTokens).toBe(55);
+  });
+
   it("sets model/provider/api from modelInfo", () => {
     const response = makeResponseObject("resp_6", "Hi");
     const msg = buildAssistantMessageFromResponse(response, modelInfo);