refactor: dedupe agent and reply runtimes

src/providers/google-shared.test-helpers.ts

@@ -1,5 +1,6 @@
 import type { Model } from "@mariozechner/pi-ai/dist/types.js";
 import { expect } from "vitest";
+import { makeZeroUsageSnapshot } from "../agents/usage.js";
 
 export const asRecord = (value: unknown): Record<string, unknown> => {
   expect(value).toBeTruthy();
@@ -48,23 +49,6 @@ export const makeGeminiCliModel = (id: string): Model<"google-gemini-cli"> =>
     maxTokens: 1,
   }) as Model<"google-gemini-cli">;
 
-function makeZeroUsage() {
-  return {
-    input: 0,
-    output: 0,
-    cacheRead: 0,
-    cacheWrite: 0,
-    totalTokens: 0,
-    cost: {
-      input: 0,
-      output: 0,
-      cacheRead: 0,
-      cacheWrite: 0,
-      total: 0,
-    },
-  };
-}
-
 export function makeGoogleAssistantMessage(model: string, content: unknown) {
   return {
     role: "assistant",
@@ -72,7 +56,7 @@ export function makeGoogleAssistantMessage(model: string, content: unknown) {
     api: "google-generative-ai",
     provider: "google",
     model,
-    usage: makeZeroUsage(),
+    usage: makeZeroUsageSnapshot(),
     stopReason: "stop",
     timestamp: 0,
   };
@@ -85,7 +69,7 @@ export function makeGeminiCliAssistantMessage(model: string, content: unknown) {
     api: "google-gemini-cli",
     provider: "google-gemini-cli",
     model,
-    usage: makeZeroUsage(),
+    usage: makeZeroUsageSnapshot(),
     stopReason: "stop",
     timestamp: 0,
   };