refactor: dedupe provider usage fetch logic and tests

src/infra/provider-usage.fetch.shared.test.ts

@@ -0,0 +1,38 @@
+import { describe, expect, it } from "vitest";
+import {
+  buildUsageErrorSnapshot,
+  buildUsageHttpErrorSnapshot,
+} from "./provider-usage.fetch.shared.js";
+
+describe("provider usage fetch shared helpers", () => {
+  it("builds a provider error snapshot", () => {
+    expect(buildUsageErrorSnapshot("zai", "API error")).toEqual({
+      provider: "zai",
+      displayName: "z.ai",
+      windows: [],
+      error: "API error",
+    });
+  });
+
+  it("maps configured status codes to token expired", () => {
+    const snapshot = buildUsageHttpErrorSnapshot({
+      provider: "openai-codex",
+      status: 401,
+      tokenExpiredStatuses: [401, 403],
+    });
+
+    expect(snapshot.error).toBe("Token expired");
+    expect(snapshot.provider).toBe("openai-codex");
+    expect(snapshot.windows).toHaveLength(0);
+  });
+
+  it("includes trimmed API error messages in HTTP errors", () => {
+    const snapshot = buildUsageHttpErrorSnapshot({
+      provider: "anthropic",
+      status: 403,
+      message: " missing scope ",
+    });
+
+    expect(snapshot.error).toBe("HTTP 403: missing scope");
+  });
+});