diff --git a/src/infra/provider-usage.fetch.copilot.test.ts b/src/infra/provider-usage.fetch.copilot.test.ts
index 7df17118159..0abfd5f782f 100644
--- a/src/infra/provider-usage.fetch.copilot.test.ts
+++ b/src/infra/provider-usage.fetch.copilot.test.ts
@@ -34,4 +34,40 @@ describe("fetchCopilotUsage", () => {
       { label: "Chat", usedPercent: 25 },
     ]);
   });
+
+  it("defaults missing snapshot values and clamps invalid remaining percentages", async () => {
+    const mockFetch = createProviderUsageFetch(async () =>
+      makeResponse(200, {
+        quota_snapshots: {
+          premium_interactions: { percent_remaining: null },
+          chat: { percent_remaining: 140 },
+        },
+      }),
+    );
+
+    const result = await fetchCopilotUsage("token", 5000, mockFetch);
+
+    expect(result.windows).toEqual([
+      { label: "Premium", usedPercent: 100 },
+      { label: "Chat", usedPercent: 0 },
+    ]);
+    expect(result.plan).toBeUndefined();
+  });
+
+  it("returns an empty window list when quota snapshots are missing", async () => {
+    const mockFetch = createProviderUsageFetch(async () =>
+      makeResponse(200, {
+        copilot_plan: "free",
+      }),
+    );
+
+    const result = await fetchCopilotUsage("token", 5000, mockFetch);
+
+    expect(result).toEqual({
+      provider: "github-copilot",
+      displayName: "Copilot",
+      windows: [],
+      plan: "free",
+    });
+  });
 });
diff --git a/src/infra/provider-usage.shared.test.ts b/src/infra/provider-usage.shared.test.ts
index 578cb876a4f..048352a183d 100644
--- a/src/infra/provider-usage.shared.test.ts
+++ b/src/infra/provider-usage.shared.test.ts
@@ -1,7 +1,12 @@
-import { describe, expect, it } from "vitest";
+import { afterEach, describe, expect, it, vi } from "vitest";
 import { clampPercent, resolveUsageProviderId, withTimeout } from "./provider-usage.shared.js";
 
 describe("provider-usage.shared", () => {
+  afterEach(() => {
+    vi.useRealTimers();
+    vi.restoreAllMocks();
+  });
+
   it.each([
     { value: "z-ai", expected: "zai" },
     { value: " GOOGLE-GEMINI-CLI ", expected: "google-gemini-cli" },
@@ -33,7 +38,18 @@ describe("provider-usage.shared", () => {
   });
 
   it("returns fallback when timeout wins", async () => {
+    vi.useFakeTimers();
     const late = new Promise<string>((resolve) => setTimeout(() => resolve("late"), 50));
-    await expect(withTimeout(late, 1, "fallback")).resolves.toBe("fallback");
+    const result = withTimeout(late, 1, "fallback");
+    await vi.advanceTimersByTimeAsync(1);
+    await expect(result).resolves.toBe("fallback");
+  });
+
+  it("clears the timeout after successful work", async () => {
+    const clearTimeoutSpy = vi.spyOn(globalThis, "clearTimeout");
+
+    await expect(withTimeout(Promise.resolve("ok"), 100, "fallback")).resolves.toBe("ok");
+
+    expect(clearTimeoutSpy).toHaveBeenCalledTimes(1);
   });
 });