diff --git a/packages/ai/src/auth-storage.ts b/packages/ai/src/auth-storage.ts
index 705684afe..66bf5e9ec 100644
--- a/packages/ai/src/auth-storage.ts
+++ b/packages/ai/src/auth-storage.ts
@@ -3195,6 +3195,13 @@ export class AuthStorage {
 			}
 			return report;
 		} catch (error) {
+			if (error instanceof AIError.ProviderHttpError && (error.status === 401 || error.status === 403)) {
+				// Definitive auth failure (revoked key, lapsed subscription): purge
+				// the last-good report so #fetchUsageCached's failure branch can't
+				// keep rendering and ranking from stale quota the way it does for
+				// transient failures. Mirrors the definitive-OAuth-refresh path.
+				this.#usageCache.set(this.#buildUsageReportCacheKey(request), { value: null, expiresAt: 0 });
+			}
 			logger.debug("AuthStorage usage fetch failed", {
 				provider: request.provider,
 				error: String(error),
diff --git a/packages/ai/src/usage/opencode-go.ts b/packages/ai/src/usage/opencode-go.ts
index 981fa3abd..dcc66872f 100644
--- a/packages/ai/src/usage/opencode-go.ts
+++ b/packages/ai/src/usage/opencode-go.ts
@@ -137,7 +137,16 @@ async function fetchOpenCodeGoUsage(params: UsageFetchParams, ctx: UsageFetchCon
 		const limit = buildWindowLimit(descriptor, usage[descriptor.key]);
 		if (limit) limits.push(limit);
 	}
-	if (limits.length === 0) return null;
+	// All-or-nothing: a partial report would overwrite the complete last-good
+	// report in the usage cache, silently dropping the windows used for
+	// ranking and display. Treat any malformed/missing window like a
+	// transient failure so the cached report keeps serving instead.
+	if (limits.length !== OPENCODE_GO_WINDOWS.length) {
+		ctx.logger?.warn("OpenCode Go usage response missing or malformed windows", {
+			decoded: limits.map(limit => limit.id),
+		});
+		return null;
+	}
 
 	return {
 		provider: OPENCODE_GO_PROVIDER,
diff --git a/packages/ai/test/auth-storage-usage-history.test.ts b/packages/ai/test/auth-storage-usage-history.test.ts
index 4e96bd561..e9697316a 100644
--- a/packages/ai/test/auth-storage-usage-history.test.ts
+++ b/packages/ai/test/auth-storage-usage-history.test.ts
@@ -267,7 +267,11 @@ describe("OpenCode Go usage via the upstream endpoint", () => {
 				});
 				return new Response(
 					JSON.stringify({
-						usage: { rolling: { status: "ok", percent: 5, resetsAt: "2026-08-12T15:09:04.847Z" } },
+						usage: {
+							rolling: { status: "ok", percent: 5, resetsAt: "2026-08-12T15:09:04.847Z" },
+							weekly: { status: "ok", percent: 8, resetsAt: "2026-08-17T00:00:00.847Z" },
+							monthly: { status: "ok", percent: 10, resetsAt: "2026-08-19T00:31:53.847Z" },
+						},
 					}),
 					{ status: 200, headers: { "content-type": "application/json" } },
 				);
@@ -286,4 +290,92 @@ describe("OpenCode Go usage via the upstream endpoint", () => {
 			referenceStorage.close();
 		}
 	});
+
+	it("drops the last-good report when the key turns definitively unauthorized", async () => {
+		// Transient failures serve the cached report; a 401/403 must not — a
+		// revoked key or lapsed subscription would otherwise keep rendering and
+		// ranking from stale quota until the process restarts.
+		let respondWith: "success" | "unauthorized" = "success";
+		const transitionStorage = new AuthStorage(new SqliteAuthCredentialStore(new Database(":memory:")), {
+			usageProviderResolver: provider =>
+				provider === "opencode-go" ? opencodeGoUsage.opencodeGoUsageProvider : undefined,
+			usageFetch: (async () =>
+				respondWith === "success"
+					? new Response(
+							JSON.stringify({
+								usage: {
+									rolling: { status: "ok", percent: 12, resetsAt: "2026-08-12T15:09:04.847Z" },
+									weekly: { status: "ok", percent: 8, resetsAt: "2026-08-17T00:00:00.847Z" },
+									monthly: { status: "ok", percent: 10, resetsAt: "2026-08-19T00:31:53.847Z" },
+								},
+							}),
+							{ status: 200, headers: { "content-type": "application/json" } },
+						)
+					: new Response(
+							JSON.stringify({ type: "error", error: { type: "AuthError", message: "Unauthorized" } }),
+							{
+								status: 401,
+								headers: { "content-type": "application/json" },
+							},
+						)) as unknown as typeof fetch,
+		});
+		try {
+			await transitionStorage.reload();
+			await transitionStorage.set("opencode-go", { type: "api_key", key: "opencode-go-key" });
+
+			const nowMs = Date.now();
+			setSystemTime(new Date(nowMs));
+			const fresh = await transitionStorage.fetchUsageReports();
+			expect(fresh?.some(candidate => candidate.provider === "opencode-go")).toBe(true);
+
+			// Past the report TTL the next poll re-hits the endpoint and gets 401.
+			respondWith = "unauthorized";
+			setSystemTime(new Date(nowMs + 10 * 60_000));
+			const afterRevocation = await transitionStorage.fetchUsageReports();
+			expect(afterRevocation?.some(candidate => candidate.provider === "opencode-go")).toBe(false);
+		} finally {
+			transitionStorage.close();
+		}
+	});
+
+	it("retains the last-good report through a partial payload", async () => {
+		// One malformed window fails the whole decode, which must fall back to
+		// the cached complete report instead of replacing it with fewer windows.
+		let respondWith: "success" | "partial" = "success";
+		const partialStorage = new AuthStorage(new SqliteAuthCredentialStore(new Database(":memory:")), {
+			usageProviderResolver: provider =>
+				provider === "opencode-go" ? opencodeGoUsage.opencodeGoUsageProvider : undefined,
+			usageFetch: (async () =>
+				new Response(
+					JSON.stringify({
+						usage: {
+							rolling:
+								respondWith === "success"
+									? { status: "ok", percent: 12, resetsAt: "2026-08-12T15:09:04.847Z" }
+									: { status: "ok", percent: "abc" },
+							weekly: { status: "ok", percent: 8, resetsAt: "2026-08-17T00:00:00.847Z" },
+							monthly: { status: "ok", percent: 10, resetsAt: "2026-08-19T00:31:53.847Z" },
+						},
+					}),
+					{ status: 200, headers: { "content-type": "application/json" } },
+				)) as unknown as typeof fetch,
+		});
+		try {
+			await partialStorage.reload();
+			await partialStorage.set("opencode-go", { type: "api_key", key: "opencode-go-key" });
+
+			const nowMs = Date.now();
+			setSystemTime(new Date(nowMs));
+			const fresh = await partialStorage.fetchUsageReports();
+			expect(fresh?.find(candidate => candidate.provider === "opencode-go")?.limits).toHaveLength(3);
+
+			respondWith = "partial";
+			setSystemTime(new Date(nowMs + 10 * 60_000));
+			const afterPartial = await partialStorage.fetchUsageReports();
+			const retained = afterPartial?.find(candidate => candidate.provider === "opencode-go");
+			expect(retained?.limits.map(limit => limit.id)).toEqual(["rolling-5h", "weekly", "monthly"]);
+		} finally {
+			partialStorage.close();
+		}
+	});
 });
diff --git a/packages/ai/test/opencode-go-usage.test.ts b/packages/ai/test/opencode-go-usage.test.ts
index b19866faf..f121b63f6 100644
--- a/packages/ai/test/opencode-go-usage.test.ts
+++ b/packages/ai/test/opencode-go-usage.test.ts
@@ -137,14 +137,16 @@ describe("opencode-go usage provider", () => {
 		expect(report).toBeNull();
 	});
 
-	it("skips malformed windows and returns null when no window parses", async () => {
+	it("rejects the whole payload unless all three windows decode", async () => {
+		// A partial report would overwrite the complete last-good report in the
+		// usage cache, so one malformed window must fail the entire payload.
 		const partial = await opencodeGoUsageProvider.fetchUsage(
 			{ provider: "opencode-go", credential: { type: "api_key", apiKey: "sk-test" } },
 			{
 				fetch: fakeFetch(usagePayload({ rolling: { status: "ok", percent: "abc" }, weekly: null })),
 			},
 		);
-		expect(partial?.limits.map(limit => limit.id)).toEqual(["monthly"]);
+		expect(partial).toBeNull();
 
 		const empty = await opencodeGoUsageProvider.fetchUsage(
 			{ provider: "opencode-go", credential: { type: "api_key", apiKey: "sk-test" } },