diff --git a/packages/ai/src/auth-storage.ts b/packages/ai/src/auth-storage.ts
index ae04587ca..60e535093 100644
--- a/packages/ai/src/auth-storage.ts
+++ b/packages/ai/src/auth-storage.ts
@@ -308,13 +308,28 @@ export interface AuthCredentialSnapshot {
  *   a remote broker; mutating methods (`replace*`, `upsert*`, `delete*ForProvider`)
  *   throw because login flows route through the broker, not the client.
  */
+export interface CredentialRefreshLeaseFence {
+	owner: string;
+	nowMs: number;
+}
+
 export interface AuthCredentialStore {
 	close(): void;
 	listAuthCredentials(provider?: string): StoredAuthCredential[];
 	updateAuthCredential(id: number, credential: AuthCredential): void;
 	deleteAuthCredential(id: number, disabledCause: string): void;
-	tryDisableAuthCredentialIfMatches(id: number, expectedData: string, disabledCause: string): boolean;
-	tryUpdateAuthCredentialIfMatches?(id: number, expectedData: string, credential: AuthCredential): boolean;
+	tryDisableAuthCredentialIfMatches(
+		id: number,
+		expectedData: string,
+		disabledCause: string,
+		lease?: CredentialRefreshLeaseFence,
+	): boolean;
+	tryUpdateAuthCredentialIfMatches?(
+		id: number,
+		expectedData: string,
+		credential: AuthCredential,
+		lease?: CredentialRefreshLeaseFence,
+	): boolean;
 	replaceAuthCredentialsForProvider(provider: string, credentials: AuthCredential[]): StoredAuthCredential[];
 	upsertAuthCredentialForProvider(provider: string, credential: AuthCredential): StoredAuthCredential[];
 	deleteAuthCredentialsForProvider(provider: string, disabledCause: string): void;
@@ -601,6 +616,7 @@ const OAUTH_REFRESH_SKEW_MS = 60_000;
 const OAUTH_REFRESH_LEASE_TTL_MS = 15_000;
 const OAUTH_REFRESH_LEASE_POLL_MS = 50;
 const OAUTH_REFRESH_LEASE_RENEW_MS = 5_000;
+const OAUTH_REFRESH_OPERATION_TIMEOUT_MS = 10_000;
 /**
  * Cap on the buffered credential_disabled backlog held while no handler is attached.
  * In practice the backlog is 0–N where N ≈ active providers (≤ ~20). The cap exists so
@@ -736,7 +752,8 @@ export interface StoredOAuthRefreshOptions<T extends OAuthCredential = OAuthCred
 	signal?: AbortSignal;
 	keepCredentialOnRefreshFailure?: boolean | ((error: unknown) => boolean);
 	onRefreshFailure?: (error: unknown) => void;
-	refresh: (credential: T) => Promise<OAuthCredentials>;
+	refreshTimeoutMs?: number;
+	refresh: (credential: T, signal?: AbortSignal) => Promise<OAuthCredentials>;
 	mergeRefreshedCredential?: (credential: T, refreshed: OAuthCredentials) => T;
 	isDefinitiveFailure?: (error: unknown) => boolean;
 	disabledCause?: (error: unknown) => string;
@@ -1968,11 +1985,20 @@ export class AuthStorage {
 							leaseRenewalError = error;
 						})
 					: undefined;
+			const refreshAbort = new AbortController();
+			const refreshTimeout = setTimeout(() => {
+				refreshAbort.abort(
+					new AIError.OAuthError(`OAuth token refresh timed out for provider: ${provider}`, {
+						kind: "timeout",
+						provider,
+					}),
+				);
+			}, options.refreshTimeoutMs ?? OAUTH_REFRESH_OPERATION_TIMEOUT_MS);
 
 			let refreshed: OAuthCredentials;
 			try {
 				try {
-					refreshed = await options.refresh(current);
+					refreshed = await options.refresh(current, refreshAbort.signal);
 				} catch (error) {
 					if (options.isDefinitiveFailure?.(error)) {
 						const disabledCause = options.disabledCause?.(error) ?? `oauth refresh failed: ${String(error)}`;
@@ -1980,6 +2006,7 @@ export class AuthStorage {
 							row.id,
 							serialized.data,
 							disabledCause,
+							leasedCredentialId !== undefined ? { owner, nowMs: Date.now() } : undefined,
 						);
 						if (disabled) {
 							this.#setStoredCredentials(
@@ -2014,6 +2041,7 @@ export class AuthStorage {
 				stopLeaseRenewal = true;
 				leaseRenewalStopped.resolve();
 				await leaseRenewal;
+				clearTimeout(refreshTimeout);
 			}
 			if (leaseRenewalError) throw leaseRenewalError;
 
@@ -2031,7 +2059,14 @@ export class AuthStorage {
 						apiEndpoint: refreshed.apiEndpoint ?? current.apiEndpoint,
 					};
 			if (this.#store.tryUpdateAuthCredentialIfMatches) {
-				if (!this.#store.tryUpdateAuthCredentialIfMatches(row.id, serialized.data, merged)) {
+				if (
+					!this.#store.tryUpdateAuthCredentialIfMatches(
+						row.id,
+						serialized.data,
+						merged,
+						leasedCredentialId !== undefined ? { owner, nowMs: Date.now() } : undefined,
+					)
+				) {
 					await this.reload();
 					const latest = this.get(provider);
 					return {
@@ -5443,6 +5478,8 @@ export class SqliteAuthCredentialStore implements AuthCredentialStore {
 	#getCacheIncludingExpiredStmt: Statement;
 	#upsertCacheStmt: Statement;
 	#deleteExpiredCacheStmt: Statement;
+	#updateIfMatchesWithLeaseStmt: Statement;
+	#deleteIfMatchesWithLeaseStmt: Statement;
 	#getCredentialBlockStmt: Statement;
 	#listCredentialBlocksByCredentialStmt: Statement;
 	#upsertCredentialBlockStmt: Statement;
@@ -5483,12 +5520,30 @@ export class SqliteAuthCredentialStore implements AuthCredentialStore {
 		this.#updateIfMatchesStmt = this.#db.prepare(
 			`UPDATE auth_credentials SET credential_type = ?, data = ?, identity_key = ?, updated_at = ${SQLITE_NOW_EPOCH} WHERE id = ? AND data = ? AND disabled_cause IS NULL`,
 		);
+		this.#updateIfMatchesWithLeaseStmt = this.#db.prepare(
+			`UPDATE auth_credentials
+			SET credential_type = ?, data = ?, identity_key = ?, updated_at = ${SQLITE_NOW_EPOCH}
+			WHERE id = ? AND data = ? AND disabled_cause IS NULL
+				AND EXISTS (
+					SELECT 1 FROM auth_credential_refresh_leases
+					WHERE credential_id = ? AND owner = ? AND expires_at_ms > ?
+				)`,
+		);
 		this.#deleteStmt = this.#db.prepare(
 			`UPDATE auth_credentials SET disabled_cause = ?, updated_at = ${SQLITE_NOW_EPOCH} WHERE id = ?`,
 		);
 		this.#deleteIfMatchesStmt = this.#db.prepare(
 			`UPDATE auth_credentials SET disabled_cause = ?, updated_at = ${SQLITE_NOW_EPOCH} WHERE id = ? AND data = ? AND disabled_cause IS NULL`,
 		);
+		this.#deleteIfMatchesWithLeaseStmt = this.#db.prepare(
+			`UPDATE auth_credentials
+			SET disabled_cause = ?, updated_at = ${SQLITE_NOW_EPOCH}
+			WHERE id = ? AND data = ? AND disabled_cause IS NULL
+				AND EXISTS (
+					SELECT 1 FROM auth_credential_refresh_leases
+					WHERE credential_id = ? AND owner = ? AND expires_at_ms > ?
+				)`,
+		);
 		this.#deleteByProviderStmt = this.#db.prepare(
 			`UPDATE auth_credentials SET disabled_cause = ?, updated_at = ${SQLITE_NOW_EPOCH} WHERE provider = ? AND disabled_cause IS NULL`,
 		);
@@ -6098,7 +6153,12 @@ export class SqliteAuthCredentialStore implements AuthCredentialStore {
 		}
 	}
 
-	tryUpdateAuthCredentialIfMatches(id: number, expectedData: string, credential: AuthCredential): boolean {
+	tryUpdateAuthCredentialIfMatches(
+		id: number,
+		expectedData: string,
+		credential: AuthCredential,
+		lease?: CredentialRefreshLeaseFence,
+	): boolean {
 		const providerStmt = this.#db.prepare("SELECT provider FROM auth_credentials WHERE id = ?");
 		let providerRow: { provider?: string } | undefined;
 		try {
@@ -6109,13 +6169,24 @@ export class SqliteAuthCredentialStore implements AuthCredentialStore {
 		const provider = providerRow?.provider ?? "";
 		const serialized = serializeCredential(provider, credential);
 		if (!serialized) return false;
-		const result = this.#updateIfMatchesStmt.run(
-			serialized.credentialType,
-			serialized.data,
-			serialized.identityKey,
-			id,
-			expectedData,
-		) as { changes: number };
+		const result = lease
+			? (this.#updateIfMatchesWithLeaseStmt.run(
+					serialized.credentialType,
+					serialized.data,
+					serialized.identityKey,
+					id,
+					expectedData,
+					id,
+					lease.owner,
+					lease.nowMs,
+				) as { changes: number })
+			: (this.#updateIfMatchesStmt.run(
+					serialized.credentialType,
+					serialized.data,
+					serialized.identityKey,
+					id,
+					expectedData,
+				) as { changes: number });
 		if (result.changes !== 1) return false;
 		if (provider) {
 			this.#purgeSupersededDisabledRows(provider, this.listAuthCredentials(provider));
@@ -6137,10 +6208,24 @@ export class SqliteAuthCredentialStore implements AuthCredentialStore {
 	 * the OAuth refresh-failure path to avoid clobbering a peer that rotated the
 	 * row between our pre-check and the disable.
 	 */
-	tryDisableAuthCredentialIfMatches(id: number, expectedData: string, disabledCause: string): boolean {
-		const result = this.#deleteIfMatchesStmt.run(normalizeDisabledCause(disabledCause), id, expectedData) as {
-			changes: number;
-		};
+	tryDisableAuthCredentialIfMatches(
+		id: number,
+		expectedData: string,
+		disabledCause: string,
+		lease?: CredentialRefreshLeaseFence,
+	): boolean {
+		const result = lease
+			? (this.#deleteIfMatchesWithLeaseStmt.run(
+					normalizeDisabledCause(disabledCause),
+					id,
+					expectedData,
+					id,
+					lease.owner,
+					lease.nowMs,
+				) as { changes: number })
+			: (this.#deleteIfMatchesStmt.run(normalizeDisabledCause(disabledCause), id, expectedData) as {
+					changes: number;
+				});
 		return result.changes === 1;
 	}
 	deleteAuthCredentialsForProvider(provider: string, disabledCause: string): void {
diff --git a/packages/ai/test/auth-storage-oauth-refresh-race.test.ts b/packages/ai/test/auth-storage-oauth-refresh-race.test.ts
index b5179e450..312a073dd 100644
--- a/packages/ai/test/auth-storage-oauth-refresh-race.test.ts
+++ b/packages/ai/test/auth-storage-oauth-refresh-race.test.ts
@@ -1,4 +1,4 @@
-import { afterEach, beforeEach, describe, expect, test, vi } from "bun:test";
+import { afterEach, beforeEach, describe, expect, setSystemTime, test, vi } from "bun:test";
 import * as fs from "node:fs/promises";
 import * as os from "node:os";
 import * as path from "node:path";
@@ -36,6 +36,7 @@ describe("AuthStorage OAuth refresh race", () => {
 
 	afterEach(async () => {
 		vi.restoreAllMocks();
+		setSystemTime();
 		oauthUtils.unregisterOAuthProviders("auth-storage-oauth-refresh-race-test");
 		store?.close();
 		store = null;
@@ -510,4 +511,110 @@ describe("AuthStorage OAuth refresh race", () => {
 			refresh: "refresh-old",
 		});
 	});
+
+	test("does not persist a refresh when durable lease ownership is lost before CAS update", async () => {
+		if (!authStorage || !store) throw new Error("test setup failed");
+
+		const now = Date.parse("2026-07-10T12:00:00.000Z");
+		setSystemTime(new Date(now));
+		await authStorage.set("unit-oauth-lease-update", [
+			{
+				type: "oauth",
+				access: "access-old",
+				refresh: "refresh-old",
+				expires: now - 60_000,
+			},
+		]);
+		const storedBefore = store.listAuthCredentials("unit-oauth-lease-update");
+		expect(storedBefore).toHaveLength(1);
+		const credentialId = storedBefore[0]!.id;
+		const stealLease = store.tryAcquireCredentialRefreshLease?.bind(store);
+		if (!stealLease) throw new Error("test store does not support refresh leases");
+		const updateSpy = vi.spyOn(store, "tryUpdateAuthCredentialIfMatches");
+
+		const result = await authStorage.refreshStoredOAuthCredential("unit-oauth-lease-update", {
+			credentialFromRow: row => row,
+			forceRefresh: true,
+			refresh: async credential => {
+				// Keep the credential row bytes unchanged while expiring owner A's
+				// lease. A non-lease-fenced final CAS would still persist this token.
+				setSystemTime(new Date(now + 16_000));
+				expect(stealLease(credentialId, "peer-owner", now + 31_000)).toBe(true);
+				return {
+					...credential,
+					access: "access-from-lost-owner",
+					refresh: "refresh-from-lost-owner",
+					expires: now + 60 * 60_000,
+				};
+			},
+		});
+
+		expect(updateSpy).toHaveBeenCalled();
+		expect(result).toMatchObject({ refreshed: false, removed: false });
+		expect(result.credential).toMatchObject({
+			type: "oauth",
+			access: "access-old",
+			refresh: "refresh-old",
+		});
+		const stored = store.listAuthCredentials("unit-oauth-lease-update");
+		expect(stored).toHaveLength(1);
+		expect(stored[0]?.id).toBe(credentialId);
+		expect(stored[0]?.credential).toMatchObject({
+			type: "oauth",
+			access: "access-old",
+			refresh: "refresh-old",
+		});
+	});
+
+	test("does not terminal-disable a credential when durable lease ownership is lost before CAS disable", async () => {
+		if (!authStorage || !store) throw new Error("test setup failed");
+
+		const now = Date.parse("2026-07-10T12:30:00.000Z");
+		setSystemTime(new Date(now));
+		await authStorage.set("unit-oauth-lease-disable", [
+			{
+				type: "oauth",
+				access: "access-old",
+				refresh: "refresh-old",
+				expires: now - 60_000,
+			},
+		]);
+		const storedBefore = store.listAuthCredentials("unit-oauth-lease-disable");
+		expect(storedBefore).toHaveLength(1);
+		const credentialId = storedBefore[0]!.id;
+		const stealLease = store.tryAcquireCredentialRefreshLease?.bind(store);
+		if (!stealLease) throw new Error("test store does not support refresh leases");
+		const disableSpy = vi.spyOn(store, "tryDisableAuthCredentialIfMatches");
+
+		const result = await authStorage.refreshStoredOAuthCredential("unit-oauth-lease-disable", {
+			credentialFromRow: row => row,
+			forceRefresh: true,
+			refresh: async () => {
+				// The row still contains the same stale refresh token. Only the lease
+				// fence distinguishes stale owner A from the current row owner.
+				setSystemTime(new Date(now + 16_000));
+				expect(stealLease(credentialId, "peer-owner", now + 31_000)).toBe(true);
+				throw new Error('HTTP 400 invalid_grant {"error":"invalid_grant"}');
+			},
+			isDefinitiveFailure: error => error instanceof Error && error.message.includes("invalid_grant"),
+			disabledCause: error => `oauth refresh failed: ${error instanceof Error ? error.message : String(error)}`,
+		});
+
+		expect(disableSpy).toHaveBeenCalled();
+		expect(result).toMatchObject({ refreshed: false, removed: false });
+		expect(result.credential).toMatchObject({
+			type: "oauth",
+			access: "access-old",
+			refresh: "refresh-old",
+		});
+		expect(events).toHaveLength(0);
+		const stored = store.listAuthCredentials("unit-oauth-lease-disable");
+		expect(stored).toHaveLength(1);
+		expect(stored[0]?.id).toBe(credentialId);
+		expect(stored[0]?.credential).toMatchObject({
+			type: "oauth",
+			access: "access-old",
+			refresh: "refresh-old",
+		});
+	});
 });
diff --git a/packages/coding-agent/src/mcp/manager.ts b/packages/coding-agent/src/mcp/manager.ts
index 304a0d245..1cb1adeb0 100644
--- a/packages/coding-agent/src/mcp/manager.ts
+++ b/packages/coding-agent/src/mcp/manager.ts
@@ -1238,7 +1238,7 @@ export class MCPManager {
 							const material = selectMcpOAuthRefreshMaterial(current, auth);
 							return Boolean(current.refresh && material?.tokenUrl);
 						},
-						refresh: current => {
+						refresh: (current, signal) => {
 							if (current.refresh === REMOTE_REFRESH_SENTINEL) {
 								throw new Error("MCP OAuth refresh token is broker-redacted; local refresh is unavailable");
 							}
@@ -1257,6 +1257,7 @@ export class MCPManager {
 							return refreshMCPOAuthToken(tokenUrl, current.refresh, clientId, clientSecret, resource, {
 								authorizationUrl,
 								stripSameOriginResource: resourceIsFallback,
+								signal,
 							});
 						},
 						mergeRefreshedCredential: (current, refreshed) => {
diff --git a/packages/coding-agent/src/mcp/oauth-flow.ts b/packages/coding-agent/src/mcp/oauth-flow.ts
index 36e6f9bf7..c68916638 100644
--- a/packages/coding-agent/src/mcp/oauth-flow.ts
+++ b/packages/coding-agent/src/mcp/oauth-flow.ts
@@ -715,6 +715,7 @@ export class MCPOAuthFlow extends OAuthCallbackFlow {
  */
 export interface RefreshMCPOAuthTokenOptions {
 	fetch?: FetchImpl;
+	signal?: AbortSignal;
 	/**
 	 * Authorization-server URL the original grant was minted against. Used to
 	 * filter same-origin resource indicators on refresh. Defaults to `tokenUrl`'s
@@ -766,6 +767,7 @@ export async function refreshMCPOAuthToken(
 		method: "POST",
 		headers: { "Content-Type": "application/x-www-form-urlencoded" },
 		body: params.toString(),
+		signal: optsFromTrailing?.signal,
 	});
 
 	if (!response.ok) {
diff --git a/packages/coding-agent/test/mcp-manager-oauth-refresh.test.ts b/packages/coding-agent/test/mcp-manager-oauth-refresh.test.ts
index 8ad061a0f..997e4edad 100644
--- a/packages/coding-agent/test/mcp-manager-oauth-refresh.test.ts
+++ b/packages/coding-agent/test/mcp-manager-oauth-refresh.test.ts
@@ -115,10 +115,11 @@ async function withSharedSQLiteAuth<T>(
 describe("MCPManager OAuth refresh failure", () => {
 	let manager: MCPManager;
 	let authStorage: AuthStorage;
+	let store: SqliteAuthCredentialStore;
 	let serverConfig: MCPServerConfig;
 
 	beforeEach(async () => {
-		const store = new SqliteAuthCredentialStore(new Database(":memory:"));
+		store = new SqliteAuthCredentialStore(new Database(":memory:"));
 		authStorage = new AuthStorage(store);
 		await authStorage.reload();
 
@@ -147,6 +148,7 @@ describe("MCPManager OAuth refresh failure", () => {
 	});
 
 	afterEach(() => {
+		vi.useRealTimers();
 		authStorage.close();
 		vi.restoreAllMocks();
 	});
@@ -169,7 +171,7 @@ describe("MCPManager OAuth refresh failure", () => {
 			undefined,
 			undefined,
 			"https://logfire.example.com/mcp",
-			{ authorizationUrl: undefined, stripSameOriginResource: true },
+			{ authorizationUrl: undefined, stripSameOriginResource: true, signal: expect.any(AbortSignal) },
 		);
 		// The poisoned Bearer must not be re-injected — that is the loop the user
 		// reported (#1908).
@@ -221,6 +223,60 @@ describe("MCPManager OAuth refresh failure", () => {
 		const remaining = authStorage.get(CREDENTIAL_ID);
 		expect(remaining).toMatchObject({ type: "oauth", access: "fresh-access", refresh: "fresh-refresh" });
 	});
+
+	test("aborts a timed-out token fetch and waits for it before releasing refresh ownership", async () => {
+		vi.useFakeTimers();
+		const fetchCalled = Promise.withResolvers<void>();
+		const abortObserved = Promise.withResolvers<void>();
+		const allowFetchReject = Promise.withResolvers<void>();
+		let capturedSignal: AbortSignal | undefined;
+		let preparedSettled = false;
+		const releaseSpy = vi.spyOn(store, "releaseCredentialRefreshLease");
+		const fetchImpl = Object.assign(
+			async (_input: string | URL | Request, init?: RequestInit | BunFetchRequestInit): Promise<Response> => {
+				capturedSignal = init?.signal ?? undefined;
+				if (!capturedSignal) throw new Error("token refresh fetch did not receive an AbortSignal");
+				fetchCalled.resolve();
+				capturedSignal.addEventListener(
+					"abort",
+					() => {
+						abortObserved.resolve();
+					},
+					{ once: true },
+				);
+				await allowFetchReject.promise;
+				throw capturedSignal.reason ?? new Error("fetch aborted");
+			},
+			{ preconnect: globalThis.fetch.preconnect },
+		);
+		vi.spyOn(globalThis, "fetch").mockImplementation(fetchImpl);
+
+		const prepared = manager.prepareConfig(serverConfig).finally(() => {
+			preparedSettled = true;
+		});
+		await fetchCalled.promise;
+		expect(capturedSignal).toBeDefined();
+
+		vi.advanceTimersByTime(9_999);
+		await drainMicrotasks();
+		expect(capturedSignal!.aborted).toBe(false);
+		expect(preparedSettled).toBe(false);
+		expect(releaseSpy).not.toHaveBeenCalled();
+
+		vi.advanceTimersByTime(1);
+		await abortObserved.promise;
+		expect(capturedSignal!.aborted).toBe(true);
+		await drainMicrotasks();
+		expect(preparedSettled).toBe(false);
+		expect(releaseSpy).not.toHaveBeenCalled();
+
+		allowFetchReject.resolve();
+		const preparedConfig = await prepared;
+
+		expect(preparedSettled).toBe(true);
+		expect(releaseSpy).toHaveBeenCalledTimes(1);
+		expect(getAuthorizationHeader(preparedConfig)).toBe(`Bearer ${STALE_ACCESS}`);
+	});
 });
 
 describe("MCPManager shared SQLite OAuth refresh", () => {