diff --git a/lib/keys/__tests__/mintEphemeralAccountKey.test.ts b/lib/keys/__tests__/mintEphemeralAccountKey.test.ts
index 1c7ba361..57572ff6 100644
--- a/lib/keys/__tests__/mintEphemeralAccountKey.test.ts
+++ b/lib/keys/__tests__/mintEphemeralAccountKey.test.ts
@@ -20,7 +20,11 @@ vi.mock("@/lib/const", () => ({ PRIVY_PROJECT_SECRET: "secret" }));
 describe("mintEphemeralAccountKey", () => {
   beforeEach(() => vi.clearAllMocks());
 
-  it("mints an account-scoped recoup_sk_ key with a ~15m expiry and returns rawKey + keyId", async () => {
+  it("defaults the ephemeral TTL to 60 minutes (long runs with step retries outlive 15m — chat#1839)", () => {
+    expect(DEFAULT_EPHEMERAL_KEY_TTL_MS).toBe(60 * 60 * 1000);
+  });
+
+  it("mints an account-scoped recoup_sk_ key with the default expiry and returns rawKey + keyId", async () => {
     vi.mocked(insertApiKey).mockResolvedValue({ data: { id: "key-1" }, error: null } as never);
 
     const before = Date.now();
diff --git a/lib/keys/mintEphemeralAccountKey.ts b/lib/keys/mintEphemeralAccountKey.ts
index 8b138f27..52144b90 100644
--- a/lib/keys/mintEphemeralAccountKey.ts
+++ b/lib/keys/mintEphemeralAccountKey.ts
@@ -3,8 +3,16 @@ import { hashApiKey } from "@/lib/keys/hashApiKey";
 import { insertApiKey } from "@/lib/supabase/account_api_keys/insertApiKey";
 import { PRIVY_PROJECT_SECRET } from "@/lib/const";
 
-/** Default lifetime for an ephemeral key: 15 minutes. */
-export const DEFAULT_EPHEMERAL_KEY_TTL_MS = 15 * 60 * 1000;
+/**
+ * Default lifetime for an ephemeral key: 60 minutes. The TTL is only the
+ * backstop — `runAgentWorkflow` revokes the key the moment the run ends
+ * (`deleteEphemeralKeyStep`), so a longer TTL does not extend key life on
+ * normal completion. 15 minutes proved too short for real runs: a
+ * `runAgentStep` timeout retries the whole agent loop (~10+ min per attempt),
+ * and on 2026-07-03 a customer run's final sends all 401'd on the expired key
+ * (chat#1839). 60 minutes covers several retry cycles.
+ */
+export const DEFAULT_EPHEMERAL_KEY_TTL_MS = 60 * 60 * 1000;
 
 export type EphemeralAccountKey = { rawKey: string; keyId: string };