diff --git a/src/gateway/server-methods/chat.inject.parentid.test.ts b/src/gateway/server-methods/chat.inject.parentid.test.ts
index b901304087e..31c41f23a94 100644
--- a/src/gateway/server-methods/chat.inject.parentid.test.ts
+++ b/src/gateway/server-methods/chat.inject.parentid.test.ts
@@ -18,7 +18,7 @@ describe("gateway chat.inject transcript writes", () => {
         message: "hello",
       });
       expect(appended.ok).toBe(true);
-      expect(appended.messageId).toEqual(expect.any(String));
+      expect(appended.messageId).toBeTypeOf("string");
       const messageId = appended.messageId;
       if (!messageId) {
         throw new Error("expected appended message id");
@@ -65,7 +65,7 @@ describe("gateway chat.inject transcript writes", () => {
         message: "hello",
       });
       expect(appended.ok).toBe(true);
-      expect(appended.messageId).toEqual(expect.any(String));
+      expect(appended.messageId).toBeTypeOf("string");
       const messageId = appended.messageId;
       if (!messageId) {
         throw new Error("expected appended message id");
diff --git a/src/gateway/server.agent.gateway-server-agent-b.test.ts b/src/gateway/server.agent.gateway-server-agent-b.test.ts
index 3ae47e22277..e73067a0e46 100644
--- a/src/gateway/server.agent.gateway-server-agent-b.test.ts
+++ b/src/gateway/server.agent.gateway-server-agent-b.test.ts
@@ -529,7 +529,8 @@ describe("gateway server agent", () => {
     if (!ackPayload || !finalPayload) {
       throw new Error("missing websocket payload");
     }
-    expect(ackPayload.runId).toEqual(expect.any(String));
+    expect(ackPayload.runId).toBeTypeOf("string");
+    expect(ackPayload.runId).not.toBe("");
     expect(finalPayload.runId).toBe(ackPayload.runId);
     expect(finalPayload.status).toBe("ok");
   });
diff --git a/src/gateway/server.sessions.reset-hooks.test.ts b/src/gateway/server.sessions.reset-hooks.test.ts
index ee1c8ade4ba..f0efa97cda8 100644
--- a/src/gateway/server.sessions.reset-hooks.test.ts
+++ b/src/gateway/server.sessions.reset-hooks.test.ts
@@ -403,7 +403,8 @@ test("sessions.create with emitCommandHooks=true emits reset lifecycle hooks aga
   expect(startEvent).toMatchObject({
     resumedFrom: "sess-parent-hooks",
   });
-  expect((startEvent as { sessionId?: string } | undefined)?.sessionId).toEqual(expect.any(String));
+  expect((startEvent as { sessionId?: string } | undefined)?.sessionId).toBeTypeOf("string");
+  expect((startEvent as { sessionId?: string } | undefined)?.sessionId).not.toBe("");
   expect((startEvent as { sessionKey?: string } | undefined)?.sessionKey).toMatch(
     /^agent:main:dashboard:/,
   );
diff --git a/src/gateway/session-utils.fs.test.ts b/src/gateway/session-utils.fs.test.ts
index f4239e65484..7a3b7bd9fce 100644
--- a/src/gateway/session-utils.fs.test.ts
+++ b/src/gateway/session-utils.fs.test.ts
@@ -1302,7 +1302,7 @@ describe("readSessionMessages", () => {
       pluginId: "hitl-test-hooks",
     });
 
-    expect(messageId).toEqual(expect.any(String));
+    expect(messageId).toBeTypeOf("string");
     expect(messageId.length).toBeGreaterThan(0);
     const out = readSessionMessages(sessionId, storePath, sessionFile);
     expect(