diff --git a/extensions/mattermost/src/channel-actions-setup-status.contract.test.ts b/extensions/mattermost/src/channel-actions-setup-status.contract.test.ts
index 3ed1863efa9..d399c603943 100644
--- a/extensions/mattermost/src/channel-actions-setup-status.contract.test.ts
+++ b/extensions/mattermost/src/channel-actions-setup-status.contract.test.ts
@@ -71,7 +71,6 @@ describe("mattermost setup contract", () => {
         expectedAccountId: "default",
         assertPatchedConfig: (cfg) => {
           const mattermostConfig = cfg.channels?.mattermost;
-          expect(mattermostConfig).toBeDefined();
           if (!mattermostConfig) {
             throw new Error("expected Mattermost config patch");
           }
diff --git a/extensions/mattermost/src/doctor.test.ts b/extensions/mattermost/src/doctor.test.ts
index 96ecd7b0357..cc16ff3b2f7 100644
--- a/extensions/mattermost/src/doctor.test.ts
+++ b/extensions/mattermost/src/doctor.test.ts
@@ -31,15 +31,18 @@ describe("mattermost doctor", () => {
     });
 
     const mattermostConfig = result.config.channels?.mattermost;
-    expect(mattermostConfig).toBeDefined();
     if (!mattermostConfig) {
       throw new Error("expected normalized Mattermost config");
     }
     expect(mattermostConfig.network).toEqual({
       dangerouslyAllowPrivateNetwork: true,
     });
-    const workAccount = mattermostConfig.accounts?.work as { network?: Record<string, unknown> };
-    expect(workAccount).toBeDefined();
+    const workAccount = mattermostConfig.accounts?.work as
+      | { network?: Record<string, unknown> }
+      | undefined;
+    if (!workAccount) {
+      throw new Error("expected Mattermost work account config");
+    }
     expect(workAccount.network).toEqual({
       dangerouslyAllowPrivateNetwork: false,
     });
diff --git a/extensions/mattermost/src/mattermost/client.test.ts b/extensions/mattermost/src/mattermost/client.test.ts
index c280fcfd903..6cbf3a91f7f 100644
--- a/extensions/mattermost/src/mattermost/client.test.ts
+++ b/extensions/mattermost/src/mattermost/client.test.ts
@@ -277,12 +277,10 @@ describe("updateMattermostPost", () => {
     const { calls } = await updatePostAndCapture({ message: "Updated" });
 
     const firstCall = calls[0];
-    expect(firstCall).toBeDefined();
     if (!firstCall) {
       throw new Error("expected Mattermost update post request");
     }
     expect(firstCall.url).toContain("/posts/post1");
-    expect(firstCall.init).toBeDefined();
     if (!firstCall.init) {
       throw new Error("expected Mattermost update post request init");
     }
diff --git a/extensions/mattermost/src/mattermost/model-picker.test.ts b/extensions/mattermost/src/mattermost/model-picker.test.ts
index 2e53b9e336f..c3c37e94dcc 100644
--- a/extensions/mattermost/src/mattermost/model-picker.test.ts
+++ b/extensions/mattermost/src/mattermost/model-picker.test.ts
@@ -60,12 +60,10 @@ describe("Mattermost model picker", () => {
     expect(view.text).toContain("Browse keeps the current runtime");
     expect(view.text).toContain("/oc_model <provider/model> --runtime <runtime>");
     const firstRow = view.buttons[0];
-    expect(firstRow).toBeDefined();
     if (!firstRow) {
       throw new Error("expected Mattermost model picker button row");
     }
     const browseButton = firstRow[0];
-    expect(browseButton).toBeDefined();
     if (!browseButton) {
       throw new Error("expected Mattermost browse providers button");
     }
diff --git a/extensions/mattermost/src/mattermost/slash-commands.test.ts b/extensions/mattermost/src/mattermost/slash-commands.test.ts
index 2e3fb09f192..d2f756f08d9 100644
--- a/extensions/mattermost/src/mattermost/slash-commands.test.ts
+++ b/extensions/mattermost/src/mattermost/slash-commands.test.ts
@@ -131,7 +131,6 @@ describe("slash-commands", () => {
 
     expect(result).toHaveLength(1);
     const firstCommand = result[0];
-    expect(firstCommand).toBeDefined();
     if (!firstCommand) {
       throw new Error("expected Mattermost slash command result");
     }
diff --git a/extensions/mattermost/src/setup.test.ts b/extensions/mattermost/src/setup.test.ts
index 361abb6b12d..9af8238d314 100644
--- a/extensions/mattermost/src/setup.test.ts
+++ b/extensions/mattermost/src/setup.test.ts
@@ -392,7 +392,6 @@ describe("mattermost setup", () => {
     );
     expect(textMessages).toEqual(["Enter Mattermost bot token", "Enter Mattermost base URL"]);
     const mattermostConfig = result.cfg.channels?.mattermost;
-    expect(mattermostConfig).toBeDefined();
     if (!mattermostConfig) {
       throw new Error("expected Mattermost config");
     }
diff --git a/extensions/synology-chat/src/client.test.ts b/extensions/synology-chat/src/client.test.ts
index 37bf9cd26a4..d305342faeb 100644
--- a/extensions/synology-chat/src/client.test.ts
+++ b/extensions/synology-chat/src/client.test.ts
@@ -122,7 +122,6 @@ describe("Synology Chat TLS verification defaults", () => {
     await settleTimers(invoke());
     const httpsRequest = vi.mocked(https.request);
     const firstCall = httpsRequest.mock.calls[0];
-    expect(firstCall).toBeDefined();
     if (!firstCall) {
       throw new Error("expected Synology Chat HTTPS request");
     }
@@ -159,7 +158,6 @@ describe("sendMessage", () => {
     await settleTimers(sendMessage("https://nas.example.com/incoming", "Hello", undefined, true));
     const httpsRequest = vi.mocked(https.request);
     const firstCall = httpsRequest.mock.calls[0];
-    expect(firstCall).toBeDefined();
     if (!firstCall) {
       throw new Error("expected Synology Chat HTTPS request");
     }
@@ -387,7 +385,6 @@ describe("fetchChatUsers", () => {
 
     const httpsGet = vi.mocked(https.get);
     const firstCall = httpsGet.mock.calls[0];
-    expect(firstCall).toBeDefined();
     if (!firstCall) {
       throw new Error("expected Synology Chat HTTPS get");
     }
diff --git a/test/scripts/vitest-process-group.test.ts b/test/scripts/vitest-process-group.test.ts
index f8d1c321050..c0c2a7d47fc 100644
--- a/test/scripts/vitest-process-group.test.ts
+++ b/test/scripts/vitest-process-group.test.ts
@@ -9,7 +9,6 @@ import {
 describe("vitest process group helpers", () => {
   function getListenerSet(listeners: Map<string, Set<() => void>>, event: string) {
     const set = listeners.get(event);
-    expect(set).toBeDefined();
     if (!set) {
       throw new Error(`expected ${event} listener set`);
     }