diff --git a/coderd/exp_chats_chatstate_test.go b/coderd/exp_chats_chatstate_test.go
index 5b78886e4d..e89be9a9d2 100644
--- a/coderd/exp_chats_chatstate_test.go
+++ b/coderd/exp_chats_chatstate_test.go
@@ -22,6 +22,15 @@ import (
 	"github.com/coder/coder/v2/testutil"
 )
 
+// withChatWorkerDisabled turns off the chat daemon's background worker
+// so every test in this file observes synchronous chatstate endpoint
+// behavior deterministically. Without it the worker races the tests:
+// it can finish a turn (running -> waiting), promote queued messages,
+// or commit steps concurrently with the driveChatTo* fixtures.
+func withChatWorkerDisabled(o *coderdtest.Options) {
+	o.ChatWorkerDisabled = true
+}
+
 // driveChatToWaiting transitions the chat from `running` (its initial
 // state per the RFC) to `waiting` by running chatstate.FinishTurn.
 // Tests use this when they need to exercise endpoint behavior that
@@ -88,7 +97,7 @@ func TestPostChatsStartsRunning(t *testing.T) {
 	t.Parallel()
 
 	ctx := testutil.Context(t, testutil.WaitLong)
-	client, api := newChatClientWithAPI(t)
+	client, api := newChatClientWithAPI(t, withChatWorkerDisabled)
 	firstUser := coderdtest.CreateFirstUser(t, client.Client)
 	_ = createChatModelConfig(t, client)
 
@@ -122,7 +131,7 @@ func TestArchiveChatStateTransitions(t *testing.T) {
 		t.Parallel()
 
 		ctx := testutil.Context(t, testutil.WaitLong)
-		client, api := newChatClientWithAPI(t)
+		client, api := newChatClientWithAPI(t, withChatWorkerDisabled)
 		firstUser := coderdtest.CreateFirstUser(t, client.Client)
 		_ = createChatModelConfig(t, client)
 
@@ -146,7 +155,7 @@ func TestArchiveChatStateTransitions(t *testing.T) {
 		t.Parallel()
 
 		ctx := testutil.Context(t, testutil.WaitLong)
-		client := newChatClient(t)
+		client := newChatClient(t, withChatWorkerDisabled)
 		firstUser := coderdtest.CreateFirstUser(t, client.Client)
 		_ = createChatModelConfig(t, client)
 
@@ -172,9 +181,7 @@ func TestPostChatMessagesBusyInterrupt(t *testing.T) {
 	t.Parallel()
 
 	ctx := testutil.Context(t, testutil.WaitLong)
-	client := newChatClient(t, func(o *coderdtest.Options) {
-		o.ChatWorkerDisabled = true
-	})
+	client := newChatClient(t, withChatWorkerDisabled)
 	firstUser := coderdtest.CreateFirstUser(t, client.Client)
 	_ = createChatModelConfig(t, client)
 
@@ -210,7 +217,7 @@ func TestDeleteChatQueuedMessageMissingReturns404(t *testing.T) {
 	t.Parallel()
 
 	ctx := testutil.Context(t, testutil.WaitLong)
-	client := newChatClient(t)
+	client := newChatClient(t, withChatWorkerDisabled)
 	firstUser := coderdtest.CreateFirstUser(t, client.Client)
 	_ = createChatModelConfig(t, client)
 
@@ -245,7 +252,7 @@ func TestDeleteChatQueuedMessageEmptyQueueReturnsConflict(t *testing.T) {
 	t.Parallel()
 
 	ctx := testutil.Context(t, testutil.WaitLong)
-	client := newChatClient(t)
+	client := newChatClient(t, withChatWorkerDisabled)
 	firstUser := coderdtest.CreateFirstUser(t, client.Client)
 	_ = createChatModelConfig(t, client)
 
@@ -273,7 +280,7 @@ func TestPromoteChatQueuedMessageMissingReturns404(t *testing.T) {
 	t.Parallel()
 
 	ctx := testutil.Context(t, testutil.WaitLong)
-	client := newChatClient(t)
+	client := newChatClient(t, withChatWorkerDisabled)
 	firstUser := coderdtest.CreateFirstUser(t, client.Client)
 	_ = createChatModelConfig(t, client)
 
@@ -307,7 +314,7 @@ func TestPromoteChatQueuedMessageEmptyQueueReturnsConflict(t *testing.T) {
 	t.Parallel()
 
 	ctx := testutil.Context(t, testutil.WaitLong)
-	client := newChatClient(t)
+	client := newChatClient(t, withChatWorkerDisabled)
 	firstUser := coderdtest.CreateFirstUser(t, client.Client)
 	_ = createChatModelConfig(t, client)
 
@@ -336,7 +343,7 @@ func TestInterruptChatIdleReturnsConflict(t *testing.T) {
 	t.Parallel()
 
 	ctx := testutil.Context(t, testutil.WaitLong)
-	client, api := newChatClientWithAPI(t)
+	client, api := newChatClientWithAPI(t, withChatWorkerDisabled)
 	firstUser := coderdtest.CreateFirstUser(t, client.Client)
 	_ = createChatModelConfig(t, client)
 
@@ -358,7 +365,7 @@ func TestSubmitToolResultsWrongStateReturnsConflict(t *testing.T) {
 	t.Parallel()
 
 	ctx := testutil.Context(t, testutil.WaitLong)
-	client := newChatClient(t)
+	client := newChatClient(t, withChatWorkerDisabled)
 	firstUser := coderdtest.CreateFirstUser(t, client.Client)
 	_ = createChatModelConfig(t, client)
 
@@ -386,7 +393,7 @@ func TestSubmitToolResultsRequiresActionSucceeds(t *testing.T) {
 	t.Parallel()
 
 	ctx := testutil.Context(t, testutil.WaitLong)
-	client, api := newChatClientWithAPI(t)
+	client, api := newChatClientWithAPI(t, withChatWorkerDisabled)
 	firstUser := coderdtest.CreateFirstUser(t, client.Client)
 	_ = createChatModelConfig(t, client)
 
@@ -438,7 +445,7 @@ func TestPatchChatArchiveChildRejected(t *testing.T) {
 	t.Parallel()
 
 	ctx := testutil.Context(t, testutil.WaitLong)
-	client, db, api := newChatClientWithAPIAndDatabase(t)
+	client, db, api := newChatClientWithAPIAndDatabase(t, withChatWorkerDisabled)
 	firstUser := coderdtest.CreateFirstUser(t, client.Client)
 	modelConfig := createChatModelConfig(t, client)
 
@@ -488,7 +495,7 @@ func TestPatchChatUnarchiveChildRejected(t *testing.T) {
 	t.Parallel()
 
 	ctx := testutil.Context(t, testutil.WaitLong)
-	client, db, api := newChatClientWithAPIAndDatabase(t)
+	client, db, api := newChatClientWithAPIAndDatabase(t, withChatWorkerDisabled)
 	firstUser := coderdtest.CreateFirstUser(t, client.Client)
 	modelConfig := createChatModelConfig(t, client)
 
@@ -547,7 +554,7 @@ func TestPatchChatArchiveRootRollsBackWhenChildCannotArchive(t *testing.T) {
 	t.Parallel()
 
 	ctx := testutil.Context(t, testutil.WaitLong)
-	client, db, api := newChatClientWithAPIAndDatabase(t)
+	client, db, api := newChatClientWithAPIAndDatabase(t, withChatWorkerDisabled)
 	firstUser := coderdtest.CreateFirstUser(t, client.Client)
 	modelConfig := createChatModelConfig(t, client)
 
@@ -587,7 +594,7 @@ func TestPostChatMessagesInvalidStateReturnsSharedResponse(t *testing.T) {
 	t.Parallel()
 
 	ctx := testutil.Context(t, testutil.WaitLong)
-	client, _, api := newChatClientWithAPIAndDatabase(t)
+	client, _, api := newChatClientWithAPIAndDatabase(t, withChatWorkerDisabled)
 	firstUser := coderdtest.CreateFirstUser(t, client.Client)
 	_ = createChatModelConfig(t, client)
 
@@ -620,7 +627,7 @@ func TestPostChatToolResultsInvalidStateReturnsSharedResponse(t *testing.T) {
 	t.Parallel()
 
 	ctx := testutil.Context(t, testutil.WaitLong)
-	client, _, api := newChatClientWithAPIAndDatabase(t)
+	client, _, api := newChatClientWithAPIAndDatabase(t, withChatWorkerDisabled)
 	firstUser := coderdtest.CreateFirstUser(t, client.Client)
 	_ = createChatModelConfig(t, client)
 
@@ -654,7 +661,7 @@ func TestReconcileInvalidChatStateSucceeds(t *testing.T) {
 	t.Parallel()
 
 	ctx := testutil.Context(t, testutil.WaitLong)
-	client, db, api := newChatClientWithAPIAndDatabase(t)
+	client, db, api := newChatClientWithAPIAndDatabase(t, withChatWorkerDisabled)
 	firstUser := coderdtest.CreateFirstUser(t, client.Client)
 	_ = createChatModelConfig(t, client)
 
@@ -694,7 +701,7 @@ func TestReconcileInvalidChatStateNotInvalidReturnsConflict(t *testing.T) {
 	t.Parallel()
 
 	ctx := testutil.Context(t, testutil.WaitLong)
-	client := newChatClient(t)
+	client := newChatClient(t, withChatWorkerDisabled)
 	firstUser := coderdtest.CreateFirstUser(t, client.Client)
 	_ = createChatModelConfig(t, client)
 
@@ -717,7 +724,7 @@ func TestReconcileInvalidChatStateNotFound(t *testing.T) {
 	t.Parallel()
 
 	ctx := testutil.Context(t, testutil.WaitLong)
-	client := newChatClient(t)
+	client := newChatClient(t, withChatWorkerDisabled)
 	_ = coderdtest.CreateFirstUser(t, client.Client)
 
 	_, err := client.ReconcileInvalidChatState(ctx, uuid.New())