diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index 5191e7d2..6b2376b0 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -21,7 +21,7 @@ jobs:
         go-version:
           - "1.24"
           - "1.25"
-        postgres-version: [17, 16, 15]
+        postgres-version: [18, 17, 16]
       fail-fast: false
     timeout-minutes: 5
 
diff --git a/handler_api_endpoint_test.go b/handler_api_endpoint_test.go
index 8c9c5247..b555f54d 100644
--- a/handler_api_endpoint_test.go
+++ b/handler_api_endpoint_test.go
@@ -36,11 +36,16 @@ type setupEndpointTestBundle struct {
 
 func setupEndpoint[TEndpoint any](ctx context.Context, t *testing.T, initFunc func(bundle apibundle.APIBundle[pgx.Tx]) *TEndpoint) (*TEndpoint, *setupEndpointTestBundle) {
 	t.Helper()
+	return setupEndpointWithOpts(ctx, t, initFunc, nil)
+}
+
+func setupEndpointWithOpts[TEndpoint any](ctx context.Context, t *testing.T, initFunc func(bundle apibundle.APIBundle[pgx.Tx]) *TEndpoint, opts *riverdbtest.TestTxOpts) (*TEndpoint, *setupEndpointTestBundle) {
+	t.Helper()
 
 	var (
 		logger = riversharedtest.Logger(t)
 		driver = riverpgxv5.New(riversharedtest.DBPool(ctx, t))
-		tx, _  = riverdbtest.TestTxPgxDriver(ctx, t, driver, nil)
+		tx, _  = riverdbtest.TestTxPgxDriver(ctx, t, driver, opts)
 		exec   = driver.UnwrapExecutor(tx)
 	)
 
@@ -234,9 +239,11 @@ func TestAPIHandlerFeaturesGet(t *testing.T) {
 
 	ctx := context.Background()
 
-	t.Run("SuccessWithEverythingFalse", func(t *testing.T) { //nolint:paralleltest
-		// This can't be parallelized because it tries to make DB schema changes.
-		endpoint, bundle := setupEndpoint(ctx, t, newFeaturesGetEndpoint)
+	t.Run("SuccessWithEverythingFalse", func(t *testing.T) {
+		t.Parallel()
+
+		// DisableSchemaSharing is required because we're making DB schema changes.
+		endpoint, bundle := setupEndpointWithOpts(ctx, t, newFeaturesGetEndpoint, &riverdbtest.TestTxOpts{DisableSchemaSharing: true})
 
 		_, err := bundle.tx.Exec(ctx, `DROP TABLE IF EXISTS river_client CASCADE;`)
 		require.NoError(t, err)
@@ -257,9 +264,11 @@ func TestAPIHandlerFeaturesGet(t *testing.T) {
 		}, resp)
 	})
 
-	t.Run("SuccessWithEverythingTrue", func(t *testing.T) { //nolint:paralleltest
-		// This can't be parallelized because it tries to make DB schema changes.
-		endpoint, bundle := setupEndpoint(ctx, t, newFeaturesGetEndpoint)
+	t.Run("SuccessWithEverythingTrue", func(t *testing.T) {
+		t.Parallel()
+
+		// DisableSchemaSharing is required because we're making DB schema changes.
+		endpoint, bundle := setupEndpointWithOpts(ctx, t, newFeaturesGetEndpoint, &riverdbtest.TestTxOpts{DisableSchemaSharing: true})
 
 		_, err := bundle.tx.Exec(ctx, `CREATE TABLE IF NOT EXISTS river_client (id SERIAL PRIMARY KEY);`)
 		require.NoError(t, err)
diff --git a/internal/riveruicmd/auth_middleware_test.go b/internal/riveruicmd/auth_middleware_test.go
index c153a2f7..85a88a2a 100644
--- a/internal/riveruicmd/auth_middleware_test.go
+++ b/internal/riveruicmd/auth_middleware_test.go
@@ -20,7 +20,8 @@ import (
 	"riverqueue.com/riverui/uiendpoints"
 )
 
-func TestAuthMiddleware(t *testing.T) {
+func TestAuthMiddleware(t *testing.T) { //nolint:tparallel
+	// Cannot be parallelized because of Setenv calls.
 	var (
 		ctx               = context.Background()
 		databaseURL       = cmp.Or(os.Getenv("TEST_DATABASE_URL"), "postgres://localhost/river_test")
@@ -49,7 +50,9 @@ func TestAuthMiddleware(t *testing.T) {
 		return initRes.httpServer.Handler
 	}
 
-	t.Run("Unauthorized", func(t *testing.T) { //nolint:paralleltest
+	t.Run("Unauthorized", func(t *testing.T) {
+		t.Parallel()
+
 		handler := setup(t, "/")
 		req := httptest.NewRequest(http.MethodGet, "/api/jobs", nil)
 		recorder := httptest.NewRecorder()
@@ -59,7 +62,9 @@ func TestAuthMiddleware(t *testing.T) {
 		require.Equal(t, http.StatusUnauthorized, recorder.Code)
 	})
 
-	t.Run("Authorized", func(t *testing.T) { //nolint:paralleltest
+	t.Run("Authorized", func(t *testing.T) {
+		t.Parallel()
+
 		handler := setup(t, "/")
 		req := httptest.NewRequest(http.MethodGet, "/api/jobs", nil)
 		req.SetBasicAuth(basicAuthUser, basicAuthPassword)
@@ -71,7 +76,9 @@ func TestAuthMiddleware(t *testing.T) {
 		require.Equal(t, http.StatusOK, recorder.Code)
 	})
 
-	t.Run("Healthcheck exemption", func(t *testing.T) { //nolint:paralleltest
+	t.Run("Healthcheck exemption", func(t *testing.T) {
+		t.Parallel()
+
 		handler := setup(t, "/")
 		req := httptest.NewRequest(http.MethodGet, "/api/health-checks/complete", nil)
 		recorder := httptest.NewRecorder()
@@ -81,7 +88,9 @@ func TestAuthMiddleware(t *testing.T) {
 		require.Equal(t, http.StatusOK, recorder.Code)
 	})
 
-	t.Run("Healthcheck exemption with prefix", func(t *testing.T) { //nolint:paralleltest
+	t.Run("Healthcheck exemption with prefix", func(t *testing.T) {
+		t.Parallel()
+
 		handler := setup(t, "/test-prefix")
 		req := httptest.NewRequest(http.MethodGet, "/test-prefix/api/health-checks/complete", nil)
 		recorder := httptest.NewRecorder()
diff --git a/internal/riveruicmd/riveruicmd_test.go b/internal/riveruicmd/riveruicmd_test.go
index 4b9de38c..cf12ee2f 100644
--- a/internal/riveruicmd/riveruicmd_test.go
+++ b/internal/riveruicmd/riveruicmd_test.go
@@ -22,8 +22,8 @@ import (
 	"riverqueue.com/riverui/uiendpoints"
 )
 
-func TestInitServer(t *testing.T) {
-	// TODO: this should be upgradeable to our latest test patterns to be parallelizable.
+func TestInitServer(t *testing.T) { //nolint:tparallel
+	// Cannot be parallelized because of Setenv calls.
 	var (
 		ctx         = context.Background()
 		databaseURL = cmp.Or(os.Getenv("TEST_DATABASE_URL"), "postgres://localhost/river_test")
@@ -51,14 +51,16 @@ func TestInitServer(t *testing.T) {
 		return initRes, &testBundle{}
 	}
 
-	t.Run("WithDatabaseURL", func(t *testing.T) { //nolint:paralleltest
+	t.Run("WithDatabaseURL", func(t *testing.T) {
+		t.Parallel()
 		initRes, _ := setup(t)
 
 		_, err := initRes.dbPool.Exec(ctx, "SELECT 1")
 		require.NoError(t, err)
 	})
 
-	t.Run("WithPGEnvVars", func(t *testing.T) {
+	t.Run("WithPGEnvVars", func(t *testing.T) { //nolint:paralleltest
+		// Cannot be parallelized because of Setenv calls.
 		t.Setenv("DATABASE_URL", "")
 
 		parsedURL, err := url.Parse(databaseURL)
@@ -79,7 +81,9 @@ func TestInitServer(t *testing.T) {
 	})
 
 	t.Run("JobListHideArgsByDefault", func(t *testing.T) {
-		t.Run("default value is false", func(t *testing.T) { //nolint:paralleltest
+		t.Run("DefaultValueIsFalse", func(t *testing.T) {
+			t.Parallel()
+
 			initRes, _ := setup(t)
 			req := httptest.NewRequest(http.MethodGet, "/api/features", nil)
 			recorder := httptest.NewRecorder()
@@ -94,7 +98,8 @@ func TestInitServer(t *testing.T) {
 			require.False(t, resp.JobListHideArgsByDefault)
 		})
 
-		t.Run("set to true with true", func(t *testing.T) {
+		t.Run("SetToTrueWithTrue", func(t *testing.T) { //nolint:paralleltest
+			// Cannot be parallelized because of Setenv calls.
 			t.Setenv("RIVER_JOB_LIST_HIDE_ARGS_BY_DEFAULT", "true")
 			initRes, _ := setup(t)
 			req := httptest.NewRequest(http.MethodGet, "/api/features", nil)
@@ -110,7 +115,8 @@ func TestInitServer(t *testing.T) {
 			require.True(t, resp.JobListHideArgsByDefault)
 		})
 
-		t.Run("set to true with 1", func(t *testing.T) {
+		t.Run("SetToTrueWith1", func(t *testing.T) { //nolint:paralleltest
+			// Cannot be parallelized because of Setenv calls.
 			t.Setenv("RIVER_JOB_LIST_HIDE_ARGS_BY_DEFAULT", "1")
 			initRes, _ := setup(t)
 			req := httptest.NewRequest(http.MethodGet, "/api/features", nil)