diff --git a/cmd/server/tests/test_helpers_test.go b/cmd/server/tests/test_helpers_test.go
index d7a86ab..9a4b593 100644
--- a/cmd/server/tests/test_helpers_test.go
+++ b/cmd/server/tests/test_helpers_test.go
@@ -544,6 +544,10 @@ func setupTestServer(t *testing.T) *TestServerSetup {
 		AnnotationService:     annotationService,
 		DeviceAuthMiddleware:  deviceAuthMiddleware,
 		LoginTracker:          loginAttemptTracker,
+		// RegisterRoutes dereferences Settings for the auth rate limit;
+		// the main binary wires database.NewSettingsRegistry(queries) —
+		// the test harness must too or route registration nil-panics.
+		Settings: database.NewSettingsRegistry(queries),
 	}
 
 	router.RegisterRoutes(routerConfig)
@@ -588,21 +592,31 @@ func setupTestServer(t *testing.T) *TestServerSetup {
 		}
 	}
 
-	// Create fresh admin test user
+	// The admin test user doubles as the shared dev admin and is
+	// deliberately PRESERVED by the cleanup above — reuse it when it
+	// already exists instead of re-creating (a blind INSERT hits
+	// users_email_key on every run after the first).
 	passwordHash := "$2a$10$JjAtK7PPa1WexQC3AUGe8OXLeuseZ/haN1Mz7emMo6CfOvMiTVXWq"
-	adminUser, err := queries.CreateUser(ctx, database.CreateUserParams{
-		Email:        "testuser@tests.bookhoard.internal",
-		Username:     "testuser",
-		PasswordHash: passwordHash,
-		FirstName:    pgtype.Text{String: "Test", Valid: true},
-		LastName:     pgtype.Text{String: "User", Valid: true},
-		Role:         "admin",
-	})
-	require.NoError(t, err, "Failed to create admin test user")
-
-	adminUUID, err := uuid.FromBytes(adminUser.ID.Bytes[:])
-	require.NoError(t, err, "Failed to parse admin user UUID")
-	createDefaultCollectionsForUser(t, queries, pgtype.UUID{Bytes: adminUUID, Valid: true})
+	var adminUUID uuid.UUID
+	if existing, gerr := queries.GetUserByEmail(ctx, "testuser@tests.bookhoard.internal"); gerr == nil {
+		adminUUID, err = uuid.FromBytes(existing.ID.Bytes[:])
+		require.NoError(t, err, "Failed to parse admin user UUID")
+	} else {
+		adminUser, cerr := queries.CreateUser(ctx, database.CreateUserParams{
+			Email:        "testuser@tests.bookhoard.internal",
+			Username:     "testuser",
+			PasswordHash: passwordHash,
+			FirstName:    pgtype.Text{String: "Test", Valid: true},
+			LastName:     pgtype.Text{String: "User", Valid: true},
+			Role:         "admin",
+		})
+		require.NoError(t, cerr, "Failed to create admin test user")
+		adminUUID, err = uuid.FromBytes(adminUser.ID.Bytes[:])
+		require.NoError(t, err, "Failed to parse admin user UUID")
+		// Default collections are created exactly once per user; the
+		// preserved dev admin already has its set from the first run.
+		createDefaultCollectionsForUser(t, queries, pgtype.UUID{Bytes: adminUUID, Valid: true})
+	}
 
 	// Create fresh regular test user
 	regularUser, err := queries.CreateUser(ctx, database.CreateUserParams{