refactor: collapse feature flags to federation+nats

crates/composition/src/factory.rs

@@ -123,9 +123,14 @@ pub fn build_profile_fields_repo(
     pool: &DbPool,
 ) -> anyhow::Result<Arc<dyn UserProfileFieldsRepository>> {
     match pool {
-        #[cfg(feature = "sqlite")]
         DbPool::Sqlite(pool) => Ok(sqlite::create_profile_fields_repo(pool.clone())),
-        #[cfg(not(feature = "sqlite"))]
-        _ => anyhow::bail!("no profile fields repo for this backend"),
+    }
+}
+
+pub fn warn_if_database_backend_set() {
+    if let Ok(v) = std::env::var("DATABASE_BACKEND")
+        && v != "sqlite"
+    {
+        tracing::warn!("DATABASE_BACKEND is ignored; SQLite is the only backend");
     }
 }

crates/composition/src/tests/build.rs

@@ -265,11 +265,7 @@ fn test_repositories() -> Repositories {
 }
 
 /// A lazily-connected in-memory sqlite pool — never actually opened in this test,
-/// just a value to satisfy `DatabaseOutput::db_pool`. Requires the `sqlite` feature,
-/// which `cargo test --workspace` enables transitively (presentation/worker both
-/// default to it), matching how `DbPool::Sqlite` is only constructible under that
-/// feature everywhere else in the workspace.
-#[cfg(feature = "sqlite")]
+/// just a value to satisfy `DatabaseOutput::db_pool`.
 fn test_db_pool() -> infra_wiring::DbPool {
     let pool = sqlx::sqlite::SqlitePoolOptions::new()
         .connect_lazy("sqlite::memory:")
@@ -277,14 +273,6 @@ fn test_db_pool() -> infra_wiring::DbPool {
     infra_wiring::DbPool::Sqlite(pool)
 }
 
-#[cfg(not(feature = "sqlite"))]
-fn test_db_pool() -> infra_wiring::DbPool {
-    unreachable!(
-        "worker_deps_wiring needs the sqlite feature; cargo test --workspace enables it \
-         transitively via presentation/worker's default features"
-    )
-}
-
 fn test_database_output() -> DatabaseOutput {
     let movies = InMemoryMovieRepository::new();
     let watch_events = InMemoryWatchEventRepository::new();