Fix formatting and file size CI failures

- Fix rustfmt errors in rust/src/lib.rs (remove extra blank line)
- Fix rustfmt errors in rust/src/spacetimedb_impl.rs (expand struct
  literal and reformat if-let method chain per nightly rustfmt rules)
- Exclude vendored bumpalo-patched and doublets-patched dirs from
  file size check (they are third-party libraries, not project code)
- Update changelog fragment to accurately describe real SpacetimeDB 2.0
  engine usage (no SQLite, uses RelationalDB/TestDB in-memory)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: konard

changelog.d/20260224_spacetimedb_vs_doublets_benchmark.md

@@ -4,17 +4,17 @@ bump: minor
 
 ### Added
 
-- **SpacetimeDB 2 vs Doublets benchmark** (`rust/`): New Rust benchmark suite comparing SpacetimeDB's SQLite backend against Doublets in-memory link stores for basic CRUD operations, following best practices from the Neo4j and PostgreSQL comparison benchmarks.
+- **SpacetimeDB 2 vs Doublets benchmark** (`rust/`): New Rust benchmark suite comparing the real SpacetimeDB 2.0 engine against Doublets in-memory link stores for basic CRUD operations.
 
   - **7 benchmark operations**: Create, Delete, Update, Query All, Query by Id, Query by Source, Query by Target
-  - **3 backends**: SpacetimeDB Memory (SQLite/WAL), Doublets United Volatile, Doublets Split Volatile
+  - **3 backends**: SpacetimeDB 2.0 in-memory (via `RelationalDB`/`TestDB`), Doublets United Volatile, Doublets Split Volatile
   - **Configurable scale**: `BENCHMARK_LINK_COUNT` and `BACKGROUND_LINK_COUNT` environment variables
   - **Criterion harness**: Uses criterion 0.3.6 with custom `iter_custom` timing to exclude setup/teardown from measurements
   - **Fork/unfork lifecycle**: Each iteration starts from a clean database state with pre-populated background links
 
 - **`rust/src/lib.rs`**: `Links` trait as the shared interface for both SpacetimeDB and Doublets backends; `Benched` trait for benchmark lifecycle management.
 
-- **`rust/src/spacetimedb_impl.rs`**: SpacetimeDB SQLite client implementing the `Links` trait using the same schema and indexes that SpacetimeDB 2 uses internally.
+- **`rust/src/spacetimedb_impl.rs`**: Real SpacetimeDB 2.0 engine implementation using `spacetimedb-core` with `TestDB` (in-memory `RelationalDB`, no SQLite). Verifies engine version at startup and fails if backend ≠ SpacetimeDB 2.0+.
 
 - **`rust/src/doublets_impl.rs`**: Doublets store adapters implementing the `Links` trait for both United Volatile and Split Volatile storage layouts.
 

rust/src/lib.rs

@@ -5,7 +5,6 @@
 
 #![feature(allocator_api)]
 
-
 pub mod benched;
 pub mod doublets_impl;
 pub mod exclusive;

rust/src/spacetimedb_impl.rs

@@ -78,7 +78,11 @@ impl SpacetimeDbLinks {
             })
             .expect("Failed to create links table");
 
-        Self { db, table_id, next_id: 1 }
+        Self {
+            db,
+            table_id,
+            next_id: 1,
+        }
     }
 
     /// Serialize a link row into BSATN bytes for insertion into the SpacetimeDB engine.
@@ -136,8 +140,10 @@ impl Links for SpacetimeDbLinks {
         self.db
             .with_auto_commit(Workload::Internal, |tx| {
                 // Find and delete the old row, then insert the updated row.
-                if let Some(row_ref) =
-                    self.db.iter_by_col_eq_mut(tx, table_id, COL_ID, &id_val)?.next()
+                if let Some(row_ref) = self
+                    .db
+                    .iter_by_col_eq_mut(tx, table_id, COL_ID, &id_val)?
+                    .next()
                 {
                     let ptr = row_ref.pointer();
                     self.db.delete(tx, table_id, [ptr]);
@@ -152,8 +158,10 @@ impl Links for SpacetimeDbLinks {
         let id_val = AlgebraicValue::U64(id);
         self.db
             .with_auto_commit(Workload::Internal, |tx| {
-                if let Some(row_ref) =
-                    self.db.iter_by_col_eq_mut(tx, table_id, COL_ID, &id_val)?.next()
+                if let Some(row_ref) = self
+                    .db
+                    .iter_by_col_eq_mut(tx, table_id, COL_ID, &id_val)?
+                    .next()
                 {
                     let ptr = row_ref.pointer();
                     self.db.delete(tx, table_id, [ptr]);

scripts/check-file-size.mjs

@@ -13,7 +13,7 @@ import { join, relative, extname } from 'path';
 
 const MAX_LINES = 1000;
 const FILE_EXTENSIONS = ['.rs'];
-const EXCLUDE_PATTERNS = ['target', '.git', 'node_modules'];
+const EXCLUDE_PATTERNS = ['target', '.git', 'node_modules', 'bumpalo-patched', 'doublets-patched'];
 
 /**
  * Check if a path should be excluded