refactor: unify SQL backends with sqlx::Any

Replace separate PostgreSQL and SQLite implementations (~1670 lines of
near-duplicate code) with a single SqlColdBackend using sqlx::Any.
The database type is auto-detected from the connection URL.

- Add sqlx/any feature to both backend feature flags
- Unify boolean columns to INTEGER in both migrations for Any driver compat
- Add SqlColdBackend::connect(url) and SqlColdBackend::new(AnyPool)
- Keep SqliteColdBackend/PostgresColdBackend as type aliases

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

Author: prestwich

crates/cold-sql/Cargo.toml

@@ -29,6 +29,6 @@ tokio = { workspace = true, features = ["rt-multi-thread", "macros"] }
 
 [features]
 default = []
-postgres = ["sqlx/postgres", "sqlx/runtime-tokio-rustls", "dep:alloy", "dep:signet-storage-types", "dep:signet-zenith"]
-sqlite = ["sqlx/sqlite", "sqlx/runtime-tokio-rustls", "dep:alloy", "dep:signet-storage-types", "dep:signet-zenith"]
+postgres = ["sqlx/postgres", "sqlx/any", "sqlx/runtime-tokio-rustls", "dep:alloy", "dep:signet-storage-types", "dep:signet-zenith"]
+sqlite = ["sqlx/sqlite", "sqlx/any", "sqlx/runtime-tokio-rustls", "dep:alloy", "dep:signet-storage-types", "dep:signet-zenith"]
 test-utils = ["signet-cold/test-utils", "sqlite", "postgres"]

crates/cold-sql/migrations/001_initial_pg.sql

@@ -34,7 +34,7 @@ CREATE TABLE IF NOT EXISTS transactions (
     tx_index                  BIGINT NOT NULL,
     tx_hash                   BYTEA NOT NULL,
     tx_type                   INTEGER NOT NULL,
-    sig_y_parity              BOOLEAN NOT NULL,
+    sig_y_parity              INTEGER NOT NULL,
     sig_r                     BYTEA NOT NULL,
     sig_s                     BYTEA NOT NULL,
     chain_id                  BIGINT,
@@ -59,7 +59,7 @@ CREATE TABLE IF NOT EXISTS receipts (
     block_number              BIGINT NOT NULL,
     tx_index                  BIGINT NOT NULL,
     tx_type                   INTEGER NOT NULL,
-    success                   BOOLEAN NOT NULL,
+    success                   INTEGER NOT NULL,
     cumulative_gas_used       BIGINT NOT NULL,
     PRIMARY KEY (block_number, tx_index)
 );

crates/cold-sql/src/postgres.rs crates/cold-sql/src/backend.rscrates/cold-sql/src/postgres.rs renamed to crates/cold-sql/src/backend.rs

@@ -1,4 +1,8 @@
-//! PostgreSQL backend for cold storage.
+//! Unified SQL backend for cold storage.
+//!
+//! Supports both PostgreSQL and SQLite via [`sqlx::Any`]. The backend
+//! auto-detects the database type at construction time and runs the
+//! appropriate migration.
 
 use crate::SqlColdError;
 use crate::convert::{
@@ -13,37 +17,74 @@ use signet_cold::{
 use signet_storage_types::{
     ConfirmationMeta, DbSignetEvent, DbZenithHeader, Receipt, TransactionSigned,
 };
-use sqlx::{PgPool, Row};
+use sqlx::{AnyPool, Row};
 
-/// PostgreSQL-based cold storage backend.
+/// SQL-based cold storage backend.
 ///
-/// Uses an `sqlx::PgPool` for connection management and connection pooling.
+/// Uses [`sqlx::Any`] for database-agnostic access, supporting both
+/// PostgreSQL and SQLite through a single implementation. The backend
+/// is determined by the connection URL at construction time.
 ///
 /// # Example
 ///
 /// ```no_run
 /// # async fn example() {
-/// use signet_cold_sql::PostgresColdBackend;
-/// use sqlx::PgPool;
+/// use signet_cold_sql::SqlColdBackend;
 ///
-/// let pool = PgPool::connect("postgres://localhost/signet").await.unwrap();
-/// let backend = PostgresColdBackend::new(pool).await.unwrap();
+/// // SQLite (in-memory)
+/// let backend = SqlColdBackend::connect("sqlite::memory:").await.unwrap();
+///
+/// // PostgreSQL
+/// let backend = SqlColdBackend::connect("postgres://localhost/signet").await.unwrap();
 /// # }
 /// ```
 #[derive(Debug, Clone)]
-pub struct PostgresColdBackend {
-    pool: PgPool,
+pub struct SqlColdBackend {
+    pool: AnyPool,
 }
 
-impl PostgresColdBackend {
-    /// Create a new PostgreSQL cold storage backend.
+impl SqlColdBackend {
+    /// Create a new SQL cold storage backend from an existing [`AnyPool`].
     ///
-    /// Creates all tables if they do not already exist.
-    pub async fn new(pool: PgPool) -> Result<Self, SqlColdError> {
-        sqlx::raw_sql(include_str!("../migrations/001_initial_pg.sql")).execute(&pool).await?;
+    /// Auto-detects the database backend and creates all tables if they
+    /// do not already exist. Callers must ensure
+    /// [`sqlx::any::install_default_drivers`] has been called before
+    /// constructing the pool.
+    pub async fn new(pool: AnyPool) -> Result<Self, SqlColdError> {
+        // Detect backend from a pooled connection.
+        let conn = pool.acquire().await?;
+        let backend = conn.backend_name().to_owned();
+        drop(conn);
+
+        let migration = match backend.as_str() {
+            "PostgreSQL" => include_str!("../migrations/001_initial_pg.sql"),
+            "SQLite" => include_str!("../migrations/001_initial.sql"),
+            other => {
+                return Err(SqlColdError::Convert(format!(
+                    "unsupported database backend: {other}"
+                )));
+            }
+        };
+        // Execute via pool to ensure the migration uses the same
+        // connection that subsequent queries will use.
+        sqlx::raw_sql(migration).execute(&pool).await?;
         Ok(Self { pool })
     }
 
+    /// Connect to a database URL and create the backend.
+    ///
+    /// Installs the default sqlx drivers on the first call. The database
+    /// type is inferred from the URL scheme (`sqlite:` or `postgres:`).
+    ///
+    /// For SQLite in-memory databases (`sqlite::memory:`), the pool is
+    /// limited to one connection to ensure all operations share the same
+    /// database.
+    pub async fn connect(url: &str) -> Result<Self, SqlColdError> {
+        sqlx::any::install_default_drivers();
+        let pool: AnyPool = sqlx::pool::PoolOptions::new().max_connections(1).connect(url).await?;
+        Self::new(pool).await
+    }
+
     // ========================================================================
     // Specifier resolution
     // ========================================================================
@@ -231,7 +272,7 @@ impl PostgresColdBackend {
             block_number: rr.get("block_number"),
             tx_index: rr.get("tx_index"),
             tx_type: rr.get::<i32, _>("tx_type") as i16,
-            success: rr.get::<bool, _>("success"),
+            success: rr.get::<i32, _>("success") != 0,
             cumulative_gas_used: rr.get("cumulative_gas_used"),
         };
 
@@ -329,7 +370,7 @@ impl PostgresColdBackend {
             .bind(tr.tx_index)
             .bind(&tr.tx_hash)
             .bind(tr.tx_type as i32)
-            .bind(tr.sig_y_parity)
+            .bind(tr.sig_y_parity as i32)
             .bind(&tr.sig_r)
             .bind(&tr.sig_s)
             .bind(tr.chain_id)
@@ -359,7 +400,7 @@ impl PostgresColdBackend {
             .bind(rr.block_number)
             .bind(rr.tx_index)
             .bind(rr.tx_type as i32)
-            .bind(rr.success)
+            .bind(rr.success as i32)
             .bind(rr.cumulative_gas_used)
             .execute(&mut *tx)
             .await?;
@@ -468,13 +509,13 @@ impl PostgresColdBackend {
 }
 
 /// Convert a sqlx row to a TxRow.
-fn row_to_tx_row(r: &sqlx::postgres::PgRow) -> TxRow {
+fn row_to_tx_row(r: &sqlx::any::AnyRow) -> TxRow {
     TxRow {
         block_number: r.get("block_number"),
         tx_index: r.get("tx_index"),
         tx_hash: r.get("tx_hash"),
         tx_type: r.get::<i32, _>("tx_type") as i16,
-        sig_y_parity: r.get("sig_y_parity"),
+        sig_y_parity: r.get::<i32, _>("sig_y_parity") != 0,
         sig_r: r.get("sig_r"),
         sig_s: r.get("sig_s"),
         chain_id: r.get("chain_id"),
@@ -493,7 +534,7 @@ fn row_to_tx_row(r: &sqlx::postgres::PgRow) -> TxRow {
     }
 }
 
-fn row_to_signet_event_row(r: &sqlx::postgres::PgRow) -> SignetEventRow {
+fn row_to_signet_event_row(r: &sqlx::any::AnyRow) -> SignetEventRow {
     SignetEventRow {
         block_number: r.get("block_number"),
         event_index: r.get("event_index"),
@@ -512,7 +553,7 @@ fn row_to_signet_event_row(r: &sqlx::postgres::PgRow) -> SignetEventRow {
     }
 }
 
-fn row_to_zenith_header_row(r: &sqlx::postgres::PgRow) -> ZenithHeaderRow {
+fn row_to_zenith_header_row(r: &sqlx::any::AnyRow) -> ZenithHeaderRow {
     ZenithHeaderRow {
         block_number: r.get("block_number"),
         host_block_number: r.get("host_block_number"),
@@ -523,7 +564,7 @@ fn row_to_zenith_header_row(r: &sqlx::postgres::PgRow) -> ZenithHeaderRow {
     }
 }
 
-impl ColdStorage for PostgresColdBackend {
+impl ColdStorage for SqlColdBackend {
     async fn get_header(&self, spec: HeaderSpecifier) -> ColdResult<Option<Header>> {
         let Some(block_num) = self.resolve_header_spec(spec).await? else {
             return Ok(None);
@@ -616,7 +657,7 @@ impl ColdStorage for PostgresColdBackend {
                 block_number: rr.get("block_number"),
                 tx_index: tx_idx,
                 tx_type: rr.get::<i32, _>("tx_type") as i16,
-                success: rr.get::<bool, _>("success"),
+                success: rr.get::<i32, _>("success") != 0,
                 cumulative_gas_used: rr.get("cumulative_gas_used"),
             };
 
@@ -825,13 +866,18 @@ mod tests {
     use signet_cold::conformance::conformance;
 
     #[tokio::test]
-    async fn pg_backend_conformance() {
+    async fn sqlite_conformance() {
+        let backend = SqlColdBackend::connect("sqlite::memory:").await.unwrap();
+        conformance(&backend).await.unwrap();
+    }
+
+    #[tokio::test]
+    async fn pg_conformance() {
         let Ok(url) = std::env::var("DATABASE_URL") else {
             eprintln!("skipping pg conformance: DATABASE_URL not set");
             return;
         };
-        let pool = PgPool::connect(&url).await.unwrap();
-        let backend = PostgresColdBackend::new(pool).await.unwrap();
+        let backend = SqlColdBackend::connect(&url).await.unwrap();
         conformance(&backend).await.unwrap();
     }
 }

crates/cold-sql/src/lib.rs

@@ -15,7 +15,7 @@
 //!
 //! - **`postgres`**: Enables the PostgreSQL backend.
 //! - **`sqlite`**: Enables the SQLite backend.
-//! - **`test-utils`**: Enables the SQLite backend and propagates
+//! - **`test-utils`**: Enables both backends and propagates
 //!   `signet-cold/test-utils` for conformance testing.
 //!
 //! [`ColdStorage`]: signet_cold::ColdStorage
@@ -38,12 +38,15 @@ pub use error::SqlColdError;
 #[cfg(any(feature = "sqlite", feature = "postgres"))]
 mod convert;
 
+#[cfg(any(feature = "sqlite", feature = "postgres"))]
+mod backend;
+#[cfg(any(feature = "sqlite", feature = "postgres"))]
+pub use backend::SqlColdBackend;
+
+/// Backward-compatible alias for [`SqlColdBackend`] when using SQLite.
 #[cfg(feature = "sqlite")]
-mod sqlite;
-#[cfg(feature = "sqlite")]
-pub use sqlite::SqliteColdBackend;
+pub type SqliteColdBackend = SqlColdBackend;
 
+/// Backward-compatible alias for [`SqlColdBackend`] when using PostgreSQL.
 #[cfg(feature = "postgres")]
-mod postgres;
-#[cfg(feature = "postgres")]
-pub use self::postgres::PostgresColdBackend;
+pub type PostgresColdBackend = SqlColdBackend;