diff --git a/.gitignore b/.gitignore
index 73640bd..7ae1d6a 100644
--- a/.gitignore
+++ b/.gitignore
@@ -3,3 +3,4 @@
 logs/
 data/*
 !data/.gitkeep
+docs/book/
diff --git a/dev-config.toml b/dev-config.toml
new file mode 100644
index 0000000..6dd1674
--- /dev/null
+++ b/dev-config.toml
@@ -0,0 +1,6 @@
+log_dir = "/tmp/st0x-logs"
+database_url = "sqlite:///tmp/st0x-dev.db"
+registry_url = "https://raw.githubusercontent.com/rainlanguage/rain.strategies/aeaf8d5eaac90b08fe01b9a5d69089d1a0cc1a8f/registry"
+rate_limit_global_rpm = 1000
+rate_limit_per_key_rpm = 100
+docs_dir = "docs/book"
diff --git a/flake.nix b/flake.nix
index c03cdc2..417ed40 100644
--- a/flake.nix
+++ b/flake.nix
@@ -167,7 +167,9 @@
 
         devShells.default = pkgs.mkShell {
           inherit (rainix.devShells.${system}.default) nativeBuildInputs;
-          inherit (rainix.devShells.${system}.default) shellHook;
+          shellHook = rainix.devShells.${system}.default.shellHook + ''
+            export COMMIT_SHA="$(git rev-parse HEAD 2>/dev/null || echo "dev")"
+          '';
           buildInputs = with pkgs;
             [
               sqlx-cli
diff --git a/src/routes/swap/mod.rs b/src/routes/swap/mod.rs
index 2cffbce..e0db8bb 100644
--- a/src/routes/swap/mod.rs
+++ b/src/routes/swap/mod.rs
@@ -138,6 +138,10 @@ fn map_raindex_error(e: RaindexError) -> ApiError {
             tracing::warn!(error = %e, "invalid request parameters");
             ApiError::BadRequest(e.to_string())
         }
+        RaindexError::PreflightError(_) => {
+            tracing::warn!(error = %e, "preflight simulation failed");
+            ApiError::BadRequest(e.to_readable_msg())
+        }
         _ => {
             tracing::error!(error = %e, "calldata generation failed");
             ApiError::Internal("failed to generate calldata".into())