diff --git a/src/simulator/build-gdext.sh b/src/simulator/build-gdext.sh
new file mode 100755
index 00000000..8054cfb1
--- /dev/null
+++ b/src/simulator/build-gdext.sh
@@ -0,0 +1,31 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+TARGET=${1:-x86_64-unknown-linux-gnu}
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+ADDON_DIR="$SCRIPT_DIR/../../engine/addons/magic_civ_physics"
+
+cargo build --release -p magic-civ-physics-gdext --target "$TARGET"
+
+mkdir -p "$ADDON_DIR"
+
+case "$TARGET" in
+  x86_64-unknown-linux-gnu)
+    cp "$SCRIPT_DIR/target/$TARGET/release/libmagic_civ_physics_gdext.so" \
+       "$ADDON_DIR/libmagic_civ_physics.x86_64.so"
+    echo "Copied → engine/addons/magic_civ_physics/libmagic_civ_physics.x86_64.so"
+    ;;
+  x86_64-pc-windows-gnu|x86_64-pc-windows-msvc)
+    cp "$SCRIPT_DIR/target/$TARGET/release/magic_civ_physics_gdext.dll" \
+       "$ADDON_DIR/magic_civ_physics.x86_64.dll"
+    echo "Copied → engine/addons/magic_civ_physics/magic_civ_physics.x86_64.dll"
+    ;;
+  aarch64-apple-darwin|x86_64-apple-darwin)
+    cp "$SCRIPT_DIR/target/$TARGET/release/libmagic_civ_physics_gdext.dylib" \
+       "$ADDON_DIR/libmagic_civ_physics.dylib"
+    echo "Copied → engine/addons/magic_civ_physics/libmagic_civ_physics.dylib"
+    ;;
+  *)
+    echo "Unknown target $TARGET — skipping copy. Place .so/.dll manually in engine/addons/magic_civ_physics/"
+    ;;
+esac
diff --git a/src/simulator/build-wasm.sh b/src/simulator/build-wasm.sh
new file mode 100755
index 00000000..81fb6df5
--- /dev/null
+++ b/src/simulator/build-wasm.sh
@@ -0,0 +1,5 @@
+#!/usr/bin/env bash
+set -euo pipefail
+wasm-pack build api-wasm \
+  --target bundler \
+  --out-dir ../pkg