Try installing go

kobopatch-wasm/setup.sh

@@ -15,20 +15,10 @@ fi
 
 echo "Copying wasm_exec.js from Go SDK..."
 GOROOT="$(go env GOROOT)"
-GOPATH="$(go env GOPATH 2>/dev/null || echo "")"
-WASM_EXEC=""
-for dir in "$GOROOT" "$GOPATH" /usr/local/go; do
-    [ -z "$dir" ] && continue
-    [ -d "$dir" ] || continue
-    found="$(find "$dir" -name "wasm_exec.js" 2>/dev/null | head -1)" || true
-    if [ -n "$found" ]; then
-        WASM_EXEC="$found"
-        break
-    fi
-done
-if [ -n "$WASM_EXEC" ]; then
-    echo "Found wasm_exec.js at: $WASM_EXEC"
-    cp "$WASM_EXEC" "$SCRIPT_DIR/wasm_exec.js"
+if [ -f "$GOROOT/lib/wasm/wasm_exec.js" ]; then
+    cp "$GOROOT/lib/wasm/wasm_exec.js" "$SCRIPT_DIR/wasm_exec.js"
+elif [ -f "$GOROOT/misc/wasm/wasm_exec.js" ]; then
+    cp "$GOROOT/misc/wasm/wasm_exec.js" "$SCRIPT_DIR/wasm_exec.js"
 else
     echo "Error: could not find wasm_exec.js in Go SDK"
     echo "GOROOT=$GOROOT"

nixpacks.toml

@@ -1,8 +1,10 @@
 providers = ["python"]
 
 [phases.setup]
-nixPkgs = ["go", "git", "python3Minimal"]
+nixPkgs = ["git", "curl", "python3Minimal"]
+paths = ["/usr/local/go/bin"]
 cmds = [
+    "curl -sSfL https://go.dev/dl/go1.23.12.linux-amd64.tar.gz | tar -xz -C /usr/local",
     "cd kobopatch-wasm && bash setup.sh",
     "cd kobopatch-wasm && bash build.sh",
 ]