diff --git a/dag/extdeps/exec/command.dag b/dag/extdeps/exec/command.dag
index 8f11ceae14d..f539ed2373d 100644
--- a/dag/extdeps/exec/command.dag
+++ b/dag/extdeps/exec/command.dag
@@ -121,6 +121,7 @@ fn argv_command(program: ProgramIdentity, arguments: List<String>) -> ArgvComman
     decl_ref(module_path: "extdeps.tools.ldd", decl_name: "ldd_command"),
     decl_ref(module_path: "extdeps.tools.dpkg_deb", decl_name: "dpkg_deb_extract_command"),
     decl_ref(module_path: "extdeps.tools.node", decl_name: "node_eval_command"),
+    decl_ref(module_path: "extdeps.tools.node", decl_name: "node_run_file_command"),
     decl_ref(module_path: "extdeps.tools.node", decl_name: "node_version_command"),
     decl_ref(module_path: "extdeps.browser.chromium", decl_name: "chromium_version_command"),
     decl_ref(module_path: "extdeps.tools.squashfs_tools", decl_name: "unsquashfs_extract_command"),
diff --git a/dag/extdeps/exec/program.dag b/dag/extdeps/exec/program.dag
index d7384a029d0..57c6bae470d 100644
--- a/dag/extdeps/exec/program.dag
+++ b/dag/extdeps/exec/program.dag
@@ -67,6 +67,7 @@ fn cataloged_program(invocation: NonEmptyStr) -> ProgramIdentity
     decl_ref(module_path: "extdeps.tools.busybox", decl_name: "busybox_dd_sparse_image_command"),
     decl_ref(module_path: "extdeps.tools.unzip", decl_name: "unzip_program"),
     decl_ref(module_path: "extdeps.tools.node", decl_name: "node_version_command"),
+    decl_ref(module_path: "extdeps.tools.node", decl_name: "node_run_file_command"),
     decl_ref(module_path: "extdeps.tools.node", decl_name: "node_eval_command"),
     decl_ref(module_path: "extdeps.tools.xorriso", decl_name: "xorriso_program"),
     decl_ref(module_path: "extdeps.nftables.ruleset", decl_name: "nft_program"),
diff --git a/dag/extdeps/tools/node.dag b/dag/extdeps/tools/node.dag
index d6772b9402a..c688a65814b 100644
--- a/dag/extdeps/tools/node.dag
+++ b/dag/extdeps/tools/node.dag
@@ -114,3 +114,8 @@ fn node_version_command(node_binary: NonEmptyStr) -> ArgvCommand {
 fn node_eval_command(node_binary: NonEmptyStr, script: String, operands: List<String>) -> ArgvCommand {
   argv_command(program: cataloged_program(invocation: node_binary), arguments: concat(["-e", script], operands))
 }
+
+// `node <script> <args...>`: runs a Node script file with arguments.
+fn node_run_file_command(node_binary: NonEmptyStr, script_path: NonEmptyStr, operands: List<String> = []) -> ArgvCommand {
+  argv_command(program: cataloged_program(invocation: node_binary), arguments: concat([script_path], operands))
+}
diff --git a/dag/gunbc/instruments/emit_host_transport.dag b/dag/gunbc/instruments/emit_host_transport.dag
index 84747bff561..aa1ae4c0e67 100644
--- a/dag/gunbc/instruments/emit_host_transport.dag
+++ b/dag/gunbc/instruments/emit_host_transport.dag
@@ -43,10 +43,13 @@ import tools.emit_host_fixtures {
   ts_signed_i32_le_byte_count
 }
 import gunbc.node_http_server_emit { gunbhub_node_http_server_source }
+import v2.std.orchestration { EnvSet }
 import extdeps.posix.process
 import extdeps.posix.signal
 import extdeps.http.client
 import extdeps.tools.sleep
+import extdeps.exec.command { env_prefixed_command_in }
+import extdeps.tools.node { node_run_file_command, node_program }
 import extdeps.numeric.base16
 import std.content_hash { content_hash_atom }
 import v2.std.collection { list_at_optional }
@@ -271,15 +274,22 @@ fn run_node_http_serve_smoke() -> Bool {
     Absent => false
     Present { value: port } => {
       let server_js = Filesystem.Write(path: concat(dir.path, "/server.js"), content: gunbhub_node_http_server_source())
-      let spawn = posix.Process.StartDetached(
-        program: "env" as NonEmptyStr,
-        arguments: [
-          "-C", dir.path,
-          "HOST=127.0.0.1",
-          concat("PORT=", to_string(port)),
-          "node",
-          concat(dir.path, "/server.js")
+      let inner_cmd = node_run_file_command(
+        node_binary: node_program().invocation,
+        script_path: concat(dir.path, "/server.js") as NonEmptyStr,
+        operands: []
+      )
+      let prefixed_cmd = env_prefixed_command_in(
+        directory: dir.path,
+        bindings: [
+          EnvSet { name: "HOST", value: "127.0.0.1" },
+          EnvSet { name: "PORT", value: to_string(port) }
         ],
+        command: inner_cmd
+      )
+      let spawn = posix.Process.StartDetached(
+        program: prefixed_cmd.program.invocation,
+        arguments: prefixed_cmd.arguments,
         stdout_file: concat(dir.path, "/server.stdout.log") as NonEmptyStr,
         stderr_file: concat(dir.path, "/server.stderr.log") as NonEmptyStr
       )