diff --git a/.gitea/workflows/validate-pr.yml b/.gitea/workflows/validate-pr.yml
index 14f60ec..879d660 100644
--- a/.gitea/workflows/validate-pr.yml
+++ b/.gitea/workflows/validate-pr.yml
@@ -10,6 +10,8 @@ jobs:
     runs-on: self-hosted
     steps:
       - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0           # need full history for `git diff base...HEAD`
 
       # 1. Identify which recipes the PR touches.
       - name: detect changed packages
diff --git a/recipes/_smoke/.keep b/recipes/_smoke/.keep
new file mode 100644
index 0000000..e69de29
diff --git a/runner/compose.yml b/runner/compose.yml
index a4b0ab8..7146a33 100644
--- a/runner/compose.yml
+++ b/runner/compose.yml
@@ -3,7 +3,6 @@
 # is built reproducibly from runner/flake.nix — run `nix run .#load-image`
 # in this directory to load it into the host's Docker daemon before
 # starting the runner.
-version: "3.8"
 services:
   runner:
     image: docker.io/gitea/act_runner:nightly
diff --git a/runner/flake.nix b/runner/flake.nix
index af46c70..d76b95c 100644
--- a/runner/flake.nix
+++ b/runner/flake.nix
@@ -42,6 +42,7 @@
             curl
             jq
             tea
+            nodejs_20            # JS-based actions/checkout@v4 etc. need `node` on PATH
 
             cacert
             iana-etc
@@ -50,7 +51,7 @@
           # Skeleton filesystem layout: /tmp, /etc/passwd for nix,
           # writable nix store, cacert pointer.
           extraCommands = ''
-            mkdir -p tmp etc nix/var/{nix,log/nix} root
+            mkdir -p tmp etc/nix nix/var/{nix,log/nix} root
             chmod 1777 tmp
 
             cat > etc/passwd <<'EOF'