nf-update shell helper

shell.nix

@@ -2,6 +2,26 @@
   meta = import ./default.nix;
   config = meta;
   inherit (meta) pkgs;
+  fixedSources = removeAttrs config.sources [ "__functor" ];
+  nf-update = pkgs.writeShellScriptBin "nf-update" ''
+    TEMP=$(mktemp -d)
+    git init -q $TEMP
+    ${pkgs.lib.concatStringsSep "\n" (pkgs.lib.mapAttrsToList (source: spec: let
+              update = "niv update ${source}";
+              fetch = "timeout 30 git -C $TEMP fetch -q --depth 1 ${spec.repo} ${spec.branch}:source-${source}";
+              revision = "$(git -C $TEMP show-ref -s source-${source})";
+              isGit = pkgs.lib.hasPrefix "https://" spec.repo or "";
+              git = ''
+                if ${fetch}; then
+                  echo "${source}:${spec.branch} HEAD at ${revision}" >&2
+                  ${update} -r ${revision} || true
+                else
+                  echo "failed to fetch latest revision from ${spec.repo}" >&2
+                fi
+              '';
+              auto = "${update} || true";
+            in if isGit then git else auto) fixedSources)}
+  '';
   nf-actions = pkgs.writeShellScriptBin "nf-actions" ''
     export START_DIR="$PWD"
     cd ${toString ./.}
@@ -20,7 +40,7 @@
     done
     cd $START_DIR
   '';
-  nf-test = pkgs.writeShellScriptBin "nf-test" ''
+  nf-actions-test = pkgs.writeShellScriptBin "nf-actions-test" ''
     export START_DIR="$PWD"
     cd ${toString ./.}
     export NF_CONFIG_ROOT=${toString ./.}/ci
@@ -41,8 +61,9 @@
 in pkgs.mkShell {
   nativeBuildInputs = with pkgs; [
     inetutils
+    nf-update
     nf-actions
-    nf-test
+    nf-actions-test
   ] ++ config.runners.lazy.nativeBuildInputs;
 
   HISTFILE = toString (config.deploy.dataDir + "/.history");