add herdr + herdr-caffeinate

1 files changed, 62 insertions, 0 deletions

diff --git a/modules/darwin/herdr-caffeinate.nix b/modules/darwin/herdr-caffeinate.nix
new file mode 100644
index 0000000..fb23589
--- /dev/null
+++ b/modules/darwin/herdr-caffeinate.nix
@@ -0,0 +1,62 @@
+{ pkgs, ... }:
+
+# Keep the Mac awake while a herdr agent is actively working.
+# A launchd user agent polls `herdr agent list` and holds a `caffeinate`
+# process for as long as at least one agent reports the `working` status.
+let
+  interval = 20;
+
+  supervisor = pkgs.writeShellScript "herdr-caffeinate" ''
+    set -u
+
+    herdr=${pkgs.herdr}/bin/herdr
+    jq=${pkgs.jq}/bin/jq
+    caffeinate=/usr/bin/caffeinate
+
+    caff_pid=""
+
+    stop_caffeinate() {
+      if [ -n "$caff_pid" ] && kill -0 "$caff_pid" 2>/dev/null; then
+        kill "$caff_pid" 2>/dev/null || true
+      fi
+      caff_pid=""
+    }
+
+    trap 'stop_caffeinate; exit 0' TERM INT EXIT
+
+    while true; do
+      working=0
+      # `agent list` fails (nonzero, stderr) when no herdr server is running;
+      # that safely resolves to "no agents working".
+      if list=$("$herdr" agent list 2>/dev/null); then
+        count=$(printf '%s' "$list" \
+          | "$jq" -r '[.result.agents[]? | select(.agent_status == "working")] | length' 2>/dev/null \
+          || printf '0')
+        [ "''${count:-0}" -gt 0 ] && working=1
+      fi
+
+      if [ "$working" -eq 1 ]; then
+        if [ -z "$caff_pid" ] || ! kill -0 "$caff_pid" 2>/dev/null; then
+          # -s prevents system sleep (AC), -i prevents idle sleep (also on battery)
+          "$caffeinate" -s -i &
+          caff_pid=$!
+        fi
+      else
+        stop_caffeinate
+      fi
+
+      sleep ${toString interval}
+    done
+  '';
+in
+{
+  launchd.user.agents.herdr-caffeinate = {
+    serviceConfig = {
+      ProgramArguments = [ "${supervisor}" ];
+      RunAtLoad = true;
+      KeepAlive = true;
+      ProcessType = "Background";
+      StandardErrorPath = "/tmp/herdr-caffeinate.err.log";
+    };
+  };
+}