diff --git a/Makefile b/Makefile
index bb35775e5..56151984d 100644
--- a/Makefile
+++ b/Makefile
@@ -936,7 +936,7 @@ fish-test-dev: ## Run fish tests inside the Nix dev shell (mirrors CI).
 .PHONY: shell-check
 shell-check: ## Run ShellCheck on shell scripts.
 	@echo "🔍 Running ShellCheck..."
-	@find . -name '*.sh' -not -path './node_modules/*' -not -path './.git/*' -not -path './result/*' -not -path './.venv/*' -not -path './.claude/*' -not -path './dotagents/.claude/*' -not -path './dotagents/.codex/*' -print0 | xargs -0 shellcheck
+	@find . -name '*.sh' -not -path './node_modules/*' -not -path './.git/*' -not -path './.worktrees/*' -not -path './result/*' -not -path './.venv/*' -not -path './.claude/*' -not -path './dotagents/.claude/*' -not -path './dotagents/.codex/*' -print0 | xargs -0 shellcheck
 
 .PHONY: shell-check-dev
 shell-check-dev: ## Run ShellCheck inside the Nix dev shell (mirrors CI).
diff --git a/nix-darwin/default.nix b/nix-darwin/default.nix
index 43c4934f4..61c4df138 100644
--- a/nix-darwin/default.nix
+++ b/nix-darwin/default.nix
@@ -14,6 +14,7 @@ let
   networking = import ./config/networking.nix;
   nix = import ./config/nix.nix;
   security = import ./config/security.nix { inherit username; };
+  serviceModules = import ./services { inherit lib isRunner pkgs; };
   system = import ./config/system.nix { inherit isRunner pkgs username; };
   time = import ./config/time.nix;
 in
@@ -27,6 +28,7 @@ in
     security
     system
     time
-  ];
+  ]
+  ++ serviceModules;
 
 }
diff --git a/nix-darwin/services/default.nix b/nix-darwin/services/default.nix
new file mode 100644
index 000000000..37ff3ef7a
--- /dev/null
+++ b/nix-darwin/services/default.nix
@@ -0,0 +1,11 @@
+{
+  lib,
+  isRunner,
+  pkgs,
+}:
+let
+  pmsetBatteryPolicyModule = import ./pmset-battery-policy { inherit lib isRunner pkgs; };
+in
+[
+  pmsetBatteryPolicyModule
+]
diff --git a/nix-darwin/services/pmset-battery-policy/default.nix b/nix-darwin/services/pmset-battery-policy/default.nix
new file mode 100644
index 000000000..e124d82c2
--- /dev/null
+++ b/nix-darwin/services/pmset-battery-policy/default.nix
@@ -0,0 +1,28 @@
+{
+  lib,
+  isRunner,
+  pkgs,
+}:
+let
+  highBatteryThreshold = 30;
+  highBatterySleepMinutes = 300;
+  lowBatterySleepMinutes = 30;
+  pmsetBatteryPolicyScript = builtins.readFile (
+    pkgs.replaceVars ./power-policy.sh {
+      awkBin = "/usr/bin/awk";
+      inherit highBatteryThreshold highBatterySleepMinutes lowBatterySleepMinutes;
+      pmsetBin = "/usr/bin/pmset";
+    }
+  );
+in
+lib.mkIf (!isRunner) {
+  system.activationScripts.pmsetBatteryPolicy.text = lib.mkAfter pmsetBatteryPolicyScript;
+
+  launchd.daemons."com.shunkakinoki.pmset-battery-policy" = {
+    script = pmsetBatteryPolicyScript;
+    serviceConfig = {
+      RunAtLoad = true;
+      StartInterval = 86400;
+    };
+  };
+}
diff --git a/nix-darwin/services/pmset-battery-policy/power-policy.sh b/nix-darwin/services/pmset-battery-policy/power-policy.sh
new file mode 100644
index 000000000..d27bbe053
--- /dev/null
+++ b/nix-darwin/services/pmset-battery-policy/power-policy.sh
@@ -0,0 +1,26 @@
+#!/usr/bin/env bash
+set -eu
+
+pmset_bin="@pmsetBin@"
+awk_bin="@awkBin@"
+high_battery_threshold=@highBatteryThreshold@
+high_battery_sleep_minutes=@highBatterySleepMinutes@
+low_battery_sleep_minutes=@lowBatterySleepMinutes@
+
+# Idle sleep timers do not override the hardware lid-close sleep path.
+# shellcheck disable=SC2016
+battery_percentage_awk='NR == 2 { if (match($0, /[0-9]+%/)) print substr($0, RSTART, RLENGTH - 1); exit }'
+batteryPercentage="$($pmset_bin -g batt | $awk_bin "$battery_percentage_awk")"
+batterySleepMinutes=$low_battery_sleep_minutes
+batteryPowerNap=0
+
+$pmset_bin -c sleep 0
+$pmset_bin -c powernap 1
+
+if [ -n "$batteryPercentage" ] && [ "$batteryPercentage" -ge "$high_battery_threshold" ]; then
+  batterySleepMinutes=$high_battery_sleep_minutes
+  batteryPowerNap=1
+fi
+
+$pmset_bin -b sleep "$batterySleepMinutes"
+$pmset_bin -b powernap "$batteryPowerNap"
diff --git a/spec/coverage_spec.sh b/spec/coverage_spec.sh
index c1f0de3de..8128aa0e9 100644
--- a/spec/coverage_spec.sh
+++ b/spec/coverage_spec.sh
@@ -168,6 +168,10 @@ End
 It 'has spec file for home-manager/services/docker/docker-setup.sh'
 The path "spec/docker_setup_wrapper_spec.sh" should be exist
 End
+It 'has spec file for nix-darwin/services/pmset-battery-policy/power-policy.sh'
+The path "spec/pmset_battery_policy_spec.sh" should be exist
+End
+
 End
 
 Describe 'fish shortcut declarations'
@@ -244,6 +248,7 @@ named-hosts/kyber/rekey-galactica.sh
 named-hosts/kyber/setup.sh
 named-hosts/matic/falcon-init.sh
 named-hosts/matic/pam-gnome-keyring-tpm-unlock.sh
+nix-darwin/services/pmset-battery-policy/power-policy.sh
 scripts/check-nix-inline-scripts.sh
 scripts/fishtape-wrapper.sh
 scripts/llm-update.sh
diff --git a/spec/pmset_battery_policy_spec.sh b/spec/pmset_battery_policy_spec.sh
new file mode 100644
index 000000000..6051d1da9
--- /dev/null
+++ b/spec/pmset_battery_policy_spec.sh
@@ -0,0 +1,71 @@
+#!/usr/bin/env bash
+# shellcheck disable=SC2329
+
+Describe 'nix-darwin/services/pmset-battery-policy/power-policy.sh'
+SCRIPT="$PWD/nix-darwin/services/pmset-battery-policy/power-policy.sh"
+
+Describe 'script properties'
+It 'uses bash shebang'
+When run bash -c "head -1 '$SCRIPT'"
+The output should include '#!/usr/bin/env bash'
+End
+
+It 'passes bash syntax check after replacing placeholders'
+When run bash -c "sed -e 's|@pmsetBin@|/usr/bin/pmset|g' -e 's|@awkBin@|/usr/bin/awk|g' -e 's|@highBatteryThreshold@|30|g' -e 's|@highBatterySleepMinutes@|300|g' -e 's|@lowBatterySleepMinutes@|30|g' '$SCRIPT' | bash -n"
+The status should be success
+End
+End
+
+setup_policy_script() {
+  TEST_DIR=$(mktemp -d)
+  PMSET_LOG="$TEST_DIR/pmset.log"
+  PMSET_BIN="$TEST_DIR/pmset"
+  PREPROCESSED_SCRIPT="$TEST_DIR/power-policy.sh"
+  : >"$PMSET_LOG"
+
+  cat >"$PMSET_BIN" <<'EOF'
+#!/usr/bin/env bash
+set -eu
+printf '%s\n' "$*" >>"$PMSET_LOG"
+if [ "$1" = "-g" ] && [ "$2" = "batt" ]; then
+  printf "Now drawing from 'Battery Power'\n -InternalBattery-0 (id=1)\t%s%%; discharging; 4:00 remaining present: true\n" "$BATTERY_PERCENTAGE"
+fi
+EOF
+  chmod +x "$PMSET_BIN"
+
+  sed \
+    -e "s|@pmsetBin@|$PMSET_BIN|g" \
+    -e 's|@awkBin@|/usr/bin/awk|g' \
+    -e 's|@highBatteryThreshold@|30|g' \
+    -e 's|@highBatterySleepMinutes@|300|g' \
+    -e 's|@lowBatterySleepMinutes@|30|g' \
+    "$SCRIPT" >"$PREPROCESSED_SCRIPT"
+  chmod +x "$PREPROCESSED_SCRIPT"
+}
+
+cleanup_policy_script() {
+  rm -rf "$TEST_DIR"
+}
+
+Describe 'percentage-based policy'
+Before 'setup_policy_script'
+After 'cleanup_policy_script'
+
+It 'extends battery sleep at or above the threshold'
+When run bash -c ': >"'"$PMSET_LOG"'"; BATTERY_PERCENTAGE=35 PMSET_LOG="'"$PMSET_LOG"'" "'"$PREPROCESSED_SCRIPT"'" >/dev/null && cat "'"$PMSET_LOG"'"'
+The status should be success
+The output should include '-c sleep 0'
+The output should include '-c powernap 1'
+The output should include '-b sleep 300'
+The output should include '-b powernap 1'
+End
+
+It 'keeps the conservative battery sleep below the threshold'
+When run bash -c ': >"'"$PMSET_LOG"'"; BATTERY_PERCENTAGE=12 PMSET_LOG="'"$PMSET_LOG"'" "'"$PREPROCESSED_SCRIPT"'" >/dev/null && cat "'"$PMSET_LOG"'"'
+The status should be success
+The output should include '-b sleep 30'
+The output should include '-b powernap 0'
+End
+End
+
+End