fix: leave run-mode apps unpinned when all cores are selected

tools/linuxfs/overlay/usr/local/bin/droiddeck-session

@@ -298,6 +298,7 @@ program_cores() {
   [ "${BL_PIN_CORES:-1}" = 0 ] && return 0
   command -v taskset >/dev/null 2>&1 || return 0
   if [ -n "${BL_GAME_CPUS:-}" ]; then echo "$BL_GAME_CPUS"; return 0; fi
+  [ "$mode" = run ] && return 0
   local f n max min= list=
   for f in /sys/devices/system/cpu/cpu[0-9]*/cpufreq/cpuinfo_max_freq; do
     max=$(cat "$f" 2>/dev/null) || continue

tools/tests/test_session_cpu.py

@@ -0,0 +1,51 @@
+import os
+from pathlib import Path
+import re
+import subprocess
+import unittest
+
+
+SESSION = Path(__file__).resolve().parents[1] / 'linuxfs/overlay/usr/local/bin/droiddeck-session'
+
+
+class SessionCpuTest(unittest.TestCase):
+    def cores(self, mode, cpus='', pin='1'):
+        function = re.search(r'^program_cores\(\) \{\n.*?^\}\n', SESSION.read_text(), re.M | re.S).group(0)
+        script = '''
+set -u
+taskset() { echo 'unexpected taskset invocation' >&2; return 1; }
+cat() {
+  case "$1" in
+    */cpu[0-5]/cpufreq/*) echo 3630000 ;;
+    */cpu[67]/cpufreq/*) echo 4610000 ;;
+    *) return 1 ;;
+  esac
+}
+'''
+        paths = ' '.join(f'/sys/devices/system/cpu/cpu{i}/cpufreq/cpuinfo_max_freq' for i in range(8))
+        function = function.replace('/sys/devices/system/cpu/cpu[0-9]*/cpufreq/cpuinfo_max_freq', paths)
+        env = dict(os.environ, mode=mode, BL_GAME_CPUS=cpus, BL_PIN_CORES=pin)
+        result = subprocess.run(['bash', '-c', script + function + '\nprogram_cores\n'],
+                                env=env, capture_output=True, text=True, timeout=10)
+        self.assertEqual(0, result.returncode, result.stderr)
+        self.assertEqual('', result.stderr)
+        return result.stdout.strip()
+
+    def test_run_with_all_cores_leaves_scheduling_unrestricted(self):
+        self.assertEqual('', self.cores('run'))
+
+    def test_run_preserves_an_explicit_core_selection(self):
+        self.assertEqual('1,2,3,4,5,6,7', self.cores('run', '1,2,3,4,5,6,7'))
+
+    def test_disabled_pinning_takes_precedence_over_explicit_cores(self):
+        self.assertEqual('', self.cores('run', '6,7', pin='0'))
+
+    def test_desktop_keeps_its_fast_core_default(self):
+        self.assertEqual('6,7', self.cores('lxqt'))
+
+    def test_desktop_preserves_an_explicit_core_selection(self):
+        self.assertEqual('0,1,2', self.cores('lxqt', '0,1,2'))
+
+
+if __name__ == '__main__':
+    unittest.main()