feat: add kernel ACPI support for querying battery percentage, add battery indicator to desktop, move log state to 0:/state directory

programs/include/Api/Syscall.hpp

@@ -256,6 +256,9 @@ namespace montauk::abi {
     // in one at a time. For buffers the caller is about to touch in full.
     static constexpr uint64_t SYS_ALLOC_EAGER         = 187;  // (bytes) -> va, 0 on failure
 
+    /* Battery.hpp -- ACPI battery status */
+    static constexpr uint64_t SYS_BATTERYINFO          = 188;  // (BatteryInfo*) -> 0, -1 no battery device
+
     /* Kernel-owned process capabilities. User identities may namespace
        per-user resources, but never participate in authorization decisions. */
     static constexpr uint64_t CAP_PROCESS_ADMIN = 1ULL << 0;
@@ -808,6 +811,26 @@ namespace montauk::abi {
         uint64_t pageSize;
     };
 
+    // Battery status (returned by SYS_BATTERYINFO). A machine with no battery
+    // device fails the call outright; `present` distinguishes a laptop with the
+    // pack removed from one that is running on it.
+    struct BatteryInfo {
+        uint8_t  present;            // a battery is installed
+        uint8_t  charging;
+        uint8_t  discharging;
+        uint8_t  critical;
+        uint8_t  acOnline;           // AC adapter connected
+        uint8_t  hasAcAdapter;       // an AC adapter device exists at all
+        uint8_t  percent;            // 0..100, 0 when capacity is unknown
+        uint8_t  powerUnitMilliAmps; // capacities are mAh/mA, not mWh/mW
+        uint32_t remainingCapacity;
+        uint32_t fullCapacity;       // last full charge capacity
+        uint32_t designCapacity;
+        uint32_t presentRate;        // mW or mA, 0 when unknown
+        uint32_t voltageMv;
+        int32_t  minutesRemaining;   // -1 when not estimable (e.g. charging)
+    };
+
     // Crash report (filled by kernel on process fault, returned via SYS_CRASH_REPORT)
     struct CrashReportInfo {
         int pid;

programs/include/gui/desktop.hpp

@@ -217,6 +217,16 @@ struct DesktopState {
     uint64_t wifi_status_time;
 
 
+    // Battery indicator.  Absent entirely on a machine with no ACPI battery
+    // device, which is how a desktop keeps a clean panel.
+    SvgIcon icon_battery;
+    char battery_icon_name[64];            // which glyph icon_battery holds
+    bool battery_present;                  // a battery device exists
+    bool battery_popup_open;
+    Rect battery_icon_rect;
+    montauk::abi::BatteryInfo battery_info;
+    uint64_t battery_last_poll;
+
     bool vol_popup_open;
     Rect vol_icon_rect;
     int vol_level;            // 0-100

programs/include/libc/montauk.h

@@ -211,6 +211,7 @@ extern "C" {
 #define MTK_SYS_SPAWN_CAPS         185
 #define MTK_SYS_SPAWN_REDIR_CAPS   186
 #define MTK_SYS_ALLOC_EAGER        187
+#define MTK_SYS_BATTERYINFO        188
 /* @SYSCALLS-END */
 
 #define MTK_SOCK_TCP 1

programs/include/montauk/syscall.h

@@ -639,6 +639,13 @@ namespace montauk {
         return (int)syscall1(montauk::abi::SYS_BTINFO, (uint64_t)buf);
     }
 
+    // ACPI battery status. Returns 0 on success, or -1 on a machine with no
+    // battery device at all -- which is the signal not to draw an indicator.
+    // A laptop with the pack removed still returns 0, with present == 0.
+    inline int battery_info(montauk::abi::BatteryInfo* out) {
+        return (int)syscall1(montauk::abi::SYS_BATTERYINFO, (uint64_t)out);
+    }
+
     // Wi-Fi. scan() runs a full channel sweep and blocks until it finishes or
     // timeoutMs elapses, then fills buf with the networks seen; it returns the
     // number of entries written, or -1 when no adapter is ready.