feat: add is_terminal_attached syscall

programs/include/Api/Syscall.hpp

@@ -240,6 +240,7 @@ namespace montauk::abi {
     static constexpr uint64_t SYS_SPAWN_ENV           = 173;
 
     static constexpr uint64_t SYS_LOG_WRITE           = 176;  // (logMessage) -> 0
+    static constexpr uint64_t SYS_TERMINAL_ATTACHED   = 177;  // () -> 1 when connected to a userspace terminal
 
     // Tunable parameters (for SYS_SDR_SETPARAM / SYS_SDR_GETPARAM).
     static constexpr int SDR_PARAM_FREQ        = 0;  // center frequency, Hz

programs/include/libc/montauk.h

@@ -69,7 +69,7 @@ extern "C" {
 #define MTK_SYS_TERMSCALE          43
 #define MTK_SYS_RESOLVE            44
 #define MTK_SYS_GETRANDOM          45
-#define MTK_SYS_LOG               46
+#define MTK_SYS_LOG                46
 #define MTK_SYS_MOUSESTATE         47
 #define MTK_SYS_SETMOUSEBOUNDS     48
 #define MTK_SYS_SPAWN_REDIR        49
@@ -200,6 +200,7 @@ extern "C" {
 #define MTK_SYS_SETSESSION         174
 #define MTK_SYS_KILLSESSION        175
 #define MTK_SYS_LOG_WRITE          176
+#define MTK_SYS_TERMINAL_ATTACHED  177
 /* @SYSCALLS-END */
 
 #define MTK_SOCK_TCP 1
@@ -419,6 +420,10 @@ static inline int mtk_getpid(void) {
     return (int)_mtk_syscall0(MTK_SYS_GETPID);
 }
 
+static inline int mtk_terminal_attached(void) {
+    return (int)_mtk_syscall0(MTK_SYS_TERMINAL_ATTACHED) != 0;
+}
+
 static inline int mtk_spawn(const char *path, const char *args) {
     return (int)_mtk_syscall2(MTK_SYS_SPAWN, (long)path, (long)args);
 }

programs/include/montauk/syscall.h

@@ -438,6 +438,11 @@ namespace montauk {
         return syscall1(montauk::abi::SYS_LOG_WRITE, (uint64_t)logMessage);
     }
 
+    // True when stdout is connected to a redirected userspace terminal.
+    inline bool terminal_attached() {
+        return syscall0(montauk::abi::SYS_TERMINAL_ATTACHED) != 0;
+    }
+
     // I/O redirection
     inline int spawn_redir(const char* path, const char* args = nullptr) {
         return (int)syscall2(montauk::abi::SYS_SPAWN_REDIR, (uint64_t)path, (uint64_t)args);

programs/man/syscalls.2

@@ -422,6 +422,10 @@
     Read from the kernel ring log buffer.
         int64_t montauk::read_log(char* buf, uint64_t size);
 
+.B SYS_LOG_WRITE (176)
+    Append a userspace message to the system log.
+        int64_t montauk::write_log(const char* message);
+
 .SH I/O REDIRECTION
     Used by the terminal app and similar programs to run a child
     process with its console I/O captured instead of going directly
@@ -447,6 +451,11 @@
     Tell a redirected child its terminal dimensions changed.
         int montauk::childio_settermsz(int childPid, int cols, int rows);
 
+.B SYS_TERMINAL_ATTACHED (177)
+    Return 1 when the calling process has a redirected userspace
+    terminal output stream, otherwise return 0.
+        bool montauk::terminal_attached();
+
 .SH WINDOW SERVER
     Window server syscalls are used by GUI programs to create and
     drive an on-screen window (see montauk/Window.hpp for the