Document title/path truncation behavior in Win32 binding

internal/winapi/winapi.go

@@ -27,6 +27,7 @@ func ForegroundWindow() (hwnd uintptr, title, class string, ok bool) {
 }
 
 func windowTitle(h windows.HWND) string {
+	// 512 uint16s; titles over 511 chars are truncated — acceptable for a sensor tag.
 	const max = 512
 	buf := make([]uint16, max)
 	n, _, _ := procGetWindowTextW.Call(
@@ -34,6 +35,7 @@ func windowTitle(h windows.HWND) string {
 		uintptr(unsafe.Pointer(&buf[0])),
 		uintptr(max),
 	)
+	// n==0 covers both call failure and a genuinely empty title; both are fine here.
 	return windows.UTF16ToString(buf[:n])
 }
 
@@ -50,6 +52,8 @@ func windowClass(h windows.HWND) string {
 
 	buf := make([]uint16, windows.MAX_PATH)
 	size := uint32(len(buf))
+	// MAX_PATH suffices for almost all paths; an over-long path fails here and
+	// degrades windowClass to "" (window left unclassified), never a crash.
 	if err := windows.QueryFullProcessImageName(proc, 0, &buf[0], &size); err != nil {
 		return ""
 	}