Simple mock-up starting point.

Makefile

@@ -0,0 +1,2 @@
+all: calx
+CXXFLAGS+= -std=c++26

calx.cc

@@ -0,0 +1,130 @@
+#include <iostream>
+#include <iomanip>
+#include <string>
+
+#include <unistd.h>
+
+namespace
+{
+
+	namespace C
+	{
+		const int startHour= 6;
+	}
+
+	enum Color : int { red= 1, green= 2, yellow= 3, blue= 4, magenta= 5, cyan= 6, white= 7 };
+	struct Appointment
+	{
+		std::string name;
+		int startHour;
+		int startQuarter;
+		int duration; // Quarter hours
+		int day;
+		Color color;
+
+		friend std::ostream &
+		operator << ( std::ostream &os, const Appointment &appointment )
+		{
+			if( false )
+			{
+				std::cout << " Wakeup  ";
+			}
+			for( int i= 0; i < appointment.duration; ++i )
+			{
+				os << "[" << 10 * appointment.day << "G["
+						<< ( 1 + ( appointment.startHour - 6 ) * 4 + appointment.startQuarter + i )
+						<< "B[4" << appointment.color
+						<< ";1m";
+				if( i == 0 )
+				{
+					if( appointment.name.size() <= 9 ) os << std::left << std::setw( 9 ) << appointment.name;
+					else os << std::setw( 6 ) << appointment.name.substr(0,6) << "...";
+				}
+				else os << std::setw( 9 ) << "";
+				os << "";
+			}
+			return os;
+		}
+	};
+
+	Appointment appointments[]=
+	{
+		{ "Wakeup",  6, 0, 1, 3, red },
+		{ "Wakeup",  7, 1, 2, 2, red },
+		{ "Meeting", 9, 1, 5, 5, blue },
+		{ "Long Meeting Name", 8, 1, 8, 6, cyan },
+	};
+}
+
+int
+main()
+{
+	using namespace std::literals::string_literals;
+
+
+	
+	
+
+/*                                                                           */
+	auto example= R"(
+| Time  |   Mon   |   Tue   |   Wed   |   Thu   |   Fri   |   Sat   |   Sun   |
+| 06:00 |         |         |         |         |         |         |         |
+|       |         |         |         |         |         |         |         |
+|       |         |         |         |         |         |         |         |
+|_______|         |         |         |         |         |         |         |
+| 07:00 |         |         |         |         |         |         |         |
+|       |         |         |         |         |         |         |         |
+|       |         |         |         |         |         |         |         |
+|_______|         |         |         |         |         |         |         |
+| 08:00 |         |         |         |         |         |         |         |
+|       |         |         |         |         |         |         |         |
+|       |         |         |         |         |         |         |         |
+|_______|         |         |         |         |         |         |         |
+| 09:00 |         |         |         |         |         |         |         |
+|       |         |         |         |         |         |         |         |
+|       |         |         |         |         |         |         |         |
+|_______|         |         |         |         |         |         |         |
+| 10:00 |         |         |         |         |         |         |         |
+|       |         |         |         |         |         |         |         |
+|       |         |         |         |         |         |         |         |
+|_______|         |         |         |         |         |         |         |
+| 11:00 |         |         |         |         |         |         |         |
+|       |         |         |         |         |         |         |         |
+|       |         |         |         |         |         |         |         |
+|_______|         |         |         |         |         |         |         |
+	)"s.substr( 1 );
+	example.pop_back(); example.pop_back();
+
+	std::cout << "" << example;
+
+	if( false )
+	{
+		std::cout << " Wakeup  ";
+		std::cout << "         ";
+		std::cout << "         ";
+
+
+		std::cout << " Wakeup  ";
+		std::cout << "         ";
+		std::cout << "         ";
+		std::cout << "         ";
+
+
+		std::cout << " Meeting ";
+		std::cout << "         ";
+		std::cout << "         ";
+		std::cout << "         ";
+	}
+
+	for( auto &appt: appointments )
+	{
+		std::cout << appt;
+	}
+
+
+	std::cout << "[?25l" << std::flush;
+
+
+	sleep( 20 );
+	std::cout << "[?25h" << std::flush;
+}