011 transition metatype

// Test transition meta-type - universal observer with metadata
// Shows both non-terminal (hello->goodbye) and terminal (goodbye->null) transitions
const std = @import("std");

~event hello {}
| done {}

~event goodbye {}
| done {}

~[comptime|runtime] event logger { source: []const u8, branch: []const u8, destination: ?[]const u8 }
| done {}

~proc hello {
    std.debug.print("Hello executed\n", .{});
    return .{ .done = .{} };
}

~proc goodbye {
    std.debug.print("Goodbye executed\n", .{});
    return .{ .done = .{} };
}

~[comptime|runtime] proc logger {
    if (destination) |dest| {
        std.debug.print("Transition: {s}.{s} -> {s}\n", .{source, branch, dest});
    } else {
        std.debug.print("Transition: {s}.{s} -> terminal\n", .{source, branch});
    }
    return .{ .done = .{} };
}

// Universal tap using transition meta-type
// Captures source event, branch, and destination (next event in original flow)
// NOTE: Transition uses enum-based fields, so we convert to strings for logging
// [comptime|runtime] annotation makes this tap observe BOTH compiler events and user events
~[comptime|runtime]* -> *
| Transition t |> logger(source: taps.eventToString(t.source), branch: taps.branchToString(t.branch), destination: if (t.destination) |d| taps.eventToString(d) else null)
    | done |> _

~hello()
| done |> goodbye()
    | done |> _