042 tap nested invocation

// Test 310_042: Tap Nested Invocation
//
// CRITICAL: Taps must work on NESTED invocations, not just top-level flows.
// This is essential for profiling/observability - you want to tap ALL calls
// to an event, regardless of where they appear in the call graph.
//
// Structure:
//   ~hello() | tap_target |> goodbye() | tap_target |> _
//
// The tap on 'goodbye' should fire even though goodbye() is nested
// inside hello()'s continuation, not a top-level flow.

const std = @import("std");
~import "$std/taps"

~event hello {}
| tap_target {}

~event goodbye {}
| tap_target {}

~event observer {}

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

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

~proc observer {
    std.debug.print("TAP FIRED!\n", .{});
}

// Tap on goodbye - should fire even when goodbye is nested
~tap(goodbye -> *)
| tap_target |> observer()

// hello is top-level, goodbye is NESTED in hello's continuation
~hello()
| tap_target |> goodbye()
    | tap_target |> _