104 effect branch cannot discharge outer

// REQUIREMENT (effect-branch obligations, FORBIDDEN — hard invariant):
// A `!` branch fires 0-to-N times. Declaring that it DISCHARGES an obligation
// (`<!state>` on its payload) is incoherent — that promises "discharge exactly
// once" via a branch that may fire zero or many times. Must be rejected at the
// signature level (NOT a body check). If accepted, the invariant is unenforced.
~import std/build
~std/build:requires { exe.linkLibC(); }
const std = @import("std");
const Resource = struct { id: usize };

// An effect branch whose payload claims to DISCHARGE an outer obligation.
~pub tor drain { items: []const *Resource }
! each *Resource<!active>
| done usize
~proc drain|zig {
    for (items) |it| { each(it); }
    return .{ .done = items.len };
}