103 effect obligation cannot escape

// REQUIREMENT (effect-branch obligations, no-escape negative — the discriminator):
// The `! each` signature carries NO `<state!>` resume, so an obligation created
// in the handler CANNOT escape the firing. Here the handler creates an `active!`
// obligation and only USES it (no discharge, no destroy event) — so it is
// unbalanced and MUST be rejected. (Mirror of old-for 330_053 on the new path.)
// If this is silently accepted, obligation tracking is NOT wired through `! each`.
~import std/build
~std/build:requires { exe.linkLibC(); }
const std = @import("std");
const Resource = struct { id: usize };
const allocator = std.heap.c_allocator;

~event create { id: usize } -> *Resource<active!>
~proc create|zig {
    const r = allocator.create(Resource) catch unreachable;
    r.* = Resource{ .id = id };
    return r;
}

~event use { r: *Resource<active> }
~proc use|zig { std.debug.print("using {}\n", .{r.id}); }

~pub event gen { n: usize }
! each usize
| done usize
~proc gen|zig {
    for (0..n) |i| { each(i); }
    return .{ .done = n };
}

~gen(n: 3)
! each i |> create(id: i): r |> use(r)
| done _ |> _