092 phantom direct return rechain drops obligation

// FRONTIER (pinned RED): a direct-return (`->`) event that CONSUMES a phantom
// obligation and MINTS a fresh one of the same name loses track of the
// re-minted obligation when called TWICE in a row in one flow — the phantom
// semantic checker rejects the SECOND call.
//
// Surfaced 2026-07-10 by independent LIFT-challenge contestants building
// @korulang/yyjson: `mut.set.str` used the direct-return accessor form (the
// sqlite3/pcre2 house style for non-branching accessors) and hit this the
// moment two field-sets were chained. Minimal, yyjson-free repro.
//
//   ~make(): h0 |> bump(h: h0): h1 |> bump(h: h1): h2 |> dispose(h: h2)
//
// EXPECTED (if fixed): compiles and runs, printing `n=2`.
// ACTUAL: error[KORU030]: Phantom state mismatch: argument 'h' carries no
// obligation here, but this event consumes '<!owned>' — on the SECOND `bump`.
// See expected_error.txt.
//
// The equivalent BRANCHING event (`| ok *Handle<owned!>`) chains twice fine
// (that is the shipped workaround in yyjson); only the direct-return spelling
// drops the re-minted obligation. So the phantom checker's re-mint tracking is
// wrong specifically for `->` producers chained in sequence.

const std = @import("std");
const Handle = struct { n: i32 };

~event make {} -> *Handle<owned!>
~proc make|zig {
    const h = std.heap.page_allocator.create(Handle) catch unreachable;
    h.* = .{ .n = 0 };
    return h;
}

// direct-return event: consumes <!owned>, mints fresh <owned!>
~event bump { h: *Handle<!owned> } -> *Handle<owned!>
~proc bump|zig {
    h.n += 1;
    return h;
}

~event dispose { h: *Handle<!owned> }
~proc dispose|zig {
    std.debug.print("n={}\n", .{h.n});
    std.heap.page_allocator.destroy(h);
}

~make(): h0 |> bump(h: h0): h1 |> bump(h: h1): h2 |> dispose(h: h2)