040 subflow drops obligation on input

✓ Passing Passing: the compiler rejects this program as expected.

Code

// PIN (design gap): A subflow that takes a *File<opened!> as input
// but silently ignores the obligation — never closes the file and
// never re-exports the obligation in its output signature.
//
// `process-file` is a void event (no output branches). It receives a file
// with an open obligation and the caller has no way to recover the file for
// closing. The phantom checker SHOULD reject because the input obligation
// <!opened> is not consumed inside the subflow body.
//
// This is the session-type delegation gap: once a value is handed to a
// callee, the callee OWNS the discharge responsibility. If the callee's
// body does not consume or re-export the obligation, the resource leaks.
//
// PREDICTION: RED PIN — the compiler likely accepts this today because
// phantom obligation tracking does not follow values into void-event bodies.
// The expected error below is what SHOULD fire when enforcement lands.
//
// Grounding:
//   import syntax             — 330_007/input.kz line 1
//   *File<opened!> as param    — 330_040_undisposed_nested_obligation/fs.kz line 20
//   pub event open {...}      — 330_007/fs.kz line 4
//   | opened *File<opened!>    — 330_007/fs.kz line 5
//   event void (no branches)  — 330_020/input.kz line 2 (event log-done {})
//   invocation chain |>        — 330_007/input.kz line 3

~import app/fs

// BAD: accepts the opened file, declares no output branches, but never calls
// close and never discharges <!opened>. Obligation is silently lost.
~tor process-file { file: *File<opened!> }

~proc process-file|zig {
    std.debug.print("processing\n", .{});
}

const std = @import("std");

~app/fs:open(path: "data.txt"): f |> process-file(file: f)

input.kz

Supporting Files

// File-resource module reused verbatim from:
// tests/regression/300_ADVANCED_FEATURES/330_PHANTOM_TYPES/330_007_use_after_disposal/fs.kz
// — syntax is ground-truth from a passing test.

const std = @import("std");
const File = struct { handle: i32 };

~pub tor open { path: string } -> *File<opened!>

~proc open|zig {
    std.debug.print("Opening file: {s}\n", .{path});
    const allocator = std.heap.page_allocator;
    const f = allocator.create(File) catch unreachable;
    f.* = File{ .handle = 42 };
    return f;
}

// Consumes the opened! obligation — grounded in 330_007/fs.kz line 13
~pub tor close { file: *File<!opened> }

~proc close|zig {
    std.debug.print("Closing file\n", .{});
}

fs.kz

Actual compiler output

error[KORU033]: Cannot issue obligation '<opened!>' on input parameter (event: process-file). Use '<!opened>' to consume an existing obligation, or remove the '!' suffix.
  --> tests/regression/300_ADVANCED_FEATURES/335_OBLIGATION_STRESS/335_040_subflow_drops_obligation_on_input/input.kz:30:0

❌ Compiler coordination error: Phantom semantic validation failed
   (set KORU_BACKEND_TRACE=1 for the backend return trace)

Must fail at runtime with:

CONTAINS obligation

Flows

flow ~open click a branch to expand · @labels scroll to their anchor

open (path: "data.txt")

Test Configuration

MUST_ERROR

← 025 stale tx after commit 042 read file no free →