obligation lost at boundary

✓ Passing This code compiles and runs correctly.

Code

// Test 518: Obligation lost at boundary
// Tests that obligations cannot disappear at flow boundaries
//
// Key points:
// - bad_subflow internally opens a file (*File[opened!])
// - bad_subflow returns 'done {}' with NO [!] in signature
// - This loses track of the obligation
// - ERROR: Obligation must either be cleaned OR returned with [!]

~import "$app/bad_subflow"

~app.bad_subflow:bad_subflow()
| done |> _

input.kz

Error Verification

Expected Error Pattern

This test must fail because bad_subflow opens a file with cleanup obligation
but returns without documenting the obligation in its return signature.
The obligation is lost at the flow boundary.

Actual Compiler Output

error[KORU030]: branch 'done' has payload but no binding
  --> structural_check:13:0

❌ Compiler coordination error: Incomplete branch coverage
error: CompilerCoordinationFailed
/Users/larsde/src/koru/tests/regression/300_ADVANCED_FEATURES/330_PHANTOM_TYPES/518_obligation_lost_at_boundary/backend.zig:9391:17: 0x1048d64af in emit (backend)
                return error.CompilerCoordinationFailed;
                ^
/Users/larsde/src/koru/tests/regression/300_ADVANCED_FEATURES/330_PHANTOM_TYPES/518_obligation_lost_at_boundary/backend.zig:9475:28: 0x1048d72b7 in main (backend)
    const generated_code = try RuntimeEmitter.emit(compile_allocator, final_ast);
                           ^

Imported Files

~import "$app/fs"

// BAD: Opens file but doesn't document obligation in signature
~pub event bad_subflow {}
| done  // NO [!] in signature - obligation disappears!

~proc bad_subflow {
    ~app.fs:open(path: "data.txt")
    | opened f |> done {}
    // ERROR: f.file has [opened!] obligation
    // but 'done' branch has no [!] in signature
    // Obligation is lost!
}

bad_subflow.kz

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

~pub event open { path: []const u8 }
| opened *File[opened!]

~proc open {
    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 .{ .opened = f };
}

fs.kz

Test Configuration

MUST_FAIL

← 060 reject state mismatch on input multiple cleanup paths →