142 effect inliner singleline body discard

// PINNED BUG (2026-07-02, surfaced by koru-libs config-effect spike): a |zig
// proc containing an effect-branch call, whose body sits on ONE physical line
// with a `_ = param;` discard, fails at backend — the effect-branch inliner
// auto-emits `_ = &url;` for the param AND keeps the user's own `_ = url;`,
// a double discard Zig rejects. The SAME program with a multi-line body
// compiles and runs (prints "done 30"). Source layout must never change
// codegen correctness => defect. Secondary defect: the failure surfaces as a
// raw Zig diagnostic on generated output_emitted.zig with no koru-level wall.
// Expected (correct) behavior below; today: backend failure — honest red.

~import std/io

const std = @import("std");
const Config = struct { timeout_ms: usize = 30 };

~pub event fetch { url: []const u8 }
! ?configure *Config
| done usize

// The offending shape: entire proc body on one physical line, param discarded.
~proc fetch|zig { _ = url; var cfg = Config{}; configure(&cfg); return .{ .done = cfg.timeout_ms }; }

~fetch(url: "http://example.com")
| done n |> std/io:print.blk {
    done {{ n:d }}
}