042 read file no free

// PIN (design gap — RED): std/io:read-file allocates a []const u8 via
// koru_allocator() (io.kz line 185: file.readToEndAlloc) and returns it
// in the `| ok []const u8` branch. The caller uses the content and then
// drops it — no free call, no phantom obligation, no checker warning.
//
// The leak is REAL at the allocator level: the `content` slice lives until
// process exit. But Koru's obligation system has no handle on it because
// `[]const u8` carries no phantom state (unlike *String<view!> from std/string).
//
// This pin documents the TYPE SYSTEM GAP: the bare-slice IO surface is
// invisible to the phantom checker. The compiler accepts this program today.
// When a `[]const u8<allocated!>` surface is added to io.kz, this test
// becomes green-reject and the design gap is closed.
//
// PREDICTION: RED PIN (compiler accepts; no phantom = no check).
// The expected error below is what SHOULD fire after the gap is closed.
//
// Grounding:
//   ~import syntax             — 330_007/input.kz line 1
//   std/io:read-file event     — koru_std/io.kz line 169: event read-file { path }
//   | ok []const u8 branch     — koru_std/io.kz line 170
//   | not-found branch         — koru_std/io.kz line 171
//   | failed branch            — koru_std/io.kz line 172
//   std/io:print.ln usage      — 330_068/input.kz line 26 (positive test)

~import std/io

// Read a file and use its content — then drop the slice without freeing.
// The allocator-owned []const u8 leaks. No phantom obligation exists to
// force a free() call, so the phantom checker is blind.
~std/io:read-file(path: "data.txt")
| ok content |> std/io:print.ln("{{ content:s }}")
| not-found |> _
| failed _ |> _