Slice 1: Meson skeleton — kernel links wlroots 0.20 from C++, RMLUi 6.2 vendored

Root meson.build (C++23, WLR_USE_UNSTABLE, ccache-detected) with RMLUi 6.2
as a wrap-file tarball built through the cmake module (no git submodules —
settled decision) and doctest 2.5.2 from wrapdb. kernel unit: extern-"C"
wlr.hpp wrapper (with the C99 [static N] array-param workaround documented
in kernel.md), slice-1 probe contract, doctest suite (1/1 green). host-bin:
composition root printing versions, exit 0. tasks.md slice 1 done.

2 files changed, 54 insertions, 0 deletions

diff --git a/packages/kernel/include/unbox/kernel/kernel.hpp b/packages/kernel/include/unbox/kernel/kernel.hpp
new file mode 100644
index 0000000..9836a14
--- /dev/null
+++ b/packages/kernel/include/unbox/kernel/kernel.hpp
@@ -0,0 +1,26 @@
+#pragma once
+
+#include <string>
+
+// Slice-1 probe surface: proves the kernel compiles against wlroots from
+// C++ and links wlroots, libwayland-server, and the vendored RMLUi. The
+// real contracts (extension host, bus, scene/seat glue, ui substrate)
+// replace this from slice 2 on.
+//
+// Calling context: everything in unbox runs on the single wl_event_loop
+// thread unless a contract explicitly states otherwise.
+
+namespace unbox::kernel {
+
+/// The wlroots version this kernel was compiled against (the 0.20 pin).
+[[nodiscard]] auto wlroots_version() -> std::string;
+
+/// The RMLUi version linked from the vendored subproject.
+[[nodiscard]] auto rmlui_version() -> std::string;
+
+/// Creates and immediately destroys a wl_display: proves we can call into
+/// libwayland-server/wlroots at runtime, not just link. Returns true on
+/// success. No side effects beyond wlroots log initialization.
+[[nodiscard]] auto link_probe() -> bool;
+
+} // namespace unbox::kernel
diff --git a/packages/kernel/include/unbox/kernel/wlr.hpp b/packages/kernel/include/unbox/kernel/wlr.hpp
new file mode 100644
index 0000000..6374a52
--- /dev/null
+++ b/packages/kernel/include/unbox/kernel/wlr.hpp
@@ -0,0 +1,28 @@
+#pragma once
+
+// The ONLY file in the project allowed to include wlroots / libwayland
+// headers (.unbox/rules/wlroots-include.md). wlroots is C; this wrapper
+// provides the extern-"C" guards C++ needs. WLR_USE_UNSTABLE is defined
+// project-wide in the root meson.build; the version pin is wlroots 0.20.
+//
+// Grow this include list as kernel glue needs more types — never include
+// <wlr/...> anywhere else, in any unit.
+
+extern "C" {
+#include <wayland-server-core.h>
+
+// wlroots headers use C99 array-parameter syntax (`float color[static 4]`),
+// which is invalid C++. Blanking `static` around the wlr includes is the
+// proven workaround (Hyprland shipped years on it): `static inline` header
+// helpers become plain `inline`, which C++ ODR-merges safely. Keep the
+// #define scoped to EXACTLY these includes.
+#define static
+#include <wlr/backend.h>
+#include <wlr/render/allocator.h>
+#include <wlr/render/wlr_renderer.h>
+#include <wlr/types/wlr_output.h>
+#include <wlr/types/wlr_scene.h>
+#include <wlr/util/log.h>
+#include <wlr/version.h>
+#undef static
+}