docs: build round 2 — mesa Redox port (alloca, wayland-scanner) + ISO wiring

local/docs/REDBEAR-FULL-SDDM-BRINGUP.md

@@ -81,3 +81,22 @@ Post-login session launch is SDDM's job (`SessionDir=/usr/share/wayland-sessions
   fine in the doomed round. Plan: let round 1 cache the desktop stack, then
   restart incrementally with the fix so the driver/graphics layer cooks correctly.
 - **Next:** on restart, watch mesa (first real EGL-gate validation) + redox-drm.
+
+### Round 2 (2026-07-24) — mesa Redox port + full-ISO wiring
+- **EGL gate validated**: mesa configured (with_dri→egl/gbm) and compiled — the
+  historical hard blocker is cleared. Two C-level Redox port gaps fixed, in order:
+  1. `alloca` not declared (shader_query.cpp + others): force-include `alloca.h`
+     via recipe meson c_args/cpp_args (relibc provides `#define alloca __builtin_alloca`).
+  2. wayland-scanner exit 127: meson resolved the TARGET (Redox) wayland-scanner
+     from wayland-scanner.pc (can't run on host); recipe now overwrites the sysroot
+     copy with the host wayland-scanner before meson (protocol codegen is portable).
+- **Full-ISO wiring fixed to reach SDDM** (assessment + fixes):
+  - VirGL: added priority-61 redox-drm 0x1AF4 entry to the INSTALLED inline
+    30-graphics.toml in config/redbear-full.toml (local/config/ copy was NOT shipped).
+  - redbear-compositor: create_dir_all(XDG_RUNTIME_DIR) before Wayland socket bind.
+  - redbear-iwlwifi excluded from redbear-meta deps (operator-authorized, temporary)
+    so `make live` assembles.
+  - SDDM-only greeter: 20_greeter/20_display gated off (earlier).
+- **Next:** mesa.pkgar → cook redox-drm/qt/kwin/sddm → assemble ISO
+  (REDBEAR_SKIP_ABI_STALENESS=1 build-redbear.sh --upstream redbear-full) → boot
+  QEMU virtio-gpu → SDDM prompt.