docs: StarletOS X11 window build and the phase 11 reference launch

Co-Authored-By: Claude Opus 5.5 <[email protected]>

docs/StarletOS_Handoff.md

@@ -114,3 +114,24 @@ fetch found no divergence. Companion: StarletOS Phase 11 proposal L2
 
 Next: the companion's Phase 11 L2c (the user launches the Mii Channel from the
 Menu in a window with the trace on); analysis stays in the companion.
+
+## X11 window build and the reference launch — 2026-10-06
+
+No source change. The user installed `libxi-dev` and `libxrandr-dev`; a
+separate build directory `.starlet_linux_x11` (the qualified options with
+`ENABLE_X11=ON`, tests off) built `dolphin-nogui` in 2 min 53 s
+(SHA-256 `a7d372f47e7265a4ebe20c71bde6f8dd63f22416b422551b960f526a604ebda4`).
+The qualified headless `.starlet_linux` build is unchanged. On KDE Plasma
+Wayland the window runs through XWayland (`-p x11`, Vulkan); the emulated
+Wii Remote reads the mouse through XInput2.
+
+Companion session L2c (emulation, supporting only): original boot chain and
+IOS80, the companion's Phase 10C NAND read-only (hash unchanged after), no
+Ethernet NAT; the user launched the Mii Channel from the System Menu and it
+started. The `IPCTRACE` log shows ES LAUNCH right after the WiiConnect24
+shutdown request; analysis is in the companion's Phase 11 STATUS (finding 9).
+
+Known limit for the next companion step: in bootstrap (Revolution) mode the
+emulated Wii Remotes are not initialized (`m_initialized` stays false), so
+nobody can point at a channel there. Changing that is proposed in the
+companion (proposal M1), not done.