docs(agent): #95 is two Ghostty failures, not one OpenGL floor

Photo A (Acer): OpenGL 4.2 → OpenGLOutdated / SurfaceError.
Photo B (XPS): silent exit after GDK_DISABLE=gles-api,vulkan with no
OpenGL line — different machine, different root cause. A fix for only
one is not done.

agent/BACKLOG.md

@@ -144,13 +144,14 @@ template source. Pass = Chromium launches after installation and HTTP/HTTPS
 mime defaults resolve to `chromium-browser.desktop` (and the intended live-ISO
 browser posture is explicit).
 
-### 95. Live ISO/install: Ghostty does not open on old OpenGL
+### 95. Live ISO/install: Ghostty does not open — **two distinct failures**
 
-**Diagnosed 2026-07-14 on Acer Aspire M5-481T** (Dell XPS 9350 starts Ghostty
-fine — machine-specific). From a working shell:
+Two photos, two machines, **two different Ghostty death modes**. Do not
+collapse them into one "old GPU" fix; a fix for (A) can leave (B) broken.
+
+**A — Acer Aspire M5-481T: OpenGL too old (explicit)**
 
 ```
-info: renderer=renderer.generic.Renderer(renderer.OpenGL)
 info(opengl): loaded OpenGL 4.2
 warning(opengl): OpenGL version is too old. Ghostty requires OpenGL 4.3
 warning(gtk_ghostty_surface): failed to initialize surface
@@ -159,20 +160,41 @@ warning(gtk_ghostty_surface): surface failed to initialize
   err=error.SurfaceError
 ```
 
-Not a packaging/missing-binary bug: Ghostty 1.3.1 runs, reads config, then
-refuses the GPU. Default terminal is Ghostty (`nomarchy.terminal`), so
-SUPER+Return and the launcher entry are dead on anything ≤ GL 4.2 (Ivy Bridge
-era and similar).
+Ghostty 1.3.1 starts, loads config, hits the GPU floor, prints the reason,
+returns to the shell (~2s). Anything ≤ GL 4.2 (Ivy Bridge era) is dead for
+the default terminal.
 
-**Fix direction:** detect/soft-fallback — e.g. Ghostty config for a software
-GL path if one exists and works; or auto-pick a second terminal (kitty is what
-Bernardo added by hand on the Acer) when `glxinfo`/EGL reports < 4.3; or
-document + installer/hardware probe that swaps the default. Do not silently
-leave SUPER+Return bound to a terminal that cannot map a surface.
+**B — Dell XPS 9350 (photo without Acer bezel): silent exit after GDK_DISABLE**
 
-**Pass:** on a GL 4.2 (or softGL) guest/host, SUPER+Return opens a usable
-terminal; on modern GL, Ghostty remains default and themed. V2 softGL/QEMU is
-acceptable for the fallback path; V3 on the Acer confirms the real iGPU.
+```
+warning(gtk_ghostty_application): setting GDK_DEBUG=
+warning(gtk_ghostty_application): setting GDK_DISABLE=gles-api,vulkan
+~ 9s )
+```
+
+Same Ghostty 1.3.1 / GTK path / config read — but **no** `info(opengl):`
+line, **no** OpenGLOutdated, **no** SurfaceError. Process ends after ~9s
+and leaves only the two `GDK_*` warnings. XPS Skylake iGPU is not a GL-4.2
+floor machine; this is a different surface/backend failure (forced desktop
+OpenGL after disabling GLES+Vulkan, Wayland/EGL context, incomplete first
+session after #123, …). Capture a second run with `GDK_DEBUG` / Ghostty
+`-e` verbosity or `WAYLAND_DEBUG=1` before guessing the patch.
+
+**Shared product impact:** default terminal is Ghostty (`nomarchy.terminal`),
+so SUPER+Return and the launcher entry are dead when either mode hits.
+Bernardo worked around on the Acer by adding `kitty` to `home.packages`.
+
+**Fix direction (likely two slices):**
+1. **(A)** soft-fallback or alternate default when GL < 4.3 (probe, or
+   ship a second terminal and bind/fallback).
+2. **(B)** reproduce on XPS-class hardware or QEMU with a capable GL stack;
+   fix the silent path (must never exit without a user-visible error or a
+   working window). May interact with #123 if the first session is half-baked.
+
+**Pass:** SUPER+Return opens a usable terminal on **both** the Acer (A) and
+the XPS (B); modern-GL machines still get themed Ghostty by default; a
+regression that only fixes A or only B is not done. V2 may cover (A) via
+softGL version pinning; (B) needs the XPS or a faithful GL/Wayland guest.
 
 ### 98. Boreal: button text renders black and is difficult to read