meta: document xvfb gaps, newer libadwaita setup, and tsharness checks in skills

.agents/skills/drive-trayscale/SKILL.md

@@ -137,7 +137,22 @@ The search entry has no accessible name; address it as `--role entry` without `-
 
 `press` synthesizes AT-SPI key events, which often do nothing on GNOME Wayland but work on X11 (including Xvfb). Prefer actions.
 
-Without a GNOME session (for example Xvfb plus a private `dbus-daemon --session` as the caller's bus), everything above works except `screenshot`, which needs GNOME Shell; use `--allow-fail`. The app needs a libadwaita new enough for `AdwViewSwitcherSidebar` (Debian trixie's 1.7 fails at startup with `Invalid object type 'AdwViewSwitcherSidebar'`).
+Without a GNOME session (for example Xvfb plus a private `dbus-daemon --session` as the caller's bus), expect these gaps:
+
+- `screenshot` needs GNOME Shell. Pass `--allow-fail`.
+- Under Xvfb with openbox, popovers do not draw, including the main menu and dropdown lists, so their items cannot be captured.
+- An `AdwComboRow` (`combo box`) has no AT-SPI action, so `click` cannot open it. Use a pointer click, for example with `xdotool`.
+- To return to the this-machine page, use a pointer click on its sidebar row.
+
+The app needs a libadwaita new enough for `AdwViewSwitcherSidebar` (Debian trixie's 1.7 fails at startup with `Invalid object type 'AdwViewSwitcherSidebar'`). To use a newer GTK and libadwaita than the system's, point puregotk at them and point `LD_LIBRARY_PATH` at their directory. GDK and GSK are in `libgtk-4.so.1`. A runtime built in an earlier session may be gone, so check that the files exist first:
+
+```bash
+LIB=<runtime>/lib/x86_64-linux-gnu
+ls "$LIB/libadwaita-1.so.0" "$LIB/libgtk-4.so.1"
+export LD_LIBRARY_PATH=$LIB PUREGOTK_ADW_PATH=$LIB/libadwaita-1.so.0 PUREGOTK_GTK_PATH=$LIB/libgtk-4.so.1 PUREGOTK_GDK_PATH=$LIB/libgtk-4.so.1 PUREGOTK_GSK_PATH=$LIB/libgtk-4.so.1
+```
+
+`launch` passes these variables to the app. They work only for libraries built against the host's glibc. A runtime that ships its own libc, such as the Flatpak GNOME SDK, fails with a `GLIBC_PRIVATE` symbol lookup error. Run the command inside that runtime instead, for example with `bwrap` binding it over `/usr`.
 
 ## Fake peers (tsharness)
 
@@ -151,6 +166,8 @@ Flags: `-extra N` adds `peer-NN` peers (every third offline); `-mullvad N` adds
 
 It serves the LocalAPI on `/run/tailscale/tailscaled.sock`, Trayscale's default socket, so use it only where no system `tailscaled` runs (create `/run/tailscale` writable by you first). Its `go.mod` pins `tailscale.com` separately from the app's; `run.sh` builds `tailscale`/`tailscaled` at the app's version into `$DIR` (default `/tmp/tsharness`). Go skips dot-directories, so CI does not build it.
 
+To find out what `tailscaled` actually does in some state, reproduce the state on tsharness instead of reading its code or faking the LocalAPI. Read the result with `/tmp/tsharness/tailscale status --json` and `/tmp/tsharness/tailscale debug prefs`.
+
 Against tsharness the forbidden actions only touch the fake node, so a calling skill may allow them, including sending files to `receiver`. Confirm with `check-fake-tailnet` first.
 
 ## Cleanup

.agents/skills/verify-trayscale/SKILL.md

@@ -1,6 +1,6 @@
 ---
 name: verify-trayscale
-description: Prove a Trayscale UI change by driving the GTK 4 / Libadwaita window the way a user does and capturing AT-SPI evidence. Use when proving a Trayscale UI change, checking the main window, About, Preferences, peer search, the this-machine page, or a peer page.
+description: Prove a Trayscale UI change by driving the GTK 4 / Libadwaita window the way a user does and capturing AT-SPI evidence. Use when proving a Trayscale UI change, including a refactor of widget trees, `.ui` templates, or GObject subclasses that should look the same, or when checking the main window, About, Preferences, peer search, the this-machine page, or a peer page.
 ---
 
 # Verify Trayscale