refharness/ #

The pixel oracle: real Windows XP draws visual-style parts, and XPlasma's renderer has to match what comes back. PLAN.md §7.

File	Runs on	What
`vm.sh`	host	Boots `~/clod/xpvm/xp.sh` with a QMP socket and `-snapshot` (test runs never write to `xp.qcow2`). `XPVM_PERSIST=1` to change the VM for real.
`vm.py`	host	QMP client: `screendump`, `type`, `key`, `run`, `wait`, `powerdown`. One connection per process: QMP serves one client at a time, and a second connect blocks.
`oracle.py`	host	Runs a job: builds an ISO, hot-swaps it into XP's CD drive, XP autoruns it, results come back over HTTP, and the black/white BMP pairs become RGBA PNGs.
`uxdump.c`	XP	Draws `class part state w h` with real uxtheme, over black and over white, and records uxtheme's metrics. Loads non-applied styles through uxtheme's ordinals 2/3/16 (`OpenThemeFile`, `CloseThemeFile`, `OpenThemeDataFromFile`).
`xput.c`	XP	PUTs a directory's files to the host (`10.0.2.2:8765`).
`build.sh`	host	Cross-compiles both in the dev container: 32-bit, no C runtime (mingw-w64 now links the UCRT, which XP lacks), XP 5.1 subsystem.

refharness/build.sh
refharness/vm.sh &                     # boot (≈50 s to a settled desktop)
.venv/bin/python3 refharness/vm.py wait
.venv/bin/python3 refharness/oracle.py job.txt out/ --style path/to/Royale.msstyles

A job:

style -                                                   # the applied style
part Button 1 1 75 23
style {style:Royale.msstyles} NormalColor NormalSize      # a style by file
part Button 1 2 75 23

Outputs are prefixed s<N>_ by style section (s1 = the first style line). A class may be Sub::Class (part Start::Button 1 1 99 32): uxdump applies it the way applications do -- SetWindowTheme(hwnd, Sub, NULL), then the plain class -- and names the files Sub--Class.

What we've learned from it #

A Sub::Class is complete before its class: XP draws Start::Button's push button (part 1) from [Start::Button], a class-level section, rather than from [Button.PushButton] -- not Wine's order.
The taskbar (Luna, 800 x 600): 30px; task buttons are TaskBand::Toolbar buttons the full height of it (the checked frame for the active window); the Start button is 99 x 32 from the bar's top (2px off the screen), the flag (explorer.exe bitmap 143) at its content's left, centred.
Windows Classic (Windows Standard, after restarting explorer so the taskbar lays itself out afresh): the taskbar is 30px too, its top edge Light3D then the highlight; task buttons are 22px push buttons 4px down; the Start button is a 22px push button at (2, 4) with bitmap 176 (16 x 16) 2px in and "Start" in bold Tahoma, drawn bi-level as Tahoma's gasp table asks. (Switching to Classic live left a 34px bar until explorer restarted.)
Transport: QEMU's read-write vvfat crashes on the guest's first write ("cluster 0 used more than once"), so jobs go in on an ISO and results come out over HTTP. A round trip takes about 2 s.
Semi-transparent pixels: recovering RGBA from the two renders is only exact to ±1 per channel (XP blends premultiplied). Compare composited renders, ours over black and white against uxdump's BMPs, not un-premultiplied RGBA.
uxtheme stretches without filtering. On Royale's push button every opaque pixel of a naive nine-slice already matches; the ±1 differences sit on the semi-transparent outer ring and come from filtering plus rounding.