minesweeper/README.md

# Minesweeper

Minesweeper X, running under wine on a headless X display, streamed into an Officer panel.

It is a game. It is also the smallest honest proof that Officer can put an arbitrary X11 program in a
panel — a framebuffer, a process on it, a VNC server reading it, a client in the browser — and it is the
first plugin to use the platform's per-plugin websocket relay.

## What it needs

Six host binaries, declared in `manifest.ts` and checked before install: `wine`, `Xvfb`, `x11vnc`,
`xdotool`, `xdpyinfo`, `winetricks`.

The awkward one is wine. Minesweeper X is a **32-bit** PE (machine `0x014c`, Visual Basic 6), so the host
needs i386 multiarch and a `win32` prefix. A 64-bit-only wine cannot load it, and the failure is a bare
`Bad EXE format`. On Debian or Ubuntu:

```
sudo dpkg --add-architecture i386
sudo apt update
sudo apt install wine wine32:i386 xvfb x11vnc x11-utils xdotool winetricks
```

## The game

[Minesweeper X](https://minesweepergame.com/download/minesweeper-x.zip) — the competition build, with
timing and replay extras. `game/Minesweeper X.exe` is committed; it is 68 KB and it is the thing being
run rather than state produced by running it.

| | |
| --- | --- |
| zip sha256 | `21089193924919ef876a5b464f06bed9cc149867c51e40c259288ebe623014f0` |
| exe sha256 | `e414c207adaa14999b0464c3d0a701f20ed11282d5ed0f84b27b62d25389f661` |

The download needs a browser `User-Agent`; the site answers `403` to curl's default.

## Where its state lives

`DATA_PATH/minesweeper/` — never in this directory, which `plugins:update` will `git pull` over.

- `prefix/` — the wine prefix, ~600 MB, built on first `POST /start`. Deleting it is still the standard fix
  for a wedged wine and the next start rebuilds it — but it now takes the replays with it, see below.
- `prefix/drive_c/Minesweeper/` — where the game RUNS from, and where its replays land. The executable is
  copied here on every start; `C:` is the only drive the prefix has, so this is the only directory the game
  has a writable path to. Launched from the plugin checkout instead, its own path came back as
  `\\?\unix\home\…` and finishing a game raised `Run-time error '76': Path not found` while it tried to
  auto-save the recording.
- `run/` — pid state, logs, and `vnc.sock`. **Mode 0700, and that is load-bearing.**

## Two gaps, both from having no window manager

Worth knowing before you conclude something is broken. Neither is hard to fix; neither is fixed.

**Some dialogs cannot be closed.** There is no window manager, so no window has a title bar. A dialog with
its own OK button is fine — the run-time error box is — but Extras → Auto Options has neither an OK button
nor a Cancel, and its only exit was the title bar. Restarting the sidecar clears it.

**Keys go to the canvas, and only while it has focus.** It takes focus on mousedown — the gesture you use
to play — and `keysymFor` in `rfb.ts` maps `KeyboardEvent.key` to an X11 keysym. Anything with a modifier,
and anything unmapped, is left to the browser rather than swallowed: this is one panel on a dashboard, not
a full-screen viewer, so a global key trap would be the wrong shape.

Keys reach wine perfectly well without a window manager — verified by pressing F2 on the display and
watching the board reset. The Auto Options dialog ignoring Escape is that VB6 form having no Cancel button,
which is a different thing from keys not arriving.

## Two things worth knowing before you change anything

**x11vnc has no password, and that is correct — but only because it also has no port.** It binds a unix
socket inside `run/`, mode 0700. The kernel refuses every other account before x11vnc is asked anything,
so a password would be a second lock on a door only one person can reach. The version this replaced bound
`127.0.0.1:5907` with `-nopw`, which is a different claim entirely — every local account could open it and
take the display.

**`-unixsock` does not remove the TCP listener, and the first alpha shipped believing it did.** It adds a
unix socket beside the port; x11vnc was on `0.0.0.0:5900` and `[::]:5900` with no password, reachable from
the whole tailnet and the whole LAN, under a comment saying there was no port at all. Three flags close it
and each one earns its place: `-rfbport 0` for IPv4, `-rfbportv6 0` for IPv6 — `-rfbport 0` alone leaves
`[::]:5900` up — and `-noipv6` for outgoing sockets.

The check that matters is `ss -lntp` against the **running** process. Reading the arguments cannot show a
listener that exists because a flag is missing, and running the same arguments by hand did not reproduce
it either.

**The game is centred on a fixed stage, and the whole stage is what you see.** The framebuffer is 512x352
whatever the difficulty, `sidecar/session.ts` keeps the window in the middle of it, and the panel draws the
framebuffer entire — scaled to fit, never cropped. So changing difficulty moves the board rather than
resizing the panel, and the surround is teal (`-solid`) rather than the root's black.

**The stage is small because the panel scales it by whole numbers.** Pixel art at a fractional scale gets
uneven cells — some three screen pixels wide, their neighbours two — which reads as "not quite right"
rather than as blur, and `image-rendering: pixelated` does not help because unevenness is not blur. So the
panel snaps the scale, in DEVICE pixels, to whole numbers below 2x and QUARTER steps above it. Quarters are
safe because the unit that has to stay regular is the CELL: the board is a 16px grid, so at 2.25x a cell is
exactly 36 screen pixels, as even as at 2x, and only sub-cell pixels alternate. They are quarters rather
than halves because coarse steps overshoot — with halves this jumped 2x to 2.5x, too small to too large
with nothing in between.

Two things the scale has to know about that are easy to miss. `devicePixelRatio` is not the whole story:
the panel header has its own CSS `zoom`, so the effective ratio is `devicePixelRatio × zoom`, read as
`getBoundingClientRect().width / offsetWidth`. And the stage is fitted into the box MINUS a margin, because
filling the panel edge to edge is most of what "too large" looks like.

That makes the size QUANTISED, which is the thing to understand before changing the stage: at 3x the game
is the same width whether the stage is 512 or 560. Trimming the surround is worth nothing on its own — it
only helps when it crosses a step. 512x352 is expert (504x342) plus four pixels a side, and there is no
room left: intermediate is 342 tall too. A custom board bigger than that is clipped at the right and bottom
rather than shrunk, with the menu bar kept reachable, and the Auto Options dialog needs a 554-wide stage to
fit whole from beginner.

It used to park the window at the origin and have the client crop to the window's size, polled every four
seconds. That resized the panel under the player, and it was off by the 3x29 wine puts between the root
origin and the window — a black strip along the top and a row of cut-off cells along the bottom, worst on
expert. `GET /status` still reports the window geometry; nothing consumes it now, it is a diagnostic.

**The wine prefix is confined to `C:` on every start.** A fresh prefix maps the whole filesystem to `Z:`
and symlinks the profile into the real home, and Minesweeper X has Open and Save dialogs for its replays.
That is why this was an ungrantable `execution` capability in the platform. `sidecar/prefix.ts` closes it
instead, which is what makes the plugin's permission safe to grant. Wine restores `z:` whenever it updates
a prefix, so the confinement is re-asserted rather than done once.

## Contract

```
GET  /api/minesweeper/status     { installed, running, window, error? }
POST /api/minesweeper/start      idempotent; builds the prefix on a cold install (minutes)
POST /api/minesweeper/stop
     /api/plugin-ws/minesweeper  the display, as RFB
```

## Where this came from

Built first as a standalone directory, `officer-dev/wine-minesweeper`, and folded in here when it became a
plugin. Two things from that work are worth keeping, because both are judgement calls somebody will
otherwise make again from scratch.

**Wine came from Ubuntu noble, not the WineHQ repository.** The distribution package is older — 9.0 — and
that is fine for a 2017 VB6 application. The alternative was adding a third-party apt source, with its key
and its update cadence, to a machine that runs a bitcoin wallet and a mail store, for a game of Minesweeper.
If a future version genuinely needs newer wine, that trade is worth revisiting; until then it is not.

**Enabling i386 pulled four krb5 libraries forward** within noble-updates. That was checked before
installing rather than after: nothing moved near libc, systemd, openssl or postgres. Worth re-checking on
any host where `dpkg --add-architecture i386` is new, since it is the one step here that changes how the
whole machine resolves packages and is never undone by uninstalling the plugin.

### The original verification baseline

From the standalone build, on Ubuntu noble with wine 9.0. Useful as a comparison when something feels wrong
rather than as a test to run:

- The game launches in about a second and draws the classic beginner board at **152x214**.
- A synthetic `xdotool` click opens a region and starts the timer — so **input reaches the game**, which is
  the part that matters for a playable stream and the part a screenshot cannot tell you.
- x11vnc completes an **RFB 003.008** handshake and reports an 800x600 32bpp framebuffer.
- Cold start, display through to game window, in under two seconds. That excludes building the prefix,
  which happens once and takes minutes.

The shell prototype that ran all this (`bin/session.sh`) is not kept. Everything it knew — waiting for a
usable display rather than a live pid, parking the window at the origin, and clearing the whole wine
process family on stop — is in `sidecar/session.ts`, with the reasoning attached to the code that depends
on it.