cursor-lang/README.md

# cursor-lang

[Русская версия](README.RU.md)

The WPF application displays the keyboard layout at the cursor.

## Cloning

Binary assets — the exe icon and the MSIX logos — are stored in Git LFS, so
[git-lfs](https://git-lfs.com) has to be installed before cloning:

```powershell
git lfs install
git clone git@git.alrakis.kz:alrakis/cursor-lang.git
```

Cloning without it succeeds but leaves text pointer files in place of the
images, and the build then fails on an unreadable icon. An existing clone is
repaired with `git lfs install` followed by `git lfs pull`.

## Running it while working on it

```powershell
dotnet run --project CursorLang.Agent
```

That is the whole application, not just the background half: building the agent puts
the settings window next to it, because that is where the agent looks for it — the
tray menu starts it by path, and an installation has the two in one folder. Build the
agent alone and the Settings item would silently do nothing.

Rider and Visual Studio pick the launch profiles up from
`CursorLang.Agent/Properties/launchSettings.json` and
`CursorLang.Settings/Properties/launchSettings.json`, so the run configuration
dropdown offers three:

| Profile | What it does |
|---|---|
| `Agent` | The user's launch: tray icon and the settings window straight away |
| `Agent (started by Windows)` | Adds `--startup`: tray only, no window — the sign-in case |
| `Settings` | The settings window on its own, with no agent behind it |

Both halves read `%APPDATA%\CursorLang\settings.json`, the same file the installed
application uses — there is one code path resolving it and both call it. Debugging
therefore edits the real settings; that is deliberate, since watching the agent pick
up a change made in the window is most of what there is to watch.

To step through both at once, turn on attaching to child processes in the debugger:
the settings window is started by the agent as a separate process, and without that
the debugger stays with the agent.

## Administrator rights

The app runs as the ordinary user. Elevation was dropped so that the app can be
published in the Microsoft Store: MSIX packages always run in the context of the
signed-in user, and Store policy rejects apps that need administrator rights for
any part of their functionality.

The cost is the optional Caps Lock hotkey. While a window of a higher integrity
level holds the focus — Task Manager, Registry Editor, UAC prompts — Windows
neither delivers keystrokes to the low-level hook nor accepts the layout change
request, so the hotkey does nothing there. Reading the layout of a foreign window
is not restricted, so the tooltip itself keeps working everywhere.

## Two processes

The app is two executables sharing one folder.

`CursorLang.exe` is the agent: the keyboard hook, the layout polling, the tooltip
and the tray icon. It is what Windows starts at sign-in and what sits in the tray
all day, so it is built without WPF — a background process that carries the
rendering stack costs around a hundred megabytes for a tooltip it draws with Win32
in eight. It holds under 9 MB instead.

`CursorLang.Settings.exe` is the settings window, and nothing else. The agent
starts it from the tray menu; closing the window ends the process, and the memory
WPF took goes back to the system. The price is a cold start of half a second or so
the next time the window is asked for.

`CursorLang.Core.dll` is what both hold in common: the models, the settings file,
the layout tracking, the updates. No UI, and it must stay that way — whatever lands
there lands in the background process.

The connection between the two is `settings.json` and nothing else. The window
writes it — whole, into a temporary file moved into place in one step — and then
posts a registered window message to the agent, which re-reads. The message carries
no data: sending the changed values along would make the file stop being the only
source of truth. An agent that is not running is a normal case — the window works the
same. Nobody watches the file: it has one writer, and that writer speaks up.

## The tray

The settings window is a guest on the screen rather than the app itself: it shows
up after the installation and whenever the icon or its menu is asked for. Both
buttons in its title bar mean what they say — the window closes and its process
ends. The way out of the app itself is the Exit item of the tray menu.

The menu of the icon is a system one, drawn by Windows. Its captions still follow
the language chosen in the settings, but the theme no longer reaches it: a WPF
menu would mean the whole rendering stack in the background process, which is the
one thing that process is built to avoid.

Started by Windows itself, the app shows no window at all and goes straight to the
tray — the user asked for it to be there when they sign in, not for a window to
greet them every morning. The two builds tell such a launch apart differently: the
registry entry of an unpacked build carries the `--startup` argument, while a
package has no say in its command line, and Windows is asked about the activation
instead.

Should Windows refuse the icon — there is no notification area in a session without
a desktop — the agent opens the settings window whatever the launch was. The
alternative would be an app the user can neither see nor quit.

## Startup

Startup is switched on from the app's settings by whichever means the build has.
A package declares it in the manifest as a `windows.startupTask`. A build unpacked
into a folder registers itself the way desktop programs always have — under
`HKCU\Software\Microsoft\Windows\CurrentVersion\Run`, which needs no administrator
rights. The command names `CursorLang.exe` — the agent, not the settings window
the checkbox was clicked in — and ends with `--startup`: that is how the agent
tells a launch of Windows' own doing from a launch by the user.

Either way Windows lists the app in Settings — Apps — Startup; if the user turns
it off there, the app can no longer turn it back on and says so instead of
silently failing. The registry entry stays where it is in that case: Windows keeps
the user's verdict apart from it, under `StartupApproved`, and the app obeys it.

## Settings

Where `settings.json` lives depends on how the app was installed. A separate
install keeps it in `%APPDATA%\CursorLang`. The packaged build keeps it in the
package's own data folder, which Windows removes together with the app — Store
apps are expected to leave nothing behind.

On its first run the packaged build picks up the settings left by a separate
install and copies them over. The original file stays where it is: both builds
may be installed side by side, and the app has no business deleting settings it
does not own.

Everything about the popup belongs to a placement mode rather than to the app, and
the file keeps a section per mode — `AtCursor`, `AtCaret` and `FixedPoint`. Each of
them holds the side, the offset, the font size, the opacity and both colours. The
popup next to the caret sits inside a text being read and is wanted small and quiet;
the one in the corner of the monitor is looked for on purpose and is wanted large. A
look shared by the modes meant setting it up again after every switch, so the settings
window shows the look of the mode chosen above it and writes into that mode alone.

What the side means differs by mode, and each of them has a type saying so. Next to
the cursor it is any of the six corners and sides. Next to the caret it is left or
right and nothing else — above or below the caret is exactly where the next line of
the text is, so the popup would cover what is being read. For the fixed point it is a
place on the monitor, and the offset is the distance from its edge: in the middle
there is no edge to stand off from, so choosing the middle puts the offset back to
zero and the settings window shows it greyed out. It stays in place rather than
leaving the section — a row that comes and goes would move everything below it on
every switch of the place.

Which mode the look belongs to is explained in a tooltip next to the mode itself
rather than by a line of text in the section: the sliders below show other numbers
after a switch of the mode, and that is a question asked once.

## Updates

The check runs when the settings window is opened, not when the machine is
switched on: the background half no longer goes to the network at all, and there
would be nothing in it to show the answer. The setting in the window says as much.

The app looks for new versions among the releases of its own repository. A
release counts when its tag is a plain version — `v1.2.3` or `1.2.3` — and an
MSIX package is attached to it. A tag with anything else in it, `v1.2.3-beta`
among them, is passed over: a pre-release version is asked for on purpose, not
offered by the app.

Out of the attached files the `.msixbundle` is preferred — it carries both
architectures. Failing that, the package whose name holds the architecture of
this machine is taken: `CursorLang-1.2.3.0-x64.msix`. Those are the names
`build-msix.ps1` produces, so a release is made by attaching what it built.

The package is downloaded to the temp folder and handed to the Windows app
installer: it shows the publisher, asks for a confirmation and replaces the
installed version. Windows checks the signature, so the package attached to a
release has to be signed — an unsigned one installs nowhere but a machine in
developer mode. The running app keeps working off the old files until it is
restarted.

An app installed from the Store has no updates section at all: the Store
updates it, and a package from the side is something Windows would not accept
over it anyway.

The app asks about releases every time the settings window appears, and the
answer stays in the section as it is — an unreachable network included. Opening
that window is a deliberate act, rare enough for a request to cost nothing, so
nothing is remembered between openings and there is nothing to turn off. The
button next to the version asks the same question again on demand.

Where the releases are looked for is set in `UpdateOptions` — the repository
belongs to whoever publishes the app, not to the user, so the values live in the
build rather than in `settings.json`:

```csharp
services.AddSingleton(new UpdateOptions
{
    ServiceUri = new Uri("https://git.alrakis.kz/"),   // the Gitea server itself
    Project = "alrakis/cursor-lang",
});
```

The releases come from Gitea, and its API sits on the server itself: the address
is the one the repository is opened at in a browser, and the app asks
`/api/v1/repos/{owner}/{repo}/releases` under it.

A closed repository needs a token. It is read from the `CURSORLANG_UPDATE_TOKEN`
environment variable rather than kept in the source: a secret built into the app
is a secret handed to everyone who got the app.

## Tests

```powershell
dotnet test
```

There is a suite per project — `CursorLang.Core.Tests`, `CursorLang.Agent.Tests`
and `CursorLang.Settings.Tests` — all on xUnit, with the fakes and the helpers in a
library of their own, `CursorLang.Tests.Shared`. That library knows nothing about
xUnit: the one thing that wanted an assertion says so with an exception instead.
Core's suite carries no WPF reference, which is a check in itself: anything that
would drag WPF into the background process fails to compile there.

Half of the app — windows, timers, the keyboard hook — only works on an STA thread
with a message loop, so the tests keep one such thread for the whole run and drive
everything through it. For Core and the agent that thread runs a plain Win32 loop
(`CursorLang.Tests.Shared/Pump.cs`); the settings window gets a WPF dispatcher
instead.

A few checks need a real foreground window: the caret position and the layout
switch request are only observable there. Windows does not always grant the
right to bring a window forward, and those checks report themselves as skipped
rather than as failures — there is nothing to verify without a foreground
window. The end-to-end checks start the built application as a separate process
and skip themselves if the app is already running: interfering with someone
else's running instance is not their business.

Coverage is collected with:

```powershell
dotnet test --collect:"XPlat Code Coverage" --settings coverage.runsettings
```

What stays uncovered is what a test process cannot reach: the code paths that
require an MSIX package identity — `StartupTask` and the package data folder —
and the composition roots — `App.xaml.cs` and `Agent.cs` — which are exercised
end-to-end instead. One of those end-to-end checks reads the module list of the
running agent and fails if any part of the WPF renderer is in it.

## Continuous integration

The pipelines live in `.gitea/workflows` and run on Gitea Actions. A pull
request into `master` is built and tested; a tag of the form `v1.2.3` is built,
tested, packed into an MSIX and published as a release with the packages
attached. The version is taken from the tag alone — a tag shaped any other way
stops the run right at the start. The package version ends up as `1.2.3.0`: the
Store takes four numbers and keeps the last one for itself, so the tag has no
say in it.

Both pipelines ask for a Windows runner labelled `windows-x64` with the .NET 10
SDK and git-lfs on it. The checkout pulls LFS files: without them the icon is a
text pointer and the build fails on it. The runner is better off working in an
interactive desktop session: the tests raise real windows, and the checks that
need a desktop of their own — the end-to-end ones, and those that ask for the
foreground window or the caret — skip themselves on a runner that lives as a
service in session 0, where there is no desktop to show a window on.

The package the release carries goes to Partner Center as it is. The identity
comes from repository variables and falls back to the defaults of the script when
unset: `MSIX_IDENTITY_NAME`, `MSIX_PUBLISHER` and `MSIX_PUBLISHER_DISPLAY_NAME`.

## Building the MSIX package

Neither Visual Studio nor the Windows SDK is required — `makeappx` comes from a
NuGet package. The full publishing procedure — from opening a developer account
to submitting for certification — is written up in
[Packaging/PUBLISHING.RU.md](Packaging/PUBLISHING.RU.md) (Russian only).

```powershell
# One-off: draw the logos and the exe icon (already committed, rerun after edits)
powershell -File Packaging\New-Assets.ps1

# A check on your own machine: your architecture alone
powershell -File Packaging\build-msix.ps1 -Architectures x64

# For Partner Center — the identity is the one reserved there
powershell -File Packaging\build-msix.ps1 -Version 1.0.1.0 `
    -IdentityName 12345AleksandrNeychev.CursorLang -Publisher "CN=ABCD1234-..."
```

The result is `artifacts\packages\CursorLang-<version>.msixbundle` covering x64
and arm64; next to it lie the packages of single architectures. Upload the bundle
to Partner Center as it is.

The app ships with its own copy of .NET: Windows does not include .NET 10, and
MSIX cannot install a runtime as a package dependency.

To see the package working on this machine, build it with `-Install`:

```powershell
pwsh -File Packaging\build-msix.ps1 -Architectures x64 -Install
```

The application then shows up in the Start menu like any installed one. What
gets registered is the layout the package is made of rather than the package
file, so no signature is needed — only Developer Mode. The flip side is that the
application runs straight out of `artifacts\layout`, and a rebuild would pull
the files out from under it; the script removes such a registration before it
wipes the folder, whether or not `-Install` was asked for. A copy installed from
the Store answers to the same name and is left alone.

To remove it by hand:

```powershell
Remove-AppxPackage (Get-AppxPackage -Name AleksandrNeychev.CursorLang).PackageFullName
```