Commit Graph
16 Commits
Author SHA1 Message Date
LGUG2Z 5eaa613f50 feat(wm): configuration in komorebi.json
The daemon takes its settings from a komorebi.json: the file --config names, or
the one in the config home ($KOMOREBI_CONFIG_HOME, else ~/.config/komorebi).
Without a file it runs on its defaults, as before.

StaticConfig reads the file in three steps, because the monitors are known only
after the backend has been asked. preload makes the window manager and applies
the settings that are process-wide, postload gives each monitor and workspace
the entry of its place (by the index display_index_preferences gives a monitor's
serial number id, else in order), and main asks KWin for a desktop for each
workspace the file lists. A watcher on the file sends the daemon a
ReloadStaticConfiguration about two seconds after it changes, whether an editor
wrote the file in place or renamed a new one over it, and a file that does not
parse changes nothing.

A workspace can change its layout, its work area offset and its layout options
with the number of its containers, from the file or with komorebic
(workspace-layout-rule, its named form and the two that clear), and
layout_defaults gives every workspace of a layout the options it sets none of.
One file is meant to serve every platform, so a key that does nothing on Plasma
is accepted and ignored. config_parity checks the example and the files of other
platforms; the keys of features that are not in yet are listed there, and the
test fails when a list names a key that is read.

The file also sets what the stacks, the float override, the floating layer and
monocle set while the daemon runs: window_container_behaviour, with its rules by
container count in a workspace, float_override, float_override_placement,
floating_layer_behaviour (for a monitor and a workspace too),
floating_layer_placement and monocle_focus_behaviour. Their features come before
this commit, but a file to put the keys in does not, so they are part of this
one.

komorebic gains configuration, generate-static-config and start --config. The
NixOS module gets configFile, which the unit gives the daemon as --config.
2026-10-28 07:20:37 -07:00
LGUG2Z 05de20749b feat(wm): maximize
A window could be given the work area only as a tile of the layout, which has
padding around it. `komorebic toggle-maximize` has KWin maximize the focused
window instead: it gets the work area of its monitor with the panels left alone,
and it leaves the layout, so that it is in no container. Toggled again, the
window is restored, put in a container of its own at the index it was taken
from, and the workspace is tiled again.

The window is kept in the workspace as its maximized window, with the index it
goes back to, and the state shows both. While it is maximized the workspace asks
KWin to maximize it again on every tiling, and does not move the containers
behind it. The messages that are about the tiles (move, stack, resize, promote,
preselect, lock, float, monocle, and the ones that send a container to another
monitor or workspace) are dropped before they are handled, since there is no
tile to act on. Focusing in a direction finds no container on any side of it, so
the focus goes to the monitor on that side, where a maximized window or a
monocle is given the focus whole. Showing the workspace again restores the
maximized window and focuses it ahead of the containers' windows. A window in
monocle that is maximized leaves the monocle, and one that closes takes the
maximize with it. Backend gets a maximize command, which does nothing unless a
backend implements it; the fake desktop and the KWin backend do, and the bridge
carries it out with KWin's own `setMaximize`. A maximize also makes the bridge
forget the position it was last asked to put the window at, which it would
otherwise set again on the work area's size when the window's frame changed
within a second of a tiling.

komorebi/tests/maximize.rs and maximize_commands.rs drive it against the fake
desktop, with one monitor and with two. The bridge's tests and the backend's
tests read the maximize command from the same fixture, so that what one sends is
what the other carries out. vm-features is a new session suite that reads
screenshots: the first thing it checks is that the maximized window fills the
work area, is the one on top, and goes back to its tile; the vm-commands sweep
runs the new command.
2026-10-28 07:20:37 -07:00
LGUG2Z 0d21dd332c feat(wm): monocle
A workspace could show its windows only side by side. Monocle gives one
container the whole work area: the focused container is taken out of the
workspace's containers, so the layout gives no container a tile, and the next
tiling puts its window on the work area less the padding. Turning it off puts
the container back at the index it came from, and the tiles come back as they
were resized: the container keeps its resize adjustment, and the workspace does
not shorten the list of adjustments while a monocle is on.

The windows of the other containers are hidden on the parking desktop, as the
windows behind the front one of a stack are, and the front window of each is
shown again when the monocle is turned off or the window in monocle closes. A
stack in monocle stays a stack.

`komorebic toggle-monocle` turns it on and off. What focusing in a direction
does meanwhile is set with `monocle-focus-behaviour` or switched with
`toggle-monocle-focus-behaviour`: with `cycle` the monocle goes to the previous
or the next container, with `no-op`, the default, no container is on any side
and the focus falls through to the monitor on that side, where the monocle
window of its workspace, if it has one, is given the focus, and the command
fails where there is no monitor. A container that is moved to a monitor or sent
to a workspace in monocle turns that monocle off first. `cycle-focus` always
carries the monocle along. Giving the focus to another window gives it back to
the monocle window, so that it stays in front. `move` and `cycle-move` are
refused and `toggle-float` is ignored while a window is in monocle, since the
focused container is not the window in front. The monocle container is in the
state, with the index it goes back to, and a window in it that closes takes the
monocle with it.

komorebi/tests/monocle.rs drives it against the fake desktop, with one monitor
and with two. vm-core-e2e checks in a real KWin that the focused window fills
the work area, that the state has the monocle container, that toggling back
restores the tile, that the cycle behavior gives another window the work area,
and that the windows behind a monocle are parked, which a clean stop and the
next start after a crash put right; vm-stacks checks a monocle over a stack; the
vm-commands sweep runs the new commands.
2026-10-28 07:20:37 -07:00
LGUG2Z 331db681e2 feat(wm): stack out of sight on a parking desktop
A container has one tile, so the windows of a stack that are not in front have
to be out of sight. KWin has nothing a script can set to hide a window except a
virtual desktop nobody looks at, which the first spike measured to cost no focus
change where minimizing a window cost two. Backend::hide takes a window out of
sight and Backend::restore brings it back; the KWin backend parks the window on
a desktop named komorebi-park, which the table keeps out of the workspaces, and
remembers where each hidden window came from so that it is still on its
workspace.

KWin saves a desktop in kwinrc as soon as it is made, so komorebi removes the
parking desktop when it stops, after the windows are back, and the first
snapshot of the next run finds one a killed run left, sends its windows home and
removes it. The windows komorebi hid are recorded, so that a minimize the
compositor reports for one is not mistaken for the user's.

komorebic stack, unstack, stack-all and unstack-all stack and unstack windows.
The window container behavior and the float override decide whether a window
that opens joins the focused container or floats, for every workspace or for
one. vm-stacks stacks windows in a headless KWin, shows a workspace and goes
back, stops, and kills the daemon with a window parked.
2026-10-28 07:20:37 -07:00
LGUG2Z 62e37e44cf feat(kwin): workspaces are KWin's own desktops
komorebi's workspaces exist on Windows and macOS because neither has a virtual
desktop API: switching hides every window of the workspace being left. KWin has
virtual desktops, per output since 6.8, so here workspace i is KWin's desktop i
on every monitor, and each monitor shows one. KWin shows, hides and focuses the
windows of a desktop; komorebi asks for a switch, puts a window on a desktop,
and follows what anything else does.

The Backend gets the workspace methods (ensure_workspaces, switch_workspace,
set_window_workspace, window_workspace, current_workspaces), and the fake its
desktops. The bridge reports the desktops, the desktop each output shows and a
window's desktops, and carries out output_desktop and desktop commands, typed
and tested with the fixtures like the rest. The table turns a switch or a move
komorebi did not make into a WorkspaceChange or a WorkspaceMove, and records its
own when it sends them, so that KWin's report of those raises nothing. The
window manager follows a switch with no command in reply
(adopt_workspace_change), puts windows on their desktops before a desktop is
shown (focusing a window first would take the monitor back), and loads the
windows open at startup onto the workspace of their desktop.

Per-output desktops are a kwinrc setting that is off by default, and
kwriteconfig6 was not on the PATH of the user service in a live session, so
komorebi edits kwinrc itself (kwin::kwinrc) and puts the user's value back when
it stops, also after a crash.

focus-workspace, move-to-workspace and send-to-workspace come with this commit,
since the tests of switching and moving, and vm-workspace-switch, need them; the
named and cycling workspace commands follow. vm-workspace-switch runs the daemon
against a real KWin; vm-kwin-contract checks what komorebi relies on from KWin's
per-output desktops, on a headless KWin with two outputs and no komorebi.
2026-10-28 07:20:37 -07:00
LGUG2Z 37b06993d2 feat(wm): tune layouts, and the scrolling layout
`komorebic layout-ratios --columns ... --rows ...` sets the share of the work
area the first columns and rows of the focused workspace's layout take, and
`scrolling-layout-columns N` how many columns of the scrolling layout are in
view. Both are layout options of the workspace, which komorebi-layouts reads.

The scrolling layout is a strip of columns that runs past the edges of the work
area, so its tiles are not clamped to it: the windows of the columns out of view
are off the screen. When a window of a scrolling workspace gets the focus, the
workspace is tiled after the focused container changed, which scrolls the strip
to it.

KWin moves a window anywhere, but keeps 100 pixels of a window it resizes on an
output once the client has drawn at the new size, which pulls the columns out of
view back onto the screen. The bridge remembers the position it was asked for,
for a second, and asks again for the position alone when KWin moved the window
elsewhere, three times at most.

komorebi-layouts compiles `Rect::percentage_within_horizontal_bounds` only with
its darwin feature, which this repository does not enable, so the workspace has
its own copy of it.

A new VM suite, vm-scrolling, after the spike's m2-scrolling script, checks in a
real KWin that the columns out of view stay where komorebi put them and that the
strip follows `komorebic focus`; vm-commands sweeps the two new commands.
2026-10-28 07:20:37 -07:00
LGUG2Z a86e2bdc63 build(nix): a NixOS module for komorebi
On NixOS, running komorebi should take one flake input and one module line. The
flake exports `services.komorebi` as nixosModules.default (and .komorebi). It
adds the flake's overlay, which gains komorebi-full, installs komorebi and
komorebic, and runs the daemon in every Plasma session as a systemd user unit,
wanted by plasma-workspace.target and ordered after plasma-core.target, which
Plasma orders after KWin. systemd starts a daemon that fails again; the exit
status of a SIGTERM (130) counts as success, so a stopped unit is not failed.
The unit's PATH is the one a terminal in the session has, instead of the few
store paths NixOS gives a unit.

The options are enable, package, logLevel and a read-only execStart, the command
line the unit runs. There is no configFile: the daemon reads no configuration
file yet, and an option that linked one would do nothing.

nixos-module-eval evaluates seven scenarios as real NixOS systems and checks
their assertions, the unit and execStart, with builtins.tryEval for the two that
must not evaluate. Nothing in it builds a Linux package, so it runs on a Mac as
well.

The VM nodes import the module, so every suite runs komorebi as the module
installs it. The headless node's komorebi@NAME runs execStart, which has
--log-level, so the nodes set logLevel to debug and the suites stop passing it;
latency, which times the daemon, keeps the default level. The session node
starts the module's unit at login; render-smoke turns it off, since a tiled
terminal would cover the desktop it looks at. A new fast suite, vm-module, logs
in to Plasma and checks that the unit runs the daemon with the module's log
level and PATH, that a window opened in the session is tiled, that a killed
daemon is started again, and that a stop is not a failure.

docs/installation.md covers NixOS first, and building from source on other
distributions. There is no binary cache: the Komorebi license does not allow
third parties to redistribute binaries.
2026-10-28 07:20:37 -07:00
LGUG2Z e2d757bbb0 feat(wm): subscribe to notifications
A program such as a status bar has to follow the window manager, and so far it
could only ask: komorebi on Windows and on macOS sends notifications for that.
The daemon now keeps subscribers, each a Unix socket in its data directory that
a program listens on, and after each event and each message it handles, it
connects to every subscriber and writes the event or the message with the state
after it.

A subscriber can ask to be sent only what changed the state; a window that is
shown and a new subscription are always sent, so a subscriber has the state as
soon as it subscribes. A subscriber that cannot be connected to is dropped with
its socket file and not tried again, and a stopping daemon closes an empty
connection to each one.

komorebic gains subscribe-socket and unsubscribe-socket, and komorebi-client
subscribe and subscribe_with_options, which bind the socket and subscribe. The
tests subscribe through real sockets against the fake desktop: a shown window is
sent with the state that has it, a subscriber that filters is not sent a
question that changed nothing, and one that is gone is dropped.
2026-10-28 07:20:37 -07:00
LGUG2Z 6f657e53e3 feat(cli): komorebic
The daemon answers on its socket, but a person has no way to write a message on
it. komorebic is that way: each subcommand that asks something of the daemon is
one message, sent with komorebi-client, and a question's answer is printed.
komorebic is a separate program because the daemon takes no input but its
socket, so a key binding, a script and a terminal all drive it the same way.

It has what the daemon can answer so far: state, monitor-information, query,
retile and stop. Around them, start runs the komorebi on the PATH in the
background and passes it what follows a --, such as --fake-backend to try it
without a compositor; log follows the daemon's log, which the daemon now writes
to a file a day in LOG_DIR as well as to stdout; data-directory shows where the
socket is; completions prints a shell completion script. The hidden docgen
writes each subcommand's help to docs/cli, in fences that name their language
and wrapped at 100 columns whatever the width of the terminal, so that the pages
are the same wherever they are generated; just docgen runs it.

The user guide starts here: docs/index.md for KDE Plasma, and a page on running
komorebi. tests/cli.rs runs each subcommand against a socket the test serves in
place of the daemon. In the VM tests the guests get komorebic next to the
daemon, and vm-core-e2e reads the daemon's state with it (the windows it
manages, the one it focuses, after KWin restarts too) and stops it with
komorebic stop, which unloads the bridge and removes the socket.

In the VM test library, Kde.state asks again, a second (times the scale) after
an empty answer or a failed command, up to 10 times. The daemon drops a query
when it cannot take hold of the window manager within a second, and komorebic
then prints an empty line and succeeds; komorebic itself gives the daemon a
second to answer and fails when that is not enough. A daemon busy with the first
windows does either on a machine that is loaded or slow, and a suite that polled
the state died on JSONDecodeError. An answer that is not JSON still fails at
once.
2026-10-28 07:20:37 -07:00
LGUG2Z 88aa78b874 feat(wm): a command socket and the first messages
Until now the daemon tiled what KWin reported and nothing else could reach it.
komorebi takes its orders on a socket, as it does on Windows and on macOS: it
handles no key itself, and whatever binds keys runs a command that writes a
message.

The daemon binds komorebi.sock in $XDG_RUNTIME_DIR/komorebi (DATA_DIR), reads
one JSON SocketMessage per line on a thread per connection, and handles each
message with the window manager locked, as the thread that handles events does.
The first messages are the ones the first komorebic needs: State (the window
manager as JSON, from state.rs), MonitorInformation, Query with a StateQuery,
Retile and Stop. A question is answered on the same connection, and the answer
ends when the daemon closes it. Stop unloads the bridge from KWin, removes the
socket and exits; so does a stop signal.

The socket is bound once the daemon is connected to KWin, so a komorebi that
cannot connect, such as a second one in the same session, which the bus refuses,
leaves the socket of the one that runs alone. With --fake-backend the daemon
answers on its socket with no compositor at all, which is how the tests run it.

komorebi-client is the other end: send_message, send_batch and send_query, and
the types the messages are made of. Its doctests serve the socket themselves,
tests/daemon.rs runs it against a window manager over the fake desktop, and
komorebi/tests/socket.rs runs the daemon binary from its start to a Stop.
2026-10-27 15:17:30 -07:00
LGUG2Z 4386003e30 feat(kwin): survive KWin restarting
KWin can go away under a running daemon while the session bus stays: it crashed,
or kwin_wayland --replace took its place. Its windows go with it, and so does
the bridge, which would have reported them closing; in the spikes the old
windows vanished without a single removed event. What the daemon does see is the
bus, so the thread that serves the connection watches NameOwnerChanged for
org.kde.KWin. When the name loses its owner, Table::compositor_lost marks every
window closed and returns a Destroy for each, so the window manager takes them
out of its layout, and their ids are not given out again. When the name has an
owner again, the daemon loads the bridge into the new KWin, trying for up to 15
seconds while KWin is not ready for it, and the bridge reports the new desktop
in a snapshot.

zbus does not end a held call when its caller leaves the bus, so the Poll of the
old bridge is still waiting when the new bridge calls, and it was woken first:
it took the commands for the new KWin and answered them to nobody.
vm-kwin-restart lost the tile of a window opened in the third KWin that way in
one run of three, and a recording of the bus showed the batch going to the old
bridge. A Poll held since before KWin last left the bus is answered with nothing
and passes its wake-up on to the next call, which a unit test holds.

The VM suite vm-kwin-restart (from the spike's spike7-resync) restarts the
headless KWin twice under a running daemon, through Kde.restart_kwin in the VM
library, and checks that the daemon sees KWin go, takes the old windows out of
its layout, loads the bridge into the new KWin, and tiles the windows that open
there.
2026-10-27 14:50:53 -07:00
LGUG2Z b463191d00 feat(kwin): move and focus windows through a held call
With the commands of the Backend trait carried out, the daemon tiles a real
KWin. A command looks up the UUID KWin knows the window by, is queued as JSON
for the bridge, and returns; the held Poll call is answered with the queue, one
millisecond after the first command, so that a retile reaches KWin as one batch.
The bridge sets the frame, activates, raises, minimizes, restores or closes the
window, and reports what it could not do. set_rect records the frame it asked
for in the table, so the window manager sees it at once, and the geometry event
that follows says what the client made of it.

A KWin script cannot move the pointer, so the pointer follows the focus through
KWin's own "Move Mouse to Focus" action, invoked over kglobalaccel once KWin
reports the window active.

The commands are typed in bridge.js, and the declarations of KWin's API let the
bridge set a window's frame, its minimized state and the active window, raise
and close it, and nothing else. The session the tests of both sides share grows
a second batch: the backend's tests check that set_rect, focus, raise, minimize,
unminimize and close send it, and the bridge's tests answer the bridge with it
and check what KWin is asked to do, down to the command for a window that has
closed, which comes back as failed. The bridge's tests also cover findWindow's
fallback to KWin's list, a frame set as a plain object, and a command KWin
throws on.

Three VM suites check it against a real KWin. vm-core-e2e (from the spike's
m2-e2e, the sections that need no komorebic) compares what the daemon asked for,
read from its debug log, with what KWin has, read with kdotool: three windows
inside the screen, not overlapping, sharing it, the same focused window on both
sides, and the same again after a minimize, a restore and a close.
vm-client-geometry (slow) has eight real clients answer the frames komorebi asks
for: Qt programs and xterm take them exactly, foot sizes itself to whole cells,
GTK 4 programs and Firefox keep to their minimum sizes. vm-latency (slow) times
retiles from a recording of the session bus: on HVF, from the daemon's answer to
the last frame KWin reports, p50 17.3 ms, p95 27.7 ms. vm-kwin-events no longer
checks that nothing moves. The VM library gives session commands the test user's
home and data directories rather than root's, which a GTK client was refused.

The bridge's second request for a position after a resize, which matters for
windows off the screen, comes with the scrolling layout.
2026-10-27 14:48:56 -07:00
LGUG2Z 15ec3c1274 feat(kwin): read the desktop through a script in KWin
KWin has no protocol that lets another process read or set the geometry of a
window, but its scripting API has both, and a signal for every change the window
manager follows. So the KWin backend is in two parts: bridge.js, a script the
daemon loads into KWin, which reports what KWin sees and holds no window manager
logic, and a D-Bus service in the daemon, org.komorebi.Bridge, which the script
calls with every event as a JSON string.

Every decision about what an event means is made by the table in kwin::state,
which is pure and is unit-tested with the JSON the script sends: which windows
may be managed, the ids komorebi gives KWin's windows, and the Show, Destroy,
FocusChange, Minimize and Restore events of the window manager. Events reach the
window manager in the order KWin raised them: the Event interface handles its
calls inline (zbus reordered them otherwise), and one channel and one thread,
window_manager_event_listener and listen_for_events, carry them on.

Commands go to the script as the answer to a Poll call that the script always
has open and the daemon holds until it has something to send: in the spikes this
was as fast as any other channel, and it makes one call every 10 seconds when
nothing happens. Here the only command is the cursor query. Every command of the
Backend trait is refused with "the KWin backend only reads the desktop", so the
daemon follows KWin and moves nothing.

The bridge is JavaScript that KWin runs as it is, and it gets types and tests
without a JavaScript build chain. tsc checks it as strict TypeScript through
JSDoc types of every message, against kwin-api.d.ts, a declaration of the part
of KWin's scripting API it uses, in which every property is read-only and
callDBus takes one string. bridge.test.js runs it under node --test against a
fake KWin in a node:vm context. The messages of a session are JSON fixtures that
both sides' tests read: the bridge's tests check that it sends those events, and
the table's and the backend's tests read the same events and commands, so a
message cannot change on one side alone. just check-js and the flake's
komorebi-bridge-js check run both, with nodejs and typescript from nixpkgs;
there is no package.json.

The daemon now connects to KWin by default, and --fake-backend is hidden. The VM
suite vm-kwin-events starts it against a headless KWin and checks, from its
debug log, that the script loads and reports what was open, that KWin's signals
arrive as events and in order, and that stopping the daemon unloads the script.
docs/dev/PLATFORM.md starts with what komorebi needs from Plasma.

zbus 5's zvariant, zbus_names and zvariant_derive are flagged unmaintained,
since their code moved into zbus 6; deny.toml ignores the three advisories.
2026-10-27 14:46:35 -07:00
LGUG2Z 02231d232c feat(wm): tile what the backend reports
With the model in place, the window manager can do its job: load the desktop
from the backend, tile it, and keep it tiled as the compositor reports what
happens to windows. The events are the Windows implementation's, each about one
window and carrying it: a window is shown, destroyed, given the focus, minimized
or restored. A new window gets a container of its own after the focused one, a
closed one leaves whichever workspace has it, a window the user minimizes is out
of the layout until it is restored, and every event ends with the workspace in
front tiled again.

At startup every monitor is loaded, and every open window that is normal, alive
and not minimized goes on the monitor its middle is on. An index from each
managed window to its monitor and workspace is rebuilt around every event, so
that the first event komorebi sees can be the close of a window it picked up at
startup.

Whether a window is managed is, for now, only whether the compositor calls it a
normal window and it is alive; the rules that ignore, manage or float
applications come later. When a window closes, komorebi leaves the choice of the
next focus to KWin unless KWin focuses nothing, so the two do not fight.

The daemon runs this against a backend chosen on the command line.
--fake-backend, an in-memory desktop with one monitor, is the only one, and
without it komorebi exits with a usage error instead of pretending to manage a
desktop it cannot reach.
2026-10-27 14:07:28 -07:00
LGUG2Z c0345eb0e9 feat(wm): windows, containers, workspaces and monitors
The window manager tiles a tree of four levels: monitors, each with a ring of
workspaces, each with a ring of containers, each with a ring of windows. It is
the model komorebi has on Windows and macOS, and the first thing the daemon
keeps that the backend does not give it.

A window is a Copy handle that carries the compositor's id and asks the backend
for everything else, so moving one is a call on the handle and needs no context
passed to it. A workspace tiles itself: the layout gives each container a tile
of the work area its monitor hands it, less the offset and the padding, and
every window of the container is asked to move there. A locked container keeps
its index because the workspace inserts, removes and swaps its containers
through LockableSequence.

This is tiling only. Stacks, monocle, maximize, the floating layer, resize
adjustments, placement rules and the link between workspaces and KWin's desktops
come with the commits that use them. impl_ring_elements!, which gives every
holder of a ring the same accessors, lands here with its first users.
2026-10-27 14:07:28 -07:00
LGUG2Z ed6a8e96c3 feat(backend): reach the compositor through one trait
The window manager decides where every window goes, and asks a compositor to put
it there. If it asked KWin directly, every test of its logic would have to boot
a virtual machine, so everything it needs from the desktop goes through one
trait, `Backend`: queries for windows, monitors, the focus and the pointer, and
commands to move, focus, raise, minimize and close a window and to put the
pointer somewhere. A real backend answers from a table that compositor events
keep up to date, so a query never waits for the compositor; a command returns
once it has been accepted, not once the client has acted.

`FakeBackend` is the other implementation: an in-memory desktop that does what
it is told, at once and exactly, and records every command so that a test can
assert on what the window manager asked for. A test can also do what a user does
without the window manager asking: move a window, close it, change the focus,
turn a window into a dialog. It is strict where KWin is (a command about a
window that is gone is an error) and clamps where a GTK4 client does (a minimum
size). `with_backend` overrides the process-wide backend for the current thread
only and puts the previous one back on drop, also on a panic, which is what
keeps one test's desktop out of the next.

The module is the first to have `#![deny(missing_docs)]`. The contract (what
must be implemented, that a backend is `Send + Sync`) is proved by two
`compile_fail` examples with their error codes, and the rules nothing checks are
listed as such.

docs/dev/ARCHITECTURE.md describes the trait, its roles and the layer that
enforces each rule, and docs/dev/DESIGN.md has the first decisions with their
reasons. Both grow with the code.
2026-10-27 14:07:28 -07:00