Feature and support matrix

What works on which backend. Honest and narrow claims.

For the long-form status write-up, see Feature status and limitations.

Backend summary

Backend	Mode	Tested
`headless`	Deterministic in-process runtime, no display	Heavily tested (unit + integration)
`winit`	Nested compositor in a window	Heavily tested (unit + live smoke)
`udev`	Standalone tty/DRM compositor	Tested (unit + virt harness), still experimental

Feature matrix

Feature	headless	winit	udev/tty
Canvas / viewport logic	✅	✅	✅
Focus stack	✅	✅	✅
Window model + rules	✅	✅	✅
Placement fallback	✅	✅	✅
Move / resize commands	✅	✅	✅
Key bindings	✅	✅	✅
Lua config loading	✅	✅	✅
Lua hooks (headless)	✅	—	—
Lua hooks (live)	—	✅	✅
Runtime snapshot (IPC)	✅	✅	✅
Interactive move/resize	—	✅	✅
Gesture hooks	—	✅	✅
Draw hooks	—	✅	✅
Pointer zoom (Super+scroll)	—	✅	✅
Middle-click pan	—	✅	✅
Trackpad swipe/pinch nav	—	✅	✅
XDG shell (xdg-toplevel)	—	✅	✅
XDG popups	—	✅	✅
Layer-shell (wlr-layer-shell)	—	✅	⚠️ maps, not rendered
XDG decoration negotiation	—	✅	✅
Output management (wlr-output-management)	—	⚠️ position-only	⚠️ position-only
XWayland	—	✅	✅
Clipboard / data device	—	✅	✅
Primary selection	—	✅	✅
DnD (compositor-originated)	—	❌	❌
Session lock	—	✅	✅
Idle inhibit	—	✅	✅
IPC screenshot	—	✅ (PPM)	❌
Multi-output	—	✅	⚠️ narrow contract
Output hotplug	—	⚠️ basic	⚠️ basic
VT switching	—	—	✅
TTY session state machine	—	—	✅
Tap-to-click / natural scroll	—	—	✅

Legend

✅ — proven, tested, claimed
⚠️ — partially supported, narrow scope, or backend-qualified (read the caveats)
❌ — not yet supported
— — not applicable

Feature caveats (backend-qualified)

Layer-shell on tty

Layer-shell clients map and participate in session artifacts (event log, IPC snapshots), but the tty (udev) render path does not yet visually render wlr-layer-shell surfaces. The panel probe proves protocol/lifecycle correctness, not visual rendering. The winit backend renders layer-shell surfaces normally.

Output management

Only position changes and head enable/disable are currently supported. Mode, custom mode, transform, and scale changes are rejected. Multi-output behavior follows a narrow explicit contract; broad hotplug coverage is still pending.

TTY multi-output

Startup with multiple outputs builds a deterministic layout from tty.output_layout. Pointer crossing and output lookup follow that layout. Output removal prunes stale state. Broad real-hardware multi-output confidence is still pending.

Pointer zoom / middle-click pan / gesture nav

Rust directly applies built-in canvas behavior. Lua config can enable/disable via boolean flags but cannot repurpose the input for other behaviors. A known design limitation.