A client can now request which compositor backend the host drives its virtual
output on (gamescope/KWin/Mutter/wlroots). The host honors the request if that
backend is available, else falls back to auto-detect and reports the resolved
choice back — wire-compatible both directions (no ABI bump).
Protocol (punktfunk-core):
- New CompositorPref (config.rs): Auto|Kwin|Wlroots|Mutter|Gamescope with
u8/name mappings. Appended as one optional byte to Hello (client preference)
and Welcome (host's resolved choice). Both decoders already tolerate trailing
bytes, so old↔new interop is preserved — ABI_VERSION stays 2. Round-trip +
back-compat (truncated-message) tests.
- C ABI: punktfunk_connect_ex(compositor) + PUNKTFUNK_COMPOSITOR_* constants;
punktfunk_connect delegates with AUTO, so the existing symbol is unchanged.
NativeClient::connect / worker_main thread the preference through.
Host:
- vdisplay::available() enumerates usable backends via cheap, side-effect-free
probes (KWin zkde global, gamescope binary+version, GNOME/Sway env), plus
Compositor id/label/as_pref/from_pref/all helpers.
- m3 handshake resolves the preference to a concrete backend during the
handshake (pick_compositor pure + resolved logging), reports it in Welcome,
and threads it into virtual_stream (replacing the unconditional detect()).
- mgmt GET /v1/compositors lists every backend with availability + the
auto-detected default (OpenAPI regenerated).
Client:
- punktfunk-client-rs --compositor NAME; logs the host's resolved choice from
the Welcome ("session offer … compositor=…").
Web console:
- Host page gains a Compositors card (availability + default badges) via the
codegen'd useListCompositors hook; en/de strings added.
Also fixes a pre-existing, env-dependent test-isolation bug:
mgmt::tests::paired_clients_list_and_unpair seeded the real
~/.config/punktfunk/paired.json (AppState::new loads it), so a real
GameStream-paired client leaked into body[0] on a dev box — now cleared first.
Live-validated against headless KWin: --compositor kwin honored, --compositor
mutter falls back to kwin (available=[kwin, gamescope]), resolved choice
round-trips to the client. Tests: +6 (wire/back-compat, resolution precedence,
endpoint); workspace green, clippy/fmt clean, C ABI harness PASS at abi_version=2,
web typecheck + build clean.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
enricobuehler
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