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fix(vdisplay): the wlr-family backends asserted a cursor mode instead of negotiating it, so the portal refused the call
Hyprland and wlroots both hardcoded portal `CursorMode::Metadata` whenever the
session had negotiated the cursor channel, and never asked the backend what it
supports. That is not a soft failure: xdg-desktop-portal's FRONTEND validates the
requested mode against the backend's `AvailableCursorModes` and fails the call
with `"Unavailable cursor mode %x"` before the backend ever sees it.

So a cursor-forward session (desktop mouse mode) died at `select_sources`,
surfacing as "pipeline build failed" and a black client, with
`unavailable cursor mode 4` in the portal log. Field report 2026-08-14.

MEASURED on .21 the same day, and it is worse than the report suggested: against
a LIVE Hyprland 0.56.2 with xdg-desktop-portal-hyprland 1.4.1 and
xdg-desktop-portal 1.22.1 — all current — `AvailableCursorModes` reads **3**
(Hidden|Embedded) on both the backend impl interface and the frontend. xdph does
not offer the metadata cursor at all, so this broke EVERY cursor-forward session
on current Hyprland, not merely on old installs. Updating the portal would not
have helped. xdpw is the same from the other end: its screencast.c refuses
METADATA outright.

pf-capture's own portal path has always negotiated (`choose_cursor_mode`); this
restates that ladder in pf-vdisplay, which may not depend on pf-capture. The
downgrade is graceful rather than merely survivable: with the portal on Embedded
no `SPA_META_Cursor` arrives, so the host feeds the cursor channel nothing and a
cursor-forward client draws nothing of its own — one pointer, not two.

`PUNKTFUNK_PORTAL_CURSOR_MODE=auto|hidden|embedded|metadata` pins the preference
for a backend that advertises a mode it implements badly, which negotiation
cannot detect. It is a preference only: pins run the same ladder, so no value can
re-create the refused request.

The module is declared unconditionally so its ladder tests run on every CI leg
rather than only the one that compiles `mod hyprland` — including a Linux-only
test pinning our bit values against ashpd's enum, verified non-vacuous by
planting a wrong discriminant (ashpd answers 4 for Metadata, the number in the
report). The regression test uses 3, the bitfield measured on glass. Linux: 225
tests pass, clippy --all-targets -D warnings clean.
2026-08-14 10:27:14 +02:00
..