forked from unom/punktfunk
The Linux native plane has been 8-bit for a reason that stopped being true: `capturer_supports_hdr()` returned a flat `false` because Mutter's virtual monitors are SDR-only upstream. That is still right for Mutter, KWin and wlroots — and wrong for gamescope, whose node can now offer 10-bit BT.2020 PQ (packaging/gamescope). Open the three gates that held it off, together: * the capture-side gate becomes SOURCE-AWARE (`capturer_supports_hdr_for`): Windows keeps its platform answer, gamescope asks whether the resolved binary offers the formats, everything else stays false. It must be truthful rather than optimistic — the Welcome is irrevocable, and PQ frames on an 8-bit encoder are a deliberate hard error — so every term is a static fact resolved before anything is spawned, including "do we spawn gamescope at all" (an attach inherits someone else's flags and can promise nothing); * `want_hdr` reaches the capturer: `open_virtual_output` grew the parameter it never had, and the host arm stopped dropping `want.hdr` on the floor; * the spawn gains `--hdr-enabled --hdr-debug-force-support` on all three sub-modes (bare args, the `GAMESCOPE_BIN` wrapper, the SteamOS PATH shim), from one shared `hdr_args` — the force flag is what makes it work headless, and forgetting it looks exactly like a negotiation failure. Two things that would have gone wrong quietly: * the keep-alive reuse key gains `hdr`. gamescope cannot turn HDR on live, so a kept SDR display handed to an HDR session would give the game no HDR surfaces while the stream negotiated PQ over an SDR composite — wrong, and not obviously broken. Same for the managed session-plus/SteamOS reuse check. * the HDR-negotiation-failure latch becomes PER SOURCE. It was one process-wide flag, so a monitor that left HDR mode would have disabled gamescope HDR until the host restarted, and vice versa — two facts with nothing in common but the word HDR. GameStream follows the same shape: `host_hdr_capable` gains the gamescope arm, and the RTSP gate's live BT.2100 monitor probe is scoped to the portal source — a headless box has no monitor to be in HDR mode, so running it there would hard-refuse every gamescope HDR session. Off by default for one release (`PUNKTFUNK_GAMESCOPE_HDR=1`), and `punktfunk-host hdr-probe` now answers for both Linux HDR sources.