[yacineolivier-maker]

A title can draw its own heads-up display on the host side (ImGui, like the
in-game overlay provider), once per presented frame -- real and generated
frames -- under the in-game menu and with the same thread and GL rules as
psx_host_overlay_set_draw_cb. Registered once at title activation; NULL
unregisters. No callback registered: no change in behaviour.

Used by a modern race HUD for R4 (lap, timing, tachometer, track map) drawn
at window resolution instead of the 320x240 native one.

Verification

• Game-agnostic: no title check or game address in the framework; behaviour is unchanged unless a title registers a HUD callback.
• Build: R4 (tetrisgm/RidgeRacerType4Recomp master 737827c, USA config, its committed generated C) built against this branch alone: cmake-clang-v1 1.0.14 (clang, Ninja, Release), Windows 11.
• Runtime: exercised in R4's PAL build (SCES-01706) with all of our framework branches combined on current master fe8d937d: boot, menus, a full Time Attack lap. The same changes on the previous base (379565a6) went through several days of play-testing: intro movie, menus, races, VS split screen, attract demo. Windows 11, i5-12400F, RTX 3060, OpenGL renderer; Vulkan and the software renderer were not tested.
• Pin / regen: runtime only, no regen. A game consumes it with a pin bump.

Game side: tetrisgm/RidgeRacerType4Recomp#49 (PAL / Europe support) and tetrisgm/RidgeRacerType4Recomp#50 (race HUD, car effects, lighting; overview in tetrisgm/RidgeRacerType4Recomp#51)

I cannot follow up on review comments, sorry. Maintainers are welcome to edit, split, take over or close this.

🤖 Generated with Claude Code

https://claude.ai/code/session_01Rkyma8rbyPiccs9n2bkyG6

[mstan]

Reviewed head 0127fcf.

The separate HUD layer is a useful elective presentation capability: it can draw below the menu without stealing the menu provider. This head needs a defined session/thread lifetime before merge. host_overlay.c publishes s_hud_fn and s_hud_ctx as two ordinary globals while the renderer reads them on another thread; unlike the existing overlay callback, there is no publication/drain protocol. NULL unregister explicitly does not wait, and no restart/package-deactivation path clears this new slot. A callback/context valid only for the old session can therefore survive into the next session or race teardown. Reuse the existing callback ownership/drain pattern and connect it to session cleanup; verify register -> present -> unregister/restart with a render in flight. State the OpenGL-only capability explicitly so a consuming title can refuse/fall back on other backends. The R4 combined-stack play report is relevant, but does not test that lifecycle. Tracking: beads-8zz2.

[mstan]

Maintainer fixes pushed in 570c4c8. The HUD function/context now publish coherently, replacement/unregister drains prior calls, and activation reset / GL shutdown clear the session slot. The header explicitly states OpenGL-only support and registrant ownership. Focused concurrent unregister, self-unregister and activation-reset checks pass. The combined native checks and real GL threaded/unthreaded fixture pass; the four-title smoke batch is underway. I will make the merge decision on the qualified head rather than ask you to redo these objective corrections. Tracking: beads-kgof.

[mstan]

Maintainer fixes address coherent HUD callback/context publication, unregister lifetime, session reset and GL shutdown. Concurrent unregister, self-unregister and activation-reset fixtures pass. The Windows test escape models non-unwinding guest callbacks without the CRT SEH crash. OpenGL-only scope and callback ownership are explicit.

One bounded muted OpenGL boot/progression/visual smoke passed for Tomba, Tomba 2, Ape Escape and Mega Man X6. Tomba 2 reached its title screen after the opening FMV at native aspect; its unsupported widescreen package remains disabled. Supported debug quit returned exit 0 for all four; this is not extended gameplay, normal-teardown or native-card-write qualification.

Combined integration 9ee1a8c63996cc91e4068aa27f100d407ab1ac0e includes #710/#723/#736/#737/#746; #736 remains held for residency policy. Six focused native checks and the GL fixture passed. This evidence qualifies the reviewed heads as a compatible subset, not an exact final-master-tree claim. Tracking: beads-kgof.