Release notes: 2026-05-27 — studio-wgpu-readback-a¶

Status: Ready for review (rebased onto main 2026-05-27)
Repo: li-langverse/lic
PR: cursor/studio-wgpu-readback-5599
PH / REQ: PH-HW viewport, UX-14 native pixels
Author: agent

Summary (one sentence)¶

Phase A wgpu readback scaffold: lig_present_blit_paint_summary / present_blit_rgba8 records native_pixel_source=paint_blit before host-present compose claims native_pixels=1.

Agent continuation (required)¶

Read: docs/game-dev/wgpu-readback-path.md, packages/lig/present/lib.li, docs/game-dev/lig-kernel-catalog.md (present_blit_rgba8 row).
Run: LIC=build/compiler/lic/lic ./scripts/lic-workspace-build.sh packages/li.toml (lig + li-studio); lic check packages/lig/li-tests/smoke/present_blit_rgba8.li; with LIG_HOST_PRESENT=1 run studio vertical native capture scripts.
Then: Phase B — wire li_rt_lig_kernel_run kid=3 dispatch and in-tree wgpu-rs swapchain readback (native_pixel_source_wgpu_readback).
Blocked on: wgpu-rs surface in CI images for real GPU readback — not required for phase A merge.

Changed (specific)¶

Area	What	Evidence
`packages/lig/present/lib.li`	`lig_present_blit_paint_summary`, `native_pixel_source` on `LigPresentFrame`, `lig_kernel_present_blit_rgba8` kid id	`present_blit_rgba8.li`
`runtime/li_rt.c` / `li_rt.h`	`li_rt_lig_present_blit_rgba8`, pixel source globals	host-present gate
`packages/li-studio/src/lib.li`	Vertical demo requires blit before present; checks `native_pixel_source_paint_blit`	compose path
`packages/lig/lkir/blit.lkir`	LKIR stub for kernel catalog	bench registry
`li-tests/manifest.toml`	`T-PKG-lig-present-blit` compile_open_ok	manifest row

Not changed (scope fence)¶

Full wgpu-rs swapchain / texture readback (phase B).
li-render HUD native_pixels simulation path (still lig_present_surface_ok()).
LLVM LKIR lowering for present_blit_rgba8 beyond stub comment file.
Studio HTML mocks / tier-5 httpd.

Breaking changes¶

None — li_std_lig_present_version is 2; callers checking >= 1 remain valid.

Security¶

N/A — trusted runtime edge only; no new trusted.lean axioms.

Performance¶

N/A — phase A is contract + runtime stub; no bench threshold changes.

Downstream¶

Repo	Action
benchmarks	optional ingest after phase B readback benches
li-render / package mirrors	N/A until phase B

CHANGELOG entry (paste into Unreleased)¶

### Added
- **PH-HW viewport phase A:** `lig_present_blit_paint_summary` / `present_blit_rgba8` scaffold (`native_pixel_source`); studio vertical demo requires paint blit before host present — [2026-05-27-studio-wgpu-readback-a.md](docs/release-notes/2026-05-27-studio-wgpu-readback-a.md).