Render LOVE demos through native KMS scanout modes

[brandonpayton]

Purpose

Keep native LOVE games on the real Kandelo KMS/EGL/GLES path while letting fixed-resolution games render at their intended logical display size and letting the Kandelo UI upscale the final scanout.

The target-resolution work fixed the first issue by allocating LOVE scanout buffers at the game-requested size. The connector-mode follow-up fixed native fullscreen/window queries. The image metadata then made each LOVE profile advertise the connector mode it expects. The final BYTEPATH follow-up caps only the browser presentation zoom so BYTEPATH's deliberately low-resolution shader offsets are not magnified across an oversized browser pane.

This keeps the fix in Kandelo's normal presentation path: /etc/kandelo/demo.json -> kandelo-session presentation parsing -> generic KMS pane -> attachKmsDisplay({ connectorMode }) and generic CSS fitting. It does not add BYTEPATH/SNKRX renderer hacks.

This is a stacked draft PR against emdash/love-port-current-base-for-target-upscale, which captures the current LOVE native-port worktree state. The feature diff is four commits: target-resolution KMS scanout/upscale, connector-mode preservation for native fullscreen/window queries, image-declared virtual KMS connector modes, and an optional KMS CSS presentation scale cap.

Changes

• Move LOVE presenter setup until after love.conf, then allocate KMS GBM BOs/DRM FBs and the GL viewport from the game window size.
• Fit the browser KMS canvas from the kernel-reported active scanout size and upscale that canvas with CSS in the Kandelo UI.
• Track the advertised KMS connector mode separately from the current scanout framebuffer in the host runtime and host protocols.
• Resize the attached OffscreenCanvas to the framebuffer committed through MODE_SETCRTC, without changing the mode reported by MODE_GETCONNECTOR.
• Make the Kandelo native LOVE window backend report the advertised connector dimensions for fullscreen/window queries.
• Add presentation.kms.connectorMode metadata parsing and validation to kandelo-session.
• Add presentation.kms.maxCssScale metadata parsing and validation to cap browser presentation zoom without changing the KMS framebuffer or dimensions visible to user software.
• Seed the KMS pane and attachKmsDisplay from image-declared connector modes, defaulting to 1920x1080 for generic KMS demos.
• Declare virtual KMS connector modes for the LOVE shell profiles: LOVE gallery 960x540, BYTEPATH 480x270, SNKRX 960x540.
• Cap BYTEPATH's browser presentation scale at 2x, so its 480x270 native scanout is displayed as 960x540 centered in larger panes.
• Remove the BYTEPATH demo-default patch that changed upstream glitch = 10 to 3.
• Document the KMS connector-mode vs scanout-size contract, the presentation scale cap, and the LOVE native runtime behavior.

Validation

• scripts/dev-shell.sh bash packages/registry/love/build-love.sh
• unzip -p packages/registry/love/love-examples.zip bytepath/globals.lua | rg -n "glitch|distortion|sx, sy" showed upstream glitch = 10.
• scripts/dev-shell.sh bash images/vfs/scripts/build-shell-vfs-image.sh
• scripts/dev-shell.sh bash -c 'cd apps/browser-demos && npm run build'
• scripts/dev-shell.sh bash -c 'cd host && npm test -- dri-kms-stats-sab.test.ts dri-registry.test.ts webgl-bridge.test.ts webgl-shadow.test.ts webgl-main-forward.test.ts webgl-registry.test.ts webgl-muxer.test.ts' passed: 7 files, 94 tests.
• scripts/dev-shell.sh bash -c 'cd host && npx vitest run ../web-libs/kandelo-session/test/kandelo-session.test.ts' passed: 1 file, 44 tests.
• git diff --check -- . ':!libc/musl' ':!tests/sortix/os-test'
• Browser smoke on http://127.0.0.1:5404/ after the virtual connector-mode fix:
  • BYTEPATH: KMS canvas attrs 480x270, CSS rect about 1857x1045; screenshot /tmp/bytepath-kms-virtual-mode.png.
  • BYTEPATH guide-closed smoke: status 480×270 · 11723 flips · captured · pid 100; screenshot /tmp/bytepath-kms-virtual-mode-guide-closed.png.
  • SNKRX: KMS canvas attrs 960x540, CSS rect about 1857x1045; screenshot /tmp/snkrx-kms-virtual-mode.png.
• Follow-up BYTEPATH shader proof on the same native renderer path:
  • With packaged settings (distortion = 5, glitch = 10), startup/game text still shows RGB separation.
  • Through BYTEPATH's own effects command, lowering glitch to 0 and distortion near 0 removed the split on the same renderer, confirming that the remaining RGB offset was game-authored post-processing rather than a Kandelo CSS-upscale artifact.
• Browser smoke after rebuilding the shell VFS with presentation.kms.maxCssScale: 2 for BYTEPATH:
  • URL: http://127.0.0.1:5404/?demo=bytepath&scalecap=2x-smoke
  • KMS canvas attrs 480x270, CSS rect 960x540, centered in the pane.
  • Status: 480×270 · 3691 flips · captured · pid 100.
  • Screenshot: /tmp/bytepath-kms-scale-cap.png.

Known unrelated browser diagnostic: the existing remote Kandelo software gallery manifest 404 warning.

Not Run

• Full POSIX/conformance suites.
• Full browser Playwright suite.
• Full ./run.sh browser; it was stopped because binary materialization for unrelated packages fell back to source builds outside the dev-shell toolchain context. The already-built VFS was served through Vite for browser smoke.

[github-actions]

Phase B-1 matrix build status — pr-843-staging

ABI v16. 67 built, 4 failed, 71 total.

Package	Arch	Status	Sha
freetype	wasm32	built	309c9846
libcurl	wasm32	built	8209531d
libcxx	wasm32	built	f2f4c9d3
libcxx	wasm64	built	0976cfa2
libpng	wasm32	built	05e136da
libxml2	wasm32	built	0135b627
libxml2	wasm64	built	eb6af6a7
lua	wasm32	built	8605336d
openssl	wasm32	built	44077384
openssl	wasm64	built	2d873da0
sqlite	wasm32	built	b0036f25
sqlite	wasm64	built	56bebe00
zlib	wasm32	built	a95074ce
zlib	wasm64	built	7ae80692
bc	wasm32	built	4839df3e
bzip2	wasm32	built	60600970
coreutils	wasm32	built	f14e966a
curl	wasm32	built	f34134af
dash	wasm32	built	dbbd40a6
diffutils	wasm32	built	16f0e3c9
dinit	wasm32	built	ae7dc838
fbdoom	wasm32	built	3431d37e
file	wasm32	built	6476c513
findutils	wasm32	built	98a5306f
gawk	wasm32	built	f4f69389
git	wasm32	built	05018df4
grep	wasm32	built	cca6e616
gzip	wasm32	built	717a6380
hello	wasm32	built	452aeb42
kandelo-sdk	wasm32	built	33898e9f
kernel	wasm32	built	2dea894c
less	wasm32	built	5edb6486
love	wasm32	built	0f5d004c
lsof	wasm32	built	e36e8981
m4	wasm32	built	0f528a5a
make	wasm32	built	ff0e311c
mariadb	wasm32	built	db55a931
mariadb	wasm64	built	65a4c7a1
modeset	wasm32	built	0bffa33a
msmtpd	wasm32	built	7264ab88
nano	wasm32	built	3cb5a232
ncurses	wasm32	built	241c562f
netcat	wasm32	built	9319fb0c
nginx	wasm32	built	0ec9ca8e
php	wasm32	built	022b8309
posix-utils-lite	wasm32	built	1c80585a
sed	wasm32	built	0c503c3f
spidermonkey	wasm32	built	bd43ea6c
tar	wasm32	built	fbe26e27
tcl	wasm32	built	b91d60ee
unzip	wasm32	built	f65de865
userspace	wasm32	built	e1a79e77
vim	wasm32	built	3e7ee130
wget	wasm32	built	7a641c0b
xz	wasm32	built	a563eeb4
zip	wasm32	built	8bb08b58
zstd	wasm32	built	8ebdffe5
bash	wasm32	built	8eb30d9a
mariadb-test	wasm32	built	2ad65ed5
mariadb-vfs	wasm32	built	600093f2
mariadb-vfs	wasm64	built	109b5075
nethack	wasm32	built	7469f8c4
node	wasm32	built	1f78e7e9
spidermonkey-node	wasm32	built	2e3a7c1e
vim-browser-bundle	wasm32	built	688ecc1d
nethack-browser-bundle	wasm32	built	447c0f87
rootfs	wasm32	built	b69f06e8
shell	wasm32	failed	—
lamp	wasm32	failed	—
node-vfs	wasm32	failed	—
wordpress	wasm32	failed	—

_{Auto-generated; replaced on each push. Raw data in the publish-status workflow artifact.}