fix(desktop): disable GPU acceleration on remote displays to stop flicker

[OutThisLife]

Summary

Users on remote/forwarded displays reported the desktop window flickering during scroll/streaming. Nobody on native Windows/macOS ever saw it — the tell that it's a remote-display problem.

• @l0gix5: "no longer jumping but still flicker" → "i'm using over remote connection."
• @etechvolution: "screen flickering (very few times)" for sessions started in the desktop app.

Root cause. The app shipped with Chromium's default GPU hardware acceleration and no remote-display handling (main.cjs had no GPU switches at all; the existing "remote" code is all about the remote gateway backend, unrelated to the display). Over a remote connection (SSH X11 forwarding, VNC, RDP), Chromium's GPU compositor can't present accelerated layers cleanly across the wire, so the surface flashes on repaint. Local sessions composite on the GPU and never hit it.

Fix. Detect a remote display before app.ready and fall back to software rendering — the standard remedy (what VS Code/Slack expose for RDP/VNC). Detection (detectRemoteDisplay in bootstrap-platform.cjs, pure + unit-tested) flags:

• SSH sessions (SSH_CONNECTION / SSH_CLIENT / SSH_TTY)
• X11 forwarding (DISPLAY=<host>:N, e.g. localhost:10.0) — but not local :0/:1
• Windows RDP (SESSIONNAME=RDP-*)

WSLg is intentionally not flagged: it renders locally via vGPU and doesn't show the flicker (confirmed by a WSL user with zero flickering). VNC/screen-sharing can't be sniffed reliably, so it's covered by the override.

When flagged: app.disableHardwareAcceleration() + --disable-gpu-compositing. HERMES_DESKTOP_DISABLE_GPU overrides both ways (1/true → always disable for VNC/screen-sharing we can't sniff; 0/false → keep GPU on for remote hosts that do have working acceleration). The decision is logged.

This also quietly fixes the terminal's WebGL surface: with --disable-gpu the WebglAddon context creation fails into its existing DOM-renderer fallback, which is stable over the wire.

Changes

• electron/bootstrap-platform.cjs — add pure detectRemoteDisplay({ env, platform }).
• electron/main.cjs — disable HW acceleration early when a remote display is detected; log the reason.
• electron/bootstrap-platform.test.cjs — tests (local stays on; WSLg stays on; SSH/X11-forward/RDP flagged; local :0/:1 not flagged; override both ways).

Test plan

• node --test electron/bootstrap-platform.test.cjs — 10/10 pass
• npm run test:desktop:platforms — pass
• eslint on changed files — 0 new problems (the 6 main.cjs errors are pre-existing on main, verified via stdin lint of origin/main)
• Local macOS npm run dev confirmed unaffected (GPU stays on; no remote display detected boot line)
• Manual: launch over SSH X11-forwarding (or set HERMES_DESKTOP_DISABLE_GPU=1), confirm the boot log shows the disable line and the flicker is gone

[github-actions]

🔎 Lint report: bb/desktop-remote-flicker vs origin/main

ruff

Total: 0 on HEAD, 0 on base (➖ 0)

🆕 New issues: none

✅ Fixed issues: none

Unchanged: 0 pre-existing issues carried over.

ty (type checker)

Total: 9709 on HEAD, 9709 on base (➖ 0)

🆕 New issues: none

✅ Fixed issues: none

Unchanged: 5031 pre-existing issues carried over.

Diagnostics are surfaced as warnings — this check never fails the build.