fix(desktop): chat videos no longer render black on hybrid NVIDIA Linux laptops

[AI091]

Summary

On hybrid Linux laptops where the iGPU drives the display, some distros set LIBVA_DRIVER_NAME=nvidia for the whole session. Omarchy does this by default, and it's already tracked there (omacom/omarchy#12594, #13081, #13549). Chromium's NVIDIA check only looks at the GPU it renders on, so video decoding moves to the NVIDIA card and the frames never reach the screen. In T3 Code, chat videos show as black boxes and pressing play spins at 0:00.

This isn't a T3 Code bug, and the real fix belongs upstream. Omarchy has already merged one (omacom/omarchy#11690), but it isn't in a release yet, and other distros or users can set the same variable. I'm opening this because a lot of T3 Code users run Omarchy and the accommodation is small, but I'm happy to close it if you'd rather leave this to the distro.

The change: on Linux, when LIBVA_DRIVER_NAME=nvidia, the desktop app starts Chromium with disable-accelerated-video-decode (5 lines in DesktopPreReadyPlatform.ts). On NVIDIA-only machines Chromium already refuses that driver, so nothing changes there. On hybrid machines video decodes on the CPU instead, which is cheap for short chat recordings. Other platforms and environments are unaffected.

Evidence

Same thread, same build, same session env (LIBVA_DRIVER_NAME=nvidia), on a hybrid AMD iGPU + RTX 4060 laptop running Hyprland.

• Before: both clips are black boxes, and play spins at 0:00. The GPU process holds about 280 MB of NVIDIA memory for the two paused clips (1.4 GB in a test thread with six).

  

  before.mp4

• After: first frames show and playback works. The NVIDIA VA-API driver no longer loads, and no NVIDIA memory is used.

  

  after.mp4

• apps/desktop typecheck, lint, and format pass.

Merge Danger

Door: two-way. One Chromium switch, only when that env var is set.
Blast radius: small. Only Linux desktop users with LIBVA_DRIVER_NAME=nvidia, who lose hardware video decode in T3 Code.

Made with Claude Opus 5.5 via Claude Code, running in T3 Code.

[macroscopeapp]

Approvability

Verdict: Not approved

Macroscope's review found this PR not approvable — This startup change fixes a targeted Linux/NVIDIA playback issue by changing Chromium's default video-decoding mode for affected sessions, with potential CPU, power, and playback-performance tradeoffs across all videos. The product-default change should be confirmed by a human maintainer.

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[coderabbitai]

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ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Repository: pingdotgg/t3code/.coderabbit.yaml

Review profile: CHILL

Plan: Advanced

Run ID: 79c43819-5fe6-49d9-a4e7-d2a5285543c7

📥 Commits

Reviewing files that changed from the base of the PR and between b528a70 and 3f57800.

📒 Files selected for processing (1)

• apps/desktop/src/app/DesktopPreReadyPlatform.ts

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📝 Walkthrough

Walkthrough

On Linux, Electron setup now appends Chromium’s disable-accelerated-video-decode switch when LIBVA_DRIVER_NAME is exactly "nvidia".

Changes

Linux video decode configuration

Layer / File(s)	Summary
Conditional Chromium switch apps/desktop/src/app/DesktopPreReadyPlatform.ts	When LIBVA_DRIVER_NAME is "nvidia", Linux setup appends disable-accelerated-video-decode to Electron’s command line.

Priority: ➖ Normal

Estimated code review effort: 1 (Trivial) | ~5 minutes

Change: Bug fix

Suggested reviewers: juliusmarminge

Merge Risk: ⚪ Minimal · up to 3f578

No confirmed issue blocks merging the Linux video workaround on the available evidence.

Security Architecture Review

Security architecture risk: 🔵 Low · up to 3f578

The change is limited to Linux launches with a specific video-driver setting. It disables hardware video decoding for that app process and does not appear to grant access or change credentials. Its process-wide effect and restart-only rollback warrant a design review.

Retained concerns
No architecture-level concerns identified.

Security review details

Security Blast Radius

• inferred — The new behavior is scoped to affected Linux desktop processes, although the switch applies across each affected Electron instance.

Trust Boundaries and Controls

• observed — The changed branch selects a fixed Chromium switch from a host environment value; it introduces no renderer input, IPC call, credential operation, or privilege-granting switch in that branch.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 1…
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Title check	✅ Passed	The title clearly identifies the desktop video rendering fix for hybrid NVIDIA Linux laptops, which matches the main change.
Description check	✅ Passed	The description clearly explains the problem, affected environment, proposed workaround, scope, evidence, and validation. It does not use the template headings or include the checklist, but it provide…

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