WebGPU-accelerated Stellar scanner (full implementation)

[truthixify]

Continues work from a Wave 6 issue that was closed at wave wrap-up. Fresh assignments welcome.

Extra labels: stellar, perf
Tier: L (5-7 days) | Type: perf

Context. Wave 6 spike (PR #118) measured ~5x further speedup on top of the current 229x view-tag baseline but was intentionally throwaway. Land it properly behind a runtime capability check.

Scope.

• Move WebGPU shader from spike into src/chains/stellar/scanner/webgpu.ts.
• Feature-detect via navigator.gpu; fall back to CPU wasm in Node + non-GPU browsers.
• Public API unchanged (fetchAnnouncementsStream).
• Extend test/chains/stellar/bench/scan.bench.ts with GPU vs CPU.

Acceptance.

• Node CI green without WebGPU
• Browser Playwright test verifies GPU path returns identical output to CPU
• Bench shows ≥ 2x GPU speedup on 10k events in Chrome
• @webgpu/types stays dev-only

Files. src/chains/stellar/scanner/webgpu.ts (new), src/chains/stellar/announcements.ts, test/chains/stellar/bench/scan.bench.ts.

[Hollujay]

I would like to work on this issue because I will get it done

[heymariam]

@heymariam has applied to work on this issue as part of the Stellar Wave Program's 7th wave.

Hello Maintainer,

I’d like to work on this issue. I’ll integrate the WebGPU scanner implementation behind a runtime capability check, preserve the existing fetchAnnouncementsStream API, add CPU fallback support for unsupported environments, and extend benchmarks and tests to verify identical results and performance improvements.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @heymariam to this issue.

[drips-wave]

Congratulations, @heymariam! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on July 30, 2026.

🧑‍💻 @heymariam: Please resolve the issue such that the repo's maintainers have enough time to review your contribution before the due date. You'll earn Points for completing the issue on-time, which will make you eligible for a share of the Stellar Wave Program's reward pool.

Warning

When opening a PR, please link it to this issue to ensure it gets tracked accurately. Points are awarded when this issue is marked as completed by the maintainer.

🤠 Repo maintainers: Please keep an eye on the contributor's progress and review their work before the due date. You can manage this issue, including adjusting its complexity and points, here.

🌊 Happy Wave 🌊