Optimize JavaScript sandbox command startup

[luke-lombardi]

Summary

• opt blocking sandbox execution into beta9's inline wait response
• consume inline exit status, stdout, and stderr without follow-up HTTP requests
• coalesce concurrent first-use runtime preparation so file/image setup only runs once
• preserve polling and streaming behavior for long-running commands, including combined inline logs
• release the canonical JS package as @beamcloud/[email protected]

Why

The ComputeSDK JavaScript benchmark runs a very short command. The SDK was paying separate status, stdout, and stderr requests plus a 100 ms polling interval after the command had already finished. Concurrent first-use calls could also duplicate runtime preparation.

Exact-artifact verification

• release source: this PR at 794837a
• published npm package: @beamcloud/[email protected]
• ComputeSDK upstream base: 61bb4727, plus computesdk/computesdk#659 at 19905c7d
• benchmark upstream: f11dd7ef

A fresh benchmark clone installed the ComputeSDK adapter branch as a packed package and resolved Beam JS 1.0.13 from the public npm registry. The only benchmark-source adjustment supplied the target gateway URL. All official modes completed without SDK errors in staging:

• sequential: 100/100, median 193.00 ms, p95 212.94 ms, p99 217.81 ms, score 97.98
• staggered: 100/100, median 183.42 ms, p95 206.10 ms, p99 227.98 ms, score 98.04
• burst: 100/100, median 1810.46 ms, p95 2223.25 ms, p99 2279.95 ms, score 80.16

The staging benchmark workspace was temporarily given the official 100-sandbox quota for the burst gate and restored afterward.

Validation

• npm ci
• npm test -- --runInBand — 138/138 tests passed
• npm run build — ESM and CJS builds passed
• npm pack dry run verified package contents
• public registry install verified exact 1.0.13 runtime resolution
• ComputeSDK adapter: 15/15 tests, typecheck, and build passed
• latest upstream benchmark: 100/100 sequential, staggered, and burst

Release

Published as @beamcloud/[email protected] from the canonical beam-client/js package.