chore(cloud-agent-next): bump sandbox runtime

[eshurakov]

Summary

• Bump cloud-agent-next to Cloudflare Sandbox SDK 0.8.9 and @cloudflare/containers 0.3.0 so the Worker code aligns with the latest sandbox release.
• Update both cloud-agent-next Docker base images from docker.io/cloudflare/sandbox:0.7.13 to docker.io/cloudflare/sandbox:0.8.9.
• No architecture changes; this keeps the SDK, Containers package, and runtime image version in sync for the existing sandbox integration.

Verification

• Passed: pnpm --filter cloud-agent-next install --frozen-lockfile
• Passed: pnpm --filter cloud-agent-next typecheck
• Passed: pnpm --filter cloud-agent-next test
• Passed: docker manifest inspect docker.io/cloudflare/sandbox:0.8.9
• Failed: pnpm --filter cloud-agent-next test:integration — 3 existing stale-reaper assertions in test/integration/session/disconnect-and-reaper.test.ts still expect stale executions to become failed, but they remain running.
• Manual check

[kilo-code-bot]

Code Review Summary

Status: No Issues Found | Recommendation: Merge

Files Reviewed (4 files)

• pnpm-lock.yaml
• services/cloud-agent-next/Dockerfile
• services/cloud-agent-next/Dockerfile.dev
• services/cloud-agent-next/package.json

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_{Reviewed by gpt-5.4-2026-03-05 · 151,263 tokens}