This skill should be used when the user asks to "build background agent", "create hosted coding agent", "set up sandboxed execution", "implement multiplayer agent", or mentions background agents, sandboxed VMs, agent infrastructure, Modal sandboxes, self-spawning agents, or remote coding environments.
View on GitHubguanyang/antigravity-skills
antigravity-skills
January 24, 2026
Select agents to install to:
npx add-skill https://github.com/guanyang/antigravity-skills/blob/main/skills/hosted-agents/SKILL.md -a claude-code --skill hosted-agentsInstallation paths:
.claude/skills/hosted-agents/# Hosted Agent Infrastructure Hosted agents run in remote sandboxed environments rather than on local machines. When designed well, they provide unlimited concurrency, consistent execution environments, and multiplayer collaboration. The critical insight is that session speed should be limited only by model provider time-to-first-token, with all infrastructure setup completed before the user starts their session. ## When to Activate Activate this skill when: - Building background coding agents that run independently of user devices - Designing sandboxed execution environments for agent workloads - Implementing multiplayer agent sessions with shared state - Creating multi-client agent interfaces (Slack, Web, Chrome extensions) - Scaling agent infrastructure beyond local machine constraints - Building systems where agents spawn sub-agents for parallel work ## Core Concepts Hosted agents address the fundamental limitation of local agent execution: resource contention, environment inconsistency, and single-user constraints. By moving agent execution to remote sandboxed environments, teams gain unlimited concurrency, reproducible environments, and collaborative workflows. The architecture consists of three layers: sandbox infrastructure for isolated execution, API layer for state management and client coordination, and client interfaces for user interaction across platforms. Each layer has specific design requirements that enable the system to scale. ## Detailed Topics ### Sandbox Infrastructure **The Core Challenge** Spinning up full development environments quickly is the primary technical challenge. Users expect near-instant session starts, but development environments require cloning repositories, installing dependencies, and running build steps. **Image Registry Pattern** Pre-build environment images on a regular cadence (every 30 minutes works well). Each image contains: - Cloned repository at a known commit - All runtime dependencies installed - Initial