d3k

Own the project's dev server and monitored browser through a small background runtime. No global d3k installation is needed. Evidence stays in bounded memory; browser authentication stays in the project Chrome profile.

Use node <skill-directory>/scripts/runtime.mjs as runtime below, from the target project root. In a development checkout the helper runs the source with Bun; installed skills use the JavaScript package through pnpm dlx (Node.js 24+ and pnpm required). Package acquisition runs in an isolated temporary directory so the target app’s pnpm workspace settings do not affect it; runtime commands still run against the target project. To try unreleased source from another project, set D3K_RUNTIME_ROOT to the dev3000 checkout. Do not use a previously published package to test unreleased changes.

Desktop MCP connection

When d3k MCP tools are available, use them directly instead of the shell runtime below. They manage a remote project without a local checkout. Call sandbox_sessions, then sandbox_start with project: "team/project" or resume: "<saved-id>". Poll sandbox_status until phase: "ready"; startup is asynchronous. If another companion owns a saved session, report it instead of taking over or killing it.

An explicit request for a remote sandbox takes precedence over a linked local repository. Use project and the requested branch to create a fresh remote checkout. Reuse with resume or attach only when requested by the user. If creation fails, report its actual error; do not assume the repository is private, attach to an old checkout, discard the requested branch, or fall back to editing locally.

For a phone user or an explicit phone-preview request, use sandbox_start with browser: "link", then present the ready sandbox_status.preview.url as a clickable link and its expiresAt. Never give the phone a .localhost URL. Companion Chrome runs headlessly for agent testing; it cannot control the phone's browser. The link grants session app access, so share it only in the user's chat and keep it out of PRs/public logs. It expires with the session and is regenerated on resume; use browser: "link" again when resuming. Local stdio carries no phone User-Agent: use explicit user/client context, not the emulated viewport. The macOS companion and access to its local MCP server are still required; this does not provide phone-only ChatGPT connectivity. App sign-in may require allowing the preview origin's exact callback URL with the auth provider.

Use sandbox_exec, sandbox_read_file, and sandbox_write_file for all project files and commands remotely. Read remote AGENTS.md before editing. Use sandbox_runtime with args: ["status"] and cursor-based events for evidence. Use sandbox_browser with args: ["snapshot", "-i"] and other agent-browser interaction arguments for the existing local Chrome; no CDP discovery or separate browser is needed. sandbox_github publishes Git objects and PRs through local repository-scoped GitHub authentication. Keep credentials out of remote commands. Do not clone or save project code/env files locally.

If the dev runtime stops or the app returns 502, use sandbox_recover with action: "start", then poll action: "status" until recovered or failed. Recovery keeps the agent, local Chrome and remote files; it does not clone, reinstall, replay commands, renew Gateway keys or extend compute lifetime. Reread runtime status and reproduce afterward; old in-memory evidence is lost on restart.

Keep the session running during user testing. sandbox_stop returns stopping; poll until stopped. Stopping or disconnecting the MCP server closes Chrome and d3k-owned compute, preserves remote files, and leaves a resumable session. One active sandbox per server. No terminal harness or Gateway key is created; the desktop client supplies the model. The desktop conversation may retain source returned by tools.