Use when the user asks to use d3k, run/dev/test/debug a web project with d3k, or reproduce a browser issue. Own the runtime: reuse or background-start d3k non-interactively, wait for readiness, use its project-stable managed Chrome profile, and inspect unified browser/server evidence.

d3k Agent Runtime d3k is the local web runtime for this task. It starts the dev server behind a stable Portless URL, owns a project stable Chrome profile, and records server logs, browser console output, network activity, interactions, and screenshots in one timeline. When this skill triggers, operate d3k. Do not merely tell the user how to run it. Interpret the Request "Let me test/dev my project with d3k": prepare the runtime and headed browser, confirm it is ready, then hand control to the user. Wait for them to reproduce the issue before inspecting evidence. "Test/debug/fix this with d3k": prepare the runtime, then drive the managed browser and investigate autonomously. If ambiguous, start the runtime and browser first. That action is safe and useful for either path. Start or Reuse d3k Run from the project root. 1. Check canonical Portless readiness before starting any app process: If "setupRequired": true , run: On macOS this opens the system administrator authorization dialog. Wait for the user to approve it, then rerun d3k portless status json . Do not start d3k until "canonical": true , "serviceInstalled": true , and "setupRequired": false . If authorization is declined or unavailable, stop and explain the blocker. Never silently substitute direct localhost. 2. Check for an existing project runtime: Reuse it only if it reports "running": true , "ready": true , "routing": "portless" , "browserConnected": true , and a genuinely port free https://...localhost appUrl . If an active session reports "routing": "direct" , stop that retained d3k session and restart after Portless is ready. Do not start a second dev server or browser. 3. If d3k is not installed, install it: Use npm install g dev3000 only when Bun is unavailable. 4. Start d3k with the agent's shell/process tool as a retained background or yielded session (non TUI by default): Do not wait for this long running command to exit. Keep its process/session handle so you can monitor or stop it later. Prefer the execution tool's background/session support over shelling with & . If the target URL is already known, pass it so the managed browser opens there: Let d3k auto detect the package manager, dev command, and port. Add command , script , or port only when detection is wrong or the user specified them. 5. Poll until the runtime is ready: A successful status response is the readiness boundary only when it reports "ready": true , "routing": "portless" , "browserConnected": true , and a port free https://...localhost appUrl . The underlying app port may change between runs. If startup fails, inspect the retained process output and d3k logs type server ; do not launch a separate dev server. User Driven Testing When the user says "let me test": 1. Confirm the status response includes the app URL and "browserConnected": true . 2. Tell the user the monitored browser is ready. 3. Keep the d3k process running and wait for the user to reproduce the behavior. 4. When they report that it happened, begin with: Do not replace the headed browser with automation while the user is testing. Agent Driven Testing Drive the exact browser d3k is monitoring: Use require d3k browser when opening a URL so failure cannot silently create another browser: After every reproduction or code change, replay the relevant interaction and check d3k errors context again. Evidence Commands Prefer these over ad hoc log scraping: Artifacts live under ~/.d3k/<project / , including session.json , logs, screenshots, and the Chrome profile. Browser and Auth Safety d3k must own browser startup by default. Its per project Chrome profile preserves login state, cookies, and local storage. For Google OAuth, Supabase auth, and other auth sensitive flows, never substitute raw Chrome, Playwright, a browser MCP session, manual CDP attachment, or agent browser profile . Those paths use a different browser/profile and can trigger "This browser or app may not be secure." If the managed browser is unavailable, stop or interrupt the retained d3k process and restart d3k cleanly. Do not work around it by creating another browser. Use headless only for CI or when explicitly requested. Use servers only only when browser monitoring is intentionally unwanted. Operating Rules Do not run npm run dev , bun run dev , or another dev server alongside d3k. Do not start a second d3k when d3k status json reports an active one. Keep d3k alive across edits and retests. Preserve the project stable Chrome profile unless the user explicitly asks for a fresh profile. Leave the runtime running when handing a headed browser to the user; stop it only when asked or when the task requires a clean restart. Canonical Portless HTTPS routing is required by default. Never add no portless or set PORTLESS=0 unless the user explicitly requests direct localhost routing.