D3k

d3k Standalone Bootstrap

Use this skill when working in a standalone AI app and you need reliable local web debugging with browser + server context.

Why d3k-first

• d3k captures server logs, browser console, network events, and screenshots in one timeline.
• d3k owns the browser session so the agent can control the same browser being monitored.
• Running npm run dev or bun run dev directly omits this unified telemetry and usually leads to weaker diagnoses.

Auth-Sensitive Browser Rule

For Google OAuth, Supabase auth, and any other auth-sensitive debugging, d3k must own browser startup. Start d3k normally so it launches the app and browser together, including --app-url when the target URL is known.

Do not use d3k agent-browser --profile ... --headed open ..., raw Chrome, Playwright, browser MCP sessions, manual CDP attachment, or any other separate automation browser for auth debugging unless the user explicitly asks for that path. Agent-browser-created/custom Chrome profiles can be rejected by Google with This browser or app may not be secure.

After d3k has launched the browser, use the safe managed-browser path:

d3k agent-browser --require-d3k-browser open "<url>"
d3k agent-browser snapshot -i
d3k agent-browser click @e1
d3k errors --context

If this fails because no d3k-managed browser exists, restart d3k cleanly with its normal browser-owning flow. Do not fall back to creating a new agent-browser Chrome for auth.

Bootstrap Workflow

1. Confirm whether d3k is installed:

command -v d3k >/dev/null && d3k --version

2. If d3k is missing, install dev3000 globally (prefer Bun):

bun install -g dev3000

Fallback if Bun is unavailable:

npm install -g dev3000

3. Start d3k as the runtime and let d3k own browser startup. When the app command, port, and target URL are known, use the normal app-debugging shape:

d3k --no-agent --command "<dev command>" --port <port> --startup-timeout <seconds> --no-tui --app-url "<url>"

For a repo-default shell with no target URL yet:

d3k --no-agent --no-tui -t

4. Keep d3k running while editing code. Do not start a second dev server with npm/bun dev.

5. Drive the page through d3k's active browser session:

d3k agent-browser snapshot -i
d3k agent-browser click @e1
d3k errors --context

Required Browser/Session Default

When a user asks to start or debug an app with d3k, prefer d3k's normal browser-owning flow, including --app-url when a target URL is known.

Do not launch a separate raw Chrome, Playwright browser, browser MCP session, or manually attach to CDP unless the user explicitly asks for that path. Separate automation-only browser profiles can break OAuth flows, especially Google sign-in with This browser or app may not be secure.

After d3k is running, drive the page through d3k agent-browser ... commands so interactions target d3k's active browser session.

If profile or daemon state seems stale, first run:

d3k agent-browser close --all

Then restart d3k cleanly with the normal browser-owning flow.

For a normal app-debugging session, use:

d3k --no-agent --command "<dev command>" --port <port> --startup-timeout <seconds> --no-tui --app-url "<url>"
d3k agent-browser --require-d3k-browser open "<url>"
d3k agent-browser snapshot -i
d3k agent-browser click @e1
d3k errors --context

Non-Auth Fresh Browser/Profile Startup

Use this special-case workflow only for non-auth debugging when the user explicitly asks Codex to start d3k with a fresh browser/profile. Do not use this workflow for Google OAuth, Supabase auth, or any sign-in flow that may reject automation browsers. The default app-debugging workflow is to let d3k own browser startup and then interact through d3k agent-browser.

1. Close any stale agent-browser daemon before launching with --profile. Otherwise agent-browser will reuse the existing daemon and print --profile ignored.

   d3k agent-browser close --all

2. Start the app through d3k in servers-only mode and keep that command running. In Codex, this is more reliable than asking d3k to launch the browser itself when a fresh profile is required.

   d3k --no-agent --no-skills --servers-only --command "npm run dev -- -H 127.0.0.1 -p 3000" --port 3000 --startup-timeout 90 --no-tui

Adjust the package-manager command and port for the project. Prefer --command over --script when passing framework flags. For npm scripts, put flags after --; otherwise tools like Next.js can interpret the port as a project directory.

3. Verify the server before opening more browser windows:

   curl -I http://127.0.0.1:3000

4. Open the fresh profile as a separate browser step:

   d3k agent-browser --allow-new-browser --profile /tmp/d3k-fresh-profile --headed open http://127.0.0.1:3000

5. Sanity-check the opened page:

   d3k agent-browser get title
   d3k agent-browser snapshot -i
   d3k errors

Practical rules:

• Prefer 127.0.0.1 for this workflow. If localhost hangs or flips between IPv4/IPv6 behavior, do not keep retrying browser launches.
• If curl -I hangs, the server is wedged even if the port appears occupied; restart the d3k server process before opening a browser.
• In servers-only mode there is no d3k-managed browser. Use --allow-new-browser only for the explicit non-auth fresh-profile open step; do not use d3k cdp-port.
• In sandboxed agent environments, rerun local-network checks and agent-browser opens outside the sandbox when sandbox networking blocks access to 127.0.0.1.

Debugging Commands

Use these first before ad-hoc log scraping:

d3k errors --context
d3k logs -n 200
d3k logs --type browser
d3k logs --type server

Browser Interaction

Use the already-monitored d3k browser session instead of launching a separate automation browser.

d3k agent-browser --require-d3k-browser open http://localhost:3000
d3k agent-browser snapshot -i
d3k agent-browser click @e2
d3k agent-browser screenshot /tmp/d3k-current.png

d3k agent-browser auto-connects to the active d3k session's browser. --require-d3k-browser fails instead of creating a new browser when no d3k-managed browser exists. Manual CDP attachment, d3k agent-browser connect <port>, and --allow-new-browser are explicit opt-in paths for targeting or creating a different browser, not the default.

Browser Tool Choice

Use the browser tool that matches the task instead of treating them as interchangeable:

• agent-browser
• Default choice.
• Best for generic web apps and for driving the exact headed browser session that d3k is already monitoring.
• Use it when you need snapshot, ref-based click, fill, or to reproduce what the user sees in the monitored tab.
• next-browser
• Next.js-specific tool.
• Best for React/Next introspection: tree, errors, logs, routes, project, PPR inspection, and related Next dev-server signals.
• It is not a drop-in replacement for agent-browser: no accessibility snapshot, no ref-based click, and no fill.
• It launches its own daemon/browser flow and does not use d3k's active browser session.

Practical rule:

• Need to drive the same browser d3k is monitoring: use agent-browser.
• Need Next.js component tree or Next-specific diagnostics: use next-browser.

Examples:

# Same monitored browser session
d3k agent-browser snapshot -i
d3k agent-browser click @e2

# Next.js-specific inspection
d3k next-browser open http://localhost:3000
d3k next-browser tree
d3k next-browser errors
d3k next-browser logs

Artifacts to Read

• ~/.d3k/{project}/d3k.log
• ~/.d3k/{project}/logs/
• ~/.d3k/{project}/screenshots/
• ~/.d3k/{project}/session.json

Operating Rules

• Prefer headed mode for interactive debugging.
• Use --headless only for CI or when explicitly requested.
• Use --servers-only only when browser monitoring is intentionally disabled, and not for auth-sensitive debugging.

Publish Notes (skills.sh)

Skill Path

• Local folder: skills/d3k
• Skill id: d3k

Publish Copy (ready to paste)

Title

d3k

Short description

Bootstraps d3k runtime for standalone AI apps

Long description

Installs/initializes dev3000 (d3k) for standalone agent shells (Codex, Cursor, Claude Code), starts d3k as the default runtime, and uses unified logs plus CDP browser control instead of raw npm/bun dev.

Default prompt

Use $d3k to initialize d3k, start the correct runtime, and drive debugging with unified logs and CDP browser controls.

Source URL

Use the GitHub path to this skill folder in your repo:

https://github.com/vercel-labs/dev3000/tree/main/skills/d3k

If you publish from another branch/ref, replace main with that ref.

Test Install (Codex)

From Codex skill installer flow, install from URL:

https://github.com/vercel-labs/dev3000/tree/main/skills/d3k

Then restart Codex and invoke:

$d3k

Smoke Test Prompt

Use $d3k in this repo and initialize d3k for me.