dev

A command that detects a project's development command and likely port, starts the development server in a separate terminal, and opens the site in a browser.

In plain words
What is it for?
Use it to launch and view a local web application while keeping the current coding session available.
Why use it?
It avoids manually finding the right start command, opening another terminal, and navigating to the local address.

Command

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add commands/ds1/boilerplate.md/dev
Clone the repo
git clone --depth 1 https://github.com/ds1/boilerplate.md
Per session 0 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 320 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00000 $0.00320
Opus 5 $0.00000 $0.00160
Sonnet 5 $0.00000 $0.00064
Haiku 4.5 $0.00000 $0.00032

Measured yesterday against content hash 670b9299cd23, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

dev scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured yesterday.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

commands/dev.md · 34 lines

What it actually says

Launch Dev Server

Start the development server in a separate terminal window and open the browser.

Steps

  1. Read package.json to detect the dev command and port:

    • Look for scripts.dev to determine the command
    • Check for port hints in the dev script (default to 3000)
    • If no package.json exists, ask the user for the command and port
  2. Launch the dev server in a new terminal window:

    • Windows (PowerShell):
      Start-Process powershell -ArgumentList '-NoExit', '-Command', 'cd \"PROJECT_PATH\"; npm run dev'
      
    • macOS/Linux: Open a new terminal tab/window with the dev command.

    This opens a separate terminal that stays open independently.

  3. Wait 3 seconds for the server to start, then open the browser:

    • Windows: Start-Process "http://localhost:PORT"
    • macOS: open http://localhost:PORT
    • Linux: xdg-open http://localhost:PORT
  4. Confirm to the user: "Dev server running in a new terminal. Browser opened to http://localhost:PORT. This chat session remains available."

Keep the chat unblocked. Never run the dev server in the foreground of this session.


By @ds1boilerplate.md

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. yesterday First seen · 34 lines · 0 tokens per session scan A 670b9299cd23

Subscribe to this mod's changes

dev is a command published in the GitHub repository ds1/boilerplate.md (5 stars, last pushed 6mo ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 320 tokens. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.