dev-environment

An agent that detects repository types and determines how to start their development servers.

In plain words
What is it for?
Use it to inspect the workspace repository list, identify projects such as Next.js applications, and prepare startup information for web, mobile, API, or all detected targets.
Why use it?
It removes the need to manually work out which projects exist and which startup command each one needs.

Agent

Part of the code plugin — 17 agents shipped together

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 agents/closedloop-ai/claude-plugins/dev-environment
Clone the repo
git clone --depth 1 https://github.com/closedloop-ai/claude-plugins

Or install code, the plugin that ships this one along with the rest of its 17 agents.

Per session 30 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,184 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. 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 $0.00030 $0.01184
Opus 5 $0.00015 $0.00592
Sonnet 5 $0.00006 $0.00237
Haiku 4.5 $0.00003 $0.00118

Measured 3d ago against content hash 316a049ea253, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

dev-environment scanned grade A with 1 finding 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 3d ago.

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.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

| Next.js | http://localhost:3000 | `curl -s -o /dev/null -w "%{http_code}" URL` |
plugins/code/agents/dev-environment.md · 135 lines

How it starts

The opening of the file, as written. The whole thing — 135 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Dev Environment Agent

Introspect workspace repositories to determine how to start development servers.

Environment

  • CLOSEDLOOP_WORKDIR: The working directory. The actual path is provided in the <closedloop-environment> block and/or as WORKDIR= in the orchestrator prompt. You MUST resolve this to the absolute path and use it for ALL file operations (Read, Glob, Bash). Never write files like .dev-environment.json to relative paths — always use the full CLOSEDLOOP_WORKDIR path as the prefix.
  • TARGET: What to start (e.g., "web", "ios", "android", "api", or "auto" to detect all) - provided by orchestrator

Process

Step 1: Load Workspace Repos

Read $CLOSEDLOOP_WORKDIR/.workspace-repos.json if it exists. This file is created by cross-repo-coordinator and contains:

{
  "currentRepo": {"name": "...", "type": "...", "path": "..."},
  "peers": [{"name": "...", "type": "...", "path": "..."}]
}

If the file doesn't exist, only introspect $CLOSEDLOOP_WORKDIR as the current repo.

Step 2: Detect Project Types

For each repo, look for these files:

Files Found Project Type
package.json + next.config.* Next.js
package.json + expo in dependencies Expo
package.json + react-native (no expo) React Native CLI
build.gradle or build.gradle.kts Android
*.xcodeproj or *.xcworkspace iOS
pyproject.toml or requirements.txt + FastAPI/Flask/Django Python API

Step 3: Find Dev Commands

For Node.js projects - read package.json scripts:

  • Common web: dev, start, web, serve
  • Common mobile: ios, android, start
  • Detect package manager: yarn.lock → yarn, pnpm-lock.yaml → pnpm, else npm

For Python projects:

  • FastAPI: uvicorn main:app --reload or check pyproject.toml scripts
  • Flask: flask run
  • Django: python manage.py runserver

Step 4: Determine Health Checks

Project Type Default URL Check Command
Next.js http://localhost:3000 curl -s -o /dev/null -w "%{http_code}" URL
Expo Web http://localhost:8081 curl -s -o /dev/null -w "%{http_code}" URL
FastAPI http://localhost:8000 curl -s -o /dev/null -w "%{http_code}" URL/docs
iOS Simulator N/A xcrun simctl list | grep Booted
Android Emulator N/A adb devices | grep -w device

Read the full file on GitHub · 135 lines

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. 3d ago First seen · 135 lines · 30 tokens per session scan A 316a049ea253

Subscribe to this mod's changes

dev-environment is an agent published in the GitHub repository closedloop-ai/claude-plugins (103 stars, last pushed 5d ago), licensed Apache-2.0. It adds 30 tokens to every session and 1,184 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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