setting-up-dev-env

Instructions for preparing a fused-render checkout or Git worktree, which is a separate working copy of a repository, before running tests or the development server.

In plain words
What is it for?
Use it when setting up a fresh worktree, starting the development server, installing test dependencies, or building the React shell.
Why use it?
It prevents missing Python dependencies, the wrong interpreter, or an unbuilt React frontend from causing misleading failures.

Skill for Claude CodeCodex

Part of the fused-render plugin — 14 skills 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 skills/fusedio/fused-render/setting-up-dev-env
Any agent
npx skills add fusedio/fused-render --skill setting-up-dev-env
Clone the repo
git clone --depth 1 https://github.com/fusedio/fused-render

Made for: Claude Code, Codex.

Or install fused-render, the plugin that ships this one along with the rest of its 14 skills.

Per session 55 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 826 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 $0.00055 $0.00826
Opus 5 $0.00028 $0.00413
Sonnet 5 $0.00011 $0.00165
Haiku 4.5 $0.00006 $0.00083

Measured 3d ago against content hash 36f1aa5502c6, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

setting-up-dev-env 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 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.

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.

.claude/skills/setting-up-dev-env/SKILL.md · 49 lines

How it starts

The opening of the file, as written. The whole thing — 49 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Setting Up the Dev Env

Overview

Every fresh checkout/worktree needs a 3.12 venv and a built React shell — both are gitignored, so they don't carry into a worktree. Without them, pytest/python silently run against the wrong interpreter or fail on missing deps, and every server test dies with RuntimeError: React shell not built.

Running the Dev Server

Use scripts/dev.sh — never launch python -m fused_render.cli (or uvicorn) directly. It does almost all the setup for you: bootstraps a repo-local .venv (with [fused,bundled]) if missing, npm installs the frontend, builds shell-dist/, then runs vite build --watch + the server with Python auto-reload and per-worktree port/state isolation.

scripts/dev.sh                 # defaults
scripts/dev.sh --port 9000     # extra args pass through to the server

Setup for Tests

dev.sh covers the server, but its auto-venv has [fused,bundled] only — not the dev extra (pytest/xdist). And tests need a built shell-dist/ or create_app() refuses to start. So the venv install is the one manual step:

uv venv --python 3.12 .venv                                         # pinned: matches what dev.sh and all three installers use
uv pip install --python .venv/bin/python -e ".[dev,bundled,fused]"  # dev extra now includes pytest-xdist

For shell-dist/: if you've run scripts/dev.sh, it's already built. If you'll only run tests and never start the server, build it once directly (repo uses npm, per package-lock.json):

cd frontend && npm install && npm run build && cd ..

Verify: ls fused_render/static/shell-dist/index.html and .venv/bin/python -m pytest -q (~1170 pass).

Reference

Item Why
Python 3.12 pinned, not a default (D214): the server passes its own interpreter to uv sync as the base for every project venv, so this version decides which wheels those venvs can resolve. A 3.14 venv made project venvs cp314, and a folder declaring tensorflow (no cp314 wheels) was an unresolvable dead end. 3.12 is what all three installers already ship, so a dev checkout matches the shipped app. scripts/dev.sh enforces it and rebuilds a .venv that is on anything else
dev extra pytest + httpx (backs TestClient)
bundled extra duckdb, pandas, numpy, pyarrow, pillow… (templates + daemons). NOT the geo/PDF/plotting stack any more (D276) — map, vector, pdf_studio and friends declare those in their own folder pyproject.toml, and the server installs them into a project venv on first render
fused extra compute-engine wheel for /api/run
frontend build create_app() refuses to start without shell-dist/

Read the full file on GitHub · 49 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 · 49 lines · 55 tokens per session scan A 36f1aa5502c6

Subscribe to this mod's changes

setting-up-dev-env is a skill published in the GitHub repository fusedio/fused-render (11 stars, last pushed 4d ago), licensed MIT. It adds 55 tokens to every session and 826 once invoked, about $0.0003 per session on Opus 5. 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 2026-08-30.

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