package-managers

A guide for choosing and using the JavaScript package manager already selected by a repository. Package managers install libraries and run project scripts, while lockfiles record the exact dependency versions.

In plain words
What is it for?
Use it before installing packages or running scripts in a JavaScript or TypeScript project, especially in a monorepo, which is a repository containing multiple related projects. It explains how to identify the correct manager and working directory.
Why use it?
It prevents mixing npm, pnpm, Yarn, or Bun and creating conflicting dependency trees or lockfiles. It also helps diagnose installation failures without masking the real cause.

Skill for Claude CodeCodex

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/zfinix/aster/package-managers
Any agent
npx skills add Zfinix/aster --skill package-managers
Clone the repo
git clone --depth 1 https://github.com/Zfinix/aster

Made for: Claude Code, Codex.

Per session 39 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 347 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 $0.00039 $0.00347
Opus 5 $0.00019 $0.00173
Sonnet 5 $0.00008 $0.00069
Haiku 4.5 $0.00004 $0.00035

Measured 2d ago against content hash cd9f84e78d12, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

package-managers 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 2d 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.

crates/aster-skills/optional-skills/package-managers/SKILL.md · 26 lines

What it actually says

Package managers

  1. The lockfile picks the manager. bun.lock/bun.lockb means bun, pnpm-lock.yaml means pnpm, yarn.lock means yarn, package-lock.json means npm. Never mix: running npm in a bun repo creates a second lockfile and a second dependency tree.
  2. Run from the directory that owns the lockfile, not the repo root of a monorepo.
  3. Scripts go through the owner. bun run build, pnpm run test; one-offs with bunx tool or pnpm dlx tool, never bare npx in a non-npm repo.
  4. A failed install is not a reason to switch managers. If bun install fails, npm install in the same repo fails for the same underlying reason and leaves a mess behind. Diagnose the actual error instead.
  5. Permission errors during installs are usually the sandbox. Writes are allowed in the repository, temp directories, and package caches (~/.npm, ~/.bun, ~/.cargo). An error naming another path means the sandbox blocked it; report the path instead of retrying.
  6. Offline or turbo mode blocks the network. Installs need the network; say that plainly instead of retrying the install.
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. 2d ago First seen · 26 lines · 39 tokens per session scan A cd9f84e78d12

Subscribe to this mod's changes

package-managers is a skill published in the GitHub repository Zfinix/aster (40 stars, last pushed 7d ago), licensed Apache-2.0. It adds 39 tokens to every session and 347 once invoked, about $0.0002 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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