add-package

A setup guide for adding a new Dart or Flutter package dependency with the `flutter pub add` or `dart pub add` command.

In plain words
What is it for?
Use it when adding a package or choosing its version constraint in a Dart or Flutter project.
Why use it?
It helps you avoid introducing discontinued packages or versions that are already behind current releases. It also keeps the package manager's output visible for checking problems.

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/devoncarew/flutter-slipstream/add-package
Any agent
npx skills add devoncarew/flutter-slipstream --skill add-package
Clone the repo
git clone --depth 1 https://github.com/devoncarew/flutter-slipstream

Made for: Claude Code, Codex.

Per session 74 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 526 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 $0.00074 $0.00526
Opus 5 $0.00037 $0.00263
Sonnet 5 $0.00015 $0.00105
Haiku 4.5 $0.00007 $0.00053

Measured 2d ago against content hash 3c423b2062e7, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

add-package 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.

skills/add-package/SKILL.md · 71 lines

What it actually says

Adding a Dart/Flutter Package Dependency

Preferred approach

Use flutter pub add <package> (or dart pub add) rather than editing pubspec.yaml directly. The pub command output is the primary signal for package health; direct edits bypass it.

Read pub output after every add

After running pub add, read the output carefully before proceeding. Two classes of problem appear inline:

Discontinued packages

+ flutter_markdown 0.7.7+1 (discontinued replaced by flutter_markdown_plus)
...
1 package is discontinued.

Action:

  • If a replacement is listed: remove the discontinued package and add the replacement instead (flutter pub remove <pkg> then flutter pub add <replacement>).
  • If no replacement is listed: find a well-maintained alternative before proceeding.

Version pinned behind current major

+ lints 4.0.0 (6.1.0 available)
...
4 packages have newer versions incompatible with dependency constraints.

The (X.Y.Z available) annotation on a package you just added means the version you requested is behind the current release — often by a major version.

Action:

  • Run flutter pub outdated to see the structured breakdown:

    Package Name  Current  Upgradable  Resolvable  Latest
    lints         *4.0.0   *4.0.0      6.1.0       6.1.0
    
  • If a direct dependency you just added shows a major-version gap between Current and Latest, remove the version pin or update the constraint to the current major (flutter pub add 'lints:^6.0.0').

  • Transitive dependency gaps are generally not actionable — note them but don't block on them.

When editing pubspec.yaml directly

If you add a dependency by editing pubspec.yaml instead of using pub add, run flutter pub get immediately after and apply the same output-reading rules.

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 · 71 lines · 74 tokens per session scan A 3c423b2062e7

Subscribe to this mod's changes

add-package is a skill published in the GitHub repository devoncarew/flutter-slipstream (5 stars, last pushed 15d ago), licensed BSD-3-Clause. It adds 74 tokens to every session and 526 once invoked, about $0.0004 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 2026-08-31.

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