dart-setup-ffi-assets

A guide to compiling and packaging C or C++ code for use from Dart through Dart's Native Assets system. Native Assets are compiled libraries that a Dart or Flutter project can build and include automatically.

In plain words
What is it for?
Use it to set up C or C++ source compilation, create build and link hooks, package static or dynamic libraries, download prebuilt native libraries, and verify the resulting assets.
Why use it?
It removes much of the manual work involved in connecting Dart code to native libraries and packaging those libraries for different development commands and platforms.

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/flutter/agent-plugins/dart-setup-ffi-assets
Any agent
npx skills add flutter/agent-plugins --skill dart-setup-ffi-assets
Clone the repo
git clone --depth 1 https://github.com/flutter/agent-plugins

Made for: Claude Code, Codex.

Per session 145 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 4,340 The whole file, excluding the scripts and references it only reads on demand.
Security scan B 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 $0.00145 $0.04340
Opus 5 $0.00072 $0.02170
Sonnet 5 $0.00029 $0.00868
Haiku 4.5 $0.00015 $0.00434

Measured yesterday against content hash 361b38a74d11, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade B, and why

dart-setup-ffi-assets scanned grade B 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 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.

Asks for rootmediumPrivilege escalation

A mod that escalates privileges can change anything on the machine, not only the project.

sudo apt install build-essential
Origin

Copies of this mod

1 near-identical copy found in the catalogue:

skills/dart-setup-ffi-assets/SKILL.md · 420 lines

How it starts

The opening of the file, as written. The whole thing — 420 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Compiling C Code into Code Assets with Native Assets Hooks

Integrate and automate the compilation and packaging of native C/C++ source code into Code Assets under Dart's overarching Native Assets feature using build and link hooks.

Contents


Introduction

Under Dart's Native Assets feature, packages can package native code (like C/C++ libraries) as Code Assets and bundle them automatically during standard development cycles (e.g., dart run, dart test, dart build, and flutter run). The packaging of Code Assets is driven by two programmatic hook scripts placed inside a package's hook/ folder:

  1. hook/build.dart: Compiles local C sources to machine code or bundles prebuilt native binaries as code assets for a specific host/target architecture.
  2. hook/link.dart: Links built code assets, applying advanced tree-shaking optimizations to strip unused native symbols and compress the runtime binary size.

Read the full file on GitHub · 420 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. yesterday First seen · 420 lines · 145 tokens per session scan B 361b38a74d11

Subscribe to this mod's changes

dart-setup-ffi-assets is a skill published in the GitHub repository flutter/agent-plugins (2,895 stars, last pushed 3d ago), licensed BSD-3-Clause. It adds 145 tokens to every session and 4,340 once invoked, about $0.0007 per session on Opus 5. A static security scan graded it B with 1 finding (asks for root). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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