ren 0.0.1

A static analysis tool that measures the performance weight of each feature in your Flutter app — detecting costly AST patterns and reporting a gravity score per feature.

REN

Flutter Feature Gravity Analyzer

REN measures the performance weight of each feature in your Flutter project by detecting costly AST patterns — reporting a gravity score per feature, without running the app, without Firebase, without manual instrumentation.

---

Installation

dart pub global activate ren

Usage

# Analyze the current project
ren

# Analyze a specific path
ren --project ./my_app

# Custom feature root
ren --project ./my_app --features lib/ui/screens

# Exclude generated or internal paths
ren --project ./my_app --exclude lib/generated,lib/_tools

# JSON output for CI/CD
ren --format json > ren-report.json

# Fail pipeline if any feature reaches HIGH or above
ren --fail-on high

How it works

ren scans your project's Dart source files using the analyzer package, visits the AST of each file, and detects patterns known to cause performance issues in Flutter apps. Each pattern carries a weight, and the total weight per feature is normalized to a 0–100 gravity score.

If no feature root is found (lib/features/, lib/modules/), ren falls back to treating lib/ as a single feature — so it always produces output regardless of your project structure.

Detected patterns

Category	Pattern	Weight
GPU	BackdropFilter	40
GPU	saveLayer	45
GPU	ShaderMask	35
GPU	ImageFiltered	35
GPU	ClipPath	25
GPU	Opacity	25
GPU	CustomPaint	20
GPU	ColorFiltered	20
Lists	ListView	30
Lists	GridView	30
Lists	SingleChildScrollView	20
Lists	Wrap	15
Images	Image.network	25
Images	NetworkImage	25
Images	FadeInImage	15
Rebuilds	MediaQuery.of	20
Rebuilds	RepaintBoundary	15
Memory leaks	Timer	20
Memory leaks	Timer.periodic	30
Memory leaks	StreamController	25
Memory leaks	StreamSubscription	25
Lifecycle	setState in dispose	60
Lifecycle	setState in build	50
Lifecycle	setState in initState	35

Gravity levels

Score	Level
0–20	🟢 LOW
21–45	🟡 MEDIUM
46–70	🟠 HIGH
71–100	🔴 CRITICAL

CI/CD

- name: Ren — Feature Gravity
  run: |
    dart pub global activate ren
    ren --format json > ren-report.json
    ren --fail-on high

License

Apache 2.0 — see LICENSE.