fCheck

fCheck provides fast local quality analysis for Flutter and Dart projects with 0-100% compliance scoring. Single analysis pass covering architecture, maintainability, and safety issues beyond standard linting, with deterministic CLI/JSON reports for CI/CD pipelines and fully private execution: it does not require any AI service, no network calls are needed, and no source code is sent to external services.

Why fCheck

Single local run for multiple quality domains
Deterministic output for CI and code review
100% private local execution (no AI service, no code sent externally)
Console, JSON, and diagram outputs
Includes test discovery metrics (hasTests, testDirectories, testFiles, testDartFiles, testCases)
Works as a CLI tool
Works as a Dart package in your own app/tooling

Checks Included

code_size
dead_code
documentation
duplicate_code
hardcoded_strings
layers
magic_numbers
one_class_per_file
secrets
source_sorting

Detailed behavior and edge cases are documented in RULES*.md.

Hardcoded-strings note:

If project localization is OFF, hardcoded-strings runs in passive mode ([-]), reports only the total count, and does not affect compliance score/focus area.
If project localization is OFF, hardcoded-string findings are also excluded from SVG warning tint/counters (fcheck_files.svg, fcheck_folders.svg, fcheck_loc.svg).
If localization is ON, hardcoded-strings is active and reports detailed issue entries.

Code-size LOC note:

Localization Dart files are excluded from LOC code-size evaluation (lib/l10n/**, app_localization.dart, app_localizations.dart, and generated locale variants such as app_localizations_<locale>.dart).

Install

Option 1: Global CLI

dart pub global activate fcheck
fcheck .

Option 2: Project Dev Dependency

dart pub add fcheck -d
dart run fcheck .

Option 3: Use as a Dart package in your app/tool

dart pub add fcheck

import 'dart:io';
import 'package:fcheck/fcheck.dart';

void main() {
  final metrics = AnalyzeFolder(Directory('.')).analyze();
  print('Score: ${metrics.complianceScore}%');
}

Quick Start (CLI)

# Analyze current folder
fcheck .

# Analyze another folder
fcheck ../my_app
fcheck --input ../my_app

# JSON output
fcheck --json

# Full list output
fcheck --list full

# Generate diagrams
fcheck --svg --mermaid --plantuml

# Auto-fix source sorting issues (class members + import directives)
fcheck --fix

What `--fix` does

Rewrites Dart source files in place.
Applies only source_sorting auto-fixes:
- Reorders Flutter widget class members to match fCheck sorting rules.
- Reorders import directives with these groups:
  - dart:*
  - all package:* imports (including flutter and your own package), alphabetical
  - other absolute URIs (for example http:)
  - relative imports
- Inserts one blank line between import groups.
- Rewrites relative imports that resolve under lib/ to package:<this-package>/....
Does not auto-fix other analyzers; it only reports their issues.

Sample Bash Output

$ fcheck .
↓------------------------------ fCheck 1.0.8 -------------------------------↓
Input              : /path/to/project
Dart Project       : my-cool-app (version: 9.0.0)
Platforms          : [✓Android] [✓iOS]  [✓MacOS] [✓Windows] [✓Linux]   [✓Web]
--------------------------------- Dashboard ---------------------------------
Dependencies       :               5  |  DevDependencies    :               2
Folders            :              21  |  Classes            :              66
Files              :             120  |  Widgets: Stateful  :              26
Excluded Files     :              39  |  Widgets: Stateless :              40
Dart Files         :              91  |  Methods            :             357
Lines of Code      :       15.0 KLoC  |  Functions          :             179
Comments           :     2,145 (14%)  |
----------------------------------- Tests -----------------------------------
Test Dart Files    :              35  |  Touched Dart Files :         41 (45%)
Test Cases         :             392  |  Touched Classes    :         31 (47%)
                                      |  Touched Methods    :        144 (40%)
                                      |  Touched Functions  :         73 (41%)
--------------------------------- Literals ----------------------------------
Localization       : ON
Strings            : 1,203 (64% dupe)
Numbers            :   842 (74 hardcoded)
--------------------------------- Analyzers ---------------------------------
[✓] Checks bypassed
[✓] Code size
[✓] Dead code
[✓] Documentation
[✓] Duplicate code
[✓] Layers architecture
[✓] Magic numbers
[✓] One class per file
[✓] Secrets
[✓] Source sorting
[✓] Hardcoded strings
--------------------------------- Scorecard ---------------------------------
Total Score        : 100%
Invest Next        : Maintain this level by enforcing fcheck in CI on every pull request.
↑------------------------ fCheck completed (1.73s) -------------------------↑

The Touched ... rows are a static inventory derived from test-file imports plus transitive project-local Dart dependencies. They indicate source reached by test dependency graphs, not code coverage.

Configuration (`.fcheck`)

Create .fcheck in the input directory (--input) or current directory.

input:
  root: app
  exclude:
    - "**/generated/**"
    - "**/*.g.dart"

analyzers:
  default: on
  disabled:
    - hardcoded_strings
    - source_sorting
  options:
    duplicate_code:
      similarity_threshold: 0.85 # 0.0..1.0
      min_tokens: 20
      min_non_empty_lines: 10
    code_size:
      max_file_loc: 900
      max_class_loc: 800
      max_function_loc: 700
      max_method_loc: 500

Notes:

analyzers.default accepts on|off and true|false
Opt-in mode:

analyzers:
  default: off
  enabled:
    - magic_numbers
    - secrets

Config precedence: built-in defaults < .fcheck < CLI flags
input.root is resolved relative to the .fcheck file location
--exclude adds patterns on top of .fcheck input.exclude

Ignore Directives

Use top-of-file or line-level ignore directives:

// ignore: fcheck_dead_code
// ignore: fcheck_documentation
// ignore: fcheck_duplicate_code
// ignore: fcheck_hardcoded_strings
// ignore_for_file: avoid_hardcoded_strings_in_widgets
// ignore: fcheck_layers
// ignore: fcheck_magic_numbers
// ignore: fcheck_one_class_per_file
// ignore: fcheck_secrets

CLI help to guide you on how to exclude some of checks

fcheck --help-ignore

Dead-code note:

// ignore: fcheck_dead_code suppresses dead-code findings for that file's declarations, while keeping its dependencies/usages in global dead-code analysis.
Dead-code usage tracking includes property-style getter/setter access and operator usage (+, -, [], etc.) inferred from expression syntax.
Functions/methods annotated with @Preview (including prefixed forms such as @ui.Preview) are treated as externally used and are not reported as dead functions.

Visual Outputs

fcheck --svg          # shortcut: fcheck_files.svg + fcheck_folders.svg + fcheck_loc.svg
fcheck --svg-files    # fcheck_files.svg
fcheck --svg-folders  # fcheck_folders.svg
fcheck --svg-loc      # fcheck_loc.svg
fcheck --mermaid      # fcheck.mmd
fcheck --plantuml     # fcheck.puml

# Custom output base directory
fcheck --svg --mermaid --plantuml --output ./reports/fcheck

# Per-artifact file overrides
fcheck --svg --output-svg-files ./artifacts/graph/files.svg
fcheck --svg-folders --output-svg-folders ./artifacts/graph/folders.svg
fcheck --svg-loc --output-svg-loc ./artifacts/graph/loc.svg
fcheck --mermaid --output-mermaid ./artifacts/graph/fcheck.mmd
fcheck --plantuml --output-plantuml ./artifacts/graph/fcheck.puml

Layers Files diagram

fcheck layers files diagram

Layers Folder diagram

fcheck Layer folders diagram

Orange upward folder dependencies in fcheck_folders.svg are also emitted in CLI report output as layers warnings (wrongFolderLayer) with the source Dart file path.

Warning/error-highlighted file and folder nodes in layers SVGs now use a softer transparent gradient tint (instead of opaque flat fills) to preserve node text/details readability.

Code size diagram

fcheck code size diagram

fcheck_loc.svg uses a unified treemap hierarchy: Folders > Files > Classes > Functions.

Warning highlighting in fcheck_loc.svg:

Artifacts with analyzer findings are tinted on a red transparency spectrum (low warnings => light pink, high warnings => stronger red).
Dead artifacts are treated as maximum severity tint.
SVG tooltips include warning counts and sampled issue details for each affected file/class/function tile.

Exclusions

# Add custom excludes
fcheck --exclude "**/generated/**" --exclude "**/*.g.dart"

# Inspect excluded items
fcheck --excluded
fcheck --excluded --json

# Inspect ignore/suppression inventory (.fcheck + Dart directives)
fcheck --ignores
fcheck --ignores --json

# Inspect literals inventory only
fcheck --literals
fcheck --literals --json

--ignores groups results by suppression type (exclude, analyzer skips, and Dart comment directive type) so cleanup work can be prioritized. --literals full list text output od all the literals in your project.

Default exclusion behavior includes hidden folders and common non-analysis directories (.git, .dart_tool, build, example, test, integration_test, platform folders, etc.).

Generated Dart files ending with *.g.dart are analyzed for dependency/usage flow, but non-actionable checks are suppressed (for example code size, one-class-per-file, dead-code declarations, hardcoded strings, magic numbers, sorting, duplicate code, and documentation).

CI Example (GitHub Actions)

name: CI
on:
  pull_request:
  push:
    branches: [main]

jobs:
  quality:
    name: Build, test, and self-check (100%)
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: subosito/flutter-action@v2
        with:
          channel: stable
      - run: flutter pub get
      - run: ./tool/generate_version.sh
      - run: dart format --output=none --set-exit-if-changed .
      - run: flutter analyze lib test --no-pub
      - run: dart test --reporter=compact
      - run: dart run ./bin/fcheck.dart --json --exclude "**/example" . > fcheck-report.json
      - run: |
          score="$(grep -oE '"complianceScore"[[:space:]]*:[[:space:]]*[0-9]+([.][0-9]+)?' fcheck-report.json | head -n1 | sed -E 's/.*:[[:space:]]*//')"
          score_int="$(awk "BEGIN { printf \"%d\", ${score} }")"
          test "$score_int" -eq 100
      - uses: actions/upload-artifact@v4
        with:
          name: fcheck-report
          path: fcheck-report.json

This repository already includes this workflow at .github/workflows/ci.yml. The CI gate fails unless fcheck's self-analysis score is exactly 100%.

License

MIT

fCheck

Why fCheck

Checks Included

Install

Option 1: Global CLI

Option 2: Project Dev Dependency

Option 3: Use as a Dart package in your app/tool

Quick Start (CLI)

What `--fix` does

Sample Bash Output

Configuration (`.fcheck`)

Ignore Directives

Visual Outputs

Layers Files diagram

Layers Folder diagram

Code size diagram

Exclusions

CI Example (GitHub Actions)

License

Libraries

fcheck package

fCheck

Why fCheck

Checks Included

Install

Option 1: Global CLI

Option 2: Project Dev Dependency

Option 3: Use as a Dart package in your app/tool

Quick Start (CLI)

What --fix does

Sample Bash Output

Configuration (.fcheck)

Ignore Directives

Visual Outputs

Layers Files diagram

Layers Folder diagram

Code size diagram

Exclusions

CI Example (GitHub Actions)

License

Libraries

fcheck package

What `--fix` does

Configuration (`.fcheck`)