modulith-android 0.1.2

Architectural audit tool for multi-module Gradle Android projects.

🧱 modulith-android

Architectural audit for multi-module Gradle Android projects — cycles, layer violations, visibility issues, unused dependencies, and impact cascades, all in a single self-contained HTML report.

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Point it at any Gradle Android repo. It parses your settings.gradle[.kts], walks every module's build file, scans your Kotlin/Java sources for cross-module imports, and produces a single self-contained HTML file with:

• 🕸️ Module graph — every :layer:name module and its dependency edges, colour-coded by layer.
• 🔁 Cycle detection — Tarjan-based strongly-connected components; any cyclic coupling between modules is flagged.
• 🚫 Layer violations — edges that cross a forbidden layer pair (e.g. core → feature under Clean Architecture), with the offending Gradle dependency listed.
• 👁️ Visibility audit — for the modules you choose, every public symbol is classified as internalize_candidate, di_required, external_consumer, or star_import_uncertain so you know what's actually load-bearing.
• 🪦 Unused module dependencies — flags project(":foo") declarations whose target module's packages the consumer's source never imports. Variant-aware: build types, product flavors, and variant combinations (preprodDebugImplementation, debugImplementation, ...) are scanned against the matching source sets, not just src/main.
• 💥 Impact cascades — pick a module, see every module that transitively depends on it.
• 📊 Rankings — modules sorted by fan-in, fan-out, instability, and abstractness.

Configuration-driven and project-agnostic. Every project-specific value (root package, layer names, forbidden layer pairs, audited modules) lives in a single modulith.toml at your repo root. Run modulith-android init and the wizard auto-detects sensible defaults in seconds — confirm with Enter, edit otherwise. Drop it into any Gradle Android project and you're scanning in under a minute.

A report generator, not a CI gate. modulith-android never fails a build and never exits non-zero based on findings. It reads, computes, and writes — interpretation and policy belong to whoever reads the report. By design.

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🚧 Status

Pre-alpha. v0.1.0 in active development. The repository scaffold is in place; CLI, wizard, and analysis pipeline land progressively as the milestones in the roadmap ship. The quick start below describes the shipped behaviour at v0.1.0.

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🚀 Quick start

# one-shot, no install — needs uv (https://docs.astral.sh/uv/)
uvx --from modulith-android modulith-android init   # wizard writes ./modulith.toml
uvx --from modulith-android modulith-android        # writes build/dependency-graph/index.html

Prefer an installed entry-point? Use pipx:

pipx install modulith-android
modulith-android init
modulith-android

The default run writes build/dependency-graph/index.html. Open it in any browser — no static server, no JavaScript build, no external assets.

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🛠️ Commands

Command	What it does	Output
modulith-android init	runs the interactive wizard with auto-detected defaults	./modulith.toml
modulith-android	runs the full analysis using ./modulith.toml	build/dependency-graph/index.html
modulith-android --repo PATH	analyse a project in a different directory	report in that project's build/
modulith-android --out PATH	write the report somewhere else	HTML at the supplied path
modulith-android --config PATH	use a config file at a non-default location	unchanged
modulith-android --quiet	suppress per-phase progress lines on stderr	unchanged

Exit codes are 0 on success and 1 on configuration / I/O errors. Findings never change the exit code.

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🪄 The wizard

modulith-android init runs four short questions, each with an auto-detected default. Confirm with Enter; edit anything that looks off.

#	Question	Auto-detected from
1	Root package (e.g. com.example)	Scans .kt/.java files, computes the longest common package prefix.
2	Layer names (e.g. core, data, feature, app)	Reads settings.gradle[.kts], extracts the first segment of each module path.
3	Modules to audit for visibility	Pre-selects all modules in the innermost layer; multi-select to customise.
4	Forbidden layer pairs	Offers presets (Clean Architecture, MVI/MVVM) or "Custom" for manual entry.

The wizard prints the generated modulith.toml for review and asks before writing.

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⚙️ Configuration

The full modulith.toml schema:

# Generated by `modulith-android init`. Hand-edit anything you like.

[scan]
# Root Java/Kotlin package. Used by the visibility analyzer to scope
# import-index scanning to symbols declared in this package tree.
root_package = "com.example"

[layers]
# Ordered list of layer names, derived from the first segment of each
# Gradle module path (e.g. ":core:logger" -> "core"). Modules whose
# first segment isn't listed are parsed for edges but excluded from
# violation checking.
names = ["core", "data", "feature", "app"]

[visibility]
# Gradle module paths whose public API will be enumerated and
# cross-checked for external references.
target_modules = [
    ":core:logger",
    ":core:network",
]

# Each [[violations]] entry forbids a directed edge between two layers.
# Multiple entries are independent — they don't compose.
[[violations]]
from = "core"
to   = "data"

[[violations]]
from = "core"
to   = "feature"

[[violations]]
from = "data"
to   = "feature"

Missing sections are silently treated as "skip this analysis" — e.g. an absent [visibility] skips the visibility audit, an empty [[violations]] table means no violation rules are active. A missing modulith.toml is a hard error with a "run modulith-android init" hint.

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📋 Requirements

Tool	Why	Notes
Python 3.10+	runs the analyzer	stdlib-only on 3.11+; one backport (tomli) on 3.10
uv or pipx (recommended)	one-shot or isolated install	pip install --user modulith-android works too
Gradle project	the analysis target	Groovy or Kotlin DSL settings.gradle — both are supported

The analyzer itself has zero runtime dependencies on Python 3.11+ and exactly one (tomli) on Python 3.10. No HTML/JS framework, no JSON schema library, no graph library — pure stdlib. No third-party Gradle plugin in the consumer's project either: every feature works against a vanilla Gradle build.

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🧩 How it works

                       modulith-android
                              │
   ┌──────────────────────────┼─────────────────────────────────────┐
   │ 1. read modulith.toml — every project-specific value           │
   ├────────────────────────────────────────────────────────────────┤
   │ 2. parse settings.gradle[.kts]            → list of modules    │
   │    parse each module's build.gradle[.kts] → edges              │
   ├────────────────────────────────────────────────────────────────┤
   │ 3. core graph algorithms (stdlib only):                        │
   │      Tarjan SCC          → cycles                              │
   │      layer-pair filter   → violations                          │
   │      reverse-BFS         → cascades                            │
   │      fan-in/out, etc.    → metrics                             │
   ├────────────────────────────────────────────────────────────────┤
   │ 4. cross-check declared project deps against source imports    │
   │      → unused module dependencies                              │
   ├────────────────────────────────────────────────────────────────┤
   │ 5. scan public API of audited modules; classify each symbol    │
   │      by external-consumer count + Hilt/Koin DI markers         │
   ├────────────────────────────────────────────────────────────────┤
   │ 6. render a single self-contained HTML file                    │
   │      → build/dependency-graph/index.html                       │
   └────────────────────────────────────────────────────────────────┘

Every output is deterministic: given identical inputs the HTML is byte-for-byte the same, so regenerating after a code change produces a clean diff you can review.

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🗂️ Project layout

modulith-android/
├── src/modulith_android/
│   ├── cli.py                 entry-point; argparse dispatch
│   ├── config.py              ModulithConfig dataclass + TOML loader
│   ├── wizard.py              interactive `init` flow with auto-detect
│   ├── parsers/
│   │   └── gradle_modules.py  settings.gradle[.kts] + build.gradle[.kts] reader
│   ├── analyzers/
│   │   ├── unused_module_deps.py  cross-checks declared project deps against source imports
│   │   └── visibility_audit.py    public-API scanner + DI-marker classifier
│   ├── core/
│   │   ├── model.py           Edge, Module, GraphSnapshot
│   │   ├── cycles.py          Tarjan SCC
│   │   ├── cascades.py        transitive impact computation
│   │   ├── metrics.py         fan-in, fan-out, instability, abstractness
│   │   └── violations.py      layer-rule checker
│   ├── reports/
│   │   ├── html.py            the self-contained HTML+CSS+JS report
│   │   └── json_export.py     machine-readable graph dump
│   ├── common/
│   │   └── paths.py           module-path utilities
│   └── flows/
│       └── analyze.py         orchestrates the full pipeline
├── tests/                     stdlib-unittest suite, no pip deps
├── pyproject.toml
├── LICENSE
└── README.md

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🧑‍💻 Direct CLI

uvx/pipx are the easy paths, but the package is a normal CLI. Once installed:

modulith-android [SUBCOMMAND] [OPTIONS]

Subcommands:
  init                run the wizard; writes ./modulith.toml

Options (default run):
  --repo PATH         repository root (default: cwd)
  --out PATH          output directory (default: <repo>/build/dependency-graph)
  --config PATH       config file (default: <repo>/modulith.toml)
  --quiet             suppress per-phase progress logging on stderr
  -h, --help          show this help and exit
  --version           show version and exit

Exit codes:
  0  success; HTML report written
  1  configuration or I/O error

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🧪 Development

pip install -e ".[dev]"
python -m pytest tests/                          # full suite
python -m pytest tests/test_visibility_audit.py  # one module
ruff check src/ tests/                           # lint

Tests use stdlib unittest; pytest discovers them with no configuration. CI runs the suite on Python 3.10 and 3.12.

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🗺️ Roadmap

• v0.1.0 — analyzer core, modulith.toml config, wizard with auto-detect, self-contained HTML report, PyPI publication.
• v0.2.0 — JSON export improvements; richer cascade visualisation; configurable Hilt/Koin marker sets.
• v0.3.0 — multi-DSL improvements (KTS multi-line includes, type-safe project accessors).
• v1.0.0 — API stability promise.

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🎯 Scope

modulith-android focuses on modularity: graph shape, layer rules, visibility, and unused inter-module dependencies. It does NOT audit external Maven dependencies or Gradle configuration hygiene (api vs implementation, scope choices). For that, plugins like the Dependency Analysis Gradle Plugin are excellent companions and orthogonal to what this tool does.

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📄 License

MIT — see LICENSE.