init: archlens — architecture diagram generator

Hex arch + DDD, tree-sitter parsing, Mermaid/ASCII output.
Supports Rust + Python. 92 tests. CI, diff, --check for staleness detection.

README.md

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+# archlens
+
+Generate architecture diagrams from source code. Runs on CI to keep docs fresh.
+
+Supports Rust and Python. Produces Mermaid or ASCII output.
+
+## Install
+
+```bash
+cargo install --path crates/presentation
+```
+
+## Usage
+
+```bash
+# Module-level dependency graph (default)
+archlens .
+
+# Project-level (crate/package dependencies from manifests)
+archlens . --level project
+
+# Type-level class diagram
+archlens . --level type
+
+# Write to file
+archlens . --output docs/architecture.mmd
+
+# Split by module (one file per module + overview)
+archlens . --level type --split-by-module --output docs/arch/
+
+# ASCII output to terminal
+archlens . --format ascii
+
+# Scope to a subtree
+archlens . --scope src/domain
+
+# Exclude directories
+archlens . --exclude tests/ --exclude generated/
+
+# Verbose logging
+archlens . -v    # info
+archlens . -vv   # debug
+```
+
+## CI Integration
+
+Check if committed diagrams are up to date:
+
+```bash
+archlens . --level project --check --output docs/architecture.mmd
+```
+
+Exit code 1 if the diagram has changed. Use `--strict` to also fail on parse warnings.
+
+Compare current state against an existing file:
+
+```bash
+archlens diff docs/architecture.mmd --level project
+```
+
+## Config
+
+Generate a config file:
+
+```bash
+archlens init
+```
+
+Creates `archlens.toml`:
+
+```toml
+[analysis]
+exclude = ["tests/", "vendor/", "generated/"]
+level = "module"
+
+[modules]
+# "src/infra" = "Infrastructure"
+
+[output]
+format = "mermaid"
+# path = "docs/architecture.mmd"
+split_by_module = false
+```
+
+## Diagram Levels
+
+| Level | What it shows | Source |
+|-------|--------------|--------|
+| `project` | Crate/package dependencies | `Cargo.toml` |
+| `module` | Module-level dependency graph | Imports + manifest deps |
+| `type` | Class diagram with fields, methods, relationships | Source code (tree-sitter) |
+
+## Supported Languages
+
+| Language | Types | Inheritance | Composition | Imports |
+|----------|-------|-------------|-------------|---------|
+| Rust | struct, enum, trait | `impl Trait for Type` | struct fields | `use`, `mod` |
+| Python | class | `class Foo(Bar)` | `__init__` params, type annotations | `import`, `from ... import` |
+| C# | planned | - | - | - |
+
+## Architecture
+
+Built with hexagonal architecture (ports and adapters) + DDD.
+
+```
+crates/
+  domain/           # Core model, zero external deps
+  application/      # Use cases, orchestration
+  adapters/
+    tree-sitter/    # Source code parsing (Rust, Python)
+    cargo-workspace/ # Cargo.toml dependency extraction
+    walkdir/        # File discovery
+    mermaid/        # Mermaid diagram output
+    ascii/          # Terminal output
+    file-writer/    # Write to disk
+    stdout-writer/  # Write to stdout
+    toml-config/    # Config file parsing
+  presentation/     # CLI (clap), composition root
+```
+
+## License
+
+MIT