praevisio 0.1.0

A CLI tool for AI governance through verifiable promises.

praevisio

A CLI tool for AI governance through verifiable promises.

This repository follows Readme-Driven Development and an outside-in approach. The white paper is the source of truth for behavior and outcomes we intend to deliver; we implement from the boundary inward until the tool matches the spec.

• White paper: docs/white-paper.md (rendered by Sphinx)
• Built docs entry point: docs/index.md

Quickstart (uv)

0. Install uv (see https://docs.astral.sh/uv/)

1. Create a virtual environment and install dependencies

• uv venv
• uv sync --all-groups # installs docs dependencies too

2. Build the docs

• uv run sphinx-build -b html docs docs/_build/html
• Open docs/_build/html/index.html in your browser

Alternative (pip/venv)

1. Create and activate a virtual environment

• macOS/Linux
  • python3 -m venv .venv
  • source .venv/bin/activate
• Windows (PowerShell)
  • py -3 -m venv .venv
  • .venv\Scripts\Activate.ps1

2. Install documentation dependencies

• pip install -r requirements.txt

3. Build the docs

• make -C docs html
• Open docs/_build/html/index.html in your browser

Build and publish (uv)

• Build artifacts (sdist/wheel):
  • uv build
• Publish to PyPI (requires a token):
  • uv publish --token $PYPI_API_TOKEN

Architecture overview

Layers

• Domain (src/praevisio/domain): Core concepts and rules
  • Entities: Hook, HookResult, ValidationRule, CommitContext
  • Value Objects: HookType, ExitCode, FilePattern
  • Services: HookSelectionService (type filtering, dependency ordering, file pattern matching)
  • Ports: PromiseRepository, GitRepository, ProcessExecutor, FileSystemService, ConfigLoader
• Application (src/praevisio/application): Use cases/orchestration
  • HookOrchestrationService (hook_service.py): run hooks of a given HookType in correct order
  • PromiseService (promise_service.py): register and persist promises
  • ConfigurationService: load .praevisio.yaml into domain Configuration
  • InstallationService: write a default .praevisio.yaml
  • ValidationService: validate configuration & hook definitions
  • services.py: compatibility re-exports for older imports
• Infrastructure (src/praevisio/infrastructure): Adapters to ports
  • git.py (InMemoryGitRepository), process.py (RecordingProcessExecutor), filesystem.py (LocalFileSystemService), config.py (YamlConfigLoader, InMemoryConfigLoader)
  • Planned: ApiClient adapter(s)
• Presentation (src/praevisio/presentation): CLI and other interfaces
  • Typer-based CLI (praevisio). Commands map to application services

Configuration as a domain concept

• Canonical file: .praevisio.yaml

• Example:

  hooks:

  • id: example-lint name: Example Lint type: pre-commit command: ["echo", "lint"] patterns: ["**/*.py"] depends_on: [] enabled: true file_scoped: true

Error handling

• ConfigurationInvalidException thrown by ValidationService
• Hook results carry ExitCode; future HookFailedException can be added for richer flow control

Dependency injection

• Application services accept ports via constructor injection for easy testing and swapping infrastructure adapters.

BDD with Behave

• Install dev dependencies (includes behave):
  • uv sync --group dev # or uv sync --all-groups
• Run the feature tests:
  • uv run behave -f progress

Example feature implemented

• Run pre-commit hooks: Skip hooks when no files match pattern
  • Given a repository with staged Python files (only .py)
  • And a hook configured for "*.js"
  • When I run pre-commit hooks
  • Then the hook should be skipped

Architecture notes:

• The project uses a layered architecture:
  • domain: core business objects and abstractions (no infra/presentation deps)
  • application: orchestrates use cases via domain and ports
  • infrastructure: adapter implementations (e.g., repositories)
  • presentation: CLI/HTTP adapters (to be added)
• Application services return domain objects or simple data structures, keeping them reusable across interfaces.

CLI entry point

• praevisio (Typer-based):
  • uv run praevisio install # writes a default .praevisio.yaml
  • uv run praevisio pre-commit # loads config, validates, runs pre-commit hooks
  • uv run praevisio evaluate-commit path/to/commit # MVP evaluation (credence + verdict)
  • python -m praevisio # equivalent entry point

Outside-in MVP flow with a separate lab repo (praevisio-test)

• In praevisio/: install as editable so the CLI and module are available to the lab
  • pip install -e .
• In praevisio-test/: write Behave tests that call the CLI, e.g.:
  • praevisio evaluate-commit commits/compliant/c1
• Minimal evaluation implemented:
  • Reads app/src/llm_client.py in the commit directory
  • If it contains a log(...) call → Credence 0.97 → Verdict green
  • Otherwise → Credence 0.42 → Verdict red

Development approach

• Readme-Driven Development: We capture intent and interfaces up front in this README and the white paper. We will keep both current as we iterate.
• Outside-in: We will define user-visible CLI behavior first, then drive implementation via tests and thin slices until the internals satisfy the external contracts.
• Documentation-first: Sphinx is set up from day one; every significant change should be reflected in the docs.

Documentation system

• Sphinx with MyST Markdown allows us to keep the white paper in Markdown while using Sphinx features.
• Theme: sphinx_rtd_theme
• Extensions enabled for future self-documentation work:
  • autodoc and napoleon (for API docs from docstrings)
  • viewcode (source links)
  • todo (TODO directives can be toggled in output)
  • autosectionlabel (stable xrefs)
  • intersphinx (cross-project linking)

Structure:

• docs/index.md: Site landing page and ToC
• docs/white-paper.md: Includes the white_paper.md via Sphinx include
• white_paper.md: Your authored white paper at the repo root

Build commands:

• make -C docs html
• Or directly: sphinx-build -b html docs docs/_build/html

Next steps (planned)

• Project skeleton for the CLI (src/ layout, package metadata)
• Test harness and initial outside-in tests for first CLI story
• Self-documenting code via autodoc, with API docs published in docs/
• Continuous docs build (Read the Docs or CI job)

Contributing

• Keep changes small and focused on an outcome.
• Update docs alongside code changes. If an interface changes, update examples in the README and white paper sections that reference it.
• Prefer tests that exercise the CLI surface area.

License

• TBD by the repository owner. No license is included yet.