ossature 0.1.1

Specification and architecture driven code generation toolkit.

Ossature

[!WARNING] Ossature is currently in its 0.x series and should be considered unstable. APIs, spec formats, CLI flags, and internal behavior may change significantly between releases without prior deprecation. Pin your version and check the changelog before upgrading.

An open-source build system that turns specs and architecture into working code.

You write a spec for what the software does, optionally lay out the architecture for how it fits together, and Ossature turns that into a build plan that runs step by step, with an LLM generating the code under tight constraints. Your specs and architecture are the source, the generated code is the output. You review the plan before anything runs, and when something breaks you fix that step and keep going instead of starting over.

Works with Anthropic, OpenAI, Mistral, Google, and most other hosted providers, as well as local models through Ollama.

Ossature (pronounced OSS-uh-cher) means the underlying framework or skeleton of a structure.

Quick start

Requires Python 3.14+.

pip install ossature

Or run it directly with uvx:

uvx ossature --version

Set your LLM provider API key:

export ANTHROPIC_API_KEY="sk-ant-..."
# or OPENAI_API_KEY, MISTRAL_API_KEY, etc.

Create and build a project:

ossature init myproject && cd myproject
ossature new my-feature
# edit specs/my-feature.smd
ossature validate
ossature audit
ossature build

The default model is anthropic:claude-sonnet-4-6. To use a different model, set the model field in ossature.toml:

[llm]
model = "openai:gpt-5.2"  # or mistral:devstral-latest, etc.

The API key you export must match the provider in your model string (e.g., OPENAI_API_KEY for openai:…). See the configuration docs for per-role overrides and all available options.

Examples

See ossature-examples for complete projects with specs, build plans, and generated code.

Documentation

Full docs at docs.ossature.dev. The workflow guide walks through a complete project from init to generated code.

License

MIT