Nebula is a local-first security workspace that combines AI-assisted chat interfaces, project management, security testing tools, and evidence collection into a desktop/web hybrid application. The system features a Python/FastAPI backend with SQLAlchemy/Alembic for data persistence, a TypeScript/React frontend with Tauri/Rust desktop shell, and extensive integration with external AI providers (Ollama, vLLM, Claude) and harnesses (Codex, Grok). Core functionality includes engagement scoping, asset discovery, vulnerability validation, remediation tracking, AI-powered agent workflows via subagents, structured result inspection, and diagnostic monitoring. The architecture emphasizes modularity with clear separation between domain models, storage, API, UI components, and state management, enabling extensibility through configuration-driven tool and provider integrations.