OASIS is a CLI-first security analysis tool written in Python. It orchestrates a multi-phase LangGraph pipeline (Discover → Scan → Expand → Deep → Verify → Report) to detect vulnerabilities in source code using local LLMs via Ollama or OpenAI-compatible servers. The tool supports 25+ vulnerability types across multiple languages, produces deterministic verdicts without LLM reliance, and integrates with CI via severity-gated exit codes, suppression registries, and report diffing. It is installed via pipx or Docker and run as `oasis -i /path --models ...`.