Agentic Chat (GPT-5.6 Terra) is positioned as an agentic assistant inside the GitLab Duo environment, designed to support code suggestions, review help, and security analysis within a DevSecOps workflow. It belongs to the gpt-terra family and is exposed through a proprietary API, sitting alongside sibling variants such as Agentic Chat GPT-5.6 Sol and Luna that share the same provider and zero-list-price listing. The model's design emphasis on reasoning and tool calling points to multi-step developer tasks rather than single-turn chat, with attachments and structured output available so it can ingest files and return machine-readable results in pipelines and IDE integrations.

From a practical standpoint, the standout trait is its very large context budget, allowing long repositories, merged diffs, issue threads, and policy documents to be loaded together for analysis without aggressive truncation, while still permitting long, detailed responses. Image and PDF inputs broaden its usefulness for design specs, screenshots, and design-doc reviews alongside traditional source code. Because the published pricing is flat at zero on both input and output, the practical decision for teams is less about cost and more about whether the gpt-terra family's reasoning-plus-tool-use profile matches the agentic workflows they want to automate inside GitLab.