Hopper vs TUI-use

Hopper, from YC S24 startup Hypercubic, is the first agentic development environment purpose-built for mainframe systems. It lets AI agents navigate TN3270 terminals autonomously, write and submit JCL jobs, monitor JES output, debug failed jobs by analyzing spool data, query VSAM datasets, compile and run COBOL code, and manage CICS transactions—all via natural language prompts. Tasks that traditionally took mainframe specialists hours of manual TN3270 navigation can now be expressed as a single instruction. The technical challenge here is real: mainframes don't have nice REST APIs or modern dev tooling. They run on green-screen terminal protocols from the 1970s, and the humans who know how to operate them are retiring faster than they can be replaced. Hopper essentially wraps the entire mainframe interaction surface in an agent-friendly interface, translating intent into the arcane sequences of keystrokes and JCL that mainframes actually require. The product is free for individual developers (all core features, macOS/Windows/Linux) with Enterprise pricing for SSO, on-prem deployment, and SOC 2 reports. Hypercubic's team includes alumni from Cognition, Apple, and Windsurf. Given that mainframes still process an estimated $3 trillion in daily commerce and the COBOL developer shortage is acute, Hopper is targeting a genuinely underserved market with unusual urgency.

TUI-use is an open-source library that gives AI agents the ability to interact with traditional interactive terminal (TUI) applications — think vim, htop, ssh sessions, database CLIs, and legacy text-based UIs that were never designed for programmatic control. Instead of requiring a GUI or a REST API, TUI-use interprets terminal output as structured state and sends synthetic keystrokes back, enabling agents to "see" and "drive" any TUI application as if they were a human at a keyboard. The project was born from a real pain point: AI coding agents can call bash commands and write files, but they fail badly the moment a tool opens an interactive prompt waiting for user input. TUI-use solves this by building a state machine layer over PTY (pseudo-terminal) interfaces, letting agents read the current screen buffer, detect interactive prompts, and respond intelligently. It ships with adapters for common TUI patterns and a clean API that works with any LLM tool-use framework. The Show HN post attracted genuine interest from the ops and DevOps community — many existing workflows depend on tools that expose only an interactive terminal interface. TUI-use fills a real gap in the "AI agents that control computers" space by handling the long tail of CLI programs that have no API, no GUI, and no intention of ever getting one.