fynk replaced a custom contract-chat system with CopilotKit and AG-UI after its original design made each new capability require changes to both the app and AI service. The old chat handled one document at a time and used a bespoke message format suited mainly to text and PDF references; comparisons, tables, and interactive follow-up required new message types and manually maintained interface logic. With AG-UI, the agent streams standardized events for text, tool calls, shared state, and pauses for user input. fynk’s LangGraph agent produces the responses, an adapter translates them into AG-UI events, CopilotKit renders them, and fynk’s backend continues to store conversation history. The redesign removed about 11,000 lines of fynk-owned code while enabling richer interactions.
Because CopilotKit initially supported React but fynk uses Vue, engineer Abel Enekes chose contribution over forking or waiting. With help from a coding agent, he built a 62,517-line Vue port across 244 files; maintainers merged it in May 2026, and the work was documented by October. The shared package has since gained more than twenty Vue fixes and features from CopilotKit and other contributors. The experience reinforced a division of effort: rely on standards and shared frameworks for general agent-interface plumbing, while focusing internal development on contract-specific tools, permissions, and citations. For a small team, the upfront work and migration of existing chat histories were worthwhile, though contributing required careful testing and coordination with maintainers.
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