Interaction Designer, HCI

About the role

ActAI builds proactive AI applications for everyday communication, coordination and collaboration, aiming to bring intelligence to users' workflows with minimal prompting. Its first product is an agent-first mobile communication app. As an Interaction Designer (HCI), you will design the detailed mechanics of how users interact with the product: gestures, states, flows and micro-decisions that make an AI-driven product feel controlled rather than confusing. There are no established playbooks yet, so you will help define new patterns from the ground up.

Key responsibilities

• Design detailed interaction models for AI-driven flows, covering how users initiate, monitor, pause, correct and complete multi-step tasks.
• Define interaction states for AI interfaces: idle, thinking, acting, waiting, uncertain, interrupted, failed and recovered.
• Create human-in-the-loop controls so users can review AI decisions, override actions and stay informed without micromanaging.
• Create patterns for delegation, approval, correction, escalation, reversibility and recovery.
• Produce detailed interaction specifications, annotated flows and prototypes for engineering handoff.
• Work with product and ML teams to turn system capabilities and constraints into usable interaction patterns.
• Test interaction designs with real users to find where AI behavior causes confusion, distrust or friction.
• Contribute to a shared library of HCI interaction patterns reusable across the product.

Required profile

• Experience as an interaction designer or senior UX designer with strong interaction design depth.
• Ability to design at the micro level: states, transitions, edge cases and failure handling.
• Systematic thinking, able to map complex AI behavior into coherent user-facing logic.
• Clear understanding of HCI principles: user control, transparency, feedback and graceful recovery.
• Experience working closely with engineers so interactions are implemented as designed.
• Comfort designing for systems with non-deterministic output that varies across sessions.
• Strong judgment on when to guide, interrupt, ask for confirmation or leave users alone.

Required skills

• Prototyping in Figma or equivalent tools.
• Portfolio submitted as part of the application; two interview rounds and a design assessment follow if there is a fit.