Interaction Designer - HCI

About Act

There are over 5 billion users using basic applications today such email, notes, tasks, calendar and they're not AI-native. Our mission is to build proactive applications for anyone in the world, who are not used to complex prompting. We aim to bring intelligence to conversations, errands, organising and workflows, with minimal to no prompting.

Our first application is an agent-first mobile communication app. We believe building applications that users use daily for communication, coordination and collaboration needs will help integrate AI into their lives. The net effect is to eliminate misinformation, achieve low coordination costs, enable high quality tasks and collaboration at scale with minimal or little prompting.

Role

You will design the detailed mechanics of how users interact with A1 - the gestures, states, flows, and micro-decisions that determine whether an AI-driven product feels controlled or confusing.

This role is focused on HCI interaction design: how users give input, receive feedback, supervise AI actions, correct mistakes, and maintain agency over AI-driven workflows.

There are no established playbooks for interaction design in proactive AI products. You will help define new patterns from the ground up.

What You'll Be Doing

• Design detailed interaction models for AI-driven flows, including 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.

• Design human-in-the-loop controls - how users review AI decisions, override actions, and stay informed without micromanaging.

• Create interaction patterns for delegation, approval, correction, escalation, reversibility, and recovery.

• Create detailed interaction specifications, annotated flows, and prototypes for engineering handoff.

• Work with product and ML teams to translate system capabilities and constraints into usable interaction patterns.

• Test interaction designs with real users to identify where AI behavior creates confusion, distrust, or friction.

• Contribute to a shared library of HCI interaction patterns that can be reused across the product.

What You Will Need

• 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.

• Strong prototyping skills in Figma or equivalent tools.

• Systematic thinking - able to map complex AI behavior into coherent user-facing interaction logic.

• Clear understanding of HCI principles: user control, transparency, feedback, and graceful recovery.

• Experience working closely with engineers to ensure interactions are implemented as designed.

• Comfort designing for systems where output is non-deterministic and behavior can vary across sessions.

• Strong judgment on when users should be guided, interrupted, asked for confirmation, or left alone.

How We Work

The best products today in the world were built by small, world class teams. We are a high talent density and hands-on team. We make decisions collectively, move at rapid speed, striking a balance between shipping high quality work and learning. Joining our team requires the ability to bring structure, exercise judgment, and execute independently. Our goal is to put in hands of our users a truly magical product

Interview process

For design roles, we expect candidates to submit a portfolio as part of the application process.

If there appears to be a fit, we'll reach out to schedule 2 rounds of interviews and a design assessment.

Applications are evaluated by our team members. Interviews will be conducted via virtual meetings and/or onsite.

We value transparency and efficiency, so expect a prompt decision. If you've demonstrated the exceptional skills and mindset we're looking for, we'll extend an offer to join us. This isn't just a job offer; it's an invitation to be part of a team that's bringing AI to have practical benefits to billions globally.