Design engineering portfolio
I design products in code, then stay for the hard part.
I move between product strategy, interaction design, working prototypes, and production engineering. My work spans AI agents, consumer creation tools, developer workflows, native Apple apps, and regulated financial products.
Santa's AI Lab, 2023 to 2026
Stella Foster and Outside Agent
Co-Founder and CTO. Product, design, engineering, and team leadership.
The product
Stella Foster was a persistent AI assistant available through phone calls, SMS, web, and native Apple apps. Its agents planned and completed real work such as reminders, calls, messages, Uber rides, and Amazon orders while carrying context across conversations. We later opened the underlying platform as Outside Agent so developers could build and deploy their own agents.
The design problem
An agent has to earn trust before a person delegates meaningful work. New users often tested a reminder five minutes into the future before trying recurring reminders, scheduled messages, or purchases. I designed the product around that trust ladder: clear confirmations, visible progress, safe intervention, and responsibility for every external action.
Designing beyond chat
Phone calls and SMS have no stop button. I specified how every new instruction should extend, edit, cancel, or start work while preserving the current conversation. That behavior became a core interaction model, not an edge case hidden in the backend.
Making autonomy legible
I built a React and TypeScript operations product that exposed the conversation, the agent's plan, each execution step, cost, failures, and the point where a person could intervene. Langfuse made model traces observable and Promptfoo helped turn quality checks into repeatable evaluations.
Building for recovery
One durable Temporal workflow powered each conversation. New instructions joined work already in progress, and failed steps resumed without repeating calls, messages, rides, orders, or payments. Deterministic code owned those side effects.
Snap Inc., Camera
Preview Filter Carousel
Lead Design Engineer. Figma and Swift prototype.
Problem and approach
Filters were useful but slow and unpredictable to browse. I designed and built a working Swift prototype that added a visible carousel and preview thumbnails, then used product analytics and close collaboration with design, product, research, data science, and engineering to refine the interaction.
Outcome
The experience reached 64M daily users. Filter impressions increased 38% on iOS and 10% on Android. Snaps sent with filters increased 9% on iOS and 5.4% on Android.
Snap Inc., Creative Tools
Voice Over and Auto-Caption
Design Engineer. Figma, Objective-C, and Swift prototypes.
From interaction to working system
I designed the complete flows and built realistic native prototypes with recording, playback, editing, layout, and caption correction. The prototypes let the team test product behavior in context before committing production engineering time.
Outcome
Voice Over reached roughly 300K daily users. Auto-Caption reached roughly 325K daily users and increased engagement with Snaps on muted devices by 6% on iOS and 9% on Android.
At Snap, I designed and built the working prototypes for these actual features. Production engineers wrote the shipping code, and I partnered with them through launch and measurement.
Story Star, 2015 to 2020
Spotlight
Co-Founder and Head of Mobile Development. Product design and iOS engineering.
Zero to one
We designed and built a social product for discovering and ranking entertaining Snaps. I worked across product, Sketch, Swift, Firebase, the Snap SDK, fundraising, and team leadership. The feed supported topic discovery, voting, creator profiles, and direct submission from Snapchat.
Outcome
Spotlight was acquired by Snap and became a core Snapchat feature. Across Story Star, I helped build more than 20 iOS and web products; the largest reached 250K+ monthly users.
How I work
Design is a way to reduce uncertainty.
Prototype the real behavior
Use code when timing, state, data, or platform behavior determines whether an idea works.
Watch what people actually do
Combine interviews with analytics, usability research, and anonymized operational data.
Own the handoff
Stay with engineering through edge cases, launch, measurement, and the next iteration.
Archive
Original 2022 portfolio deck
This page is the current, curated portfolio. The original deck preserves deeper interaction studies and prototype visuals in their 2022 context.