Pat Simmons starts with a product brief for a personal voice-note app, then asks Fable 5 to design the interface before committing to the application architecture. The design-first sequence gives him a quick visual prototype to critique before the work moves into React Native.
Fable acts as the orchestrator while Opus agents handle implementationAI agent delegation assigns a bounded task, context, authority, and expected result from one participant to an agent or another agent., preserving the more expensive model for decomposition, design judgment and final reviewAI model routing sends each request to a model chosen for that request's complexity, cost, speed, privacy, or other requirements.. An informal comparison shows that Opus can also produce a credible mock-up, although Simmons prefers how Fable responds to iterative design feedbackAn AI feedback loop occurs when AI outputs or their consequences become inputs that influence later model or agent behavior..
The prototype is translated from HTML and CSS into native Expo componentsCode generation uses AI or another automated system to create source code from instructions, examples, schemas, or higher-level specifications. with shared design tokensA design system is a maintained collection of principles, tokens, components, patterns, and documentation for creating consistent interfaces.. The resulting app records and organizes voice notes, generates summaries and next steps, lets the user append to a note, and supports follow-up questions grounded in the transcript.
Simmons then creates an internal Expo build, registers his iPhone and installs the app directly. The demonstration reaches a functioning mobile result while still exposing small visual defects, making it a useful example of rapid AI-assisted product development rather than a claim of production readiness.
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