Simon Martinelli - Lessons from Spec-driven Development - AI Native DevCon June 2026
The talk introduces the AI Unified Process, a spec-driven approach designed to combat code and specification drift in large, long-lived enterprise applications. Instead of treating code as the source of truth, this method uses system use cases (specifically SysML use cases) and domain/entity models as stable contracts. AI is leveraged not for full regeneration, but for generating and updating code and tests incrementally from these specifications, enabling modernization efforts that are more robust than simple 'lift and shift' migrations.
Key takeaways
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Spec-Driven Development (SDD) as the Source of Truth
21:33
System use cases act as a stable contract for application behavior. Code is derived from these specs, ensuring that changes are managed through formal requirements updates rather than relying solely on code maintenance.
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Modernization via Specification Extraction
23:50
For modernization projects (e.g., ERP systems), the process involves reverse-engineering use cases and entity models from existing documentation, code, and tests. This allows for feature integration without being limited to a simple technology migration.
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Architectural Shift: Self-Contained Systems
27:20
To effectively use AI in large systems, the architecture should move away from overly distributed microservices (which create context management issues) toward 'Self-contained systems'—vertical splits that keep UI, business logic, and database within a single project or application.