ACI-005: Steel Threads Beat Feature Branches

Thesis

Small, scoped, end-to-end work units with explicit design-before-code are the natural unit of work for agentic development. Steel threads give the agent bounded context and the human verifiable milestones. Feature branches give neither.

Story

Lamplight is an Elixir umbrella application with 1496 commits and 119 steel threads, of which 96 were completed and 17 were cancelled. Each steel thread has a directory with at minimum an info.md file containing the objective, context, scope, and status. Most also have design.md (architecture decisions before coding) and tasks.md (work package breakdown).