Starlight Spec

Purpose

Create an executable specification before code when the cost of ambiguity is greater than the cost of writing the contract.

When it fires

• A feature spans more than one component or repository.
• Inputs, outputs, states, permissions, or failure behavior are unclear.
• The user asks for a PRD, technical design, or implementation plan.

Inputs

• User outcome, audience, and decision owner.
• Existing architecture, conventions, and repository instructions.
• In-scope and out-of-scope behavior.
• Data sensitivity, runtime targets, compatibility, and delivery constraints.