Use when designing a feature that needs to be implemented by both Lovable AND Claude Code (or other AI agents), when LV keeps drifting from your intent across multiple prompts, when handing off a feature from one AI tool to another, when iOS / Android / Web need feature parity, or when you want a stable contract that survives many LV regenerations. Covers writing docs/feature-*.md as a shared source-of-truth, structuring spec sections (scope, schema, copy, error states, acceptance), versioning specs over time, and the rule 'specs change before code changes'.
