Lean build

• Derive observable acceptance and explicit non-goals from request and repository.
• Trace entry point through layers owning invariants.
• Deliver coherent end-to-end path across responsible layers; never force work into one file, direct expression, or local patch.
• Reuse fitting seam. Refactor when patching duplicates behavior, weakens ownership, or hides root cause.
• Omit modes, providers, config, extensibility, and polish unless acceptance needs them.
• Add surface, dependency, service, config, or migration only for lifecycle design or acceptance; state material tradeoff.
• Keep work runnable; preserve Core safety.