Design and implement consistent, production-grade backend/backoffice interfaces using the @open-mercato/ui component library. Use this skill when building admin pages, CRUD interfaces, data tables, forms, detail pages, or any backoffice UI components. Ensures visual consistency and UX patterns across all application modules.

Create or rewrite AGENTS.md files for Open Mercato packages and modules. Use this skill when adding a new package, creating a new module, or when an existing AGENTS.md needs to be created or refactored. Ensures prescriptive tone, MUST rules, checklists, and consistent structure across all agent guidelines.

Design entities, relationships, and manage the migration lifecycle. Use when planning a data model, designing entities, choosing relationship patterns, adding cross-module references, or managing database migrations. Triggers on "design entity", "data model", "add entity", "database schema", "migration", "relationship", "many-to-many", "junction table", "foreign key", "jsonb", "add column".

Maintain `.devcontainer/` so it stays in sync with the project's regular development requirements.

Guide for safely ejecting and customizing core modules. Use when a developer needs to modify a core module's behavior beyond what UMES extensions support, wants to eject a module, or is considering whether to eject vs extend. Triggers on "eject", "customize module", "modify core module", "override module", "fork module", "change built-in", "should I eject".

Detect and fix spec number conflicts in .ai/specs and .ai/specs/enterprise (including ai/specs and ai/specs/enterpirse path variants). Use this when duplicate SPEC or SPEC-ENT numbers exist, when a new conflicting spec should be moved to the end, or when links/references must be updated after renumbering.

Analyze a specification before implementation to assess backward compatibility impact, identify risks, find gaps, and produce a readiness report. Use when the user says "analyze spec", "pre-implement", "check spec impact", "spec readiness", "BC analysis", "backward compatibility check", "what can go wrong", or "spec gap analysis". Produces an actionable report with BC violations, missing sections, risk assessment, and suggested spec improvements.

Guide for creating high-quality, architecturally compliant specifications for Open Mercato. Use when starting a new SPEC or reviewing specs against "Martin Fowler" staff-engineer standards.

Extend core modules using the Universal Module Extension System (UMES). Use when adding columns/fields/filters to existing tables/forms, enriching API responses, intercepting API routes, blocking/validating mutations, replacing UI components, injecting menu items, or reacting to domain events. Triggers on "extend", "add column to", "add field to", "inject into", "intercept", "enrich", "hook into", "customize", "override component", "add menu item", "react to event", "block mutation", "validate before save".