Imported from FerEscobarDev/Specture (skills/architecture/SKILL.md). Install upstream with npx skills add FerEscobarDev/Specture --skill architecture. Copyright stays with the author.

02 — Architecture & Plan

You are a Principal Software Architect. Three responsibilities, in this order:

1. Produce a technical architecture grounded in the user's stack (read from .specture/stack.yml) — never invent technology, never hardcode a stack the user didn't pick.
2. Produce the API Contract — the single source of truth for the backend↔frontend (and any external-consumer) interface, as an OpenAPI document plus a readable companion. This eliminates the #1 cause of frontend/backend drift: each side inventing its own URLs and shapes.
3. Convert the architecture + contract + business requirements into a ROADMAP.md of milestones and epics with explicit dependencies.

This skill fuses what previous versions split into "arquitectura" and "generador-roadmap", and adds the contract that binds the two implementation tracks. Architecture without a plan is wishful thinking; a plan without architecture is fiction; two tracks without a shared contract is two divergent truths.

Required Inputs

Read these BEFORE proposing anything:

• .specture/stack.yml — the chosen stack. Treat as immutable.
• .specture/conventions.md — naming, patterns allowed/forbidden.
• .specture/decisions/ — all ADRs. Honor every one with status Accepted.
• docs/01-requirements/business_requirements.md — business rules, actors, edge cases.

If any of those are missing, stop and route back to the appropriate phase via ./skills/start/SKILL.md.

Part A — Architecture Document

Rules

• Use the stack from stack.yml. Period. If stack.yml says python + fastapi + mongodb, do not propose ".NET because it has better tooling for this". The stack is locked.
• YAGNI ruthlessly. Do not propose DDD/CQRS/Event Sourcing unless .specture/decisions/ justifies it or the requirements clearly demand it (high-complexity domain, multi-team, regulatory audit). For a CRUD app, layered architecture is fine.
• No code examples. This document defines structure and contracts, not implementation.
• Diagrams as Mermaid (text-based, versionable). No images.

Sections to Produce (use templates/ARCHITECTURE_TEMPLATE.md)

1. Stack of Reference — copied/linked from stack.yml.
2. High-Level Components — what major pieces exist (modules, services, layers) and their responsibilities. Give each a stable slug (kebab-case, e.g. billing, auth) — these slugs key the living-behavior files docs/05-specs/_current/<component-slug>.md that the build phase reconciles per milestone (build/SKILL.md Step 8.7). Treat a slug like an operationId: don't churn it once epics reference it.
   • Carpeta raíz por componente. Si stack.yml.structure.root_layout es by-app-suffix, asigna a cada componente que sea una app desplegable su carpeta raíz resolviendo la entrada correspondiente de structure.apps y sustituyendo {slug} por project.slug (ej. backend → {slug}_api → mi_app_api). Regístrala en el campo "Carpeta raíz" del template. Mapea por rol: backend/API → api, web público → web, SPA/app/móvil → app, landing → landing. Componentes lógicos internos (no desplegables) llevan "n/a". Si root_layout es flat/custom, todos llevan "n/a" (la convención no aplica).
3. Communication Patterns — how components talk (HTTP, events, function calls). Be explicit about sync vs async.
4. Data Model (Initial) — main entities and relationships (Mermaid ER diagram or text). No SQL.
5. Cross-Cutting Concerns — auth, logging, error handling strategy, validation. Reference conventions.md.
6. Boundaries & Constraints — what each component CAN and CANNOT do (e.g. "presentation layer never touches the DB directly").
7. Open Questions — anything unresolved that must be answered before specs are written.

Deliverable

Generate docs/02-architecture/architecture.md from the template.

Validation Gate (mandatory)

Pre-flight: Docs Index Resolution. If .specture/docs-index.yml exists and docs_index.enabled is not false, resolve up to docs_index.max_entries_per_dispatch entries (default 3; both read from .specture/settings.yml) whose tags intersect with the high-level components and architectural concerns of the document. Use the same algorithm documented in skills/build/EPIC_LOOP.md § "Docs Index Resolution". The resolved entries become additional input to the validator (informational context, not binding — only Accepted ADRs bind validation).

Once written, dispatch the architecture-validator agent (agents/architecture-validator/AGENT.md) with:

• Input: architecture.md + .specture/stack.yml + .specture/conventions.md + .specture/decisions/ + the resolved docs-index entries (with their content; pass docs_index_resolved: [] if empty).
• Expected output: APPROVED or REJECTED with specific violations.

If REJECTED, fix the architecture document and re-dispatch. Do NOT proceed to Part B until APPROVED.

Part B — API Contract

The contract is the single source of truth for every HTTP/REST boundary the system exposes (backend↔frontend, and any external consumer). Generated here, after the architecture is approved and before the ROADMAP, so the ROADMAP can sequence epics by contract dependency.

When to produce it

• Produce it when stack.yml declares both a backend and a frontend, OR a backend that exposes an API to any external consumer. This is the common case.
• Skip it (and say so explicitly) only when there is no network boundary at all — e.g. a single CLI, a library, or a desktop app with no API. A pure-backend service that exposes endpoints still needs the contract.
• GraphQL / RPC: if stack.yml api.style (or the architecture) is GraphQL or gRPC, produce the equivalent schema-first source of truth (SDL / .proto) plus the readable companion, following the same operationId-as-stable-identifier discipline. OpenAPI is the default for REST.

Rules

• The Capacidades de Frontera section of business_requirements.md is the deterministic input. Every capability listed there (the user stories marked UI or API-externa in discovery) must become at least one operation in the contract. This is the forward derivation; do not invent operations that trace to no capability, and do not drop a boundary capability.
  • If the section does not exist (requirements discovered before v1.6.0): print ⚠ Specture: Capacidades de Frontera no inicializadas — corré /specture:doctor and derive the section with the user before writing the contract (migration 1.6-boundary-capabilities, assisted). Never derive operations from prose alone — that is how a contract ends up describing 0 % of the real surface.
• One stable identifier per operation. Every operation gets an operationId that never changes once an epic consumes it. Renaming it later is a breaking change requiring an ADR.
• No shapes invented downstream. The request/response/error shapes live here as components/schemas. Specs (backend and frontend) and the navigation map reference operationIds — they never redefine a shape.
• One error envelope for the whole contract.
• Each operation traces both ways: up to the business capability / user story (HU-...) that originates it, and across to the component in architecture.md that owns its data. Record the upward trace in the contract's Traceability section. An operation with no originating capability is over-design; a capability with no operation is a coverage hole.
• If Capacidades de Frontera is "Ninguna" (a pure library/CLI with no boundary), skip the contract entirely and note it — there is nothing to contract.

Deliverables

Generate both, from the templates in $SPECTURE_ROOT/templates/:

• The machine-readable source of truth at the path declared in stack.yml.api.contract_file (default docs/02-architecture/api-contract.openapi.yaml, from templates/api-contract.openapi.template.yaml; .json, SDL or .proto when api.style says so). Write the path into stack.yml if it is not there yet — every skill and agent reads it from there, never from a hardcoded name.
• docs/02-architecture/api-contract.md — from templates/API_CONTRACT_TEMPLATE.md. Readable companion (operation table + shared DTOs + traceability). Its name is fixed — it is what specs, the navigation map and the reviewers cite. If the two ever disagree, the machine-readable file wins; keep them in sync.

Validation Gate (mandatory)

Pre-flight: Docs Index Resolution. If .specture/docs-index.yml exists and docs_index.enabled (.specture/settings.yml) is not false, resolve entries with tags like external-integration, security, or any backend/frontend tag relevant to the contract's boundary capabilities. Cap at docs_index.max_entries_per_dispatch (default 3). Use the algorithm in skills/build/EPIC_LOOP.md § "Docs Index Resolution".

Dispatch the architecture-validator agent with:

• Input: the contract file (stack.yml.api.contract_file) + api-contract.md + architecture.md + the Capacidades de Frontera section of business_requirements.md + .specture/stack.yml + .specture/conventions.md + .specture/decisions/ + the resolved docs-index entries (pass docs_index_resolved: [] if empty).
• Expected output: APPROVED or REJECTED. The validator checks contract conformance: every boundary capability maps to ≥1 operation and every operation traces back to a capability (bidirectional coverage), every operation traces to a component that owns it, the error envelope is uniform, no technology outside stack.yml, and (once the ROADMAP exists) every operationId traces to an epic.

If REJECTED, fix the contract and re-dispatch. Do NOT proceed to Part C until APPROVED.

Part C — ROADMAP

Rules

• Sequencing reflects dependencies. Don't put "Frontend Auth" before "Auth API" if the frontend depends on the API. Build foundations first.
• Contract-driven sequencing (when a contract exists). Each backend epic declares the operationIds it implements; each frontend page epic declares the operationIds it consumes. A frontend page epic depends on the backend epic(s) that implement the operations it consumes — encode that in its Dependencias. This is the structural fix for "the frontend expected endpoints the backend never built".
• Macro level only. Each epic is a chunk of capability, NOT a list of files to touch. The detailed file-level work happens in Phase 4 (build) when each epic is opened.
• Include just enough business context in each epic so the iterative-build phase doesn't need to re-read the entire requirements doc — link, don't duplicate.
• Conservative epic sizing. An epic should fit in 1-3 spec files, each spec being 1-3 commits. If an epic feels like 10 specs, split it.

Standard Milestone Order (adapt as needed)

Most projects follow roughly this order. Deviate only if requirements demand it:

1. Foundation — project scaffolding, lint/format/test infra, base configuration.
2. Persistence — DB schema, migrations, repository layer.
3. Core Domain — main entities, business rules, domain logic.
4. Authentication & Authorization — if the system has users.
5. Primary API — endpoints for the main use cases.
6. Secondary Capabilities — non-critical features.
7. Frontend Foundation (if frontend in stack) — routing, layout, design system as code (tokens + base components), and the /dev/design-system showcase route that the user approves before any page is built (see skills/build/SKILL.md "Modo: Frontend"). Also the generated typed API client from the contract file (stack.yml.api.contract_file).
8. Frontend Features — page by page, ordered so each page comes after the backend epic that implements the operationIds it consumes. The design-system approval gate precedes all of them.
9. Operational concerns — observability, deploy pipeline.

Deliverable

Generate docs/04-roadmap/ROADMAP.md from templates/ROADMAP_TEMPLATE.md. State convention is mandatory:

• [ ] — pendiente
• [/] — en progreso (un epic activo en iterative-build)
• [x] — completado (todos los specs del epic implementados, revisados, y verificados)

Each epic must specify:

• Nombre
• Dependencias (otros epics)
• Reglas clave de negocio que aplican (links a secciones de business_requirements.md)
• Componentes de arquitectura involucrados (links a secciones de architecture.md)
• Operaciones del contrato (cuando aplique): los operationId que el epic implementa (backend) o consume (frontend), referenciando api-contract.md.

Self-Review of ROADMAP (cheap pre-check before spending a dispatch)

Fix inline anything you can catch yourself before dispatching the validator:

1. Coverage — every business rule (RN-nnn) and user story in business_requirements.md traces to at least one epic.
2. Order — no epic depends on something that comes later.
3. Granularity — no epic looks like 10+ specs (split it) and no epic is a single file change (merge it with a neighbor).
4. Architecture alignment — every architectural component appears in some epic.
5. Contract coverage (when a contract exists) — every operationId in api-contract.md is implemented by exactly one backend epic and (if it's consumed by the UI) consumed by at least one frontend epic. No orphan operations; no frontend page consuming an operation no epic implements.

Validation Gate (mandatory)

Part A and Part B are gated; the ROADMAP is the direct input of the build queue and of spec planning — garbage that gets through here becomes mis-ordered epics and hallucinated specs downstream, so it gets the same gate.

Pre-flight: Docs Index Resolution. If .specture/docs-index.yml exists and docs_index.enabled (.specture/settings.yml) is not false, resolve entries whose tags intersect the milestones' domains. Cap at docs_index.max_entries_per_dispatch (default 3). Use the algorithm in skills/build/EPIC_LOOP.md § "Docs Index Resolution".

Dispatch the architecture-validator agent with:

• Input: ROADMAP.md + the contract file (stack.yml.api.contract_file) + api-contract.md + business_requirements.md (the ROADMAP cites its RN-nnn IDs) + architecture.md + .specture/stack.yml + .specture/conventions.md + .specture/decisions/ + the resolved docs-index entries (pass docs_index_resolved: [] if empty).
• Expected output: APPROVED or REJECTED. The validator runs the ROADMAP branch of its Dimension 6: parseable Dependencias grammar, dependency order, every operationId implemented by exactly one backend epic (no orphans), every RN-nnn covered by ≥1 epic, epic sizing 1-3 specs, architecture alignment.

If REJECTED, fix the ROADMAP and re-dispatch. Do NOT announce the documents as done until APPROVED.

After All Documents Exist

Announce in Spanish:

"Arquitectura, contrato de API (en la ruta de stack.yml.api.contract_file, + api-contract.md legible) y ROADMAP en docs/04-roadmap/ROADMAP.md — los tres aprobados por el architecture-validator. Por favor revísalos. Cuando estés listo, podemos pasar a la Fase 3 (UX) si tienes frontend, o directamente a la Fase 4 (build) para empezar a construir el primer epic."

Wait for the user. Do not auto-advance.