Design or review specx core scope boundaries in Python services. Use when deciding where code belongs across packaged scoped foundation bases, optional local foundation extensions, `core/`, capabilities, delivery, infrastructure, `shared/`, and `ioc`; when adding guardrails or splitting use cases, services, DTOs, schemas, ports, and adapters.
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Design or review specx core scope boundaries in Python services. Use when deciding where code belongs across packaged scoped foundation bases, optional local foundation extensions, `core/`, capabilities, delivery, infrastructure, `shared/`, and `ioc`; when adding guardrails or splitting use cases, services, DTOs, schemas, ports, and adapters.
specx Scope Architecture
Use this skill before broad structural changes or when a feature crosses more
than one layer. Read references/boundaries.md for the full rules.
Boundary Model
core/<scope>/: application behavior and contracts. Inner packages are
capabilities/, dtos/, entities, exceptions/, gateways/,
repositories/, services/, and use_cases/.
core/<scope>/infrastructure/: scope-owned external IO adapters such as
SQLAlchemy repositories, Redis stores, HTTP clients, file storage, and queues.
Inner core packages must not import it.
Scoped specx foundation packages: packaged base classes under
specx.core.foundation, specx.delivery.foundation, and
specx.infrastructure.foundation. Every non-foundation source class must
inherit an explicit packaged base directly or through a project-local base;
local bases explicitly inherit the packaged or framework base they extend.
foundation/: optional project-local extension point for base definitions
only: real project-local base categories or stateful framework bases that
must not be shared globally, such as a SQLAlchemy declarative base.
infrastructure/: app-wide technical resources such as SQLAlchemy session
factories, logging, telemetry, and external client factories.
Runtime logging lives in top-level infrastructure/logging. Configure it
once with a BaseConfigurator; do not inject logging.Logger.
shared/: tiny stable cross-scope primitives. It is not a dumping ground.
ioc/: diwire container creation and explicit bindings.
Decision Rules
Use a use case for an externally meaningful action.
Use a service for focused reusable business/application behavior.
Use a capability for one small replaceable injectable ability that is
narrower than a service.
Name every service class with a Service suffix.
Name direct concrete BaseCapability subclasses with a Capability suffix.
Do not call small collaborators services by default.
Core services inherit BasePureService, BaseReadService, or
BaseEffectService; do not add or use a generic BaseService.
Do not add base_ prefixes to project-local foundation module filenames.
Class names stay prefixed, for example clock.py defines BaseClock.
Use gateway ports under core/<scope>/gateways/ for outbound business
capabilities such as OpenAI summaries, payments, email, queues, and external
APIs. Gateway ports inherit BaseGateway, declare external effects, and do
not return entities.
Put concrete gateway implementations under
core/<scope>/infrastructure/<technology>/.
Use packaged scoped specx foundation bases before adding project-local bases.
Do not create an empty local foundation/ package.
Add a project-local foundation base only when a real project-local base
category exists or a stateful framework base must own project-local state,
such as SQLAlchemy MetaData.
Use a port or ABC only for a real external boundary or multiple
implementations.
Use one delivery controller per scoped set of use cases.
Use core/health when readiness checks any required external dependency or
probe policy is reusable across delivery layers. Keep a simple
framework-specific liveness probe in delivery, and do not invent core probe
services and use cases solely to satisfy the layer diagram.
When core/health is justified, keep framework route/status/header mapping
in delivery and technical checks behind gateway adapters.
Keep request/response schemas in top-level delivery/. Keep use-case DTOs in
core/<scope>/dtos/.
Prefer @dataclass(frozen=True, kw_only=True, slots=True) for commands,
queries, DTOs, entities, and other core data classes unless the user asks for
another model type. Keep Pydantic at delivery schemas and settings edges.
Code Style
Use blank lines as logical separators in all code. Keep related statements
together, but separate independent setup, action, assertion, response, branch,
and transformation groups so long blocks stay readable.
References
references/boundaries.md - layout, import rules, naming, and architecture
test targets.
Use BaseStrEnum for limited known application value sets instead of plain
str or Literal[...].
When creating or reshaping a repo, keep root AGENTS.md architecture
guidance aligned with these boundaries.
Define each use-case input as a same-file Command or Query: commands are
state-changing, queries are read-only, and even empty inputs are explicit.
Keep commands and queries independent from DTOs. They inherit BaseCommand
or BaseQuery, not BaseDTO, and live beside the use case that consumes
them.
Use cases return DTOs, not entities.
Persistence use cases inject UnitOfWorkManager for transactional work and
open the active UoW inside execute(...). They do not inject repositories,
SQLAlchemy sessions/engines/session factories, or concrete infrastructure
adapters directly.
Services may receive an active UoW from a use case, but services must not
open UoW scopes or own commit/rollback.
Give every project source class a docstring that explains scope and includes
a concrete Example:; the packaged rule checks abstract ports, local bases,
enums, and errors as well as concrete behavior classes.
Keep controller-only helpers such as auth and rate limiting in delivery/.
Keep FastAPI lifespan ownership in delivery/fastapi/lifecycle.py. The
lifecycle releases app-owned resources and closes the DI container on
shutdown.
Keep SQL and external API calls in scope infrastructure adapters.
Classes that actually emit logs create a private stdlib logger in
__post_init__ using the full module plus class name. Do not add logger
fields to DTOs, entities, commands, queries, or classes with no log records.
Logs should describe important application events and failures without
secrets, credentials, request bodies, full external URLs, or infrastructure
topology.
Do not create bare classes without explicit bases.
Packaged framework-neutral guardrails run by default when select is
omitted. New generated projects use select = ["ALL"], which enables every
rule whose required project surface exists. Projects with a narrower base
selection enable technology families explicitly, for example
extend-select = ["fastapi"]. Do not copy FastAPI paths or guidance into a
project that uses another delivery technology.
