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AgentCompany/builtin-skills/software-engineer/clean-architecture/references/usecase-single-responsibility.md
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ZacharyZhang-NY e74dafcd36 Silence render-disposed spam, unbreak bundled skills, drop board wake
Three independently ugly bugs that all fed the same log flood:

* Electron's `WebFrameMain.send` writes every "Render frame was disposed"
  to stderr via `console.error`. When the worker fans a second
  agent-event past a reloading renderer, we produced thousands of
  identical lines and stalled the main loop on stderr I/O. Added a
  `mainFrame.detached` guard so the send is short-circuited before
  Electron's own catch block fires, and installed a targeted filter in
  `suppress-warnings.ts` (now actually imported from the entry point)
  so the specific `console.error("Error sending from webFrameMain:"…)`
  noise never reaches the terminal. Any other payload still surfaces.

* `dispatchAgentMessage` accepted the human-reader sentinel as a wake
  target when an agent replied to `__board__` — `wakeAgentIfPossible`
  then called `db.getAgent("__board__")`, threw, and the dispatcher
  kept repeating on every send. Strip `HUMAN_SENDER_ID` at
  `resolveMessageWakeTargets`, and keep a defense-in-depth guard in the
  heartbeat so a stray caller (future automation fan-out) cannot
  reintroduce the crash.

* Pi's skills loader rejects any SKILL.md whose frontmatter `name`
  diverges from its parent directory. The four bundled `my-writing-style`
  copies declared `name: writing-style-skill`, so every install emitted
  a warning and dropped the skill. They also lived as orphan gitlinks
  (mode 160000 without .gitmodules), and the global `*.md` gitignore
  hid every other SKILL.md from version control. Fixed the frontmatter
  to match the dir, converted the dangling submodules to plain trees,
  and allowlisted `builtin-skills/**/*.md` so a fresh clone carries the
  catalogue instead of silently losing it.
2026-04-20 08:13:48 -04:00

3.0 KiB

title, impact, impactDescription, tags
title impact impactDescription tags
Each Use Case Has One Reason to Change HIGH isolates change impact, enables parallel development usecase, single-responsibility, cohesion, srp

Each Use Case Has One Reason to Change

Each use case class should orchestrate exactly one application-specific workflow. Combining multiple use cases creates coupling that forces unrelated changes together.

Incorrect (multiple use cases in one class):

class OrderService:
    def __init__(self, repo, payment, shipping, notification):
        self.repo = repo
        self.payment = payment
        self.shipping = shipping
        self.notification = notification

    def create_order(self, items, customer_id):
        # Use case 1: Create order
        order = Order.create(items, customer_id)
        self.repo.save(order)
        return order

    def process_payment(self, order_id, payment_method):
        # Use case 2: Process payment
        order = self.repo.find(order_id)
        self.payment.charge(order.total, payment_method)
        order.mark_paid()
        self.repo.save(order)

    def ship_order(self, order_id, address):
        # Use case 3: Ship order
        order = self.repo.find(order_id)
        tracking = self.shipping.create_shipment(order, address)
        order.mark_shipped(tracking)
        self.notification.send_shipped(order)
        self.repo.save(order)

    # Changes to shipping logic force retest of payment logic

Correct (separate use case classes):

class CreateOrderUseCase:
    def __init__(self, repo: OrderRepository):
        self.repo = repo

    def execute(self, command: CreateOrderCommand) -> OrderId:
        order = Order.create(command.items, command.customer_id)
        self.repo.save(order)
        return order.id


class ProcessPaymentUseCase:
    def __init__(self, repo: OrderRepository, payment: PaymentGateway):
        self.repo = repo
        self.payment = payment

    def execute(self, command: ProcessPaymentCommand) -> None:
        order = self.repo.find(command.order_id)
        self.payment.charge(order.total, command.payment_method)
        order.mark_paid()
        self.repo.save(order)


class ShipOrderUseCase:
    def __init__(
        self,
        repo: OrderRepository,
        shipping: ShippingService,
        notification: NotificationPort
    ):
        self.repo = repo
        self.shipping = shipping
        self.notification = notification

    def execute(self, command: ShipOrderCommand) -> TrackingNumber:
        order = self.repo.find(command.order_id)
        tracking = self.shipping.create_shipment(order, command.address)
        order.mark_shipped(tracking)
        self.notification.send_shipped(order)
        self.repo.save(order)
        return tracking

Benefits:

  • Changes to shipping don't affect payment tests
  • Teams can work on different use cases in parallel
  • Each use case has minimal dependencies

Reference: Clean Architecture - Use Cases