use-case

name

use-case

description

Creates or modifies application use-cases in src/application/use-cases/. Use when implementing business orchestration for a new feature, extracting a reusable shared use-case, adding a capability sub-use-case, or wiring a PostInstallPipeline delegation. Do NOT use for creating a new CLI command surface — use `command` instead. Do NOT use for I/O translation — use `adapter` instead. Do NOT use for domain type definitions — use `domain-model` instead.

Use Case

Builds the business orchestration layer: classes that receive typed options, coordinate ports and domain models, and return typed results. Each use-case has a single execute() method, never catches its own errors, and delegates all file-and-manifest writes to PostInstallPipelineUseCase.

Available actions

#	Action	Role	Input
01	define-types	Declare *Options and *Result interfaces	use-case name + field list
02	write-execute	Write the execute() method body (≤20 LOC)	types from 01
03	extract-methods	Extract intent-named private helper methods	execute() body from 02
04	wire-errors-and-pipeline	Add typed throws + delegate to PostInstallPipeline	methods from 03
05	test	Write integration-tier unit tests	completed use-case from 04

Default flow

01 → 02 → 03 → 04 → 05

Transversal rules

• Class name ends in UseCase; single async execute() method; never a plain function.
• Every method (public or private) ≤ 20 lines; extract named private methods before reaching the limit.
• Shared sub-use-cases live in src/application/use-cases/shared/ and are never called from commands.
• Capability sub-use-cases live in subdirectories (install/, update/) and receive narrowed types.
• Never call manifestRepo.save() in isolation; delegate to PostInstallPipelineUseCase.
• Use constructor injection order: FileSystem → Repository → Loader → Hasher → Logger → Platform → Prompter.
• Use import type for type-only imports; .js extensions on all relative imports.
• Named export only.

References

• references/use-case-rules.md — class shape, constructor order, Prompter restrictions, user-file protection
• references/shared-use-cases.md — shared sub-use-case placement and contract
• references/capability-sub-use-cases.md — capability guard pattern, narrowed types
• references/post-install-pipeline.md — pipeline delegation rules

Invariant rules

• references/use-case-rules.md — authoritative use-case rules