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atomic-design-poc/.claude/skills/mutation-command/SKILL.md
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docs(skills): extract house recipes as Claude Code skills for SSP templating
8 template-generic skills in .claude/skills/ (new-feature, new-context,
value-object, form-machine, bff-endpoint, mutation-command, ui-component,
new-ssp), condensed from CLAUDE.md/ARCHITECTURE/fp-tea/ADRs and pointing at
this repo's worked examples. CLAUDE.md gains a pointer.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
2026-07-03 10:10:38 +02:00

59 lines
2.2 KiB
Markdown

---
name: mutation-command
description: Add a write/submit operation — infrastructure adapter method plus an application command factory returning Result, keeping the reducer pure. Use for any POST/PUT/DELETE a form or action triggers.
---
# Mutation command
Reducer = "what the new state is"; command = "go do it, then say what happened".
The UI holds an application command, never the network client (lint-enforced).
## Skeleton
**Adapter method** (`<context>/infrastructure/<name>.adapter.ts`) — takes the
machine's `Valid` type, returns the server's answer, no parse (server is authority):
```ts
@Injectable({ providedIn: 'root' })
export class ChangeRequestAdapter {
private client = inject(ApiClient);
async changeRequest(data: Valid): Promise<string> { /* → server reference */ }
}
```
**Command factory** (`<context>/application/submit-<name>.ts`) — binds the adapter in
an injection context; `runSubmit` is the one try/catch + ProblemDetails mapping:
```ts
export function createSubmitChangeRequest() {
const adapter = inject(ChangeRequestAdapter);
return (data: Valid): Promise<Result<string, string>> =>
runSubmit(() => adapter.changeRequest(data), SUBMIT_FAILED);
}
```
**Caller** (organism, field initializer — same shape as `createStore`): on the
machine's `Submitting` state, run the command, then dispatch
`SubmitConfirmed` / `SubmitFailed { error }`. Never throw into the template.
## Optimistic updates on shared state
When a root store's view must reflect the write before the server confirms:
`begin*` (flip pending) → `confirm*` (clear + `resource.reload()`) / `rollback*`
(undo). See `src/app/registratie/application/big-profile.store.ts`.
## Worked examples
- `src/app/registratie/infrastructure/change-request.adapter.ts`
- `src/app/registratie/application/submit-change-request.ts`
- `src/app/registratie/application/draft-sync.ts``createDraftSync(...)` bundles
draft persistence + submit for wizard flows; prefer it when the form has a draft.
- `src/app/shared/application/submit.ts``runSubmit`, `SUBMIT_FAILED`.
## Verify
```bash
npm test && npm run lint && npm run build
# exercise the failure path in the browser: ?scenario=error on the submitting page
```