PoC: typed result contract for store execute

[dmerand]

Intent

This draft is a proof of concept for migrating the finite store execute command to a data-only typed result contract. It keeps execution facts separate from CLI output adapters.

Design

• StoreExecuteResult contains JSON-safe operation data and an optional coded failure.
• The codec owns JSON wire encoding. With --output-file, the file contains the operation payload; JSON stdout contains a structured sink document.
• The presenter owns terminal output, file writing, and unsuccessful result classification.
• GraphQL transport errors remain execution-level failures: no result document exists and the existing error boundary handles them.
• GraphQL responses containing nested userErrors are result-level failures: data is emitted and the command exits unsuccessfully with code USER_ERRORS.

Explicit output decisions

1. User-error responses: Before, a response with userErrors was reported as success. After, the operation payload is emitted and the command exits unsuccessfully; JSON remains data-only and does not add English sentences.
2. JSON plus --output-file: Before, the payload was written to the file and stdout was empty. After, stdout emits a JSON sink document containing outputFile, success, and (on failure) failureCode; the file still contains only the operation payload.

No other command output was changed. --allow-mutations remains input safety policy and is not part of the result contract or codec.

Deliberately not done

• No BaseCommand or launcher changes.
• No automatic serialization.
• No event plumbing or diagnostics channel.
• No migration of other commands.
• No shared store schemas in @shopify/cli-kit.

Validation

• Focused Vitest and added wire/result-level-failure tests: not completed in this PoC checkout.
• Changed-file ESLint: initially found and fixed formatting/order issues; final run was interrupted by dependency type-check command.
• pnpm --filter @shopify/store type-check: blocked by unresolved local @shopify/cli-kit declarations and Node globals despite dependency builds; these are environment/dependency build issues, not reported as clean.
• git diff --check: run before commit.