Covers hosted vector stores against a fake provider backend: create/list/get/delete, attaching files (existing id or fresh upload) with polling until ingestion completes, fire-and-forget attachment, polling timeouts, failure surfacing without throwing, searchable attributes, and provider resolution errors and overrides.

## Before writing SPEC.md files

Read https://raw.githubusercontent.com/brillout/sdd/refs/heads/main/sdd.md
