## Summary Closes #816. ListBuckets response was missing `` per entry, which the VS Code AWS Toolkit uses to filter visible buckets — fakecloud buckets were hidden in the IDE explorer. AWS CLI tolerates the missing field, real S3 always emits it. While fixing this, rounded out the full ListBuckets v2 surface AWS shipped alongside `BucketRegion`: - `` per bucket entry - `prefix` query parameter — name-prefix filter - `bucket-region` query parameter — region filter - `max-buckets` query parameter (1..=10000, default 10000) — page size - `continuation-token` query parameter — opaque base64 cursor - `` response element — next-page cursor when more pages remain - `` / `` echoed in response when input had them - `InvalidArgument` errors for out-of-range max-buckets and malformed tokens ## Test plan - [x] Unit tests in `fakecloud-s3`: 7 new tests covering all behaviors - [x] E2E tests via `aws-sdk-s3`: 4 new tests (region populated, pagination across pages, prefix filter, region filter with mixed-region buckets) - [x] Conformance `s3_bucket_lifecycle` still passes — Smithy checksum unchanged - [x] `cargo clippy --workspace --all-targets -- -D warnings` clean - [x] `cargo fmt --all` clean - [x] `website/static/llms-full.txt` updated to note v2 pagination + filters - [ ] VS Code AWS Toolkit smoke test against running fakecloud (manual, post-merge) --- ## Summary by cubic Implements S3 ListBuckets v2 with per-bucket `BucketRegion`, filters, and pagination. Fixes VS Code AWS Toolkit bucket visibility to match real S3 (closes #816). - **New Features** - Per-bucket `BucketRegion` in `ListBuckets` responses. - Query params: `prefix`, `bucket-region`, `max-buckets` (1..10000, default 10000), `continuation-token` (base64). Adds `` when more pages remain. - Echoes `` and `` when provided. Returns `InvalidArgument` for out-of-range `max-buckets` or malformed tokens. ^{Written for commit e3d215d78d1ac6978e82c5da8fc373d358474f58. Summary will update on new commits. Review in cubic}