V5 renames the public isolation boundary from container tag to namespace. Existing values remain valid identifiers; no stored data rename is required.

### Endpoint mapping

| Legacy | V5 |
| --- | --- |
| `GET /v3/container-tags/list` | `GET /namespaces` |
| `GET /v3/container-tags/{tag}` | `GET /ns/{namespace}` |
| `PATCH /v3/container-tags/{tag}` | `PATCH /ns/{namespace}` |
| `DELETE /v3/container-tags/{tag}` | `DELETE /ns/{namespace}` |
| Merge container tags | `DELETE /ns/{source}` with `{ "moveTo": "target" }` |

`GET /ns` is an alias for `GET /namespaces`. Prefer `/namespaces` in new integrations.

### List namespaces

Each entry now exposes `id`, `namespace`, `documentCount`, `memoryCount`, nullable `description`, and `system.createdAt/updatedAt`. Update readers that still expect `containerTag`, flat timestamps, or unbounded internal settings.

### Read and update settings

<CodeGroup>
```bash Legacy
PATCH /v3/container-tags/project_alpha
{"entityContext":"Research project for distributed systems"}
```

```bash V5
PATCH /ns/project_alpha
{"supportingContext":"Research project for distributed systems"}
```
</CodeGroup>

The public GET and PATCH shapes contain only `namespace`, `supportingContext`, and lifecycle timestamps. Profile buckets have their own `/profile/buckets` resource and are not namespace settings.

Send `supportingContext: null` to remove existing context. Omitting the field entirely is invalid because PATCH requires at least one supported setting.

### Permanently delete a namespace

```bash
DELETE /ns/project_alpha
{}
```

With no `moveTo`, deletion is synchronous and returns `200` with `deletedDocumentsCount` and `deletedMemoriesCount`. This removes the namespace and its content.

### Move then remove a namespace

```bash
DELETE /ns/project_alpha
{"moveTo":"project_archive"}
```

This returns `202` with `status: "queued"` and `operationId`. The destination must differ from the source. Do not treat acceptance as completed migration.

Legacy merge can accept multiple sources; V5 moves one source per request. Run multi-source migrations sequentially and record each operation independently.

### Verification

- Confirm existing container-tag values resolve unchanged as namespace paths.
- Compare namespace counts with namespace-scoped document and memory lists.
- Verify a permanent delete returns final counts while a move returns `202`.
- Verify restricted callers cannot read or mutate namespaces outside their scope.
- Verify only organization-authorized callers can change settings or lifecycle.