- Correct the SessionStore signature: `get(id: string)` is non-optional,
not `get(id?: string)` (only create/prepare take an optional id).
- Broaden the ACP brand-erosion description and the acceptance criterion
beyond `Map<string>`: the session-id surface also includes the
`bySession` WeakMap, the `loadingIds` Set, and the exported
`streamSessionEventUpdate(sessionId)` signature.
- Use bare inline code spans for code paths instead of markdown links,
matching the house style of the other architecture RFCs and removing the
link/bare-span inconsistency within this file (doc-to-doc cross-links
stay markdown links per docs/AGENTS.md).
Tianyi Cui
bf3cfe84c3