### Changed
- Minimum `abstractcore` optional dependency increased to `>=2.13.11` for the `abstractcore`, `multimodal`, and `mcp-worker` extras so Runtime aligns with the current Core server-auth, provider-key, generated-media, and capability-catalog contracts.
- AbstractCore integration imports now fail fast when a stale local AbstractCore install is older than the 2.13.11 Gateway/Core deployment baseline.
- Documentation now makes the Gateway handoff explicit: hosts choose Runtime plus the Core/capability/memory profile, pass Core server URLs/auth headers deliberately, and keep provider clients, auth objects, model handles, and sessions out of durable runtime state.
- Runtime no longer reads Gateway-owned environment variables directly. Prompt-cache defaults use explicit Runtime state or `ABSTRACTRUNTIME_PROMPT_CACHE`, read-file attachment registration limits use explicit Runtime state/payload values or `ABSTRACTRUNTIME_MAX_ATTACHMENT_BYTES`, and workflow bundle registries use shared/framework or explicit directories.

### Testing
- Added packaging boundary coverage proving Runtime exposes no fake hardware profile extras (`apple`, `gpu`, `all-apple`, `all-gpu`) and keeps the Core floors aligned.
- Added import-boundary coverage proving the runtime kernel and package root do not import optional Core/Vision/Voice/Memory/Music stacks.
- Added a remote client regression test proving Gateway auth/provider-key environment variables are not inherited as AbstractCore server auth or provider-key headers.
- Added regression tests proving Gateway env vars alone do not enable prompt-cache keys, shrink attachment registration limits, or select workflow bundle registry directories.
