## Why
Runtime authentication must use the credential selected by the model provider. Explicit API keys and command credentials need independent ownership so cached connections and in-flight work cannot cross credential sources.
## What changed
- Register and reuse runtimes per credential source, supporting explicit provider keys and command credentials without falling back to saved login credentials.
- Track `AuthOwner` by credential manager and owner generation across WebSocket state, compaction, and scoring.
- Preserve cached identity and runtime registration state during credential-source outages or failed storage reloads. Require a successful auth reload before logout revokes credentials.
- Reject requests whose production or staging environment differs from runtime registration, including model catalog requests.
## Testing
Add regression coverage for credential selection and runtime reuse, owner isolation, source outages, failed reloads and logout recovery, and environment mismatches.
GitOrigin-RevId: 7bab55e0ea502593393df10046309fd8502edbd0
cooper-oai
faeb379646