Z.ai keys on the coding subscription get 429 'Insufficient balance' on the standard /api/paas/v4 endpoint. Add a per-provider BaseURLField to the Z.ai registry entry, a ZaiBaseURL override on AIConfig (returned by GetBaseURLForProvider when set, else the standard default), the handler request/response/apply plumbing, and a 'Custom Base URL' field on the Z.ai provider card so operators can point at /api/coding/paas/v4. Mirrors the existing OpenAI custom-base-URL override; the standard endpoint remains the default for pay-as-you-go users. Adds config/handler/frontend proofs and updates the ai-runtime, api-contracts, frontend-primitives, agent-lifecycle, and storage-recovery contracts.
rcourtman
1f6fe16e49