[Bug] Tenant-scoped OpenAPI refresh mutates global mounted MCP state

Nexent Version

Observed in the current public API-to-MCP refactor branch logic and relevant to the recent API-to-MCP work merged around v2.0.1.

Problem Description

The tenant-scoped refresh logic for imported OpenAPI services currently mutates a global in-process mounted MCP service set.

In local validation against the public refactor logic, refreshing tenant A mounted ['local', 'svc_a'], and then refreshing tenant B replaced that with ['local', 'svc_b'].

That means the refresh behavior is tenant-scoped in input, but global in effect.

Reproduction Steps

1. Prepare two tenants with different imported OpenAPI services.
2. Refresh tenant A and observe the mounted service set.
3. Refresh tenant B in the same process.
4. Observe that the mounted set is replaced globally instead of being isolated per tenant.

Additional Information

This looks like an isolation / lifecycle problem in the API-to-MCP mounting model.

Before proposing a patch, it would help to confirm the intended model:

• one global singleton service set for the whole process,
• per-tenant isolation inside the same process,
• or per-runtime / per-container isolation.

Start by tracing the tenant-scoped refresh logic in the API-to-MCP refactor and the global in-process mounted MCP service set. Reproduce the two-tenant sequence, establish whether isolation is per tenant, process, or runtime, and add coverage showing that refreshing tenant B does not replace tenant A's mounted services under the chosen model.