## Why
MCP servers discovered on different executors can share a name. Resolving them by name alone exposes only one server and prevents tools and resources from being addressed independently.
## What changed
- Add the disabled-by-default `multi_environment_mcp` feature to expose environment-scoped servers, including multiple installations of the same plugin.
- Carry exact `McpServerKey` identities through catalogs, connections, tool calls, resources, and approval tracking. Give environment-scoped tools stable namespaces derived from their environment.
- Include `environment_id` in scoped resource listings and accept it in resource requests. Require it for environment-owned servers when multiple environments are selected.
- Preserve server ownership through hooks and use the owning environment's permissions for scoped elicitation review.
## Testing
Add coverage for same-named servers across environments, independent calls and approvals, resource selection, plugin discovery, and rejection of hook changes to the tool environment.
GitOrigin-RevId: 5593372b06a15c16aa3220faa3b19f5d3b20e67e
## What changed
Expose `McpToolRequestMetaHook` and `McpToolRequestMetaProvider` so hosts can supply a per-invocation `_meta` value using the thread, turn, and call IDs. Apply the hook before dispatch only when the tool, server name, source, and full transport configuration match the selected local MCP registration.
Reject metadata key collisions and propagate provider errors to the tool caller without dispatching the call.
## Testing
Add integration coverage for matching registrations, different contributors and routing headers, unrelated tools and servers, provider failures, and existing metadata keys.
GitOrigin-RevId: 2bf51c375a04617d61b24ca1cbbcaa810fb06720
sayan-oai