The MCP control channel now supports a tighten-only per-server permission mode override. Orchestration layers can downgrade specific MCP server permissions to 'default' (or clear the override with null) without a full session restart. Escalation attempts (e.g., setting 'auto') are rejected:
Permission mode override over the control channel is tighten-only ('default' or null); rejected 'auto'
Evidence
New Qta() function — search for "set_mcp_permission_mode_override" and "tighten-only"
Strings lifted out of the shipped bundle, so the claim above can be checked against them.