Copilot CLI 1.0.81 Adds Stateless MCP Support and Fails Closed When Enterprise Policy Refreshes Fail

GitHub released Copilot CLI 1.0.81 on August 27. Its core changes go beyond interface updates, adding support for MCP 2026-07-28 across the CLI, SDK, IDE, and in-memory clients. This MCP version eliminates the initialization handshake and transport-layer sessions, instead requiring requests to carry version, client information, and capabilities. Tool methods can also be routed through HTTP headers. As a result, when Copilot CLI connects to newer remote MCP servers, it can work with standard load-balancing architectures without relying on sticky sessions. Existing servers and plugins must still verify protocol negotiation and compatibility layers.

Observability has also advanced: hook inputs now include `traceparent` and, when necessary, `tracestate`. Command-based hooks can obtain the same information from environment variables, allowing spans generated by external scripts to be connected with agents, subagents, and tool calls in a single trace. `--usage-output-file` now includes per-agent usage, while ACP clients can receive subagent IDs along with real-time mode, command, and plan events. These additions are particularly useful for attributing costs and troubleshooting failures in multi-agent systems.

For enterprise controls, managed `enabledPlugins` and `extraKnownMarketplaces` settings now override local settings on an item-by-item basis. When `forceRemoteSettingsRefresh` is enabled and new policies cannot be retrieved, the system no longer falls back to cached policies. Instead, it temporarily blocks non-default MCP servers, bypass-permissions mode, and policy-controlled plugin changes. This reduces the risk of continuing to use stale policies, but control-plane failures may directly block work.

The upgrade also carries migration risks. The final release removes `/plugins` and the dashboard exit flag, splitting resources across entry points such as `/plugin`, `/mcp`, and `/skills`. The dashboard’s hook and LSP enable/disable controls are temporarily unavailable. Before upgrading, teams should run regression tests covering automatic updates, non-interactive `-p` execution, MCP protocol versions, and offline policy-refresh failure scenarios.