[Vritant Bhardwaj (vritant24)]

Fixes one bug from #343250 (comment): disabling an MCP server that comes from ~/.copilot/mcp-config.json never reached the agent host. The other bugs in that comment (per-profile storage, last-writer-wins merging, tool set switches) are not addressed here.

Problem

Copilot-home servers are discovered by the agent host, which owns their Global decision. The window never forwards them (CopilotHomeNotForwarded), but it also loads that file as a local MCP collection, so the row has a local twin (for example copilot.null.github).

In mcpListWidget.ts, whenever a local id existed:

• setPrimaryMcpServerEnablement wrote only the window's profile mcp.enablement and never called setCustomizationEnablement.
• isPrimaryMcpServerEnabled read that same local state, so the row showed "Disabled (Globally)".
• The row menus offered the local "Disable (Globally)", with the same problem.

The host published enablement: null, never reconciled the server off, and the next turn started it again.

Change

When the active agent-host session server is not client-bundled (isClientBundled false, the same childEnablement rule the host uses to decide Global ownership), the local twin is ignored for enablement:

• The primary switch writes to the host, and its displayed state comes from the session server's resolved enablement.
• The built-in row menu offers the host's Global, Workspace and Session actions.
• On mcp.json rows paired with a host-owned server, the local Global/Workspace actions are replaced by the host's.

Client-forwarded mcp.json servers (isClientBundled true) and non-agent-host harnesses keep their current behavior.

The local twin is not written or migrated. _syncClientMcpEnablement already mirrors an accepted host Global decision onto the single same-named local server, so the host stays the single source of truth.

Testing

• ./scripts/test.sh --run src/vs/workbench/contrib/chat/test/browser/aiCustomization/mcpListWidget.test.ts: passed (126 passing). With the source change reverted, 2 tests fail.
• New suite "MCP enablement routing for a server with a local twin" covers a host-discovered Copilot-home server with a stale local disable, a client-forwarded server, and no active agent-host session.
• npm run typecheck-client: passed.
• npm run eslint -- <changed files>: passed.
• End to end in Code OSS (Copilot harness): toggling github (from ~/.copilot/mcp-config.json) off wrote {"global":{"mcpServers#github":false}} to agent-host-storage.json; the running session logged Reconciling MCP server 'github' enablement: disable; the next turn and a new session reported github only as disabled (stopped) and never started it.

Known trade-offs

• Existing stale local disables (copilot.null.github: false) from the old bug are not migrated; they now only affect the Local harness.
• Rows are matched by name, so a mcp.json server sharing a name with a host-discovered one now controls the host's server.
• Workspace and Session decisions made in an agent-host session are not mirrored to the local twin, so the Local harness may still run a server that is off for the agent host.

[Copilot]

Warning

Copilot couldn't run its full agentic review because it didn't start before the timeout. Make sure your repository has a runner available, or add a copilot-code-review.yml file specifying one with the runs-on attribute. See the docs for more details.

Copilot review overview

3 open issues

• !server.isClientBundled treats undefined as true, which can incorrectly classify a server as… · New
• When multiple menuActionGroups contain local enablement actions, agentHostEnablementActions can… · New
• Passing undefined to trigger the default scopes is correct but obscures intent. Prefer passing an… · New

What changed in this PR

Routes enablement decisions for host-discovered MCP servers (that have a same-named “local twin”) to the agent host so global disables actually take effect, fixing the “local twin disable never reaches host” bug referenced in #343250.

Changes:

• Introduces “host-owned” server detection to ignore local enablement for host-discovered servers and to source state/actions from the agent host instead.
• Updates built-in and server-item menus to replace local enablement actions with agent-host actions when appropriate.
• Adds a dedicated test suite covering host-discovered servers with a stale local twin, client-forwarded servers, and no active agent-host session.

File	Description
src/​vs/​workbench/​contrib/​chat/​browser/​aiCustomization/​mcpListWidget.ts	Adds host-ownership routing logic and adjusts enablement/action selection to target the agent host for host-discovered servers.
src/​vs/​workbench/​contrib/​chat/​test/​browser/​aiCustomization/​mcpListWidget.test.ts	Adds/updates tests to validate routing behavior for host-owned vs client-owned servers and session/no-session cases.

_{Review effort: Lite}