feat(integrations): manage MCP servers from Connections settings

[coygeek]

Summary

Add per-environment MCP server inventory, health, authentication, and lifecycle controls to Connections settings.

Problem to solve

T3 Code already parses MCP status and OAuth events and creates MCP sessions (packages/contracts/src/providerRuntime.ts:193-245; apps/server/src/provider/Layers/ProviderService.ts:909-960), but Connections settings does not let users inspect or manage configured MCP servers.

Proposed behavior

Show configured MCP servers for each environment with connected, disconnected, and error state; last update time; tool availability; and OAuth sign-in or reconnect actions. Allow disable and remove operations where the provider supports them, with confirmation and immediate state refresh.

Acceptance criteria

• Connections settings lists MCP servers grouped by environment and provider.
• Health state, last error, and last successful update are visible without opening a thread.
• OAuth login, reconnect, disable, and remove use typed server operations and report failures clearly.
• State changes propagate to web, desktop, mobile, and remote clients without restarting unrelated threads.
• Secrets and bearer tokens never appear in the UI, logs, or exported settings.

Affected area

MCP contracts and provider adapters, environment settings APIs, ConnectionsSettings UI, and shared client-runtime state.

Non-goals

This does not create a marketplace or change provider-specific MCP configuration formats.

Alternatives considered

Relying on provider-native configuration leaves users unable to diagnose a disconnected server from T3 Code and makes remote management impractical.

Supporting context

apps/web/src/components/settings/ConnectionsSettings.tsx:1794-1845 currently covers environment connections without an MCP inventory. Existing issue #11398 requests surfacing OpenCode MCP/LSP/plugins; this proposal defines the provider-neutral MCP management slice and should coordinate with that work.

Related upstream work: /mcp controls discussion #10535, MCP reconnect PR #8737, and OpenCode inventory PR #11400. The requested management surface should reuse supported provider operations and clearly report unsupported controls.

Analysis basis: source inspection of T3 Code revision 9d4bb550a658. Statements about missing UI or contracts refer to that revision, not every provider-native capability or unmerged branch. This is a feature proposal based on source review, not a runtime bug reproduction.

[juliusmarminge]

Closing as a duplicate of #10535 (/mcp view to inspect and control each MCP server).

Same core ask: in-app inventory of configured MCP servers with health/status, tool visibility, and reconnect / disable (and related lifecycle) controls. Placing that surface in Connections settings vs a /mcp manager is a product detail that can continue on #10535.

Related but narrower OpenCode inventory work stays on #11398 / #11400; Codex reconnect-on-demand on #8737.