Desktop app: no way to enable/disable Claude Code MCP servers (`/mcp disable` fails, no Settings UI)

## What happens

In the **desktop app**, there is no way to enable or disable a Claude Code MCP server.

`/mcp disable ` fails every time:

```
MCP controls aren't available right now — the terminal is still starting up or is showing another view.
```

This is reproducible on an idle session with no other view open. The interactive `/mcp` picker never renders either — it's a terminal dialog, like `/permissions`, `/config`, and `/hooks`.

## Why this looks like a bug rather than a missing feature

The capability already exists in the terminal. The in-session MCP toggle shipped in v2.0.10, and `/mcp` there gives a clean list with per-server enable/disable. Same version, same machine, same config — it just isn't reachable from the desktop app.

It's also easy to assume the feature is present, because **Settings has two MCP panels that don't cover Claude Code**:

| Settings panel | Manages | Config |
|---|---|---|
| Extensions | Desktop app's own MCP servers (`.mcpb` / `.dxt` bundles) | `claude_desktop_config.json` |
| Connectors | claude.ai remote connectors (Gmail, Slack, Notion…) | server-side |
| — none — | **Claude Code's MCP servers** | `~/.claude.json` |

So a user with 13 servers in `~/.claude.json` opens Settings, sees an MCP screen listing one unrelated server, and has no path forward.

## Why it matters

Context. Every enabled server's tools load at session start, so disabling unused servers is the main lever a user has over startup context. In my case 4 connected servers contributed 151 tools (meta-ads 97, razorpay-pvtltd 42, Sentry 9, cloudflare-api 3). Turning them off is worth doing regularly — but in the desktop app it currently costs a config edit plus a new chat, and starting a new chat loses the conversation you're in.

## Workaround (for anyone hitting this)

Two mechanisms, because neither alone is sufficient:

1. **Live, mid-session** — add `mcp__` to `permissions.deny` in `./.claude/settings.local.json`. Permission rules are re-read while a session runs, so the block applies immediately with no restart. This stops tool *use*, not tool *loading*, so it does not save context.
2. **Persistent** — add the server to `disabledMcpServers` under `projects[""]` in `~/.claude.json`. This prevents the server launching next session, which is what actually saves context.

One trap worth documenting: `disabledMcpServers` is keyed by absolute project path, and **each git worktree is its own key with its own empty list**. Disabling a server in the main checkout has no effect in any worktree. Servers can also be defined per-project rather than globally, so enumerating only `mcpServers` at the top level of `~/.claude.json` misses some.

## Request

Either:

- port the terminal's MCP panel to the desktop app, or
- make the non-interactive form (`/mcp enable|disable|reconnect `) work there.

The non-interactive form alone would be enough — it's already the documented usage string, it just never executes.

## Environment

- Claude Code v2.1.220 (desktop app)
- macOS 27.0.0 (arm64)
- 14 MCP servers configured in `~/.claude.json` (13 global, 1 project-scoped)

## Related

#10447 · #30595 · #17921 · #4879 · #5722 · #50826 — all cover CLI or config-file toggling. None cover the desktop app having no MCP surface at all.

Start by reproducing the desktop app failure with `/mcp disable ` and compare it with the working terminal `/mcp` panel. Review the desktop app's MCP controls and the `~/.claude.json` configuration described in the report; done means Claude Code MCP servers can be enabled or disabled from the desktop app without editing configuration manually.

Written by the indexing model from the issue text.