Desktop app: add a way to restart/reload a session's MCP connections without losing history (mid-session re-auth support)

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• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

When an MCP server's auth is refreshed (e.g. re-authing after a token expired), a currently-open desktop app session doesn't pick up the new connection. MCP servers appear to be wired up only at session start, so the running session keeps using the stale/disconnected MCP state even though the MCP panel shows the server as connected and authenticated at the account/config level.

On the CLI, this is solved by claude --resume <session-id> (or /resume), which restarts the process while keeping the conversation history intact. The desktop app has no equivalent — there's no /resume slash command, no "restart this session" action, and no way to reload MCP connections short of fully quitting and relaunching the entire app.

Fully quitting the app is a heavy-handed workaround:

It kills every open session, not just the one that needs a reconnect.

If any session is actively mid-run (generating, mid-tool-call, background task), quitting interrupts that work with no auto-resume offered afterward — history survives, but the in-flight step is silently dropped and has to be manually re-prompted.

Proposed Solution

Add a lighter-weight, per-session action — something like "Reload MCP connections," "Restart session," or "Stop session" — that:

Re-establishes MCP server connections for that session only, picking up fresh auth/config, without requiring a full app relaunch.

Preserves the conversation history/context exactly like CLI --resume does.

Doesn't affect other open sessions in the sidebar.

Alternative Solutions

_No response_

Priority

High - Significant impact on productivity

Feature Category

MCP server integration

Use Case Example

_No response_

Additional Context

Why this matters

Users who re-auth an MCP server mid-session currently have no way to get that session to see the update except a full app restart, which is disruptive if other sessions are running work in the background. A scoped per-session reload would bring desktop closer to CLI parity for this specific workflow and avoid unnecessary interruption of unrelated sessions.

Related issues: #50067, #69456, #50891