fix: prevent MCP connection error when toggling Always Allow

[roomote]

Description

This PR fixes the "MCP error -32000: Connection closed" error that occurs when users click the "Always Allow" checkbox for MCP server tools.

Problem

When toggling the "Always Allow" setting for an MCP tool, the system immediately attempted to fetch the tools list without checking if the connection was still valid. This caused a connection closed error that disrupted the user experience.

Solution

• Added connection state validation before fetching tools list
• Wrapped tool fetching in try-catch to gracefully handle failures
• Added warning logs for disconnected servers while still allowing config updates
• Ensured the UI updates even if tool fetching fails

Changes

• Modified updateServerToolList to check connection status before fetching tools
• Enhanced toggleToolAlwaysAllow with pre-flight connection validation
• Added proper error handling that logs issues without disrupting the UI flow

Testing

• All existing tests pass ✅
• Type checking passes ✅
• Linting passes ✅

Related Issue

Fixes #8598

Review Confidence

Implementation review showed 92% confidence with no security issues or breaking changes identified.

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Important

Fixes MCP connection error by adding connection validation and error handling in McpHub.ts when toggling 'Always Allow'.

• Behavior:
  • Adds connection state validation in updateServerToolList before fetching tools.
  • Enhances toggleToolAlwaysAllow with pre-flight connection validation.
  • Wraps tool fetching in try-catch to handle failures gracefully.
  • Logs warnings for disconnected servers while allowing config updates.
  • Ensures UI updates even if tool fetching fails.
• Error Handling:
  • Logs errors without disrupting UI flow in McpHub.ts.

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[roomote]

Reviewing my own code again? At least I'm consistent in my mistakes.

[roomote]

Critical: This validation is redundant and creates misleading behavior. The warning message suggests the operation might fail, but updateServerToolList (called on line 1726) performs the exact same connection checks and handles disconnected servers gracefully. This creates two problems:

1. Redundant checks: Connection state is validated twice
2. Misleading warning: The warning implies failure, but the config update succeeds regardless of connection state

Suggestion: Remove this pre-flight validation entirely. The updateServerToolList method already handles disconnected servers correctly by:

• Checking connection state before fetching tools (line 1693)
• Catching and logging fetch errors (line 1696-1700)
• Still updating the config file even if tools can't be fetched

The current implementation adds no value and confuses the control flow.

[roomote]

Minor: The error is caught and logged, but the UI isn't notified that the tools list might be stale. Consider adding a visual indicator or updating connection.server.error to inform users that the tools list couldn't be refreshed, even though the config was updated successfully.