MCP client connection status goes stale after initial connect #25682

Description

Once an MCP server connects successfully, opencode never checks whether the connection is still alive. The status stays connected indefinitely, even when the underlying
connection is broken.

This means:

• GET /mcp returns stale {"status": "connected"} for dead servers
• Tool calls fail at invocation time with no prior warning
• SSE /event has no mechanism to notify clients of a status change
• There is no way to detect the problem externally without reconnecting every server on a timer

The only existing detection is ToolListChangedNotification in watch() (src/mcp/index.ts:460), which only fires when the server proactively sends a notification — it cannot
detect silent connection failures like a crashed process, a restarted remote server, or a network interruption.

This is especially problematic for users running opencode serve. The TUI has a human in the loop who can notice failures and restart, but serve mode is headless — typically
consumed by other tools or services via the HTTP API. When an MCP connection silently breaks in this mode, the server continues accepting requests and reporting everything as
healthy. There is no automatic reconnection, and no status change event for consumers to react to. The only external workaround is periodically calling POST /mcp/:name/connect
for every configured server, which tears down and rebuilds the connection each time — wasteful and disruptive

Plugins

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OpenCode version

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Steps to reproduce

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Screenshot and/or share link

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Operating System

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Terminal

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