feat: add support for SSE MCP servers

[04cfb1ed]

Description

Add support for multiple MCP server types (stdio, sse, websocket) in the YAML configuration schema, ensuring backward compatibility with legacy configurations).

mcpServers:
   - name: Debug list
     type: stdio
     command: uv.exe
     args:
       - --directory
       - test-mcp-server
       - run
       - load-folders-mcp.py

   - name: Debug Local  MCP Python
     type: sse
     url: http://127.0.0.1:8000/sse

I just saw the #5511 I was working on this PR a few days ago, I leave here, but I don't know how to proceed

Closes #5359

Checklist

• I've read the contributing guide
• The relevant docs, if any, have been updated or created
• The relevant tests, if any, have been updated or created

Screenshots

[ For visual changes, include screenshots. Screen recordings are particularly helpful, and appreciated! ]

Testing instructions

[ For new or modified features, provide step-by-step testing instructions to validate the intended behavior of the change, including any relevant tests to run. ]

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[nejch]

Thanks @04cfb1ed I closed my PR to avoid confusion as it was just a quick draft I didn't spend much time on, and yours is more complete.

[enzoescipy]

Hi @04cfb1ed,

Following @nejch's suggestion on the now-closed PR #5511, I wanted to reach out here. Thank you for picking this up and creating a more complete implementation for SSE/WebSocket MCP server support! This is a feature I was really looking forward to for my own setup.

Since the original PR was a draft and I was eager to test this out, I quickly put together a working version (for my specific SSE use case) in my fork:
https://github.com/enzoescipy/continue/tree/sse-mcp-support

It mainly involved completing the URL handling in loadYaml.ts and ensuring the schema definition was correct, building upon the existing logic in MCPConnection.ts.

Please feel free to reference it if any part might be helpful for finalizing this PR (#5517). No pressure at all, just wanted to share my work in case it's useful.

Thanks again for implementing this much-needed feature, and looking forward to seeing this merged!

[Patrick-Erichsen]

This looks solid, thanks for adding the tests as well! Just had a few small comments.

Is there an SSE server you could point me towards to test this locally?

[Patrick-Erichsen]

Suggested change

	- `type"` (**required**): The type of the MCP server. Can be "stdio", "sse", or "websocket.
	- `type"` (**required**): The type of the MCP server. Can be "stdio", "sse", or "websocket".

[Patrick-Erichsen]

Is there any way we can use the existing blockOrSchema instead of creating the new type? This will likely break typings in our repo for hub.continue.dev and in general will complicate things a lot.

Generally speaking I'd rather have a not-100%-perfect-schema rather than create a new wrapper here.

[04cfb1ed]

Is this acceptable? (adding an optional parameter to change the override parameter)

export const blockOrSchema = <T extends z.AnyZodObject>(
  schema: T,
  usesSchema: z.ZodTypeAny = defaultUsesSchema,
  isDiscriminatedUnion?: boolean,
) => {
  if (isDiscriminatedUnion) {
    return z.union([schema, z.object({
      uses: usesSchema,
      with: z.record(z.string()).optional(),
      override: z.any().optional(),
    })]);
  }
  return z.union([schema, blockItemWrapperSchema(schema, usesSchema)]);
};

// Sample
mcpServers: z.array(blockOrSchema(mcpServerSchema as any, defaultUsesSchema, true)).optional(),

[AwaisBinKaleem]

@04cfb1ed waiting for your powers for this megical feature :)