modelcontextprotocol / modelcontextprotocol/typescript-sdk
SSEClientTransport
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- Dominant language
- TypeScript
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- Avg merge
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- Merged PRs (30d)
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Description
fails to establish the connection.
This happens only in the MCP TypeScript client — Postman and browser work fine for both paths.
To Reproduce
Steps to reproduce the behavior:
- Create a new
Clientinstance using the SDK - Use
SSEClientTransportand pass the full nested SSE URL - Observe that the connection never completes or fails silently
const client = new Client(
{ name: 'TestApp', version: '1.0.0' },
{
transport: new SSEClientTransport({
url: 'https://$domain/i_0b758EBC-9BEc52b9-Ea5ac125/sse',
}),
}
)Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Reproduce the failure with the TypeScript Client and SSEClientTransport using the nested SSE URL shown in the issue. Start by inspecting SSEClientTransport and trace why the connection does not complete, then verify that the same URL establishes a working connection in the MCP TypeScript client without regressing the other path.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- typescript
- Domain
- api
- Issue type
- Bug
- Difficulty
- 3/5
- Estimated time
- 1-2 days
- Activity status
- Quiet
- Clarity
- Mostly clear
- Newbie friendliness
- 52/100