Local HTTP MCP native elicitation times out before reaching client

[shardulbee]

Problem

Native MCP approval does not reach the client through Executor's local HTTP endpoint. Browser approval works.

Reproduce

1. Connect to http://127.0.0.1:4789/mcp?elicitation_mode=native&artifacts=false.
2. Advertise capabilities.elicitation.form.
3. Register an elicitation/create handler.
4. Call execute with code that uses an approval-gated tool.

Result

The client never receives elicitation/create. After about 60 seconds, execute fails with:

McpNativeElicitationTransportError
MCP -32001: Request timed out

Executor logs show that form elicitation is enabled and the client capability was detected. A direct @modelcontextprotocol/client test reproduces the failure without any host UI or adapter.

Cause

apps/local/src/mcp.ts creates WebStandardStreamableHTTPServerTransport with:

enableJsonResponse: true

A single JSON response cannot deliver elicitation/create while the original tools/call is still waiting for approval. Native mode needs an SSE response stream.

Proposed fix

Configure the transport based on the selected mode:

enableJsonResponse: elicitationMode !== "native"