feat: add conformance tests for SEP-1699 SSE polling #47
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Adds conformance tests for SEP-1699 (SSE Polling via Server-Side Disconnect) which allows servers to close connections while maintaining SSE streams for long-polling behavior. New scenarios: - server-sse-polling: Tests server sends priming event (id + empty data) and retry field before closing connection (SHOULD requirements) - sse-retry: Tests client respects SSE retry field timing when reconnecting (MUST requirement) These tests will initially fail for TypeScript SDK as it doesn't currently respect the retry field from SSE events.
The test was incorrectly measuring timing between all requests (POST and GET), but the retry field only applies to GET SSE stream reconnections. Changes: - Only track timestamps and Last-Event-ID for GET requests - Return 202 Accepted for notifications to trigger client GET stream - Add eventsource-parser dependency
Enhance timing validation and event ordering checks: Client test (sse-retry): - Add "very late" threshold (>2x retry value) as FAILURE - Distinguish between slightly late (WARNING) and very late (FAILURE) Server test (sse-polling): - Check that priming event is sent immediately (first event) - Warn if server disconnects without sending event ID first
The eventsource-parser library delivers retry through onRetry callback, not as a property on EventSourceMessage objects.
Server may return 400 when GET request is missing session context (mcp-session-id header). Treat as INFO similar to 405.
- Rewrite server tests to validate priming events on POST SSE streams - Update client tests for POST→GET reconnection flow with retry timing - Add eventStore and retryInterval to example server - All 3 server conformance checks now pass
New scenario tests that servers properly support multiple concurrent GET SSE streams per SEP-1699 spec requirement.
The multiple-streams test was incorrectly testing standalone GET streams, which are limited to one per session by SDK design. The spec's "multiple concurrent streams" refers to POST-initiated SSE streams, where each POST request gets its own unique streamId. Changes: - Rewrite server-sse-multiple-streams to use concurrent POST requests - Each POST request may return SSE or JSON (both valid per spec) - Update test expectations to allow INFO status for JSON responses - Add documentation clarifying standalone GET vs POST stream behavior
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This was referenced Nov 23, 2025
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pcarleton
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Nov 24, 2025
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Adds conformance tests for SEP-1699 which introduces SSE polling via server-side disconnect.
Summary
sse-retry): validates retry field timing (MUST), Last-Event-ID on reconnection (SHOULD)server-sse-polling): validates priming event with id and empty data, retry fieldserver-sse-multiple-streams): validates multiple concurrent POST SSE streamsChanges since previous PR
server-sse-multiple-streamsto test POST-initiated concurrent streams (not standalone GET)How Has This Been Tested?
Tested with modelcontextprotocol/typescript-sdk#1129
Checklist