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[Server] Stop bundling queued notifications into the JSON answer of a request - #602
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chr-hertel merged 1 commit intoOct 15, 2026
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A JSON answer bundled the session's queued messages with the request's response into one array, which clients on 2025-06-18 and later reject. The queued messages now go out on an SSE answer ahead of the responses, and a JSON answer holds the response alone. 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude <noreply@anthropic.com>
chr-hertel
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October 14, 2026 23:44
chr-hertel
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🟢 Approval recommended
The focused change matches the intended behavior and includes regression coverage, with no blocking issues identified; tests were not executed.
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What changed in this PR
Fixes queued notification delivery in StreamableHttpTransport without bundling notifications into JSON responses.
Changes:
- Uses SSE when queued messages exist, sending them before request responses.
- Adds regression coverage for single requests, batches, and JSON-only responses.
- Documents the compatibility fix.
| File | Description |
|---|---|
| tests/Unit/Server/Transport/StreamableHttpTransportTest.php | Tests queued-message SSE delivery and response-only JSON. |
| src/Server/Transport/StreamableHttpTransport.php | Selects SSE for queued messages; otherwise returns JSON responses alone. |
| CHANGELOG.md | Documents the corrected response format. |
🧠 Review effort: Balanced
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Follow-up to #597: a plain request on a session with queued messages (e.g.
resources/updated) was still answered with a JSON array of those messages and its response. The spec wants one JSON object there, and since2025-06-18there is no batching at all - Pythonmcp2.x rejects it with-32700.A standalone GET stream would be the more natural home for these messages, but the transport has none yet - so the SSE answer keeps them flowing until then.
Fixes chr-hertel#73
🤖 Generated with Claude Code