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Title: diag(mcp): per-request phase logging on the streamable-HTTP transport by waleedlatif1 · Pull Request #5819 · simstudioai/sim · GitHub

Open Graph Title: diag(mcp): per-request phase logging on the streamable-HTTP transport by waleedlatif1 · Pull Request #5819 · simstudioai/sim

X Title: diag(mcp): per-request phase logging on the streamable-HTTP transport by waleedlatif1 · Pull Request #5819 · simstudioai/sim

Description: Summary Adds per-request phase logging to the pinned MCP transport fetch (createPinnedMcpFetch), mirroring the OAuth guarded-fetch instrumentation that isolated the /oauth/start body stall. Logs each transport request (host + method), the response headers with TTFB, and failures. Why: the logs prove our client's first connect to these servers consistently hangs to the 30s client timeout while a normal client's initialize returns in ~120 ms — but we haven't isolated where it stalls. This logging shows whether the first connect hangs before response headers (connect/request phase) or after (the SDK's stream/body read) — the data needed to root-cause it before touching the single-IP-pin SSRF control. Type of Change Diagnostic (temporary logging; no behavior change) Testing Type-check + biome clean. No behavior change — wraps the existing pinned fetch with logging only. Checklist Code follows project style guidelines Self-reviewed my changes Tests added/updated and passing No new warnings introduced I confirm that I have read and agree to the terms outlined in the Contributor License Agreement (CLA)

Open Graph Description: Summary Adds per-request phase logging to the pinned MCP transport fetch (createPinnedMcpFetch), mirroring the OAuth guarded-fetch instrumentation that isolated the /oauth/start body stall. Logs e...

X Description: Summary Adds per-request phase logging to the pinned MCP transport fetch (createPinnedMcpFetch), mirroring the OAuth guarded-fetch instrumentation that isolated the /oauth/start body stall. Logs e...

Opengraph URL: https://github.com/simstudioai/sim/pull/5819

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980a6fe diag(mcp): per-request phase logging on the streamable-HTTP transport waleedlatif1 Jul 21, 2026 https://github.com/simstudioai/sim/pull/5819/commits/980a6fe84e6fd2c2386ae365096e6753ec4fb50f
a12bac5 diag(mcp): include error name/code in transport failure log waleedlatif1 Jul 21, 2026 https://github.com/simstudioai/sim/pull/5819/commits/a12bac543161ed542e8b92d36bc4a401e807d753
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