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DisclaimerUnofficial, and not affiliated with Anthropic. Nearly all of this is read straight out of what ships: npm bundles, captured prompts, published docs. Anthropic's own notes go in verbatim, marked as theirs. The rest is my reading, and every entry carries the strings behind it. If one looks wrong, vote it down and say why.

← All of v2.1.236 Home All releases ←olderv2.1.235 v2.1.237newer→
Claude Code v2.1.236

MCP protocol auto-negotiation now covers the ccr-proxy transport, off by default

Not switched on
Useful2 Signal3
MCP Notable

The ccr-proxy MCP transport can negotiate protocol versions, but stays on legacy unless a flag is turned on.

Protocol auto-negotiation for the ccr-proxy MCP transport is built but gated off, so behaviour is unchanged.

Feature flag
tengu_mcp_protocol_negotiation_ccr Not enough to say

Nothing here resolved what this flag was doing on this version, so nothing here should be read as on or off.

This account: no value returned · anonymous baseline: no value returned · compiled default in v2.1.236: on

Read once, for one account on one subscription tier, against v2.1.236. It isn't a statement about your account. What a flag value here can and cannot tell you

What

The ccr-proxy MCP transport used to fall through to the legacy branch alongside sse, ws and ide. It now has its own check gated on tengu_mcp_protocol_negotiation_ccr: with the flag on it negotiates in auto mode with a probe, and with it off it stays on legacy exactly as before.

Details
  • Fallback is false, so absent a server value nothing changes.
Evidence

tengu_mcp_protocol_negotiation_ccr

Strings lifted out of the shipped bundle, so the claim above can be checked against them.

See this entry in the whole of v2.1.236 →