{"version":"2.1.299","anchor":"mcp-wire-answeredstood-aside-tracking","canonical_anchor":"mcp-protocol-negotiation-gate-default-moved-to-true-stated","heading":"MCP protocol negotiation gate for ccr-proxy now defaults to true, with new fallback handling","tier":"internal","area":"MCP","scope":"individual","heads_up":false,"url":"https:\/\/changelogs.core-directive.com\/v\/2.1.299\/e\/mcp-wire-answeredstood-aside-tracking","release_url":"https:\/\/changelogs.core-directive.com\/v\/2.1.299","markdown":"### MCP protocol negotiation gate for ccr-proxy now defaults to true, with new fallback handling\n\nThe default for `tengu_mcp_protocol_negotiation_ccr` moved from false to true, alongside a new error code and a primary-then-fallback MCP handler\n\n**Unclear.** Whether this new fallback step is tied to the protocol negotiation switch is not shown.\n\n**What**\n\nMCP is the system Claude Code uses to talk to outside programs that add tools. The gate `tengu_mcp_protocol_negotiation_ccr` controls whether the ccr-proxy connection negotiates which protocol version to use. Its default is listed as moving from false to true. Two code changes appear in the same area, though neither finding confirmed that they are tied to this gate:\n\n- Error code: a check that used to match error codes `-32601` and `-32003` now also matches `-32021`.\n\n- Fallback handler: a new wrapper tries a primary handler and, if that returns nothing, runs a fallback. It marks the result `mcpWire` as `answered` or `stood_aside`.\n\nThe flag server returned on for this gate for this site's account and for the anonymous baseline, and no reading has been taken under this release yet.\n\n**Why**\n\nWith a default of true, protocol negotiation over ccr-proxy no longer depends on a remote value to be switched on. In practice, MCP servers reached that way may negotiate their protocol version instead of using the older fixed method.\n\n- Flag `tengu_mcp_protocol_negotiation_ccr`: On for this account, and not off by default (read for one account on one subscription tier against v2.1.299; this account: on, anonymous baseline: on, compiled default: on) These values were read against a different version of Claude Code, so treat them as the nearest reading available instead of one taken on this release.\n- Area: MCP\n- Tier: Under the hood\n- Useful: 1\/5\n- Signal: 2\/5\n- Scope: individual\n- Heads-up: no"}