{"name":"tengu_mcp_protocol_negotiation_ccr","slug":"tengu-mcp-protocol-negotiation-ccr","family":"flag","title":"Feature flags","noun":"feature flag","description":"The ccr-proxy MCP transport can negotiate protocol versions, but stays on legacy unless a flag is turned on.","description_source":"entry","described_by":{"version":"2.1.236","anchor":"mcp-protocol-auto-negotiation-now-covers-the-ccr-proxy-trans"},"presence":{"first_seen":"2.1.236","removed_in":null,"in_current_build":true,"newest_mined":"2.1.308","builds":62,"mined_builds":149,"first_cited":{"version":"2.1.236","released_at":"2026-08-19 18:45:14","spans":1}},"aliases":[],"entries":[{"version":"2.1.299","anchor":"mcp-protocol-negotiation-gate-default-moved-to-true-stated","heading":"MCP error code -32021 now handled with -32003 and -32601","line":"Claude Code now treats the MCP error code -32021 the same way as -32003 and -32601 in one of its error checks","released_at":"2026-10-14 00:23:19","reason":"gate cited by this entry"},{"version":"2.1.299","anchor":"mcp-wire-answeredstood-aside-tracking","heading":"MCP requests record whether the main handler answered or stood aside","line":"MCP requests now try a main handler, fall back to a second one if it gives nothing, and record which happened","released_at":"2026-10-14 00:23:19","reason":"gate cited by this entry, found in this entry's text"},{"version":"2.1.236","anchor":"mcp-protocol-auto-negotiation-now-covers-the-ccr-proxy-trans","heading":"MCP protocol auto-negotiation now covers the ccr-proxy transport, off by default","line":"The ccr-proxy MCP transport can negotiate protocol versions, but stays on legacy unless a flag is turned on.","released_at":"2026-08-19 18:45:14","reason":"gate cited by this entry, found in this entry's text"}],"entries_total":3,"docs":[],"docs_total":0,"gates":[{"version":"2.1.299","state":"on-in-code","account":true,"baseline":true,"code_default":true},{"version":"2.1.236","state":"unknown","account":null,"baseline":null,"code_default":false}],"related":[{"name":"tengu_mcp_protocol_negotiation_","slug":"tengu-mcp-protocol-negotiation","description":"MCP servers using a newer protocol era no longer get custom notification handlers, and you see a warning."},{"name":"tengu_mcp_protocol_negotiation_claudeai","slug":"tengu-mcp-protocol-negotiation-claudeai","description":"A newer MCP protocol handshake exists per transport but every gate falls back to legacy here."},{"name":"tengu_mcp_protocol_negotiation_http","slug":"tengu-mcp-protocol-negotiation-http","description":"A newer MCP protocol handshake exists per transport but every gate falls back to legacy here."},{"name":"tengu_mcp_protocol_negotiation_stdio","slug":"tengu-mcp-protocol-negotiation-stdio","description":"A newer MCP protocol handshake exists per transport but every gate falls back to legacy here."}],"url":"https:\/\/changelogs.core-directive.com\/reference\/flag\/tengu-mcp-protocol-negotiation-ccr","family_url":"https:\/\/changelogs.core-directive.com\/reference\/flag.json"}