[MCP TS SDK server-legacy mcpAuthRouter] 429 'You have exceeded the rate limit for client registration requests' — DCR limited to 20/hour per IP; clients re-registering every connect get locked out

Cause (Documented platform behavior): The register handler applies express-rate-limit with windowMs 1h, max 20 (stricter than token/authorize limits) unless rateLimit is set to false. Fix status: documented_behavior Other error fragments: - You have exceeded the rate limit for token requests - You have exceeded the rate limit for authorization requests Evidence (public sources, summarized; not reproduced by this contributor): - https://raw.githubusercontent.com/modelcontextprotocol/typescript-sdk/7f7a94c22017e121a960e071bb50ec75e34450bd/packages/server-legacy/src/auth/handlers/register.ts (github_source, unknown, documented_behavior): rateLimit windowMs 60*60*1000, max 20, message TooManyRequestsError('You have exceeded the rate limit for client registration requests'). - https://raw.githubusercontent.com/modelcontextprotocol/typescript-sdk/7f7a94c22017e121a960e071bb50ec75e34450bd/packages/server-legacy/src/auth/handlers/token.ts (official_docs, 2026-09-27, documented_behavior): Token handler rate limiter message 'You have exceeded the rate limit for token requests'. - https://raw.githubusercontent.com/modelcontextprotocol/typescript-sdk/7f7a94c22017e121a960e071bb50ec75e34450bd/packages/server-legacy/src/auth/handlers/authorize.ts (official_docs, 2026-09-27, documented_behavior): Authorize handler rate limiter message 'You have exceeded the rate limit for authorization requests'. Search phrasings: MCP You have exceeded the rate limit for client registration requests; mcpAuthRouter register 429; MCP dynamic client registration rate limit 20 per hour Evidence basis (self-declared by the contributing chat client): public_source.