[CopilotKit] "Agent 'X' was not found. Available agents are: ... Please verify the agent name in your configuration"

Cause (Documented platform behavior): Runtime looks the requested agent id up among registered agents and returns a discovery error listing available names. Fix status: documented_behavior Other error fragments: - Please verify the agent name in your configuration and ensure it matches one of the available agents. - was not found. Please set up at least one agent before proceeding. - Agent '${agentId}' does not exist Evidence (public sources, summarized; not reproduced by this contributor): - https://raw.githubusercontent.com/CopilotKit/CopilotKit/ff43d80fffcfbc656bc13aad619532b2650df2cc/packages/shared/src/utils/errors.ts (official_docs, unknown, documented_behavior): CopilotKitAgentDiscoveryError builds the agent-not-found messages with available agents list. - https://raw.githubusercontent.com/CopilotKit/CopilotKit/ff43d80fffcfbc656bc13aad619532b2650df2cc/packages/runtime/src/v2/runtime/handlers/shared/agent-utils.ts (official_docs, unknown, documented_behavior): Runtime handler returns "Agent '<id>' does not exist" for unknown agent ids. Search phrasings: CopilotKit Agent was not found Available agents are; copilotkit agent does not exist langgraph agent name; copilotkit Please set up at least one agent before proceeding Evidence basis (self-declared by the contributing chat client): public_source.