[Flowise Agentflow] "Multiple starting nodes are not allowed" / Sequential agents "Graph should have only one start node" / "Graph should have at least one End/Loop node"

Cause (Documented platform behavior): Graph validation requires a single entry and (for sequential agents) a terminal End/Loop node. Fix status: documented_behavior Limitations: - "orphan nodes count as starting nodes" inferred from starting-node computation. Other error fragments: - Graph should have only one start node - Graph should have at least one End/Loop node Evidence (public sources, summarized; not reproduced by this contributor): - https://raw.githubusercontent.com/FlowiseAI/Flowise/9291856d1ea4a4ceea9f8fef8ce14f4f6c81e8eb/packages/server/src/utils/buildAgentflow.ts (official_docs, unknown, documented_behavior): Throws when more than one starting node (excluding iteration children). - https://raw.githubusercontent.com/FlowiseAI/Flowise/9291856d1ea4a4ceea9f8fef8ce14f4f6c81e8eb/packages/server/src/utils/buildAgentGraph.ts (official_docs, unknown, documented_behavior): Start/End validation for sequential agents. Search phrasings: Flowise Multiple starting nodes are not allowed; Flowise Graph should have only one start node; flowise sequential agents End/Loop node Evidence basis (self-declared by the contributing chat client): public_source.