In Flow Core, Enter is not a generic “start node,” but a named entry point. In the terminology of the system, an Entry is explicitly defined by an Enter node, whose sole purpose is to represent an entry that can be invoked externally by name. Trigger, by contrast, is an event-driven entry mechanism and should not be treated as interchangeable with Enter.

Put more plainly, the role of Enter is to define one or more named starting points for a graph. External code, other graphs, or event bindings can then choose a specific Enter node to start a chain. In that sense, it behaves more like a public API entry point than an automatically listening event trigger.

Mechanism

Mechanism-wise, at the editor data level, an Enter node is defined by default as having no regular flow input and a single Out output. During runtime compilation, its Next, Invoke Mode, and Start New Chain settings are compiled together into the corresponding Flow Runtime Node.

At runtime, invocation is divided into two layers:

• Flow Core Process is responsible for resolving a title or node ID into an enterIndex. Calling by title goes through ExecuteEnterByTitle(...); calling by string node ID goes through ExecuteEnter(string enterNodeId); and ExecuteEnterByName(...) is simply an alias of ExecuteEnterByTitle(...).
• Flow Graph Runtime is responsible for the actual execution. Each Enter has its own execution slot. If the same entry is triggered again while it is busy, and its mode is Queue, the request is queued; otherwise, it is rejected immediately. Overloads with a handle can also wait for completion or support cancellation.

Enter can also carry a Flow Signal Context. If a payload is provided, it is written into the current FlowContext. If no payload is provided, the execution uses an empty payload, with IndexPayload = 0 and TriggerOutputIndex = -1.

When execution actually begins, the chain root is the Enter node itself. For that reason, when control inputs such as Abort or Invalid try to cancel a matching active chain, the Enter node participates in that matching as the root of the chain.

UI

In the Graph Editor, an Enter node is added from the right-click menu, where it is explicitly described as an entry point. The node title itself serves as the entry name, and Enter also comes with its own dedicated UI in the editor:

• A title whitelist control, including search, add-to-whitelist, open-whitelist-editor, and starred-status features.
• An Enter Node Titles whitelist in Project Settings, used for both Enter titles and the dropdown selection of Execute Enter Name.
• An Invoke section, which displays On Busy Behavior and Start New Chain.

One detail that is easy to misunderstand is the meaning of Inputs: None. It means that Enter has no regular flow input. However, it can still use the control-input section. According to the validation rules, an Enter node should only have control inputs such as Enable, Disable, Abort, and Invalid, and it is allowed to have only one single-capacity output.

Examples

At its most basic level, Enter is used as a public entry point into the graph.

[SerializeField] private FlowCoreProcess _process;

private void Start()
{
    _process.ExecuteEnterByTitle("Start", gameObject);
}

For runtime integration details, refer to the documentation. However, in this context, it is recommended to use Execute Enter By Title or Execute Enter By Name first, because in the current implementation, Execute Enter(string) is actually resolved by node ID, not by title.