In Flow Core, Action refers to the core node type FlowNodeKind.Action, not the C# System.Action delegate.

Its role is straightforward: it receives a flow chain, executes a sequence of Instructions in order, and then continues to the next node through Out.

In the project’s node catalog, Action is also grouped under the Core category, making it one of the fundamental nodes that beginners should understand first.

More precisely, an Instruction is a single concrete operation, while an Action is the node container responsible for holding and orchestrating those operations. Even in the editor menu definition, its summary is simply: Execute instructions.

Mechanism

The editor-side data for an Action node is stored in FlowNodeData. Its core fields include Instructions, GuardGroup, InvokeMode, StartNewChain, as well as the standard input and output port lists.

When an Action node is first created, it starts with a single In port and a single Out port by default, along with a Guard group that is disabled by default.

When an Action actually runs, its execution flow works like this:

1. It first passes through the busy gate.
2. It then evaluates the Guard.
3. If the Guard passes, it executes the instruction list in sequence.
4. The node then determines how to finish based on the return value of those instructions.

Key Runtime Semantics:

• On Busy Behavior = Abort The current flow chain is terminated immediately.
• Queue The execution is queued and waits until the previous run finishes.
• Bypass The node is skipped, and execution continues according to the bypass rule. For an Action node, this generally means continuing directly through Out.
• Invalid The current branch ends silently without further execution.

Instruction Return Results

• Continue Proceeds to the next instruction, and eventually exits through Out.