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Agent Lifecycle ​

One of the most powerful features of Synapse is the Agent Lifecycle, which governs how an agent executes its tasks and allows for modification at various stages.

PendingAgentTask ​

The PendingAgentTask class drives the agent's execution and stores all information about the current run. This class provides several public methods that can be accessed and modified:

  • addInput(string $key, mixed $value): Adds an input to the array used to generate the prompt.
  • agent(): Returns the agent instance.
  • currentIteration(): Returns the CurrentIteration object containing the raw response and message.
  • inputs(): Retrieves the current input array.
  • getInput(string $key): Retrieves a specific input by key.
  • iterationMemory(): Accesses the agent's memory for the current task.
  • tools(): Retrieves the tools available to the agent.

Lifecycle ​

The agent lifecycle is divided into the following stages:

Initialize Agent ​

The agent is set up, and all hooks are initialized.

To modify the agent at this stage, use the HasBootAgentHook in the Hook Traits section.

Code Calls the handle Method ​

The handle method is invoked, a new CurrentIteration is created, and the inputs and extraAgentArgs are set.

php
$simpleAgent = new SimpleAgent;
$result = $agent->handle(['input' => 'hello!'], ['model' => 'gpt-4o-mini']);

To modify the agent at this stage, use the HasStartThreadHook in the Hook Traits section.

Start 'Iteration Loop' ​

The 'Iteration Loop' begins by executing the StartIterationPipeline. Each loop iteration triggers all pipelines, which are executed multiple times if the agent calls multiple tools.

To modify the agent at this stage, use the HasStartIterationHook in the Hook Traits section.

Get Prompt ​

The agent combines the view with inputs to create the prompt.

To modify the agent at this stage, use the HasPromptGeneratedHook in the Hook Traits section.

Parse the Prompt ​

The prompt is parsed into messages based on message tags.

To modify the agent at this stage, use the HasPromptParsedHook in the Hook Traits section.

Call the Integration ​

Messages are sent to the integration, and a response is awaited.

To modify the agent at this stage, use the HasIntegrationResponseHook in the Hook Traits section.

Tool Calls ​

If the integration response includes a tool call, it is parsed and sent to the tool. Two hooks are available to modify the PendingAgentTask—one before tool execution and one after.

To modify the agent at this stage, use the HasStartToolCallHook or the HasEndToolCallHook in the Hook Traits section.

Integration Called "Stop" ​

This marks the end of the iteration loop when the agent finishes.

To modify the agent at this stage, use the HasAgentFinishHook in the Hook Traits section.

End 'Iteration Loop' but Loop Again ​

If the agent needs to repeat the loop due to tool calls, this hook is invoked before the loop restarts.

To modify the agent at this stage, use the HasEndIterationHook in the Hook Traits section.

End Thread ​

Before returning the final response via handle, this is the last opportunity to modify the result. If the ValidatesOutputSchema trait is used, it performs most of its work here.

To modify the agent at this stage, use the HasEndThreadHook in the Hook Traits section.