human_in_the_loop

Human-in-the-loop (Hook-based)

The canonical Strands HITL pattern. A BeforeToolCallEvent hook gates a sensitive tool behind human approval by calling event.interrupt(...). The agent stops with stop_reason == "interrupt"; the workflow waits on a Temporal signal for the response, then resumes with InterruptResponseContent.

What This Sample Demonstrates

• Using HookProvider + BeforeToolCallEvent to interrupt before a tool runs
• Pairing Strands' interrupt machinery with Temporal signals + queries
• Resuming the agent with [{"interruptResponse": ...}] content

Running the Sample

# Terminal 1
uv run strands_plugin/human_in_the_loop/run_worker.py

# Terminal 2
uv run strands_plugin/human_in_the_loop/run_workflow.py

The starter script queries the workflow until an approval is pending, prints the reason, then signals "approve". To exercise the denial path, change the signal to anything other than "approve".

Files

File	Description
workflow.py	delete_file tool, ApprovalHook, HumanInTheLoopWorkflow
run_worker.py	Registers StrandsPlugin, starts the worker
run_workflow.py	Starts the workflow, polls for the approval, sends the signal