Durable Continue
Durable continuation legs: HITL pause/continue that survives crashes.
"""Durable continuation legs: HITL pause/continue that survives crashes.
A durable background run that pauses for human input parks its queue ticket
as PAUSED. Continuing it with background=true CAS-flips the SAME ticket back
to queued (never a new row - the ticket id IS the run id), merges your tool
confirmations into its payload, and lets whichever replica's worker claims
it drive acontinue_run. The continuation leg gets exactly one execution
(never a silent retry); a crashed leg is failed visibly and an operator
requeue re-drives the same confirmations.
Try it:
1. Start this app and submit a background run that needs confirmation:
curl -X POST localhost:7777/agents/hitl-agent/runs \
-F "message=Delete the temp files" -F "background=true" -F "stream=false"
-> 202; poll GET /agents/hitl-agent/runs/{run_id}?session_id={session_id}
until status is PAUSED. The queue ticket is now PAUSED too:
GET /queue/jobs/{run_id}
2. Confirm the tool and continue DURABLY (background=true is the switch):
curl -X POST localhost:7777/agents/hitl-agent/runs/{run_id}/continue \
-F "session_id={session_id}" -F "stream=false" -F "background=true" \
-F 'tools=[{... the paused run's tool dict with "confirmed": true ...}]'
-> 202 immediately; the ticket is queued again and the continuation leg
executes on whichever replica claims it. Kill the server after the 202
and restart: the continuation still runs.
3. Double-click safety: repeat the continue request - it attaches to the
in-flight continuation (202) or asks you to retry in a moment (409 with
Retry-After) once the leg is already executing. It never runs twice and
never drops your confirmations silently.
4. If a worker dies mid-continuation, the leg is swept to failed VISIBLY
(GET /queue/jobs?status=failed) and POST /queue/jobs/{run_id}/requeue
re-drives the same merged confirmations.
5. Cancelling a paused run cancels its ticket too; a later continue gets an
honest 409 instead of resurrecting the run.
Requirements:
- PostgreSQL running (./cookbook/scripts/run_pgvector.sh)
- OPENAI_API_KEY set
"""
from agno.agent import Agent
from agno.db.postgres import PostgresDb
from agno.models.openai import OpenAIResponses
from agno.os import AgentOS, QueueConfig
from agno.tools import tool
@tool(requires_confirmation=True)
def delete_temp_files(directory: str) -> str:
"""Delete temporary files in a directory. Requires human confirmation."""
return f"Deleted temp files in {directory}"
db = PostgresDb(db_url="postgresql+psycopg://ai:ai@localhost:5532/ai")
agent = Agent(
name="HITL Agent",
id="hitl-agent",
model=OpenAIResponses(id="gpt-5.5"),
db=db,
tools=[delete_temp_files],
instructions="Use delete_temp_files when asked to delete or clean up files.",
)
agent_os = AgentOS(
agents=[agent],
db=db,
queue=QueueConfig(durable=True),
)
app = agent_os.get_app()
if __name__ == "__main__":
agent_os.serve(app="durable_continue:app", port=7777)Continuation and retry boundaries
An accepted continuation remains queued across a restart until a worker claims it. If the worker crashes after claiming the leg, the single-attempt policy fails that leg visibly; an operator must decide whether to requeue it. This is not an exactly-once guarantee for external tool effects. The delete_temp_files function here only returns demonstration text and deletes no files.
A duplicate request attaches to the already accepted leg; it does not replace that leg's confirmations with a new decision. Inspect the returned run and queue ticket before changing an approval. A conflict response accepts no new continuation. Operator requeue can repeat effects that happened before a crash.
Run the Example
Set up your virtual environment
uv venv --python 3.12
source .venv/bin/activateInstall dependencies
uv pip install -U "agno[os]" "psycopg[binary]" openaiExport your OpenAI API key
export OPENAI_API_KEY="your_openai_api_key_here"Run PgVector
docker run -d \
-e POSTGRES_DB=ai \
-e POSTGRES_USER=ai \
-e POSTGRES_PASSWORD=ai \
-e PGDATA=/var/lib/postgresql \
-v pgvolume:/var/lib/postgresql \
-p 5532:5432 \
--name pgvector \
agnohq/pgvector:18Run the example
Save the code above as durable_continue.py, then run:
python durable_continue.pyFull source: cookbook/05_agent_os/background_tasks/durable_continue.py