Durable Execution with Restate

Heartbit integrates with Restate for durable agent execution. Agent loops survive crashes, tools execute exactly once, and state persists across restarts.

What Restate Provides

• Durable execution with replay — agent loops survive crashes
• Exactly-once tool execution — tools don’t re-execute on recovery
• Token budget tracking — persistent budget across workflow restarts
• Circuit breaker — LLM fault tolerance with automatic recovery
• Recurring tasks — scheduler for periodic agent invocations

Components

Component	Type	Description
AgentService	#[restate_sdk::service]	llm_call + tool_call activities
AgentWorkflow	#[restate_sdk::workflow]	Durable ReAct loop with replay
OrchestratorWorkflow	workflow	Delegates to child AgentWorkflow instances
Blackboard	virtual object	Shared state across agents
Budget	virtual object	Token tracking
CircuitBreaker	virtual object	LLM fault tolerance
Scheduler	virtual object	Recurring task scheduling

Quick Start

# Start Restate + worker
docker compose up -d

# Register the worker with Restate
curl -X POST http://localhost:9070/deployments \
  -H 'content-type: application/json' \
  -d '{"uri": "http://heartbit:9080"}'

# Submit a task
heartbit submit --config heartbit.toml "Analyze the Rust ecosystem"

# Check status
heartbit status <workflow-id>

# Approve tool execution (when --approve was used)
heartbit approve <child-workflow-id>

# Get result
heartbit result <workflow-id>

Configuration

[restate]
endpoint = "http://localhost:9070"

Docker

docker compose up -d

Services:

• restate — Restate server (ports 8080 ingress, 9070 admin)
• heartbit — worker (port 9080)

Feature Flag

Restate support requires the restate feature flag:

cargo build --features restate

CLI Commands

Command	Description
heartbit serve	Start the Restate HTTP worker
heartbit submit <task>	Submit task for durable execution
heartbit status <id>	Query workflow status
heartbit approve <id>	Send approval signal
heartbit result <id>	Get completed workflow result