Restate or Diagrid Catalyst for Durable Tool Calls?

"Retry the tool call" sounds harmless until the tool issues a refund. Then durability, identity, and evidence stop being three concerns owned by three different teams and turn into one incident. Take a support system built out of several agents. A triage agent classifies the ticket. An account agent retrieves customer state. A policy agent decides whether a refund is allowed. A human approves the recommendation. An action agent calls the refund tool. Then the process loses its connection before the response is recorded. Retrying is the easy part. What matters is whether the platform and your own code can work out what already happened, without sending a second refund. Restate is a runtime that sits in front of your services and records execution in a journal. Its AI documentation shows LLM calls and tool executions wrapped as durable steps. After a crash, completed results are replayed from the journal and execution continues from the first step that never finished. Restate supports services, virtual objects, and workflows, and runs through Restate Cloud or a server you host yourself. That is a good model if you want resilient functions and services with built-in state, reliable communication, and durable execution written into ordinary code. It also integrates with agent SDKs rather than asking you to adopt one agent framework. Catalyst also persists workflow activity results and resumes failed executions. Around that it adds App ID-based workload identity, access policies, mTLS-backed communication, MCP governance, and a single operational surface for agents and applications. Diagrid positions verifiable execution, meaning history, lineage, signing, and attestation, as an additional trust layer. Once money is involved, a security review will want more than proof that the run recovered: Which workload identity invoked the refund tool? Which policy authorized the call? Can you show that the execution history was not altered? Can you revoke access without editing the agent prompt? Does the same control apply across cloud, on-premises, and isolated deployments? Restate is the better fit when what you need is a lightweight durable runtime for services, stateful entities, workflows, and agents, and you want to express resilience directly in normal application code. Catalyst is the better fit when durable execution has to arrive together with organization-wide agent identity, policy-controlled tool access, verifiable evidence, and governance across several frameworks and deployment environments. Neither one takes your application off the hook once the outcome is unknown. A payment or refund integration still needs idempotency keys, reconciliation, and explicit compensation logic. Durable execution preserves progress. It cannot tell you whether an external system committed a request when the response was lost. So run the test you would rather skip. Fail the action at the worst possible moment, then check whether it recovered, whether you can prove who did what, and whether the same refund can go out twice. Restate durable agents Restate AI agents Diagrid Catalyst Diagrid AI agents