Inngest vs Temporal

Inngest

Waits are durable and cost nothing while suspended, with runs up to 30 days on Free and 366 on Business. No reviewer inbox, Slack app or email, so the human side is your code.

Temporal

Waits of any length with a timeout survive worker restarts and deploys. No reviewer inbox, notifications or routing, so the human side is all your code.

Inngest

1. Use step.waitForSignal() when one run waits for one answer, and waitForEvent only when one answer resumes many runs
2. Register the wait before you send the approval request, or check the external state first, since early events are missed
3. Use a unique approval ID per tool call and match on it, so parallel approvals resolve independently
4. Treat null or undefined as a timeout and decide on purpose whether that rejects, approves or escalates
5. Set an event id when sending the answer, so a retried send is dropped within 24 hours

Temporal

1. Put the decision in a typed Signal payload (approver, decision, comments, timestamp) instead of a bare boolean
2. Always wait with a timeout and treat the timeout path as a rejection or an escalation on purpose
3. Use the workflow ID as the approval ID, so the reviewer's tool only needs one value to send the Signal
4. Use an Update instead of a Signal when the approver's tool needs an acknowledgement back
5. Expect ResourceExhausted under load and let the SDK retry it, since signals are throttled last