[Feature]: Simplify completing (wait for) callbacks

[embano1]

What would you like?

Currently, I have to use the Lambda client SDK to complete callbacks. It would be nice if users could do this through the context (required they have the right IAM permissions).

Possible Implementation

const [promise, callbackId] = await context.createCallback("approval"); // or use waitForCallback
await context.step(...) 
const result = await promise;

await context.completeCallback("complete-approval", callbackId, { approved: true });

Is this a breaking change?

No

Does this require an RFC?

No

Additional Context

Open Questions

1. Naming convention:

   • SDK-style: completeCallback / failCallback
   • Lambda API-style: sendCallbackSuccess / sendCallbackFailure

2. Heartbeat inclusion: Should sendCallbackHeartbeat be part of the initial scope, or deferred?

3. Alternative: Namespaced approach - Should this use a namespace like context.callback.complete() similar to context.promise.all()?

4. Overloads: Should we support both named and unnamed variants (with/without name parameter) like other context methods?

5. Should these be durable operations? If called within a durable execution, should the callback completion be recorded in the execution history (for replay safety)?

6. Naming preference? completeCallback/failCallback vs sendCallbackSuccess/sendCallbackFailure (matching the API names)

7. Use case scope? Is this primarily for:

• Completing callbacks within the same durable function (self-completion)
• Completing callbacks from other durable functions
• Completing callbacks from non-durable code