`generation_id` has extra suffix for `AfterAgentThought`

Support Bug Reports
1

Where does the bug appear (feature/product)?

Cursor IDE

Describe the Bug

The generation_id in afterAgentThought is sometimes different from the generation_id used by the other hook events in the same turn.

For example:

Other events:
f1c8a21b-…-a86f8f5f1e17

afterAgentThought:
f1c8a21b-…-a86f8f5f1e17-0-7lg9
f1c8a21b-…-a86f8f5f1e17-2-32js
f1c8a21b-…-a86f8f5f1e17-9-vilj
f1c8a21b-…-a86f8f5f1e17-10-6o9s
f1c8a21b-…-a86f8f5f1e17-11-r94a

Steps to Reproduce

Just send a complex request that will have the agent to think couple times, and check the generation_id of those afterAgentThought events

Expected Behavior

afterAgentThought should use the same generation_id as the other events in the same turn.

Operating System

MacOS

Version Information

Cursor IDE
version: 3.10.11

Does this stop you from using Cursor

No - Cursor works, but with this issue

5

Hey @Morris_Hsieh!

Interesting catch!

What you’re seeing is the per-model-step invocation id (the turn request id + a step counter + a short random suffix), while the other hooks report the turn-level request id.

Workaround for now: the turn’s generation_id is always a prefix of the afterAgentThought value, so you can join events within a turn by stripping the trailing -<step>-<random> using some RegEx.

^(.*)-\d+-[a-z0-9]{4}$ → capture group 1 is the turn generation_id.

We’ve filed a bug internally to decide whether to make this consistent (report the turn id everywhere) or expose the invocation id as a separate field.

One thing we noticed while reproducing: in our runs, afterAgentThought sometimes fired twice per thought, once with the suffixed invocation id and once with the bare turn generation_id. Are you seeing that too on your side (duplicate afterAgentThought events for the same thought), or just the single suffixed value?

8

Hey @Colin,

Thanks for confirming the ID format and filing the bug. The workaround for now should work!

For the duplicating afterAgentThought, I’m seeing that as well.

Sometimes (35 out of 91 distinct thoughts in my testing) afterAgentThought fires twice for the same thought with identical text:

  • one event uses the bare turn-level generation_id

  • the other with suffixed one

Also, those duplicate events have different timestamps, from a few milliseconds to around two seconds apart

10

Thanks for confirming. I’ve filed a bug for that as well.