Expose thread_ts and parent_thread_ts

What does this MR do and why?

Expose thread_ts and parent_thread_ts

Allow FE to request thread_ts and parent_thread_ts, the FE can use these to fork from the checkpoints during retries.

Python MR has added the ability for the Python code to accept a resume_checkpoint_ts which is forwarded onto LangGraph to indicate that the user is A) creating a new branch with that thread as the parent (retrying a message with a duplicate). B) Selecting an existing branch to carry on from. This MR allows the FE to see the thread_ts and resume_checkpoint_ts of each message, so it is aware of which to send to the Python.

For example in the following conversation:

Say 1                                                                 thread_ts: 1f18b420-2d24-6f99-8000-bd98b2b46daf  parent_ts: 1f18b420-2d1f-6ba0-bfff-e5880762ca33
    1                                                                 thread_ts: 1f18b420-43e9-63d1-8001-ddf0ad2a7186  parent_ts: 1f18b420-2d24-6f99-8000-bd98b2b46daf
        Which page am I on?                                           thread_ts: 1f18b420-8623-610c-8002-2f358ff2639d  parent_ts: 1f18b420-43e9-63d1-8001-ddf0ad2a7186
            You're on the **Work items** page for th…                 thread_ts: 1f18b420-8623-610c-8002-2f358ff2639d  parent_ts: 1f18b420-43e9-63d1-8001-ddf0ad2a7186

If the user sends 1f18b420-43e9-63d1-8001-ddf0ad2a7186 as the resume_checkpoint_ts twice with the same message content but from a different page, they will create a thread like:

Say 1                                                                 thread_ts: 1f18b420-2d24-6f99-8000-bd98b2b46daf  parent_ts: 1f18b420-2d1f-6ba0-bfff-e5880762ca33
    1                                                                 thread_ts: 1f18b420-43e9-63d1-8001-ddf0ad2a7186  parent_ts: 1f18b420-2d24-6f99-8000-bd98b2b46daf
        Which page am I on?                                           thread_ts: 1f18b420-8623-610c-8002-2f358ff2639d  parent_ts: 1f18b420-43e9-63d1-8001-ddf0ad2a7186
            You're on the **Work items** page for th…                 thread_ts: 1f18b420-8623-610c-8002-2f358ff2639d  parent_ts: 1f18b420-43e9-63d1-8001-ddf0ad2a7186
        Which page am I on?                                           thread_ts: 1f18b422-3be7-60a8-8002-a51ca0a88812  parent_ts: 1f18b420-43e9-63d1-8001-ddf0ad2a7186
            You're on the **Test** project page (git…                 thread_ts: 1f18b422-504f-6aec-8003-bebe3575e92e  parent_ts: 1f18b422-3be7-60a8-8002-a51ca0a88812
        Which page am I on?                                           thread_ts: 1f18b422-c315-64a6-8002-2670783ab71d  parent_ts: 1f18b420-43e9-63d1-8001-ddf0ad2a7186
            You're on the **GitLab Duo** page (http:…                 thread_ts: 1f18b422-d458-6fe6-8003-cb13182a64da  parent_ts: 1f18b422-c315-64a6-8002-2670783ab71d

If they then send 1f18b422-504f-6aec-8003-bebe3575e92e as the resume_checkpoint_ts for "Say 2"they are choosing the middle answer as the main answer. Creating:

Say 1                                                                 thread_ts: 1f18b420-2d24-6f99-8000-bd98b2b46daf  parent_ts: 1f18b420-2d1f-6ba0-bfff-e5880762ca33
    1                                                                 thread_ts: 1f18b420-43e9-63d1-8001-ddf0ad2a7186  parent_ts: 1f18b420-2d24-6f99-8000-bd98b2b46daf
        Which page am I on?                                           thread_ts: 1f18b420-8623-610c-8002-2f358ff2639d  parent_ts: 1f18b420-43e9-63d1-8001-ddf0ad2a7186
            You're on the **Work items** page for th…                 thread_ts: 1f18b420-8623-610c-8002-2f358ff2639d  parent_ts: 1f18b420-43e9-63d1-8001-ddf0ad2a7186
        Which page am I on?                                           thread_ts: 1f18b422-3be7-60a8-8002-a51ca0a88812  parent_ts: 1f18b420-43e9-63d1-8001-ddf0ad2a7186
            You're on the **Test** project page (git…                 thread_ts: 1f18b422-504f-6aec-8003-bebe3575e92e  parent_ts: 1f18b422-3be7-60a8-8002-a51ca0a88812
                Say 2                                                 thread_ts: 1f18b429-ec48-6762-8004-446ffc760468  parent_ts: 1f18b422-504f-6aec-8003-bebe3575e92e
                    2                                                 thread_ts: 1f18b429-fd51-6c32-8005-07544e486e85  parent_ts: 1f18b429-ec48-6762-8004-446ffc760468
        Which page am I on?                                           thread_ts: 1f18b422-c315-64a6-8002-2670783ab71d  parent_ts: 1f18b420-43e9-63d1-8001-ddf0ad2a7186
            You're on the **GitLab Duo** page (http:…                 thread_ts: 1f18b422-d458-6fe6-8003-cb13182a64da  parent_ts: 1f18b422-c315-64a6-8002-2670783ab71d

At this point, a duoWorkflowWorkflows request should not return the 1st and last "Which page am I on?"a and the responses "Work items" and "Gitlab Duo"

References

Full PoC: gitlab-org/modelops/applied-ml/code-suggestions/ai-assist!6124 (closed)

Epic: gitlab-org#21289

Python implementation for retries: gitlab-org/modelops/applied-ml/code-suggestions/ai-assist!6356 (merged)

Comment with plan from @mikolaj_wawrzyniak (Slight variations): gitlab-org/modelops/applied-ml/code-suggestions/ai-assist!6124 (comment 3622972972)

Video demo: gitlab-org#21289 (comment 3666671057)

How to set up and validate locally

1. Enable flags for incremental checkpoints:

   1. Feature.enable(:duo_workflow_incremental_checkpoints)
   2. Feature.enable(:duo_workflow_read_incremental_checkpoints)
   3. Feature.enable(:dw_read_blobs_graphql)

2. Create a simple chat with a few messages

3. In http://gdk.test:8080/-/graphql-explorer run

   {
     duoWorkflowWorkflows(workflowId: "gid://gitlab/Ai::DuoWorkflows::Workflow/<Workflow ID>") {
       nodes { latestCheckpoint { duoMessages { content messageType threadTs parentTs } } }
     }
   }

   1. ID can be found in ws in the network tab, or Ai::DuoWorkflows::Workflow.last.id.

4. Confirm messages have thread_ts, and parent_thread_ts.

5. Without flags enabled, they should return null.

Optional tests:

1. With tool calls/approvals
2. Follow steps in gitlab-org/modelops/applied-ml/code-suggestions/ai-assist!6356 (merged) to make a thread with multiple branches.
   1. Only the latest branch should be returned. If 3 branches (A, B, and C), C should be returned.
   2. Use step 10 in above MR to mark B as chosen. B should be returned, and A/C ignored.

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