Add ability to stream chat responses

What does this MR do and why?

This adds the capabilities to stream messages for GitLab Duo chat.

The streamed chunks get send over aiCompletionResponse but the order is not guaranteed on the client. Each chunk has a chunkId which has a guaranteed order, starting with 1.

The client_subscription_id is meant for the client to identify which mutation belongs to which subscription response. However, chat is a special feature where we want to sync responses between multiple chat instances of the same user.

This means we want to have two different subscriptions for the same request: 1. User-specific to sync between multiple clients 2. Request-specific for streaming

By not streaming the response when a client_subscription_id is not present, we also make sure that older clients still work when the stream_gitlab_duo is enabled. Otherwise, they would receive a streamed response on a subscription on user_id and resource_id.

NOTE: Related FE MR by @dmishunov !130347 (merged)

Screenshots or screen recordings

The following only works with the FE and graphql changes. There is an MR that combines both: !130415 (closed)

Without FF	With FF
streaming-example-no-ff	streaming-example

Before	After

How to set up and validate locally

1. Have GitLab Duo and all AI features set up
2. Enable the FF stream_gitlab_duo
3. Checkout !130415 (closed) as it combines this MR with the FE changes and updates the GraphQL subscriptions

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

added groupai framework label

assigned to @nicolasdular

added devopsai-powered sectiondata-science labels

changed milestone to %16.4

added backend documentation frontend labels

	1 Warning
	This merge request is quite big (549 lines changed), please consider splitting it into multiple merge requests.

	1 Message
	This merge request adds or changes documentation files. A review from the Technical Writing team before you merge is recommended. Reviews can happen after you merge.

Documentation review

The following files require a review from a technical writer:

• doc/api/graphql/reference/index.md (Link to current live version)

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• Metadata for the *.md files that you've changed. The first few lines of each *.md file identify the stage and group most closely associated with your docs change.
• The Technical Writer assigned for that stage and group.
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Reviewer roulette

Changes that require review have been detected!

Please refer to the table below for assigning reviewers and maintainers suggested by Danger in the specified category:

Category	Reviewer	Maintainer
backend	Smriti Garg (@sgarg_gitlab) (UTC+5.5, 3.5 hours ahead of @nicolasdular)	Bojan Marjanović (@bmarjanovic) (UTC+2, same timezone as @nicolasdular)

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Generated by Danger

Proper labels assigned to this merge request. Please ignore me.

@nicolasdular - please see the following guidance and update this merge request.

	1 Error
	Please add typebug typefeature, or typemaintenance label to this merge request.

Bundle size analysis [beta]

This compares changes in bundle size for entry points between the commits 7a38200a and 581123ce

Special assets

Entrypoint / Name	Size before	Size after	Diff	Diff in percent
average	4.17 MB	4.18 MB	+3.23 KB	0.1 %
mainChunk	3.02 MB	3.02 MB	+3.23 KB	0.1 %

---

Note: We do not have exact data for 7a38200a. So we have used data from: a1a84dad.
The intended commit has no webpack pipeline, so we chose the last commit with one before it.

Please look at the full report for more details

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Allure report

allure-report-publisher generated test report!

e2e-test-on-gdk: test report for c6875651

expand test summary

+-----------------------------------------------------------------------+
|                            suites summary                             |
+------------------+--------+--------+---------+-------+-------+--------+
|                  | passed | failed | skipped | flaky | total | result |
+------------------+--------+--------+---------+-------+-------+--------+
| Plan             | 51     | 0      | 0       | 0     | 51    | ✅     |
| Create           | 46     | 0      | 1       | 2     | 47    | ❗     |
| Monitor          | 4      | 0      | 0       | 0     | 4     | ✅     |
| Verify           | 8      | 0      | 0       | 0     | 8     | ✅     |
| Govern           | 36     | 0      | 0       | 0     | 36    | ✅     |
| Manage           | 13     | 0      | 1       | 0     | 14    | ✅     |
| Package          | 0      | 0      | 1       | 0     | 1     | ➖     |
| Framework sanity | 0      | 0      | 1       | 0     | 1     | ➖     |
| Data Stores      | 22     | 0      | 0       | 0     | 22    | ✅     |
+------------------+--------+--------+---------+-------+-------+--------+
| Total            | 180    | 0      | 4       | 2     | 184   | ❗     |
+------------------+--------+--------+---------+-------+-------+--------+

e2e-review-qa: test report for 581123ce

expand test summary

+-----------------------------------------------------------------------+
|                            suites summary                             |
+------------------+--------+--------+---------+-------+-------+--------+
|                  | passed | failed | skipped | flaky | total | result |
+------------------+--------+--------+---------+-------+-------+--------+
| Create           | 8      | 0      | 1       | 0     | 9     | ✅     |
| Framework sanity | 0      | 0      | 1       | 0     | 1     | ➖     |
| Manage           | 1      | 0      | 0       | 0     | 1     | ✅     |
| Data Stores      | 2      | 0      | 0       | 0     | 2     | ✅     |
| Package          | 0      | 0      | 1       | 0     | 1     | ➖     |
| Monitor          | 4      | 0      | 0       | 0     | 4     | ✅     |
| Plan             | 3      | 0      | 1       | 0     | 4     | ✅     |
| Govern           | 2      | 0      | 0       | 0     | 2     | ✅     |
+------------------+--------+--------+---------+-------+-------+--------+
| Total            | 20     | 0      | 4       | 0     | 24    | ✅     |
+------------------+--------+--------+---------+-------+-------+--------+

e2e-package-and-test: test report for c6875651

expand test summary

+------------------------------------------------------------+
|                       suites summary                       |
+-------+--------+--------+---------+-------+-------+--------+
|       | passed | failed | skipped | flaky | total | result |
+-------+--------+--------+---------+-------+-------+--------+
+-------+--------+--------+---------+-------+-------+--------+
| Total | 0      | 0      | 0       | 0     | 0     | ➖     |
+-------+--------+--------+---------+-------+-------+--------+

mentioned in merge request !130093 (merged)

added 4 commits

• 81848b02 - Fix streaming specs and adapt code
• eeb9f9d0 - Fix specs
• 37b2cf6b - Add chunk_id
• 775a01b7 - Add yet another case for receiving chat messages

Compare with previous version

changed the description

requested review from @katiemacoy

requested review from @euko

@nicolasdular I can check out this MR tomorrow morning and sync with you later to ask any question.

added 649 commits

• 775a01b7...01254e6e - 645 commits from branch master
• 2d15d07f - WIP
• 52da2799 - Fix specs
• c8e83166 - Add chunk_id
• d7a16228 - Add yet another case for receiving chat messages

Compare with previous version