[FF] classify_code_review_mention_intent - Rollout
## Summary
This issue is to roll out [the feature](https://gitlab.com/gitlab-org/gitlab/-/work_items/595294) on production,
that is currently behind the `classify_code_review_mention_intent` feature flag.
**Feature flag definition:**
- **Name:** `classify_code_review_mention_intent`
- **Description:** Classify the intent of @GitLabDuo MR comment mentions and route code review requests to the review flow.
- **Feature issue:** https://gitlab.com/gitlab-org/gitlab/-/work_items/595294
- **Introduced by:** https://gitlab.com/gitlab-org/gitlab/-/merge_requests/230577
- **Milestone:** 18.11
- **Group:** group::ai coding
- **Type:** gitlab_com_derisk
- **Default enabled:** false
## Owners
- Most appropriate Slack channel to reach out to: `#g_ai_coding`
- Best individual to reach out to: @kinsingh
## Expectations
### What are we expecting to happen?
When enabled, `@GitLabDuo` mentions in MR comments will be classified by intent:
- `code_review_request` intents will trigger the code review flow (adding GitLabDuo as reviewer)
- `duo_developer` and `agentic_chat` intents will continue using the existing Duo Chat flow
### What can go wrong and how would we detect it?
- **Intent classification fails:** Falls back to chat flow (existing behavior preserved)
- **AI Gateway latency/errors:** Monitor error rates in Sentry and AI Gateway dashboards
- **Incorrect intent classification:** Users may get unexpected behavior (review instead of chat or vice versa)
Monitor:
- Error rates in `DuoCodeReviewChatWorker`
- AI Gateway completion latency for `classify_code_review_mention_intent`
- User feedback in `#g_ai_coding`
## Rollout Steps
Note: Please make sure to run the chatops commands in the Slack channel that gets impacted by the command.
### Rollout on non-production environments
- Verify the MR with the feature flag is merged to `master` and has been deployed to non-production environments with `/chatops gitlab run auto_deploy status <merge-commit-of-your-feature>`
- [ ] Deploy the feature flag at a percentage (recommended percentage: 50%) with `/chatops gitlab run feature set classify_code_review_mention_intent 50 --actors --dev --pre --staging --staging-ref`
- [ ] Monitor that the error rates did not increase (repeat with a different percentage as necessary).
- [ ] Enable the feature globally on non-production environments with `/chatops gitlab run feature set classify_code_review_mention_intent true --dev --pre --staging --staging-ref`
- [ ] Verify that the feature works as expected.
The best environment to validate the feature in is [`staging-canary`](https://about.gitlab.com/handbook/engineering/infrastructure/environments/#staging-canary) as this is the first environment deployed to. Make sure you are [configured to use canary](https://next.gitlab.com/).
- [ ] If the feature flag causes end-to-end tests to fail, disable the feature flag on staging to avoid blocking [deployments](https://about.gitlab.com/handbook/engineering/deployments-and-releases/deployments/).
- See [`#e2e-run-staging` Slack channel](https://gitlab.enterprise.slack.com/archives/CBS3YKMGD) and look for the following messages:
- test kicked off: `Feature flag classify_code_review_mention_intent has been set to true on **gstg**`
- test result: `This pipeline was triggered due to toggling of classify_code_review_mention_intent feature flag`
If you encounter end-to-end test failures and are unable to diagnose them, you may reach out to the [`#s_developer_experience` Slack channel](https://gitlab.enterprise.slack.com/archives/C07TWBRER7H) for assistance. Note that end-to-end test failures on `staging-ref` [don't block deployments](https://about.gitlab.com/handbook/engineering/infrastructure/environments/staging-ref/#how-to-use-staging-ref).
### Before production rollout
- [ ] If the change is significant and you wanted to announce in [#whats-happening-at-gitlab](https://gitlab.enterprise.slack.com/archives/C0259241C), it best to do it before rollout to `gitlab-org/gitlab-com`.
### Specific rollout on production
For visibility, all `/chatops` commands that target production must be executed in the [`#production` Slack channel](https://gitlab.slack.com/archives/C101F3796)
and cross-posted (with the command results) to the responsible team's Slack channel.
- Ensure that the feature MRs have been deployed to both production and canary with `/chatops gitlab run auto_deploy status <merge-commit-of-your-feature>`
- [ ] Depending on the [type of actor](https://docs.gitlab.com/development/feature_flags/#feature-actors) you are using, pick one of these options:
- For **project-actor**: `/chatops gitlab run feature set --project=gitlab-org/gitlab,gitlab-org/gitlab-foss,gitlab-com/www-gitlab-com classify_code_review_mention_intent true`
- For **group-actor**: `/chatops gitlab run feature set --group=gitlab-org,gitlab-com classify_code_review_mention_intent true`
- For **user-actor**: `/chatops gitlab run feature set --user=kinsingh classify_code_review_mention_intent true`
- For **all internal users**: `/chatops gitlab run feature set --feature-group=gitlab_team_members classify_code_review_mention_intent true`
- [ ] Verify that the feature works for the specific actors.
### Preparation before global rollout
- [ ] Set a milestone to this rollout issue to signal for enabling and removing the feature flag when it is stable.
- [ ] Check if the feature flag change needs to be accompanied with a
[change management issue](https://about.gitlab.com/handbook/engineering/infrastructure-platforms/change-management/#feature-flags-and-the-change-management-process).
Cross link the issue here if it does.
- [ ] Ensure that you or a representative in development can be available for at least 2 hours after feature flag updates in production.
If a different developer will be covering, or an exception is needed, please inform the oncall SRE by using the `@sre-oncall` Slack alias.
- [ ] Ensure that documentation exists for the feature, and the [version history text](https://docs.gitlab.com/development/documentation/feature_flags/#add-history-text) has been updated.
- [ ] Ensure that any breaking changes have been announced following the [release post process](https://about.gitlab.com/handbook/marketing/blog/release-posts/#deprecations-removals-and-breaking-changes) to ensure GitLab customers are aware.
- [ ] Notify the [`#support_gitlab-com` Slack channel](https://gitlab.slack.com/archives/C4XFU81LG) and your team channel ([more guidance when this is necessary in the dev docs](https://docs.gitlab.com/development/feature_flags/controls/#communicate-the-change)).
### Global rollout on production
For visibility, all `/chatops` commands that target production must be executed in the [`#production` Slack channel](https://gitlab.slack.com/archives/C101F3796)
and cross-posted (with the command results) to the responsible team's Slack channel.
- [ ] [Incrementally roll out](https://docs.gitlab.com/development/feature_flags/controls/#process) the feature on production.
- Example: `/chatops gitlab run feature set classify_code_review_mention_intent <rollout-percentage> --actors`.
- Between every step wait for at least 15 minutes and monitor the appropriate graphs on https://dashboards.gitlab.net.
- [ ] After the feature has been 100% enabled, wait for [at least one day before releasing the feature](#release-the-feature).
### Release the feature
After the feature has been [deemed stable](https://about.gitlab.com/handbook/product-development-flow/feature-flag-lifecycle/#including-a-feature-behind-feature-flag-in-the-final-release),
the [clean up](https://docs.gitlab.com/development/feature_flags/controls/#cleaning-up)
should be done as soon as possible to permanently enable the feature and reduce
complexity in the codebase.
You can either [create a follow-up issue for Feature Flag Cleanup](https://gitlab.com/gitlab-org/gitlab/-/issues/new?issuable_template=Feature%20Flag%20Cleanup)
or use the checklist below in this same issue.
- [ ] Create a merge request to remove the `classify_code_review_mention_intent` feature flag. Ask for review/approval/merge as usual. The MR should include the following changes:
- Remove all references to the feature flag from the codebase.
- Remove the YAML definitions for the feature from the repository.
- [ ] Ensure that the cleanup MR has been included in the release package.
If the merge request was deployed before [the monthly release was tagged](https://about.gitlab.com/handbook/engineering/releases/#self-managed-releases-1),
the feature can be officially announced in a release blog post: `/chatops gitlab run release check <merge-request-url> <milestone>`
- [ ] Close [the feature issue](https://gitlab.com/gitlab-org/gitlab/-/work_items/595294) to indicate the feature will be released in the current milestone.
- [ ] Once the cleanup MR has been deployed to production, clean up the feature flag from all environments by running these chatops command in `#production` channel: `/chatops gitlab run feature delete classify_code_review_mention_intent --dev --pre --staging --staging-ref --production`
- [ ] Close this rollout issue.
## Rollback Steps
- [ ] This feature can be disabled on production by running the following Chatops command:
```
/chatops gitlab run feature set classify_code_review_mention_intent false
```
- [ ] Disable the feature flag on non-production environments:
```
/chatops gitlab run feature set classify_code_review_mention_intent false --dev --pre --staging --staging-ref
```
- [ ] Delete feature flag from all environments:
```
/chatops gitlab run feature delete classify_code_review_mention_intent --dev --pre --staging --staging-ref --production
```
issue