Parse structured findings from Duo Code Review output

Kinshuk Singhrequested to merge
627566-structured-findings-parser into master

What does this MR do and why?

Adds a structured JSON parser for Duo Code Review findings, alongside the existing XML parser, reusing the same review_output string parameter.

  • Adds Gitlab::Duo::CodeReview::FindingsParser, which emits the same ResponseBodyParser::Comment objects the XML parser does, so line matching, deduplication, draft notes, and publishing downstream are unchanged.
  • ProcessCommentsService#parsed_body picks the parser: when the flag is on and review_output starts with {, it uses FindingsParser. A { payload with the flag off raises, so flipping the flag off mid-review surfaces the generic review error instead of a misleading "nothing to comment on" note. Anything else falls back to the XML parser as before.
  • Extracts CodeSuggestionFormatter.suggestion_block so both parsers share the suggestion fence and its line offset arithmetic. parse output is unchanged, so this part is a pure refactor.
  • No endpoint, worker, or service signature changes; this is purely a new parsing path behind the flag defined in the parent MR.

The JSON payload removes a whole class of bugs the XML regex parser caused: it needed to defuse structural tags and dropped findings whose file paths contained quotes or angle brackets. See gitlab-org/modelops/applied-ml/code-suggestions/ai-assist!6737 (merged) for the companion change that produces this payload.

Spec placeholders in process_comments_service_spec.rb changed from JSON-shaped strings to <review></review>, since a leading { now selects the structured parser.

No changelog: behind a default-off flag.

Screenshots or screen recordings

N/A, backend-only change.

How to set up and validate locally

  1. Enable the flag in a Rails console: Feature.enable(:duo_code_review_advanced_flow, User.find_by_username('your-username'))
  2. Check out the companion ai-assist branch, then run gdk restart duo-workflow-service gitlab-ai-gateway.
  3. Request a Duo Code Review and check the inline comments plus the one-click suggestions.
  4. Run the specs: bundle exec rspec ee/spec/lib/gitlab/duo/code_review/findings_parser_spec.rb ee/spec/lib/gitlab/llm/utils/code_suggestion_formatter_spec.rb ee/spec/services/ai/duo_workflows/code_review/process_comments_service_spec.rb

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References

Edited by Kinshuk Singh

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