fix: force download on agentic traffic export URLs | LLMO-4888

[calvarezg]

Please ensure your pull request adheres to the following guidelines:

• Related issue linked below (LLMO-4888)
• Fix commit includes the issue reference for release notes

If the PR is changing the API specification:

• N/A — no API contract change; presigned URL generation is internal.

If the PR is changing the API implementation or an entity exposed through the API:

• N/A — ResponseContentDisposition / ResponseContentType are Response* override parameters baked into the presigned URL query string. The stored S3 object is unchanged.

Related Issues

LLMO-4888: https://jira.corp.adobe.com/browse/LLMO-4888

Chrome opens agentic traffic export CSVs inline as text instead of downloading them. Firefox and Safari handle it correctly. Root cause: presigned S3 URLs for spacecat-prod-reports (no CORS) lacked Content-Disposition: attachment, so Chrome renders the response inline.

Adds ResponseContentDisposition: 'attachment; filename="urls.csv"' and ResponseContentType: 'text/csv; charset=utf-8' to GetObjectCommand in buildExportReadyResponse. For multi-part exports the filename becomes urls_part1.csv, urls_part2.csv, etc. No import changes needed — these are first-class GetObjectCommand options.

Thanks for contributing!

[calvarezg]

Self-review (fresh-context)

[Correctness] In the fast-path (metadata.files), safeFiles is the filtered metadata.files array with no sort applied, so array index i may not match the intended part number. listExportCsvObjects sorts by part number before returning, but validateFilesAgainstPrefix only filters — it does not sort. If the worker writes metadata.files in a different order, urls_part1.csv in Content-Disposition could be attached to the wrong S3 key. src/controllers/llmo/llmo-agentic-traffic.js:772. Fix: sort safeFiles by part number (same comparator used in listExportCsvObjects) before passing to buildExportReadyResponse.

[Test gap] No test asserts that GetObjectCommand is constructed with ResponseContentDisposition and ResponseContentType. The existing multi-part test at line 1687 only checks downloadUrls values; a future refactor could silently drop the response-override params. Consider adding a check on ctx.s3.GetObjectCommand call args (accessible via the constructor stub) that the new fields are present and correctly valued for both the single-file and multi-part cases.

[codecov]

Codecov Report

❌ Patch coverage is 89.47368% with 2 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
src/controllers/llmo/llmo-agentic-traffic.js	89.47%	2 Missing ⚠️

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This PR will trigger a patch release when merged.