Overview

The Message Filter Plugin (MFP) multi-version resmoke variants (added in SERVER-129188) validate the master-built plugin against each production server version carrying the backported loader. The matrix currently covers 7.0, 8.0, and 8.3 (weekly, arm64 + x86). 9.0 has no resmoke variant: when SERVER-129188 landed (June 2026), 9.0 was still in RC and was never added after GA. 9.0 is now a production target and the same plugin .so deploys there. So its backported loader is the only version in the matrix with no resmoke validation.

• The runner (plugin/resmoke/run_resmoke.py) takes the version as an argument (mfp_test_version expansion) and downloads that version's server binaries via db-contrib-tool; unknown versions default to the v5/python3.13 toolchain, so no code change is needed for 9.0.
• 9.0 GA binaries exist (r9.0.0, r9.0.1).

Scope of work

• Add message-filter-plugin-resmoke-arm64-90 and message-filter-plugin-resmoke-x86-90 variants mirroring the 8.3 blocks, with mfp_test_version: "9.0", same weekly cron.
• Confirm the variants run green on a patch before relying on the weekly schedule.

Context

Raised during the MFP Correctness Launch Readiness review; confirmed as needed before 9.0 rolls out to Atlas.