rseng-open-source-migration

# Migrating from commercial platforms to open source Research code locked to a commercial platform has a structural problem: every user, collaborator, student, reviewer and CI runner needs a license, and reproducibility acquires an expiry date tied to a vendor. Migration to open alternatives removes the toll booth and makes the work FAIR in practice (rseng-fair-software) - but a naive "translate the syntax" migration produces subtly wrong science. The discipline: pin behavior first, choose the target honestly, migrate incrementally with numerical parity as the acceptance test. The general safety net (characterization tests, strangler migration) lives in rseng-legacy-code; this skill adds the platform-specific knowledge. ## Before migrating: pin the baseline While the commercial license still works, capture everything the migration must reproduce (this window may not stay open): - Run the original on representative inputs and save inputs and outputs as the golden baseline (rseng-legacy-code's characterization tests). - Record the platform version, toolbox versions and settings that produced the baseline. - Export data OUT of proprietary formats now: .mat to HDF5-based or open formats, SAS/SPSS/Stata files to open tabular formats (rseng-scientific-file-formats) - data freedom precedes code freedom, and readers for proprietary formats are better used while a licensed installation can verify the export. ## Choosing the target - MATLAB, two honest paths: GNU Oc...