Traced apps/vxdatasync/__main__.py from output discovery through S3 upload and creation of one DiffsimScan plus nine DiffsimVolume children.
Compared that legacy flow with current apps/gen4ve2e/run.py: each sequence writes three NIfTI variants, one foreground mask, and a final RunInfo JSON completion marker.
Completed only the post-run section of apps/gen4ve2e/generate_vxdata.py, starting at the user-specified line 74 boundary. It keeps the known HistoDomainRep association instead of parsing an identifier from the flattened local folder name.
The post-run section iterates the actual output-scans directories and maps each back to its HistoDomainRep through RunInfo.domain.path, without interpreting output directory names. It skips incomplete output sets, uploads each complete scan directory once, uses durable S3 URLs, preserves source access policy, converts DWI b-values from s/mm² to s/m², and creates the scan and nine volumes in one API transaction.
Restored the user-authored lines 1–73 byte-for-byte after initially violating the requested edit boundary, and removed the extra test file. Targeted compilation and Pyright pass.
Lessons Learned: Pitfalls
Cedrik added apps/vxdatasync/__main__.py in commit f18194ac alongside the current RunInfo serialization. Its sequence_metadata key is a local wrapper around the full current RunInfo JSON, not evidence of an older JSON shape. The copied lower block failed only because the wrapper-building section was absent.
The legacy sync implementation contains correct output-variant and unit conventions, but also relies on filesystem-name parsing, stores a local path as the scan URL, and writes a non-resource version string into lineage.
DiffsimScan.reference_histo_map is a legacy name. The new workflow stores the HistoDomainRep identifier there so completion discovery remains consistent, although the old inline schema comment still names only HistoMap.
Runner output directories are direct diffsimscan_* children of the output root; they are not below diffsimscan/.
Lessons Learned: Improvements
Document the current gen4ve2e output-to-vxData contract: one RunInfo per base sequence, three child volumes per sequence, one shared mask, DWI b-values stored in s/m², and JSON written last as completion evidence.
Rename or generalize reference_histo_map in a future vxData schema migration so a HistoDomainRep bundle is a first-class simulation input reference.
Give simulation data releases an explicit stable run-version value if future reruns of the same HistoDomainRep must coexist independently of the installed diffsim package version.
