---
title: "2026-09-18 NanoVirDx DiffSim compatibility extraction"
description: "Extracted the Histo v2 and DiffSim compatibility boundary into a dedicated module."
image: "https://docs.virdx.dev/img/virdx-social-card.png"
---

> Documentation Index
> Fetch the complete documentation index at: https://docs.virdx.dev/llms.txt
> Use this file to discover all available pages before exploring further.

# 2026-09-18 NanoVirDx DiffSim compatibility extraction

## Work Done

- Added `nanovirdx.inference.simulation._compat` as the single compatibility boundary between Histo v2 domain representations and DiffSim.
- Preserved the fine28-to-nine-tissue mapping, calibrated tissue parameters, sparse `region_ids` remapping, resolution validation, and simulation-state construction.
- Kept Torch, NumPy, virdx-ome, and DiffSim Histo imports lazy.
- Verified the module with Ruff check, Ruff format check, and Python byte compilation in the NanoVirDx Pixi environment.

## Lessons Learned: Pitfalls

- The diffsim workstream has no `sops/index.md`, so the required startup reading points to a path that does not exist.
- `git pull --ff-only` in the knowledge repository failed with "Cannot fast-forward to multiple branches" despite a clean `main`; explicit fetch and merge worked.

## Lessons Learned: Improvements

- Document the NanoVirDx compatibility boundary and its public adapter function once the calling module is integrated.
- Add a diffsim SOP index, even if it only links to current integration notes and compatibility constraints.

Source: https://docs.virdx.dev/knowledge/inbox/2026-09-18-diffsim-nanovirdx-compat-extraction/index.mdx