---
title: "2026-09-18 Histo Gleason WSI inference API inspection"
description: "Inspected Histo 0.0.127 and main for a thin NanoVirDx Gleason segmentation adapter."
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 Histo Gleason WSI inference API inspection

## Work Done

- Inspected `histo-v0.0.127` and `origin/main` in the private Histo repository. The packaged Histo source is identical between those refs.
- Identified `histo.semantic_segmentation.inference.SemanticSegPredictor` as the public whole-slide API and documented its checkpoint loading, device behavior, `predict_wsi` signature, normalization inputs, and in-memory uint8 outputs.
- Confirmed the API is included in the 0.0.127 wheel and that the conda recipe carries its GPU/runtime dependencies.
- Proposed a thin NanoVirDx adapter that owns path opening and output persistence only, while delegating model inference and sliding-window orchestration to Histo.
- Identified missing policy decisions around target MPP, normalization, tissue-mask requirements, and ClearML model ID or local checkpoint configuration.

## Lessons Learned: Pitfalls

- The Histo Pixi CUDA feature still lists `nnunetv2`, but current packaged source does not import it. The authoritative runtime dependency check for consumers is the conda recipe, not the development Pixi feature list.
- A historical WSI runner contains useful reference orchestration but was removed and was never packaged. It must not be treated as a supported import.

## Lessons Learned: Improvements

- Add a Histo SOP for the public standalone Gleason WSI contract, including the expected 1.0 µm/px input, normalization recipe, model ID source, label IDs, and an OME-Zarr path-to-path example.
- Document whether NanoVirDx receives preprocessed single-resolution components or arbitrary WSI pyramids. This determines whether level selection belongs in the adapter.

Source: https://docs.virdx.dev/knowledge/inbox/2026-09-18-histo-gleason-wsi-inference-api/index.mdx