---
status: open
opened: 2026-09-30
located-in:
  - mesh-catalog (each module builds from its own directory, ADR 0069)
  - mesh-sdk
fixed-by:
amended-design:
---

# 167 — Code several modules share has no home

## What was observed

The download-stack write-in step (register download clients and torznab indexers through the Servarr
API) is identical for sonarr, radarr, lidarr and bookshelf. Because a module builds from its own
directory, it now exists as four byte-identical copies under `modules/<m>/downloads/`, kept honest by a
test that fails when one differs. The same shape repeats: an MQTT probe copied into two modules, and a
"write the provider into the app through its API, idempotently, refuse a minted value" step in ombi,
home-assistant, nodered, tautulli and the four downloaders.

## What would be right

A home for shared module code the builder can use — an sdk helper (a write-in step harness: read
bindings and pair credentials, probe the provider, diff, write, report) or a shared package the
catalogue builds once — so a fix lands in one place.