research 005: which modules actually change together

The domain-grouping premise is testable, so it was tested before drawing a list. Co-change across the full history of the module catalogue, current modules only, platform namespace excluded. Nine commits in ten touch exactly one module, and 50 of 89 modules have never been edited alongside anything. Two clusters exist above that floor. Reachability holds up: proxy, resolver, firewall and VPN genuinely move together under one intent, three times in recent history. That is the shape ADR 0017 describes and the only place the measurement finds it. The provider cluster does not, and this is the finding worth having. Every multi-provider commit is a cross-cutting manifest change applied N times — feature detection, hook conventions, volume binds, network scoping. None is a change to what a database is. Merging them would not have prevented one of those commits, and the history already shows the fix that worked: verify by shape in the SDK rather than copying a script into every module. Move the concern into the machinery, do not merge the modules carrying it. ADR 0017 keeps its principle and gains a pointer to this narrowing.
2026-08-23 18:48:28 +02:00
parent 3f6d939930
commit 143f8ab2f1
3 changed files with 209 additions and 1 deletions
@@ -81,7 +81,11 @@ metrics, storage and data services — but naming them here would be reconstruct
 that has not been taken.

 Settling the list is a research effort, not an act of this record. Until it concludes, this
-ADR stays `proposed`.
+ADR stays `proposed`. That effort is
+[`01-RESEARCH/005-domain-grouping`](../01-RESEARCH/005-domain-grouping/00-overview.md), and its
+first measurement already narrows this record's scope: co-change analysis supports grouping for
+reachability, argues against it for the provisioned infrastructure providers, and finds no
+signal either way for the fifty modules that never change alongside anything.

 ## References