Merge pull request #533 from mattpocock/yagni-scope-improve-architecture

improve-codebase-architecture: scope the scan to where change is landing (YAGNI)

.changeset/yagni-scope-improve-architecture.md

@@ -0,0 +1,5 @@
+---
+"mattpocock-skills": minor
+---
+
+Add a YAGNI scoping filter to the **`improve-codebase-architecture`** skill's Explore step. Instead of scanning the whole repo evenly, it now scopes to where change is actually landing: if you name a direction it takes it, otherwise it reads the last ~20 commit messages to bias exploration toward actively-developed paths. A deepening opportunity in code nobody touches is a refactor you'll never cash in — the leverage only pays off where you keep editing — so the report stops tidying dormant corners of the repo.

docs/engineering/improve-codebase-architecture.md

@@ -16,6 +16,8 @@ npx skills update improve-codebase-architecture
 
 It does **not** hand you a flat list of refactors. Every candidate has to pass the **deletion test** — would removing this module *concentrate* complexity behind a smaller interface, or just move it around? Only the "concentrates" cases earn a card. That filter is what stops the report from becoming generic cleanup advice.
 
+Unless you point it at a specific area, it also scopes itself to where development is actually landing — reading the recent commits to bias toward the code you're still changing. Deepening a module pays off by making future changes to it easier, so it puts extra weight on the parts of the repo that have recently changed.
+
 ## When to reach for it
 
 You invoke this by typing `/improve-codebase-architecture` — the agent won't reach for it on its own.

skills/engineering/improve-codebase-architecture/SKILL.md

@@ -17,6 +17,11 @@ This command is _informed_ by the project's domain model and built on a shared d
 
 ### 1. Explore
 
+**Scope before you scan — YAGNI.** Deepening a module pays off by making future changes to it easier, so put extra weight on the parts of the codebase that have recently changed. Decide *where* to look before you look:
+
+- If the user named a direction — a module, a subsystem, a pain point — take it, and skip the inference below.
+- Otherwise, walk back a good stretch of the commit history (`git log --oneline`) to find the codebase's hot spots — the files and areas that keep coming up — and let those paths pull your attention first. If the changes are scattered with no clear hot spot, widen the net.
+
 Read the project's domain glossary (`CONTEXT.md`) and any ADRs in the area you're touching first.
 
 Then use the Agent tool with `subagent_type=Explore` to walk the codebase. Don't follow rigid heuristics — explore organically and note where you experience friction: