Improve Codebase Architecture

Surface architectural friction and pitch deepening opportunities — refactors that turn shallow modules into deep ones. The goal is testability and AI-navigability.

This command draws on the project's domain model and rests on a shared design vocabulary:

• Run the /codebase-design skill for the architecture vocabulary (module, interface, depth, seam, adapter, leverage, locality) and its principles (the deletion test, "the interface is the test surface", "one adapter = hypothetical seam, two = real"). Use those exact terms in every suggestion — don't slide into "component," "service," "API," or "boundary."
• The domain language in CONTEXT.md names the good seams; the ADRs in docs/adr/ record decisions this command must not re-open.

Process

1. Explore

Read the project's domain glossary (CONTEXT.md) and any ADRs covering the area you're touching first.

Then use the Agent tool with subagent_type=Explore to walk the codebase. Skip rigid heuristics — explore organically and mark wherever you feel friction: