ctx-adopt — bring an existing project under ctx, minimally

Brownfield entry: makes ctx take effect on an existing (usually messy) project without touching what the user has — it orchestrates; the domain skills do the real writing. Lifetime model: ../ctx.

The one principle: stable mount point, swappable backend

/ctx is a mount point at the project root — the fixed place any agent looks for context. Its backend (where the bytes live) is swappable. The agent always reads <repo>/ctx; whether that is a real folder or a symlink is a deployment detail.

Three rules — what "low-disruption" MEANS

1. NEVER restructure the user's existing directories. Only ADD the /ctx mount + one pointer line.
2. Default to the lightest backend (in-repo real dir). Upgrade only when separability is actually needed.
3. Reorganize the user's tree only when the user asks, or when building ctx makes a change unavoidable — and even then guarantee one thing: ctx logic stays valid.

Execution Procedure

EP1 — pick the backend