cmux-architecturelisted

# cmux Architecture ## Package architecture cmux is migrating from a single app target into Swift Packages under `Packages/`. Every new package must be: - **Ergonomic.** Default to internal access; `public` only what downstream consumers actually use. - **Acyclic.** Packages form a strict DAG. Share a type by lifting it to a lower package or defining a protocol seam in the consumer. Every new dependency edge requires re-checking that the graph stays acyclic. - **Whole-domain.** One package owns a full domain (settings, appearance, workspace, terminal, browser, command palette). `CmuxAppearanceMath` + `CmuxAppearanceTheme` + `CmuxAppearanceSettings` is folder structure inside `CmuxAppearance`, not module structure. A boundary exists because more than one consumer needs the contents, or a build/test seam must exist. When in doubt, extract leaf-first: the package with no internal dependencies. Existing packages under `Packages/` predate this policy; do not use them as design references. Wiring a new package into `cmux.xcodeproj` needs explicit pbxproj entries in **both** the `cmux` and `cmux-unit` targets. See [references/package-boundaries.md](references/package-boundaries.md). **Group folders.** Every package lives physically under exactly one group directory: `Packages/Shared/<pkg>` (both apps), `Packages/iOS/<pkg>` (iOS only), or `Packages/macOS/<pkg>` (macOS only). `cmux.xcworkspace/contents.xcworkspacedata` mirrors that folder shape, with three groups whose container