refactor: isolate old and preview versions, add lint rule

web/eslint-plugins/isolation/index.js

@@ -0,0 +1,33 @@
+/**
+ * Local ESLint plugin "isolation".
+ *
+ * Guarantees full isolation between the old UI branch and the new (preview)
+ * branch. Unlike no-restricted-imports (which matches the literal import
+ * specifier string only), these rules RESOLVE the specifier to a real file
+ * (supporting both `$lib/...` aliases and relative `./`/`../` paths) and then
+ * classify both sides by their actual location on disk.
+ *
+ * Why this is needed:
+ *  - old code imports new things via RELATIVE paths (e.g. `../registry-schema`),
+ *    which `$lib/...` glob patterns cannot catch;
+ *  - the same target can be written many ways (`$lib/x`, `../x`, `../../x`),
+ *    so enumerating literal strings is fragile.
+ *
+ * Configuration (per rule options):
+ *   - `root`: path from the lint cwd to the source root (default "src");
+ *   - `alias`: mapping from import aliases to dirs relative to root
+ *     (default { "$lib": "lib" });
+ *   - `old`, `new`: glob patterns (gitignore-style, `!` = negation) for the two
+ *     branches. Files matched by neither are "shared" and unrestricted.
+ */
+import noMixedImports from "./no-mixed-imports.js";
+
+export default {
+	meta: {
+		name: "isolation",
+		version: "1.0.0",
+	},
+	rules: {
+		"no-mixed-imports": noMixedImports,
+	},
+};