refactor(config): extract resolve domain modules and seam tests

src/config/resolve/top-level.ts

@@ -0,0 +1,28 @@
+import { ResolveContext } from './context';
+import { asBoolean } from './shared';
+
+export function applyTopLevelConfig(context: ResolveContext): void {
+  const { src, resolved, warn } = context;
+  const knownTopLevelKeys = new Set(Object.keys(resolved));
+  for (const key of Object.keys(src)) {
+    if (!knownTopLevelKeys.has(key)) {
+      warn(key, src[key], undefined, 'Unknown top-level config key; ignored.');
+    }
+  }
+
+  if (asBoolean(src.auto_start_overlay) !== undefined) {
+    resolved.auto_start_overlay = src.auto_start_overlay as boolean;
+  }
+
+  if (asBoolean(src.bind_visible_overlay_to_mpv_sub_visibility) !== undefined) {
+    resolved.bind_visible_overlay_to_mpv_sub_visibility =
+      src.bind_visible_overlay_to_mpv_sub_visibility as boolean;
+  } else if (src.bind_visible_overlay_to_mpv_sub_visibility !== undefined) {
+    warn(
+      'bind_visible_overlay_to_mpv_sub_visibility',
+      src.bind_visible_overlay_to_mpv_sub_visibility,
+      resolved.bind_visible_overlay_to_mpv_sub_visibility,
+      'Expected boolean.',
+    );
+  }
+}