refactor: isolate Map Source controls and selection lifecycle

src/mapStackChips.js

@@ -1,8 +1,8 @@
 // MAP STACK source chips — the always-visible replacement for the `<select>`
 // that used to sit in the Map Stack panel. One button per stack, rendered from
-// `MapStackController.getStacks()`. The four owner-approved sources below are
+// `MapStackController.getStacks()`. The approved sources below are
 // the whole shipped set; keeping the allowlist explicit means a stack added to
-// `MAP_STACKS` for internal use cannot reach the tray until someone names it
+// `MAP_STACKS` for another purpose cannot reach the tray until someone names it
 // here.
 //
 // The chips are a control SURFACE only: selecting one calls back into the same
@@ -60,7 +60,7 @@ export function mapStackChipModel(stack, activeId) {
  * @param {Array<object>} stacks - `MapStackController.getStacks()` output.
  * @param {string|null} activeId - Currently active stack id.
  * @returns {Array<object>} One chip model per approved presentation id, in
- *   `PRESENTED_MAP_STACK_IDS` order; internal and future stacks stay hidden.
+ *   `PRESENTED_MAP_STACK_IDS` order; unlisted stacks stay outside this presentation.
  */
 export function mapStackChipModels(stacks, activeId) {
   const stacksById = new Map((Array.isArray(stacks) ? stacks : [])
@@ -79,9 +79,10 @@ export function mapStackChipModels(stacks, activeId) {
  * @param {string|null} [options.activeId] - Currently active stack id.
  * @param {(stackId: string) => void} [options.onSelect] - Selection callback.
  * @param {Document} [options.doc] - Document override (tests).
+ * @param {(element: HTMLElement, type: string, listener: Function) => void} [options.bind] - Listener owner override.
  * @returns {Array<object>} The rendered chip models.
  */
-export function renderMapStackChips(container, stacks, { activeId = null, onSelect = null, doc } = {}) {
+export function renderMapStackChips(container, stacks, { activeId = null, onSelect = null, doc, bind = (element, type, listener) => element.addEventListener(type, listener) } = {}) {
   if (!container) return [];
   const ownerDoc = doc || container.ownerDocument || globalThis.document;
   if (!ownerDoc?.createElement) return [];
@@ -117,7 +118,7 @@ export function renderMapStackChips(container, stacks, { activeId = null, onSele
       chip.appendChild(requirement);
     }
 
-    chip.addEventListener('click', () => {
+    bind(chip, 'click', () => {
       if (!model.available) return;
       onSelect?.(model.id);
     });