Watch article history over SSE so the tab stays current while open.

src/api/StorageManager.js

@@ -72,12 +72,67 @@ export class StorageManager extends ApiClient {
   #events = null;
   /** @type {ReturnType<typeof createCache> | null} */
   #articleIndexCache = null;
+  /** @type {Map<string, Set<() => void>>} sku → refreshers */
+  #historyWatchers = new Map();
 
   constructor(baseUrl = window.location.origin) {
     super(baseUrl);
     this.#initCaches();
   }
 
+  /**
+   * Fetch article history, then refetch whenever SSE emits `article-<sku>`.
+   * @param {string} sku
+   * @param {(history: unknown[]) => void} onHistory
+   * @param {(err: unknown) => void} onError
+   * @returns {() => void} unwatch
+   */
+  watchArticleHistory(sku, onHistory, onError) {
+    const key = String(sku);
+    let active = true;
+
+    const refresh = () =>
+      this.article.history(key).then((res) => {
+        if (!active) return;
+        requireObject(res, 'GET /api/article/{sku}/history');
+        onHistory(requireArray(res.history, 'history'));
+      });
+
+    const run = () =>
+      void refresh().catch((err) => {
+        if (!active) return;
+        onError(err);
+      });
+
+    let watchers = this.#historyWatchers.get(key);
+    if (!watchers) {
+      watchers = new Set();
+      this.#historyWatchers.set(key, watchers);
+      this.#events?.addEventListener(`article-${key}`, this.#onArticleHistorySignal);
+    }
+    watchers.add(run);
+
+    run();
+
+    return () => {
+      active = false;
+      const set = this.#historyWatchers.get(key);
+      if (!set) return;
+      set.delete(run);
+      if (set.size === 0) {
+        this.#historyWatchers.delete(key);
+        this.#events?.removeEventListener(`article-${key}`, this.#onArticleHistorySignal);
+      }
+    };
+  }
+
+  #onArticleHistorySignal = (event) => {
+    const sku = event.type.slice('article-'.length);
+    const watchers = this.#historyWatchers.get(sku);
+    if (!watchers) return;
+    for (const run of watchers) run();
+  };
+
   /** Patch local articleIndex name if already loaded; no-op otherwise. */
   setArticleIndexName(sku, name) {
     const articles = this.#articleIndexCache.value;
@@ -147,6 +202,9 @@ export class StorageManager extends ApiClient {
         console.error('[storageMgr] articles SSE refresh failed', err);
       });
     });
+    for (const sku of this.#historyWatchers.keys()) {
+      es.addEventListener(`article-${sku}`, this.#onArticleHistorySignal);
+    }
     es.onerror = () => {
       console.error('[storageMgr] events stream error');
     };