SimpleChatTCRV:iDB:GetKeys: helps decide whether restore btn shown

tools/server/public_simplechat/idb.mjs

@@ -103,3 +103,31 @@ export function db_get(dbName, storeName, key, callerTag, cb) {
         cb(false, errReason)
     })
 }
+
+
+/**
+ * Return all keys from a store in a db,
+ * through the provided callback.
+ *
+ * @param {string} dbName
+ * @param {string} storeName
+ * @param {string | undefined} callerTag
+ * @param {(status: boolean, related: IDBValidKey[] | DOMException | null) => void} cb
+ */
+export function db_getkeys(dbName, storeName, callerTag, cb) {
+    let tag = `iDB:GetKeys:${callerTag}`;
+    db_open(dbName, storeName, tag).then((/** @type {IDBDatabase} */db)=>{
+        let reqGet = db_trans_store(db, storeName, 'readonly').getAllKeys();
+        reqGet.onsuccess = (evGet) => {
+            console.info(`DBUG:${tag}:transact success`)
+            cb(true, reqGet.result)
+        }
+        reqGet.onerror = (evGet) => {
+            console.info(`ERRR:${tag}:OnError:transact failed:${reqGet.error}`)
+            cb(false, reqGet.error)
+        }
+    }).catch((errReason)=>{
+        console.info(`ERRR:${tag}:Caught:transact failed:${errReason}`)
+        cb(false, errReason)
+    })
+}

tools/server/public_simplechat/readme.md

@@ -737,7 +737,9 @@ sliding window based drop off or even before they kick in, this can help in many
 * UI Cleanup - msgs spaced out, toolcall edit hr not always, scroll ui only when required,
   hide settings/info till user requests, heading gradient
 
-* iDB module - add open, transact, put and get. Use for chat session save and load
+* iDB module
+  * add open, transact, put and get. Use for chat session save and load
+  * getKeys used to show Restore/Load button wrt chat sessions.
 
 
 #### ToDo

tools/server/public_simplechat/simplechat.js

@@ -1674,13 +1674,20 @@ export class Me {
      * @param {SimpleChat} chat
      */
     setup_load(div, chat) {
-        if (!(chat.ods_key() in localStorage)) {
+        let tag = `Me:Load:${chat.chatId}`;
+        mIdb.db_getkeys(DB_NAME, DB_STORE, tag, (status, related)=>{
+            if (!status || (related == null)) {
+                return
+            }
+            if (related.constructor.name == DOMException.name) {
+                return
+            }
+            if (/** @type {IDBValidKey[]} */(related).indexOf(chat.ods_key()) == -1) {
                 return;
             }
             div.innerHTML += `<p class="role-system">Restore</p>
             <p>Load previously saved chat session, if available</p>`;
             let btn = ui.el_create_button(chat.ods_key(), (ev)=>{
-            let tag = `Me:Load:${chat.chatId}`;
                 console.log(`DBUG:${tag}`, chat);
                 chat.load((loadStatus, dbStatus, related)=>{
                     if (!loadStatus || !dbStatus) {
@@ -1695,6 +1702,7 @@ export class Me {
                 });
             });
             div.appendChild(btn);
+        })
     }
 
     /**