make some overall QoL improvements

src/routes/chats.js

@@ -228,6 +228,24 @@ export function createChatsRouter({repositories, chatService, modelService, conf
         return res.json({message: "Chat deleted"});
     });
 
+    router.get("/chats/:id/messages/search", (req, res) => {
+        const chatId = Number(req.params.id);
+        if (!repositories.getChat(chatId, req.session.user)) return res.status(404).json({error: "Chat not found"});
+        const query = String(req.query.q || "").trim().slice(0, 200).toLocaleLowerCase();
+        if (!query) return res.json({matches: []});
+        const matches = [];
+        for (const message of repositories.listActiveBranchMessages(chatId)) {
+            const content = String(message.content || "").toLocaleLowerCase();
+            let at = content.indexOf(query);
+            let occurrence = 0;
+            while (at >= 0) {
+                matches.push({messageId: message.id, occurrence: occurrence++});
+                at = content.indexOf(query, at + query.length);
+            }
+        }
+        return res.json({matches});
+    });
+
     router.get("/chats/:id/messages", (req, res) => {
         const chatId = Number(req.params.id);
         const chat = repositories.getChat(chatId, req.session.user);