Optimize: reuse tab and smart polling for faster checks

- Keep tab open between checks (no create/close overhead)
- Poll for products every 500ms instead of fixed 10s wait
- Exit early as soon as products are found
- Max wait reduced to 8 seconds
- Should reduce check time from ~15-20s to ~3-8s

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

chrome-extension/background.js

@@ -15,6 +15,7 @@ const DEFAULT_CONFIG = {
 // Store known products
 let knownProducts = {};
 let config = DEFAULT_CONFIG;
+let persistentTabId = null; // Keep tab open for faster refreshes
 
 // Initialize
 chrome.runtime.onInstalled.addListener(() => {
@@ -129,53 +130,82 @@ async function runStockCheck() {
 async function fetchAndParseProducts(url) {
   return new Promise(async (resolve, reject) => {
     try {
-      // Create a tab to load the page
-      const tab = await chrome.tabs.create({ url, active: false });
+      let tabId;
+      let isNewTab = false;
 
-      console.log(`Created tab ${tab.id} for ${url}`);
+      // Reuse existing tab or create new one
+      if (persistentTabId) {
+        try {
+          const tab = await chrome.tabs.get(persistentTabId);
+          tabId = tab.id;
+          console.log(`Reusing tab ${tabId}, refreshing...`);
+          await chrome.tabs.update(tabId, { url });
+        } catch (e) {
+          // Tab was closed, create new one
+          persistentTabId = null;
+        }
+      }
+
+      if (!persistentTabId) {
+        const tab = await chrome.tabs.create({ url, active: false });
+        tabId = tab.id;
+        persistentTabId = tabId;
+        isNewTab = true;
+        console.log(`Created new tab ${tabId}`);
+      }
 
       // Wait for tab to finish loading
       const waitForLoad = () => {
         return new Promise((res) => {
-          const listener = (tabId, changeInfo) => {
-            if (tabId === tab.id && changeInfo.status === "complete") {
+          const listener = (tid, changeInfo) => {
+            if (tid === tabId && changeInfo.status === "complete") {
               chrome.tabs.onUpdated.removeListener(listener);
               res();
             }
           };
           chrome.tabs.onUpdated.addListener(listener);
-
-          // Timeout after 30 seconds
           setTimeout(() => {
             chrome.tabs.onUpdated.removeListener(listener);
             res();
-          }, 30000);
+          }, 20000);
         });
       };
 
       await waitForLoad();
-      console.log(`Tab ${tab.id} loaded`);
+      console.log(`Tab ${tabId} loaded`);
 
-      // Give extra time for dynamic content to load
-      console.log("Waiting for dynamic content...");
-      await new Promise(r => setTimeout(r, 10000)); // 10 seconds for slow loads
-
-      // Send message to content script to extract products
+      // Smart wait: poll for products instead of fixed wait
       let products = [];
+      const startTime = Date.now();
+      const maxWait = 8000; // Max 8 seconds
+      const pollInterval = 500; // Check every 500ms
+
+      while (Date.now() - startTime < maxWait) {
+        try {
+          // Inject content script if needed
           try {
-        const response = await chrome.tabs.sendMessage(tab.id, { type: "extractProducts" });
-        products = response || [];
-        console.log(`Content script returned ${products.length} products`);
-      } catch (e) {
-        console.log("Content script not ready, injecting manually...");
-        // Inject content script if not already there
             await chrome.scripting.executeScript({
-          target: { tabId: tab.id },
+              target: { tabId },
               files: ["content.js"]
             });
-        await new Promise(r => setTimeout(r, 500));
-        const response = await chrome.tabs.sendMessage(tab.id, { type: "extractProducts" });
+          } catch (e) { /* Already injected */ }
+
+          await new Promise(r => setTimeout(r, pollInterval));
+
+          const response = await chrome.tabs.sendMessage(tabId, { type: "extractProducts" });
           products = response || [];
+
+          if (products.length > 0) {
+            console.log(`Found ${products.length} products after ${Date.now() - startTime}ms`);
+            break;
+          }
+        } catch (e) {
+          // Content script not ready yet
+        }
+      }
+
+      if (products.length === 0) {
+        console.log(`No products found after ${maxWait}ms`);
       }
 
       // Apply keyword filter
@@ -187,13 +217,11 @@ async function fetchAndParseProducts(url) {
         console.log(`After keyword filter: ${products.length} products`);
       }
 
-      // Close the tab
-      await chrome.tabs.remove(tab.id);
-      console.log(`Closed tab ${tab.id}`);
-
+      // Don't close tab - keep for reuse
       resolve(products);
 
     } catch (error) {
+      persistentTabId = null; // Reset on error
       reject(error);
     }
   });