diff --git a/manifest-chrome.json b/manifest-chrome.json
index c1b9fd3..fb850ad 100644
--- a/manifest-chrome.json
+++ b/manifest-chrome.json
@@ -22,6 +22,7 @@
   },
   "host_permissions": [
     "http://localhost/*",
+    "http://127.0.0.1/*",
     "http://*/*",
     "https://*/*"
   ],
diff --git a/manifest-firefox.json b/manifest-firefox.json
index 82b9227..5ef1b5a 100644
--- a/manifest-firefox.json
+++ b/manifest-firefox.json
@@ -15,6 +15,7 @@
     "storage",
     "scripting",
     "declarativeNetRequest",
+    "declarativeNetRequestWithHostAccess",
     "contextMenus"
   ],
   "commands": {
@@ -28,6 +29,7 @@
   },
   "host_permissions": [
     "http://localhost/*",
+    "http://127.0.0.1/*",
     "http://*/*",
     "https://*/*"
   ],
@@ -40,6 +42,9 @@
       }
     ]
   },
+  "content_security_policy": {
+    "extension_pages": "script-src 'self'; object-src 'self'"
+  },
   "action": {
     "default_popup": "popup/popup.html",
     "default_icon": {
@@ -50,7 +55,7 @@
     }
   },
   "background": {
-    "scripts": ["scripts/background.js"]
+    "scripts": ["scripts/config.js", "scripts/background.js"]
   },
   "options_page": "options/options.html",
   "icons": {
diff --git a/manifest.json b/manifest.json
index c1b9fd3..fb850ad 100644
--- a/manifest.json
+++ b/manifest.json
@@ -22,6 +22,7 @@
   },
   "host_permissions": [
     "http://localhost/*",
+    "http://127.0.0.1/*",
     "http://*/*",
     "https://*/*"
   ],
diff --git a/options/options.js b/options/options.js
index b9836a1..cbc6b32 100644
--- a/options/options.js
+++ b/options/options.js
@@ -159,15 +159,20 @@ testBtn.addEventListener("click", async () => {
     // Provide helpful troubleshooting
     if (
       errorMsg.includes("Cannot connect") ||
-      errorMsg.includes("Failed to fetch")
+      errorMsg.includes("Failed to fetch") ||
+      errorMsg.includes("NetworkError")
     ) {
+      errorMsg +=
+        "\n\nThis error often means nothing is listening at your API URL. If you use Ollama, it may not be running.";
       errorMsg += "\n\n💡 Troubleshooting:\n";
       errorMsg += "1. Check if Ollama is running: run `ollama serve`\n";
       errorMsg +=
         "2. Check if the model is pulled: run `ollama pull " +
         settings.model +
         "`\n";
-      errorMsg += "3. Try switching API Mode (Native vs OpenAI-Compatible)";
+      errorMsg += "3. Try switching API Mode (Native vs OpenAI-Compatible)\n";
+      errorMsg +=
+        "4. If using Ollama in Firefox: restart with OLLAMA_ORIGINS=* (e.g. OLLAMA_ORIGINS=* ollama serve)";
     }
 
     showStatus("❌ " + errorMsg, "error");
diff --git a/popup/popup.css b/popup/popup.css
index 0bdf930..a383ce3 100644
--- a/popup/popup.css
+++ b/popup/popup.css
@@ -553,6 +553,7 @@ body {
     border-radius: 6px;
     font-size: 12px;
     line-height: 1.5;
+    white-space: pre-wrap;
 }
 
 /* ── PDF Error ── */
@@ -755,6 +756,7 @@ body {
     color: var(--error-text);
     padding: 10px 14px;
     border-radius: 6px;
+    white-space: pre-wrap;
 }
 
 .chat-spinner {
diff --git a/popup/popup.js b/popup/popup.js
index 314c064..3022987 100644
--- a/popup/popup.js
+++ b/popup/popup.js
@@ -189,9 +189,9 @@ function handleStreamDone(error) {
   if (!streamTarget) return; // Nothing was streaming
 
   if (error) {
-    showToast("Error: " + error);
+    showToast("Error: " + withOllamaFetchHint(error));
     if (streamElement) {
-      streamElement.innerHTML = `<div class="error-message">${escapeHtml(error)}</div>`;
+      streamElement.innerHTML = `<div class="error-message">${escapeHtml(withOllamaFetchHint(error))}</div>`;
     }
     // Still finalize to reset states
     if (streamTarget === "chat") {
@@ -801,7 +801,7 @@ async function sendChatMessage() {
     // Show error in chat
     const errorEl = document.createElement("div");
     errorEl.className = "chat-message assistant error";
-    errorEl.textContent = "Error: " + error.message;
+    errorEl.textContent = "Error: " + withOllamaFetchHint(error.message);
     chatSection.appendChild(errorEl);
 
     // Scroll to show error
@@ -823,7 +823,7 @@ function finalizeChatStream(error) {
   chatInput.focus();
 
   if (error) {
-    showToast("Error: " + error);
+    showToast("Error: " + withOllamaFetchHint(error));
     return;
   }
 
@@ -923,7 +923,7 @@ async function generateQuickSummary() {
     // The response will come via postMessage listener
   } catch (error) {
     console.error("API Error:", error);
-    resultContainer.innerHTML = `<div class="error-message">${escapeHtml(error.message)}</div>`;
+    resultContainer.innerHTML = `<div class="error-message">${escapeHtml(withOllamaFetchHint(error.message))}</div>`;
     setLoading(false);
   }
 }
@@ -932,7 +932,7 @@ function finalizeSummaryStream(error) {
   if (error) {
     setLoading(false);
     if (currentStreamElement) {
-      currentStreamElement.innerHTML = `<div class="error-message">${escapeHtml(error)}</div>`;
+      currentStreamElement.innerHTML = `<div class="error-message">${escapeHtml(withOllamaFetchHint(error))}</div>`;
     }
     return;
   }
@@ -1285,6 +1285,22 @@ function setLoading(loading) {
   }
 }
 
+function looksLikeNetworkFetchFailure(message) {
+  const m = String(message ?? "").toLowerCase();
+  return (
+    m.includes("networkerror") ||
+    m.includes("failed to fetch") ||
+    m.includes("network error when attempting to fetch")
+  );
+}
+
+/** Explains that Ollama may be stopped when the error looks like a failed fetch. */
+function withOllamaFetchHint(message) {
+  const base = String(message ?? "");
+  if (!looksLikeNetworkFetchFailure(base)) return base;
+  return `${base}\n\nIf you're using Ollama, it may not be running. Try \`ollama serve\`.`;
+}
+
 function escapeHtml(text) {
   const div = document.createElement("div");
   div.textContent = text;
diff --git a/rules.json b/rules.json
index 75b803d..699a0dc 100644
--- a/rules.json
+++ b/rules.json
@@ -13,8 +13,24 @@
       ]
     },
     "condition": {
-      "urlFilter": "http://localhost:11434/*",
-      "resourceTypes": ["xmlhttprequest"]
+      "urlFilter": "http://localhost:11434/*"
+    }
+  },
+  {
+    "id": 2,
+    "priority": 1,
+    "action": {
+      "type": "modifyHeaders",
+      "requestHeaders": [
+        {
+          "header": "Origin",
+          "operation": "set",
+          "value": "http://127.0.0.1"
+        }
+      ]
+    },
+    "condition": {
+      "urlFilter": "http://127.0.0.1:11434/*"
     }
   }
 ]
diff --git a/scripts/background.js b/scripts/background.js
index 0b970fe..cb2ddbb 100644
--- a/scripts/background.js
+++ b/scripts/background.js
@@ -1,8 +1,11 @@
 // Background script - handles API communication
 // Uses centralized CONFIG from config.js
 
-// Import shared configuration (service worker context)
-importScripts("config.js");
+// Chrome MV3: service worker — load config via importScripts.
+// Firefox MV3: event-page scripts — config.js is listed first in manifest "scripts".
+if (typeof importScripts === "function") {
+  importScripts("config.js");
+}
 
 // Cache key prefixes from CONFIG
 const QUICK_SUMMARY_CACHE_PREFIX = CONFIG.CACHE.QUICK_SUMMARY;
diff --git a/scripts/config.js b/scripts/config.js
index 46461a2..b659534 100644
--- a/scripts/config.js
+++ b/scripts/config.js
@@ -19,7 +19,7 @@ const CONFIG = {
     BASE_URL: "http://localhost:11434",
     MODEL: "gpt-oss:20b-cloud",
     KEY: "",
-    DISABLE_THINKING: false,
+    DISABLE_THINKING: true,
     AUTO_SUMMARIZE: false,
     MAX_TOKENS: 2048,
     TEMPERATURE: 0.7,