diff --git a/extension/background.js b/extension/background.js
index b05bf994..5a0049d6 100644
--- a/extension/background.js
+++ b/extension/background.js
@@ -46,7 +46,8 @@ async function loadAuthToken() {
       if (data.token) authToken = data.token;
     }
   } catch (err) {
-    console.error('[gstack bg] Failed to load auth token:', err.message);
+    if (!err?.message?.includes('Failed to fetch')) throw err;
+    console.debug('[gstack bg] Auth token not available (server may not be running):', err.message);
   }
 }
 
@@ -125,7 +126,8 @@ async function notifyContentScripts(type) {
       }
     }
   } catch (err) {
-    console.error('[gstack bg] Failed to query tabs for notification:', err.message);
+    if (!err?.message?.includes('Extension context invalidated')) throw err;
+    console.debug('[gstack bg] Tab notification skipped (extension context invalidated)');
   }
 }
 
@@ -180,7 +182,8 @@ async function fetchAndRelayRefs() {
       }
     }
   } catch (err) {
-    console.error('[gstack bg] Failed to fetch/relay refs:', err.message);
+    if (!err?.message?.includes('Failed to fetch')) throw err;
+    console.debug('[gstack bg] Refs fetch skipped (server unreachable)');
   }
 }
 
@@ -203,13 +206,15 @@ async function injectInspector(tabId) {
         files: ['inspector.css'],
       });
     } catch (err) {
+      if (!err?.message?.includes('Extension context invalidated') && !err?.message?.includes('Cannot access')) throw err;
       console.debug('[gstack bg] Inspector CSS injection failed (non-fatal):', err.message);
     }
     // Send startPicker to the injected inspector.js
     try {
       await chrome.tabs.sendMessage(tabId, { type: 'startPicker' });
     } catch (err) {
-      console.warn('[gstack bg] Failed to send startPicker:', err.message);
+      if (!err?.message?.includes('Extension context invalidated') && !err?.message?.includes('Receiving end does not exist')) throw err;
+      console.debug('[gstack bg] startPicker skipped (tab not ready):', err.message);
     }
     inspectorMode = 'full';
     return { ok: true, mode: 'full' };
@@ -232,7 +237,8 @@ async function stopInspector(tabId) {
   try {
     await chrome.tabs.sendMessage(tabId, { type: 'stopPicker' });
   } catch (err) {
-    console.debug('[gstack bg] Failed to stop picker on tab', tabId, ':', err.message);
+    if (!err?.message?.includes('Extension context invalidated') && !err?.message?.includes('Receiving end does not exist')) throw err;
+    console.debug('[gstack bg] stopPicker skipped (tab not ready):', err.message);
   }
   return { ok: true };
 }
@@ -270,7 +276,8 @@ async function sendToContentScript(tabId, message) {
   try {
     const response = await chrome.tabs.sendMessage(tabId, message);
     return response || { ok: true };
-  } catch {
+  } catch (e) {
+    if (!e?.message?.includes('Extension context invalidated') && !e?.message?.includes('Receiving end does not exist')) throw e;
     return { error: 'Content script not available' };
   }
 }
diff --git a/extension/content.js b/extension/content.js
index b1f47fc8..8af84d7f 100644
--- a/extension/content.js
+++ b/extension/content.js
@@ -207,11 +207,11 @@ function captureBasicData(el) {
                 source: sheet.href || 'inline',
               });
             }
-          } catch { /* skip rules that can't be matched */ }
+          } catch (e) { if (!(e instanceof TypeError) && !(e instanceof DOMException)) throw e; }
         }
-      } catch { /* cross-origin sheet — silently skip */ }
+      } catch (e) { if (!(e instanceof DOMException)) throw e; }
     }
-  } catch { /* CSSOM not available */ }
+  } catch (e) { if (!(e instanceof TypeError) && !(e instanceof DOMException)) throw e; }
 
   return { computedStyles, boxModel, matchedRules };
 }
@@ -219,7 +219,7 @@ function captureBasicData(el) {
 function basicBuildSelector(el) {
   if (el.id) {
     const sel = '#' + CSS.escape(el.id);
-    try { if (document.querySelectorAll(sel).length === 1) return sel; } catch {}
+    try { if (document.querySelectorAll(sel).length === 1) return sel; } catch (e) { if (!(e instanceof TypeError) && !(e instanceof DOMException)) throw e; }
   }
   const parts = [];
   let current = el;
diff --git a/extension/inspector.js b/extension/inspector.js
index df88b5a7..13e63ddc 100644
--- a/extension/inspector.js
+++ b/extension/inspector.js
@@ -159,7 +159,8 @@
   function isUnique(selector) {
     try {
       return document.querySelectorAll(selector).length === 1;
-    } catch {
+    } catch (e) {
+      if (!(e instanceof TypeError) && !(e instanceof DOMException)) throw e;
       return false;
     }
   }
@@ -244,11 +245,11 @@
                   source: sheet.href || 'inline',
                 });
               }
-            } catch { /* skip rules that can't be matched */ }
+            } catch (e) { if (!(e instanceof TypeError) && !(e instanceof DOMException)) throw e; }
           }
-        } catch { /* cross-origin sheet — silently skip */ }
+        } catch (e) { if (!(e instanceof DOMException)) throw e; }
       }
-    } catch { /* CSSOM not available */ }
+    } catch (e) { if (!(e instanceof TypeError) && !(e instanceof DOMException)) throw e; }
 
     return { computedStyles, boxModel, matchedRules };
   }
@@ -290,7 +291,7 @@
       try {
         frameInfo.frameSrc = window.location.href;
         frameInfo.frameName = window.name || null;
-      } catch { /* cross-origin frame */ }
+      } catch (e) { if (!(e instanceof DOMException)) throw e; }
     }
 
     chrome.runtime.sendMessage({
@@ -347,7 +348,8 @@
   function findElement(selector) {
     try {
       return document.querySelector(selector);
-    } catch {
+    } catch (e) {
+      if (!(e instanceof TypeError) && !(e instanceof DOMException)) throw e;
       return null;
     }
   }
diff --git a/extension/sidepanel.js b/extension/sidepanel.js
index 089f1ccd..fdc7eef5 100644
--- a/extension/sidepanel.js
+++ b/extension/sidepanel.js
@@ -451,7 +451,8 @@ async function pollChat() {
     // Show/hide stop button based on agent status
     updateStopButton(data.agentStatus === 'processing');
   } catch (err) {
-    console.error('[gstack sidebar] Chat poll error:', err.message);
+    if (!err?.message?.includes('Failed to fetch') && !err?.message?.includes('The operation was aborted')) throw err;
+    console.debug('[gstack sidebar] Chat poll skipped (server unreachable)');
   } finally {
     pollInProgress = false;
   }
@@ -529,7 +530,8 @@ async function stopAgent() {
     const resp = await fetch(`${serverUrl}/sidebar-agent/stop`, { method: 'POST', headers: authHeaders() });
     if (!resp.ok) console.warn(`[gstack sidebar] Stop agent failed: ${resp.status}`);
   } catch (err) {
-    console.error('[gstack sidebar] Stop agent error:', err.message);
+    if (!err?.message?.includes('Failed to fetch')) throw err;
+    console.debug('[gstack sidebar] Stop agent skipped (server unreachable)');
   }
   // Immediately clean up UI
   const thinking = document.getElementById('agent-thinking');
@@ -598,7 +600,8 @@ async function pollTabs() {
 
     renderTabBar(data.tabs);
   } catch (err) {
-    console.error('[gstack sidebar] Tab poll error:', err.message);
+    if (!err?.message?.includes('Failed to fetch') && !err?.message?.includes('The operation was aborted')) throw err;
+    console.debug('[gstack sidebar] Tab poll skipped (server unreachable)');
   }
 }
 
@@ -646,7 +649,8 @@ async function switchBrowserTab(tabId) {
     switchChatTab(tabId);
     pollTabs();
   } catch (err) {
-    console.error('[gstack sidebar] Failed to switch browser tab:', err.message);
+    if (!err?.message?.includes('Failed to fetch')) throw err;
+    console.debug('[gstack sidebar] Tab switch skipped (server unreachable)');
   }
 }
 
@@ -658,7 +662,8 @@ document.getElementById('clear-chat').addEventListener('click', async () => {
     const resp = await fetch(`${serverUrl}/sidebar-chat/clear`, { method: 'POST', headers: authHeaders() });
     if (!resp.ok) console.warn(`[gstack sidebar] Clear chat failed: ${resp.status}`);
   } catch (err) {
-    console.error('[gstack sidebar] Clear chat error:', err.message);
+    if (!err?.message?.includes('Failed to fetch')) throw err;
+    console.debug('[gstack sidebar] Clear chat skipped (server unreachable)');
   }
   // Reset local state
   chatLineCount = 0;
@@ -690,7 +695,8 @@ document.getElementById('chat-cookies-btn').addEventListener('click', async () =
       body: JSON.stringify({ command: 'goto', args: [`${serverUrl}/cookie-picker`] }),
     });
   } catch (err) {
-    console.error('[gstack sidebar] Failed to open cookie picker:', err.message);
+    if (!err?.message?.includes('Failed to fetch')) throw err;
+    console.debug('[gstack sidebar] Cookie picker skipped (server unreachable)');
   }
 });