diff --git a/frontend/src/simulation/AVRSimulator.ts b/frontend/src/simulation/AVRSimulator.ts
index aade5671..2dca3252 100644
--- a/frontend/src/simulation/AVRSimulator.ts
+++ b/frontend/src/simulation/AVRSimulator.ts
@@ -508,12 +508,12 @@ export class AVRSimulator {
 
     this.running = true;
     console.log('Starting AVR simulation...');
-    try {
+    // Browser-only debug hook. Guarded so node-side vitest runs don't
+    // ReferenceError on `window` and spam stderr.
+    if (typeof window !== 'undefined') {
       const dbg = (window as unknown as { __spiceDebug?: () => void }).__spiceDebug;
       if (typeof dbg === 'function') dbg();
       else console.warn('[spice] __spiceDebug not attached — startSimulation never called');
-    } catch (e) {
-      console.warn('[spice] debug dump failed', e);
     }
 
     // ATmega328p @ 16MHz
diff --git a/frontend/src/utils/pinPositionCalculator.ts b/frontend/src/utils/pinPositionCalculator.ts
index 09329cbf..704db6ce 100644
--- a/frontend/src/utils/pinPositionCalculator.ts
+++ b/frontend/src/utils/pinPositionCalculator.ts
@@ -37,14 +37,23 @@ export function calculatePinPosition(
   // Get the DOM element
   const element = document.getElementById(componentId);
   if (!element) {
-    console.warn(`[pinPositionCalculator] Component ${componentId} not found in DOM`);
+    // Don't spam the vitest log: in node-side tests there's no real
+    // DOM and this function gets called per-wire on every render
+    // (each one logs "Component foo not found in DOM"). In a browser
+    // the warning is actionable — a wire references a component that
+    // failed to mount.
+    if (import.meta.env.MODE !== 'test') {
+      console.warn(`[pinPositionCalculator] Component ${componentId} not found in DOM`);
+    }
     return null;
   }
 
   // Access the pinInfo property (all wokwi-elements expose this)
   const pinInfo = (element as any).pinInfo;
   if (!pinInfo || !Array.isArray(pinInfo)) {
-    console.warn(`[pinPositionCalculator] Component ${componentId} does not have pinInfo`);
+    if (import.meta.env.MODE !== 'test') {
+      console.warn(`[pinPositionCalculator] Component ${componentId} does not have pinInfo`);
+    }
     return null;
   }
 
diff --git a/test/backend/unit/test_esp32_wifi_args.py b/test/backend/unit/test_esp32_wifi_args.py
index 128aca58..82256209 100644
--- a/test/backend/unit/test_esp32_wifi_args.py
+++ b/test/backend/unit/test_esp32_wifi_args.py
@@ -101,8 +101,18 @@ class TestEspQemuManagerWifiArgs(unittest.TestCase):
         """start_instance should accept wifi_enabled and wifi_hostfwd_port."""
         from app.services.esp_qemu_manager import EspQemuManager
         mgr = EspQemuManager()
-        # Should not raise
-        with patch('asyncio.create_task'):
+
+        # start_instance calls `asyncio.create_task(self._boot(...))`. The
+        # `_boot(...)` call creates a coroutine BEFORE create_task sees it,
+        # so simply mocking create_task with no side-effect lets the
+        # coroutine leak and trigger a "coroutine never awaited"
+        # RuntimeWarning in the test log.  Close the coroutine inside the
+        # mock to consume it cleanly.
+        def consume_coroutine(coro):
+            coro.close()
+            return MagicMock()
+
+        with patch('asyncio.create_task', side_effect=consume_coroutine):
             mgr.start_instance(
                 'test-client', 'esp32', MagicMock(),
                 firmware_b64=None,