Suppress node examiner cancellation noise

- Treat coroutine cancellation as expected node examiner control flow
- Keep cancellation out of node_examiner_failed telemetry and circuit-breaker accounting
- Add focused coverage for cancellation classification

🤖 Auto-generated

Author: OwenMcGirr

app/src/main/java/com/enaboapps/switchify/service/techniques/nodes/NodeExaminer.kt

@@ -10,6 +10,7 @@ import com.enaboapps.switchify.service.keyboard.KeyboardNodeExtractor
 import com.enaboapps.switchify.service.utils.ScreenUtils
 import com.enaboapps.switchify.utils.LogEvent
 import com.enaboapps.switchify.utils.Logger
+import kotlinx.coroutines.CancellationException
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.MutableSharedFlow
 import kotlinx.coroutines.flow.MutableStateFlow
@@ -131,6 +132,7 @@ object NodeExaminer {
                 }
             }
         } catch (e: Exception) {
+            if (isExpectedNodeExaminerCancellation(e)) throw e
             val packageName = rootNode?.packageName?.toString()
             Log.e(TAG, "Error examining accessibility tree (app=$packageName)", e)
             Logger.log(
@@ -147,6 +149,10 @@ object NodeExaminer {
         }
     }
 
+    internal fun isExpectedNodeExaminerCancellation(error: Throwable): Boolean {
+        return error is CancellationException
+    }
+
     private fun recordFailure(packageName: String?) {
         consecutiveFailures++
         if (consecutiveFailures >= CIRCUIT_BREAKER_THRESHOLD) {

app/src/test/java/com/enaboapps/switchify/service/techniques/nodes/NodeExaminerTest.kt

@@ -0,0 +1,29 @@
+package com.enaboapps.switchify.service.techniques.nodes
+
+import kotlinx.coroutines.CancellationException
+import org.junit.Assert.assertFalse
+import org.junit.Assert.assertTrue
+import org.junit.Test
+
+class NodeExaminerTest {
+    @Test
+    fun cancellationExceptionIsExpectedNodeExaminerCancellation() {
+        val error = CancellationException("cancelled")
+
+        assertTrue(NodeExaminer.isExpectedNodeExaminerCancellation(error))
+    }
+
+    @Test
+    fun jobCancellationExceptionIsExpectedNodeExaminerCancellation() {
+        val error = CancellationException("StandaloneCoroutine was cancelled")
+
+        assertTrue(NodeExaminer.isExpectedNodeExaminerCancellation(error))
+    }
+
+    @Test
+    fun ordinaryExceptionIsNotExpectedNodeExaminerCancellation() {
+        val error = IllegalStateException("failed")
+
+        assertFalse(NodeExaminer.isExpectedNodeExaminerCancellation(error))
+    }
+}