fix(android): preserve emoji in presence reason logs (#108103)

apps/android/app/src/main/java/ai/openclaw/app/node/NodePresenceAliveBeacon.kt

@@ -1,5 +1,6 @@
 package ai.openclaw.app.node
 
+import ai.openclaw.app.takeUtf16Safe
 import android.os.Build
 import kotlinx.serialization.json.Json
 import kotlinx.serialization.json.JsonPrimitive
@@ -109,6 +110,6 @@ internal object NodePresenceAliveBeacon {
     return value
       .map { ch -> if (ch.isISOControl()) ' ' else ch }
       .joinToString("")
-      .take(200)
+      .takeUtf16Safe(200)
   }
 }

apps/android/app/src/test/java/ai/openclaw/app/node/NodePresenceAliveBeaconTest.kt

@@ -98,4 +98,19 @@ class NodePresenceAliveBeaconTest {
     assertFalse(sanitized.contains("\t"))
     assertEquals(200, sanitized.length)
   }
+
+  @Test
+  fun sanitizeReasonForLog_preservesUtf16BoundariesAtLimit() {
+    val splitPairPrefix = "bad\n${"x".repeat(195)}"
+    assertEquals(
+      "bad ${"x".repeat(195)}",
+      NodePresenceAliveBeacon.sanitizeReasonForLog("$splitPairPrefix😀tail"),
+    )
+
+    val completePairPrefix = "bad\n${"x".repeat(194)}"
+    assertEquals(
+      "bad ${"x".repeat(194)}😀",
+      NodePresenceAliveBeacon.sanitizeReasonForLog("$completePairPrefix😀tail"),
+    )
+  }
 }