diff --git a/app/src/main/java/helium314/keyboard/latin/inputlogic/InputLogic.kt b/app/src/main/java/helium314/keyboard/latin/inputlogic/InputLogic.kt
index 921d142f6..a4efb2d35 100644
--- a/app/src/main/java/helium314/keyboard/latin/inputlogic/InputLogic.kt
+++ b/app/src/main/java/helium314/keyboard/latin/inputlogic/InputLogic.kt
@@ -62,6 +62,7 @@ import helium314.keyboard.latin.utils.RecapitalizeMode
 import helium314.keyboard.latin.utils.RecapitalizeStatus
 import helium314.keyboard.latin.utils.ScriptUtils
 import helium314.keyboard.latin.utils.StatsUtils
+import helium314.keyboard.latin.utils.CustomAIKeyText
 import helium314.keyboard.latin.utils.TextExpanderUtils
 import helium314.keyboard.latin.utils.TextPlacement
 import helium314.keyboard.latin.utils.TextRange
@@ -2935,7 +2936,7 @@ class InputLogic(
             return
         }
 
-        prompt += systemInstruction
+        prompt = CustomAIKeyText.withInstructions(prompt, systemInstruction)
 
         var textToProcess: String
         val hasSelection = mConnection.hasSelection()
@@ -3000,7 +3001,10 @@ class InputLogic(
                     Log.w(TAG, "Target editor changed during custom AI operation, ignoring result")
                     return@customAsync
                 }
-                if (!hasSelection && !shouldAppend) {
+                if (shouldAppend) {
+                    val textBefore = mConnection.getTextBeforeCursor(2, 0) ?: ""
+                    mLatinIME.onTextInput(CustomAIKeyText.separatorBefore(textBefore) + resultText.trim())
+                } else if (!hasSelection) {
                     mConnection.replaceEntireText(resultText)
                 } else {
                     mLatinIME.onTextInput(resultText)
diff --git a/app/src/main/java/helium314/keyboard/latin/utils/CustomAIKeyText.kt b/app/src/main/java/helium314/keyboard/latin/utils/CustomAIKeyText.kt
new file mode 100644
index 000000000..8e4ff8889
--- /dev/null
+++ b/app/src/main/java/helium314/keyboard/latin/utils/CustomAIKeyText.kt
@@ -0,0 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+package helium314.keyboard.latin.utils
+
+/** Text handling of the custom AI keys that does not need an input connection */
+object CustomAIKeyText {
+    /**
+     * Instructions of the selected keywords go before the user's prompt, so a prompt that ends
+     * with an answer start (e.g. "Answer:") or embeds the text with `{text}` keeps its ending.
+     */
+    fun withInstructions(prompt: String, instructions: String): String {
+        val trimmed = instructions.trim()
+        return if (trimmed.isEmpty()) prompt else "$trimmed\n\n$prompt"
+    }
+
+    /** Line breaks to put before a result appended after [textBefore], so it starts in a new paragraph */
+    fun separatorBefore(textBefore: CharSequence): String = when {
+        textBefore.isBlank() -> ""
+        textBefore.endsWith("\n\n") -> ""
+        textBefore.endsWith("\n") -> "\n"
+        else -> "\n\n"
+    }
+}
diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index a94615445..a3b33ad96 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -2173,7 +2173,7 @@ New dictionary:
     <string name="custom_ai_keyword_toneshift_desc">Changes the tone (e.g., professional, casual).</string>
     <string name="custom_ai_keyword_generate_desc">Generates new text completely ignoring selected text.</string>
     <string name="custom_ai_keyword_outputonly_desc">Returns only the modified text, without conversational fillers.</string>
-    <string name="custom_ai_keyword_append_desc">Appends the result to the end of the original text.</string>
+    <string name="custom_ai_keyword_append_desc">Appends the result to the end of the original text, separated by an empty line.</string>
     <string name="custom_ai_keyword_showthought_desc">Includes AI\'s reasoning process along with result.</string>
 
     <!-- Text Editing Layout Keys -->
diff --git a/app/src/test/java/helium314/keyboard/latin/utils/CustomAIKeyTextTest.kt b/app/src/test/java/helium314/keyboard/latin/utils/CustomAIKeyTextTest.kt
new file mode 100644
index 000000000..3a462b61f
--- /dev/null
+++ b/app/src/test/java/helium314/keyboard/latin/utils/CustomAIKeyTextTest.kt
@@ -0,0 +1,27 @@
+// SPDX-License-Identifier: GPL-3.0-only
+package helium314.keyboard.latin.utils
+
+import org.junit.Assert.assertEquals
+import org.junit.Test
+
+class CustomAIKeyTextTest {
+
+    @Test
+    fun instructionsGoBeforeThePrompt() {
+        val prompt = "Message: {text}\nAnswer:"
+        assertEquals("Output ONLY the result.\n\n$prompt", CustomAIKeyText.withInstructions(prompt, " Output ONLY the result."))
+    }
+
+    @Test
+    fun noInstructionsKeepThePrompt() {
+        assertEquals("Summarize.", CustomAIKeyText.withInstructions("Summarize.", ""))
+    }
+
+    @Test
+    fun appendedResultStartsANewParagraph() {
+        assertEquals("\n\n", CustomAIKeyText.separatorBefore("Best regards, Sam"))
+        assertEquals("\n", CustomAIKeyText.separatorBefore("Best regards, Sam\n"))
+        assertEquals("", CustomAIKeyText.separatorBefore("Best regards, Sam\n\n"))
+        assertEquals("", CustomAIKeyText.separatorBefore(""))
+    }
+}