diff --git a/app/src/main/java/com/ai/assistance/operit/api/chat/llmprovider/ClaudeProvider.kt b/app/src/main/java/com/ai/assistance/operit/api/chat/llmprovider/ClaudeProvider.kt
index a2f4f07b08..bb1eeab93e 100644
--- a/app/src/main/java/com/ai/assistance/operit/api/chat/llmprovider/ClaudeProvider.kt
+++ b/app/src/main/java/com/ai/assistance/operit/api/chat/llmprovider/ClaudeProvider.kt
@@ -596,7 +596,7 @@ open class ClaudeProvider(
         return json
     }
 
-    private data class ClaudeSerializedHistory(
+    internal data class ClaudeSerializedHistory(
         val messagesArray: JSONArray,
         val systemBlocks: JSONArray?
     )
@@ -707,9 +707,9 @@ open class ClaudeProvider(
         }
     }
 
-    private fun buildSerializedHistory(
+    internal fun buildSerializedHistory(
         chatHistory: List<PromptTurn>,
-        preserveThinkInHistory: Boolean
+        preserveThinkInHistory: Boolean = false
     ): ClaudeSerializedHistory {
         val messagesArray = JSONArray()
         val effectiveHistory =
@@ -922,11 +922,14 @@ open class ClaudeProvider(
 
                         if (resultsList.isNotEmpty() && openToolUses.isNotEmpty()) {
                             val contentArray = JSONArray()
+                            val useOrder = openToolUses.mapIndexed { i, c -> c.id to i }.toMap()
                             val matchedCalls =
                                 StructuredToolCallBridge.consumeMatchingToolCalls(
                                     openToolUses,
                                     resultsList.map { it.first }
-                                )
+                                ).sortedBy { matchedCall ->
+                                    useOrder[matchedCall.call.id] ?: Int.MAX_VALUE
+                                }
                             matchedCalls.forEach { matchedCall ->
                                 val resultContent = resultsList[matchedCall.resultIndex].second
                                 contentArray.put(
diff --git a/app/src/test/java/com/ai/assistance/operit/api/chat/llmprovider/ClaudeProviderHistoryTest.kt b/app/src/test/java/com/ai/assistance/operit/api/chat/llmprovider/ClaudeProviderHistoryTest.kt
new file mode 100644
index 0000000000..9a6920b8a2
--- /dev/null
+++ b/app/src/test/java/com/ai/assistance/operit/api/chat/llmprovider/ClaudeProviderHistoryTest.kt
@@ -0,0 +1,96 @@
+package com.ai.assistance.operit.api.chat.llmprovider
+
+import com.ai.assistance.operit.core.chat.hooks.PromptTurn
+import com.ai.assistance.operit.core.chat.hooks.PromptTurnKind
+import okhttp3.OkHttpClient
+import org.junit.Assert.assertEquals
+import org.junit.Test
+
+class ClaudeProviderHistoryTest {
+
+    private fun createProvider(enableToolCall: Boolean = true): ClaudeProvider {
+        return ClaudeProvider(
+            apiEndpoint = "https://api.anthropic.com/v1/messages",
+            apiKeyProvider = SingleApiKeyProvider("sk-ant-test"),
+            modelName = "claude-3-5-sonnet-20241022",
+            client = OkHttpClient(),
+            enableToolCall = enableToolCall
+        )
+    }
+
+    private fun toolCall(name: String, vararg params: Pair<String, String>): String {
+        val body = params.joinToString("") { (key, value) ->
+            "<" + "param name=\"$key\">" + value + "</" + "param>"
+        }
+        return "<" + "tool name=\"$name\">" + body + "</" + "tool>"
+    }
+
+    private fun toolResult(name: String, content: String): String =
+        "<" + "tool_result name=\"$name\" status=\"success\"><" + "content>" + content + "</" + "content></" + "tool_result>"
+
+    @Test
+    fun parallel_tool_results_are_ordered_by_tool_use_definition_order_to_preserve_prompt_cache() {
+        val provider = createProvider(enableToolCall = true)
+
+        // Assistant calls 3 tools in order: read_file -> list_files -> grep_code
+        val assistantTurn = PromptTurn(
+            kind = PromptTurnKind.ASSISTANT,
+            content = toolCall("read_file", "path" to "fileA.txt") +
+                toolCall("list_files", "path" to "dirB") +
+                toolCall("grep_code", "pattern" to "queryC")
+        )
+
+        // Due to async parallel execution race, the database recorded them in completion order:
+        // list_files finished first, then grep_code, then read_file
+        val toolResultTurn = PromptTurn(
+            kind = PromptTurnKind.TOOL_RESULT,
+            content = toolResult("list_files", "content_list_files") +
+                toolResult("grep_code", "content_grep_code") +
+                toolResult("read_file", "content_read_file")
+        )
+
+        val history = listOf(
+            PromptTurn(kind = PromptTurnKind.USER, content = "Inspect project"),
+            assistantTurn,
+            toolResultTurn
+        )
+
+        val serialized = provider.buildSerializedHistory(history)
+        val messages = serialized.messagesArray
+
+        assertEquals(3, messages.length()) // user, then assistant, then user (tool_result)
+        val assistantMsg = messages.getJSONObject(1)
+        assertEquals("role", "assistant", assistantMsg.getString("role"))
+        val assistantContent = assistantMsg.getJSONArray("content")
+        assertEquals(3, assistantContent.length())
+
+        val toolUse0Id = assistantContent.getJSONObject(0).getString("id")
+        val toolUse1Id = assistantContent.getJSONObject(1).getString("id")
+        val toolUse2Id = assistantContent.getJSONObject(2).getString("id")
+
+        assertEquals("read_file", assistantContent.getJSONObject(0).getString("name"))
+        assertEquals("list_files", assistantContent.getJSONObject(1).getString("name"))
+        assertEquals("grep_code", assistantContent.getJSONObject(2).getString("name"))
+
+        val userMsg = messages.getJSONObject(2)
+        assertEquals("role", "user", userMsg.getString("role"))
+        val userContent = userMsg.getJSONArray("content")
+        assertEquals(3, userContent.length())
+
+        // The tool_result blocks in the user message MUST be in the exact order of tool_use (read_file, list_files, grep_code)
+        // rather than the out-of-order XML sequence (list_files, grep_code, read_file).
+        assertEquals("tool_result", userContent.getJSONObject(0).getString("type"))
+        assertEquals(toolUse0Id, userContent.getJSONObject(0).getString("tool_use_id"))
+        assertEquals("historical content match", "content_read_file", userContent.getJSONObject(0).getString("content"))
+
+
+        assertEquals("tool_result", userContent.getJSONObject(1).getString("type"))
+        assertEquals(toolUse1Id, userContent.getJSONObject(1).getString("tool_use_id"))
+        assertEquals("historical content match", "content_list_files", userContent.getJSONObject(1).getString("content"))
+
+
+        assertEquals("tool_result", userContent.getJSONObject(2).getString("type"))
+        assertEquals(toolUse2Id, userContent.getJSONObject(2).getString("tool_use_id"))
+        assertEquals("historical content match", "content_grep_code", userContent.getJSONObject(2).getString("content"))
+    }
+}