diff --git a/.changeset/deepseek-empty-reasoning.md b/.changeset/deepseek-empty-reasoning.md
new file mode 100644
index 0000000000..3ce8eebd8a
--- /dev/null
+++ b/.changeset/deepseek-empty-reasoning.md
@@ -0,0 +1,5 @@
+---
+"@kilocode/cli": patch
+---
+
+Fix multi-turn tool calls with DeepSeek thinking mode by preserving empty `reasoning_content` in the interleaved transform.
diff --git a/packages/opencode/src/provider/transform.ts b/packages/opencode/src/provider/transform.ts
index cd0de1505a..f3dee7e6ec 100644
--- a/packages/opencode/src/provider/transform.ts
+++ b/packages/opencode/src/provider/transform.ts
@@ -193,25 +193,23 @@ function normalizeMessages(
         // Filter out reasoning parts from content
         const filteredContent = msg.content.filter((part: any) => part.type !== "reasoning")
 
-        // Include reasoning_content | reasoning_details directly on the message for all assistant messages
-        if (reasoningText) {
-          return {
-            ...msg,
-            content: filteredContent,
-            providerOptions: {
-              ...msg.providerOptions,
-              openaiCompatible: {
-                ...msg.providerOptions?.openaiCompatible,
-                [field]: reasoningText,
-              },
-            },
-          }
-        }
-
+        // kilocode_change start - cherry-picked from anomalyco/opencode#24146;
+        // will be reverted on the next wholesale upstream merge.
+        // Include reasoning_content | reasoning_details directly on the message for all assistant messages.
+        // Always set the field even when empty — some providers (e.g. DeepSeek) may return empty
+        // reasoning_content which still needs to be sent back in subsequent requests.
         return {
           ...msg,
           content: filteredContent,
+          providerOptions: {
+            ...msg.providerOptions,
+            openaiCompatible: {
+              ...msg.providerOptions?.openaiCompatible,
+              [field]: reasoningText,
+            },
+          },
         }
+        // kilocode_change end
       }
 
       return msg