fix(compat): preserve GPT and Claude Code tool-call history (#12909)

* fix(compat): preserve GPT and Claude Code tool-call history

* docs(changelog): add fragment for tool-call history preservation fix

Co-authored-by: diegosouzapw <8016841+diegosouzapw@users.noreply.github.com>

---------

Co-authored-by: diegosouzapw <8016841+diegosouzapw@users.noreply.github.com>

changelog.d/fixes/12909-tool-call-history-preserve.md

@@ -0,0 +1 @@
+- **fix(compat):** preserve GPT and Claude Code tool-call history when translating OpenAI Responses API requests to Chat Completions — `role:"tool"` items and role-based assistant `tool_calls` are no longer dropped, fixing incomplete multi-turn history ([#12909](https://github.com/diegosouzapw/OmniRoute/pull/12909))

open-sse/translator/request/openai-responses.ts

@@ -79,6 +79,29 @@ function appendReasoningContent(current: unknown, next: string): string {
   return existing ? `${existing}\n\n${next}` : next;
 }
 
+function normalizeRoleBasedToolCalls(toolCalls: unknown): JsonRecord[] {
+  if (!Array.isArray(toolCalls)) return [];
+
+  return toolCalls
+    .map((toolCallValue) => {
+      const toolCall = toRecord(toolCallValue);
+      const fn = toRecord(toolCall.function);
+      const name = toString(fn.name).trim();
+      const id = toString(toolCall.id).trim();
+      if (!name || !id) return null;
+      return {
+        id,
+        type: "function",
+        function: {
+          name,
+          arguments:
+            typeof fn.arguments === "string" ? fn.arguments : JSON.stringify(fn.arguments ?? {}),
+        },
+      };
+    })
+    .filter((toolCall): toolCall is JsonRecord => toolCall !== null);
+}
+
 /**
  * Convert OpenAI Responses API request to OpenAI Chat Completions format
  */
@@ -252,6 +275,15 @@ export function openaiResponsesToOpenAIRequest(
         pendingToolResults = [];
       }
 
+      if (toString(item.role) === "tool") {
+        messages.push({
+          role: "tool",
+          tool_call_id: toString(item.tool_call_id),
+          content: toolOutputContentToString(item.content),
+        });
+        continue;
+      }
+
       // Convert content: input_text -> text, output_text -> text
       const content = Array.isArray(item.content)
         ? item.content.map((contentValue) => {
@@ -288,7 +320,17 @@ export function openaiResponsesToOpenAIRequest(
         : item.content;
 
       if (role === "assistant") {
-        if (!currentAssistantMsg) {
+        const roleBasedToolCalls = normalizeRoleBasedToolCalls(item.tool_calls);
+        if (roleBasedToolCalls.length > 0) {
+          if (currentAssistantMsg) {
+            messages.push(currentAssistantMsg);
+          }
+          currentAssistantMsg = {
+            role,
+            content,
+            tool_calls: roleBasedToolCalls,
+          };
+        } else if (!currentAssistantMsg) {
           currentAssistantMsg = { role, content };
         } else if (currentAssistantMsg.content == null && content != null) {
           currentAssistantMsg.content = content;

tests/unit/translator-openai-responses-tool-calls.test.ts

@@ -0,0 +1,68 @@
+import test from "node:test";
+import assert from "node:assert/strict";
+
+const { openaiResponsesToOpenAIRequest } =
+  await import("../../open-sse/translator/request/openai-responses.ts");
+
+test("Responses -> Chat preserves role-based assistant tool_calls and tool results", () => {
+  const result = openaiResponsesToOpenAIRequest(
+    "deepseek-v4-flash",
+    {
+      model: "deepseek-v4-flash",
+      input: [
+        { role: "user", content: "Run pwd" },
+        {
+          role: "assistant",
+          content: null,
+          tool_calls: [
+            {
+              id: "call_1",
+              type: "function",
+              function: { name: "exec_command", arguments: '{"cmd":"pwd"}' },
+            },
+          ],
+        },
+        { role: "tool", tool_call_id: "call_1", content: "/tmp" },
+      ],
+    },
+    false,
+    { provider: "deepseek" }
+  ) as { messages: Array<Record<string, unknown>> };
+
+  assert.deepEqual(result.messages[1].tool_calls, [
+    {
+      id: "call_1",
+      type: "function",
+      function: { name: "exec_command", arguments: '{"cmd":"pwd"}' },
+    },
+  ]);
+  assert.deepEqual(result.messages[2], {
+    role: "tool",
+    tool_call_id: "call_1",
+    content: "/tmp",
+  });
+});
+
+test("Responses -> Chat drops role-based tool_calls with empty name or id", () => {
+  const result = openaiResponsesToOpenAIRequest(
+    "deepseek-v4-flash",
+    {
+      model: "deepseek-v4-flash",
+      input: [
+        { role: "user", content: "Run" },
+        {
+          role: "assistant",
+          content: null,
+          tool_calls: [
+            { id: "call_nameless", type: "function", function: { name: "", arguments: "{}" } },
+            { id: "", type: "function", function: { name: "exec_command", arguments: "{}" } },
+          ],
+        },
+      ],
+    },
+    false,
+    { provider: "deepseek" }
+  ) as { messages: Array<Record<string, unknown>> };
+
+  assert.equal(result.messages[1].tool_calls, undefined);
+});