[codex] fix(prompt): unify serial tool-calling instructions

core/llm/defaultSystemMessages.ts

@@ -63,7 +63,7 @@ export const DEFAULT_AGENT_SYSTEM_MESSAGE = `\
 <important_rules>
   You are in agent mode.
 
-  If you need to use multiple tools, you can call multiple read-only tools simultaneously.
+  Call tools one at a time. Wait for each tool result before deciding whether to call another tool.
 
 ${CODEBLOCK_FORMATTING_INSTRUCTIONS}
 

core/llm/llms/OpenRouter.ts

@@ -1,5 +1,7 @@
 import { ChatCompletionCreateParams } from "openai/resources/index";
 
+import { OPENROUTER_HEADERS } from "@continuedev/openai-adapters";
+
 import { LLMOptions } from "../../index.js";
 import { osModelsEditPrompt } from "../templates/edit.js";
 
@@ -18,6 +20,19 @@ class OpenRouter extends OpenAI {
     useLegacyCompletionsEndpoint: false,
   };
 
+  constructor(options: LLMOptions) {
+    super({
+      ...options,
+      requestOptions: {
+        ...options.requestOptions,
+        headers: {
+          ...OPENROUTER_HEADERS,
+          ...options.requestOptions?.headers,
+        },
+      },
+    });
+  }
+
   private isAnthropicModel(model?: string): boolean {
     if (!model) return false;
     const modelLower = model.toLowerCase();

core/tools/systemMessageTools/toolCodeblocks/buildSystemMessage.vitest.ts

@@ -228,6 +228,30 @@ describe("generateToolsSystemMessage", () => {
     expect(hasExampleDefinition).toBe(true);
     expect(hasExampleCall).toBe(true);
   });
+
+  it("instructs models to call tools serially", () => {
+    const tools: Tool[] = [
+      {
+        function: {
+          name: "test_tool",
+          description: "Test description",
+          parameters: {
+            type: "object",
+            properties: {},
+            required: [],
+          },
+        },
+        ...SHARED_TOOL_FIELDS,
+      },
+    ];
+
+    const result = generateToolsSystemMessage(tools, framework);
+
+    expect(result).includes(
+      "Call ONE tool at a time and wait for its result before calling another tool.",
+    );
+    expect(result).not.includes("simultaneously");
+  });
 });
 
 describe("addSystemMessageToolsToSystemMessage", () => {

core/tools/systemMessageTools/toolCodeblocks/index.ts

@@ -72,7 +72,7 @@ CRITICAL: Follow the exact syntax. Do not use XML tags, JSON objects, or any oth
   systemMessageSuffix = `RULES FOR TOOL USE:
 1. To call a tool, output a tool code block using EXACTLY the format shown above.
 2. Always start the code block on a new line.
-3. You can only call ONE tool at a time.
+3. Call ONE tool at a time and wait for its result before calling another tool.
 4. The tool code block MUST be the last thing in your response. Stop immediately after the closing fence.
 5. Do NOT wrap tool calls in XML tags like <tool_call> or <function=...>.
 6. Do NOT use JSON format for tool calls.

gui/src/redux/util/getBaseSystemMessage.test.ts

@@ -84,3 +84,10 @@ test("getBaseSystemMessage should append no-tools warning for agent/plan modes w
     "Custom Plan System Message" + NO_TOOL_WARNING,
   );
 });
+
+test("default agent system message should instruct serial tool calling", () => {
+  expect(DEFAULT_AGENT_SYSTEM_MESSAGE).toContain(
+    "Call tools one at a time. Wait for each tool result before deciding whether to call another tool.",
+  );
+  expect(DEFAULT_AGENT_SYSTEM_MESSAGE).not.toContain("simultaneously");
+});

packages/openai-adapters/src/apis/OpenRouter.ts

@@ -10,9 +10,10 @@ export interface OpenRouterConfig extends OpenAIConfig {
 
 // TODO: Extract detailed error info from OpenRouter's error.metadata.raw to surface better messages
 
-const OPENROUTER_HEADERS: Record<string, string> = {
+export const OPENROUTER_HEADERS: Record<string, string> = {
   "HTTP-Referer": "https://www.continue.dev/",
-  "X-Title": "Continue",
+  "X-OpenRouter-Title": "Continue",
+  "X-OpenRouter-Categories": "ide-extension",
 };
 
 export class OpenRouterApi extends OpenAIApi {

packages/openai-adapters/src/index.ts

@@ -243,4 +243,5 @@ export {
 } from "./apis/AnthropicUtils.js";
 
 export { isResponsesModel } from "./apis/openaiResponses.js";
+export { OPENROUTER_HEADERS } from "./apis/OpenRouter.js";
 export { extractBase64FromDataUrl, parseDataUrl } from "./util/url.js";