fix(ai): use OpenRouter reasoning payload (#2298)

* fix(ai): use OpenRouter reasoning payload

* fix(coding-agent): stop updating packages on startup closes #1963

* fix(ai): add openrouter thinkingFormat compat

---------

Co-authored-by: Mario Zechner <badlogicgames@gmail.com>

packages/ai/src/providers/openai-completions.ts

@@ -408,6 +408,12 @@ function buildParams(model: Model<"openai-completions">, context: Context, optio
 		(params as any).enable_thinking = !!options?.reasoningEffort;
 	} else if (compat.thinkingFormat === "qwen-chat-template" && model.reasoning) {
 		(params as any).chat_template_kwargs = { enable_thinking: !!options?.reasoningEffort };
+	} else if (compat.thinkingFormat === "openrouter" && options?.reasoningEffort && model.reasoning) {
+		// OpenRouter normalizes reasoning across providers via a nested reasoning object.
+		const openRouterParams = params as typeof params & { reasoning?: { effort?: string } };
+		openRouterParams.reasoning = {
+			effort: mapReasoningEffort(options.reasoningEffort, compat.reasoningEffortMap),
+		};
 	} else if (options?.reasoningEffort && model.reasoning && compat.supportsReasoningEffort) {
 		// OpenAI-style reasoning_effort
 		(params as any).reasoning_effort = mapReasoningEffort(options.reasoningEffort, compat.reasoningEffortMap);
@@ -816,7 +822,11 @@ function detectCompat(model: Model<"openai-completions">): Required<OpenAIComple
 		requiresToolResultName: false,
 		requiresAssistantAfterToolResult: false,
 		requiresThinkingAsText: false,
-		thinkingFormat: isZai ? "zai" : "openai",
+		thinkingFormat: isZai
+			? "zai"
+			: provider === "openrouter" || baseUrl.includes("openrouter.ai")
+				? "openrouter"
+				: "openai",
 		openRouterRouting: {},
 		vercelGatewayRouting: {},
 		supportsStrictMode: true,

packages/ai/src/types.ts

@@ -271,8 +271,8 @@ export interface OpenAICompletionsCompat {
 	requiresAssistantAfterToolResult?: boolean;
 	/** Whether thinking blocks must be converted to text blocks with <thinking> delimiters. Default: auto-detected from URL. */
 	requiresThinkingAsText?: boolean;
-	/** Format for reasoning/thinking parameter. "openai" uses reasoning_effort, "zai" uses top-level enable_thinking: boolean, "qwen" uses top-level enable_thinking: boolean, and "qwen-chat-template" uses chat_template_kwargs.enable_thinking. Default: "openai". */
-	thinkingFormat?: "openai" | "zai" | "qwen" | "qwen-chat-template";
+	/** Format for reasoning/thinking parameter. "openai" uses reasoning_effort, "openrouter" uses reasoning: { effort }, "zai" uses top-level enable_thinking: boolean, "qwen" uses top-level enable_thinking: boolean, and "qwen-chat-template" uses chat_template_kwargs.enable_thinking. Default: "openai". */
+	thinkingFormat?: "openai" | "openrouter" | "zai" | "qwen" | "qwen-chat-template";
 	/** OpenRouter-specific routing preferences. Only used when baseUrl points to OpenRouter. */
 	openRouterRouting?: OpenRouterRouting;
 	/** Vercel AI Gateway routing preferences. Only used when baseUrl points to Vercel AI Gateway. */

packages/ai/test/openai-completions-tool-choice.test.ts

@@ -233,4 +233,36 @@ describe("openai-completions tool_choice", () => {
 		expect(response.stopReason).toBe("error");
 		expect(response.errorMessage).toBe("Provider finish_reason: network_error");
 	});
+
+	it("uses OpenRouter reasoning object instead of reasoning_effort", async () => {
+		const model = getModel("openrouter", "deepseek/deepseek-r1")!;
+		let payload: unknown;
+
+		await streamSimple(
+			model,
+			{
+				messages: [
+					{
+						role: "user",
+						content: "Hi",
+						timestamp: Date.now(),
+					},
+				],
+			},
+			{
+				apiKey: "test",
+				reasoning: "high",
+				onPayload: (params: unknown) => {
+					payload = params;
+				},
+			},
+		).result();
+
+		const params = (payload ?? mockState.lastParams) as {
+			reasoning?: { effort?: string };
+			reasoning_effort?: string;
+		};
+		expect(params.reasoning).toEqual({ effort: "high" });
+		expect(params.reasoning_effort).toBeUndefined();
+	});
 });

packages/coding-agent/src/core/model-registry.ts

@@ -63,6 +63,7 @@ const OpenAICompletionsCompatSchema = Type.Object({
 	thinkingFormat: Type.Optional(
 		Type.Union([
 			Type.Literal("openai"),
+			Type.Literal("openrouter"),
 			Type.Literal("zai"),
 			Type.Literal("qwen"),
 			Type.Literal("qwen-chat-template"),