fix: resolve AI_InvalidPromptError in OpenRouter AI SDK tool results

- Fixed tool result output format to use typed object { type: 'text', value: string }
  instead of plain string to satisfy AI SDK validation schema
- Added tool name resolution by building a map of tool call IDs to names
- Updated tests to reflect new output format

Author: daniel-lxs

src/api/providers/openrouter.ts

@@ -6,7 +6,6 @@ import {
 	type ModelRecord,
 	openRouterDefaultModelId,
 	openRouterDefaultModelInfo,
-	NATIVE_TOOL_DEFAULTS,
 	OPENROUTER_DEFAULT_PROVIDER_NAME,
 	DEEP_SEEK_DEFAULT_TEMPERATURE,
 } from "@roo-code/types"
@@ -183,7 +182,7 @@ export class OpenRouterHandler extends BaseProvider implements SingleCompletionH
 		}
 
 		// Apply tool preferences for models accessed through routers
-		info = applyRouterToolPreferences(id, { ...NATIVE_TOOL_DEFAULTS, ...info })
+		info = applyRouterToolPreferences(id, info)
 
 		const isDeepSeekR1 = id.startsWith("deepseek/deepseek-r1") || id === "perplexity/sonar-reasoning"
 

src/api/transform/__tests__/ai-sdk.spec.ts

@@ -73,8 +73,19 @@ describe("AI SDK conversion utilities", () => {
 			})
 		})
 
-		it("converts tool results into separate tool messages", () => {
+		it("converts tool results into separate tool messages with resolved tool names", () => {
 			const messages: Anthropic.Messages.MessageParam[] = [
+				{
+					role: "assistant",
+					content: [
+						{
+							type: "tool_use",
+							id: "call_123",
+							name: "read_file",
+							input: { path: "test.ts" },
+						},
+					],
+				},
 				{
 					role: "user",
 					content: [
@@ -89,15 +100,56 @@ describe("AI SDK conversion utilities", () => {
 
 			const result = convertToAiSdkMessages(messages)
 
-			expect(result).toHaveLength(1)
+			expect(result).toHaveLength(2)
 			expect(result[0]).toEqual({
+				role: "assistant",
+				content: [
+					{
+						type: "tool-call",
+						toolCallId: "call_123",
+						toolName: "read_file",
+						args: { path: "test.ts" },
+					},
+				],
+			})
+			expect(result[1]).toEqual({
 				role: "tool",
 				content: [
 					{
 						type: "tool-result",
 						toolCallId: "call_123",
-						toolName: "",
-						output: "Tool result content",
+						toolName: "read_file",
+						output: { type: "text", value: "Tool result content" },
+					},
+				],
+			})
+		})
+
+		it("uses unknown_tool for tool results without matching tool call", () => {
+			const messages: Anthropic.Messages.MessageParam[] = [
+				{
+					role: "user",
+					content: [
+						{
+							type: "tool_result",
+							tool_use_id: "call_orphan",
+							content: "Orphan result",
+						},
+					],
+				},
+			]
+
+			const result = convertToAiSdkMessages(messages)
+
+			expect(result).toHaveLength(1)
+			expect(result[0]).toEqual({
+				role: "tool",
+				content: [
+					{
+						type: "tool-result",
+						toolCallId: "call_orphan",
+						toolName: "unknown_tool",
+						output: { type: "text", value: "Orphan result" },
 					},
 				],
 			})

src/api/transform/ai-sdk.ts

@@ -18,6 +18,18 @@ import type { ApiStreamChunk } from "./stream"
 export function convertToAiSdkMessages(messages: Anthropic.Messages.MessageParam[]): CoreMessage[] {
 	const coreMessages: CoreMessage[] = []
 
+	// First pass: build a map of tool call IDs to tool names from assistant messages
+	const toolCallIdToName = new Map<string, string>()
+	for (const message of messages) {
+		if (message.role === "assistant" && typeof message.content !== "string") {
+			for (const part of message.content) {
+				if (part.type === "tool_use") {
+					toolCallIdToName.set(part.id, part.name)
+				}
+			}
+		}
+	}
+
 	for (const message of messages) {
 		if (typeof message.content === "string") {
 			coreMessages.push({
@@ -33,7 +45,7 @@ export function convertToAiSdkMessages(messages: Anthropic.Messages.MessageParam
 					type: "tool-result"
 					toolCallId: string
 					toolName: string
-					output: unknown
+					output: { type: "text"; value: string }
 				}> = []
 
 				for (const part of message.content) {
@@ -60,11 +72,13 @@ export function convertToAiSdkMessages(messages: Anthropic.Messages.MessageParam
 									})
 									.join("\n") ?? ""
 						}
+						// Look up the tool name from the tool call ID
+						const toolName = toolCallIdToName.get(part.tool_use_id) ?? "unknown_tool"
 						toolResults.push({
 							type: "tool-result",
 							toolCallId: part.tool_use_id,
-							toolName: "", // Will be filled from context
-							output: content || "(empty)",
+							toolName,
+							output: { type: "text", value: content || "(empty)" },
 						})
 					}
 				}