refactor: pass normalization function instead of modelId to convertToOpenAiMessages

Addresses PR feedback about separation of concerns. The convertToOpenAiMessages
function now accepts an optional normalizeToolCallId function instead of
checking for 'mistral' in the modelId. This allows callers to flexibly
declare the tool call ID format without the transform module needing to
know about provider-specific requirements.

Author: daniel-lxs

src/api/providers/openrouter.ts

@@ -16,7 +16,7 @@ import { NativeToolCallParser } from "../../core/assistant-message/NativeToolCal
 
 import type { ApiHandlerOptions, ModelRecord } from "../../shared/api"
 
-import { convertToOpenAiMessages } from "../transform/openai-format"
+import { convertToOpenAiMessages, normalizeToolCallId } from "../transform/openai-format"
 import { resolveToolProtocol } from "../../utils/resolveToolProtocol"
 import { TOOL_PROTOCOL } from "@roo-code/types"
 import { ApiStreamChunk } from "../transform/stream"
@@ -226,10 +226,11 @@ export class OpenRouterHandler extends BaseProvider implements SingleCompletionH
 		}
 
 		// Convert Anthropic messages to OpenAI format.
-		// Pass modelId to normalize tool call IDs for Mistral compatibility
+		// Pass normalization function for Mistral compatibility (requires 9-char alphanumeric IDs)
+		const isMistral = modelId.toLowerCase().includes("mistral")
 		let openAiMessages: OpenAI.Chat.ChatCompletionMessageParam[] = [
 			{ role: "system", content: systemPrompt },
-			...convertToOpenAiMessages(messages, { modelId }),
+			...convertToOpenAiMessages(messages, isMistral ? { normalizeToolCallId } : undefined),
 		]
 
 		// DeepSeek highly recommends using user instead of system role.

src/api/transform/__tests__/openai-format.spec.ts

@@ -107,7 +107,7 @@ describe("convertToOpenAiMessages", () => {
 		})
 	})
 
-	it("should handle assistant messages with tool use (no normalization without modelId)", () => {
+	it("should handle assistant messages with tool use (no normalization without normalizeToolCallId)", () => {
 		const anthropicMessages: Anthropic.Messages.MessageParam[] = [
 			{
 				role: "assistant",
@@ -134,7 +134,7 @@ describe("convertToOpenAiMessages", () => {
 		expect(assistantMessage.content).toBe("Let me check the weather.")
 		expect(assistantMessage.tool_calls).toHaveLength(1)
 		expect(assistantMessage.tool_calls![0]).toEqual({
-			id: "weather-123", // Not normalized without modelId
+			id: "weather-123", // Not normalized without normalizeToolCallId function
 			type: "function",
 			function: {
 				name: "get_weather",
@@ -143,7 +143,7 @@ describe("convertToOpenAiMessages", () => {
 		})
 	})
 
-	it("should handle user messages with tool results (no normalization without modelId)", () => {
+	it("should handle user messages with tool results (no normalization without normalizeToolCallId)", () => {
 		const anthropicMessages: Anthropic.Messages.MessageParam[] = [
 			{
 				role: "user",
@@ -162,11 +162,11 @@ describe("convertToOpenAiMessages", () => {
 
 		const toolMessage = openAiMessages[0] as OpenAI.Chat.ChatCompletionToolMessageParam
 		expect(toolMessage.role).toBe("tool")
-		expect(toolMessage.tool_call_id).toBe("weather-123") // Not normalized without modelId
+		expect(toolMessage.tool_call_id).toBe("weather-123") // Not normalized without normalizeToolCallId function
 		expect(toolMessage.content).toBe("Current temperature in London: 20°C")
 	})
 
-	it("should normalize tool call IDs when modelId contains 'mistral'", () => {
+	it("should normalize tool call IDs when normalizeToolCallId function is provided", () => {
 		const anthropicMessages: Anthropic.Messages.MessageParam[] = [
 			{
 				role: "assistant",
@@ -191,9 +191,9 @@ describe("convertToOpenAiMessages", () => {
 			},
 		]
 
-		// With Mistral model ID - should normalize
+		// With normalizeToolCallId function - should normalize
 		const openAiMessages = convertToOpenAiMessages(anthropicMessages, {
-			modelId: "mistralai/mistral-large-latest",
+			normalizeToolCallId,
 		})
 
 		const assistantMessage = openAiMessages[0] as OpenAI.Chat.ChatCompletionAssistantMessageParam
@@ -203,7 +203,7 @@ describe("convertToOpenAiMessages", () => {
 		expect(toolMessage.tool_call_id).toBe(normalizeToolCallId("call_5019f900a247472bacde0b82"))
 	})
 
-	it("should not normalize tool call IDs when modelId does not contain 'mistral'", () => {
+	it("should not normalize tool call IDs when normalizeToolCallId function is not provided", () => {
 		const anthropicMessages: Anthropic.Messages.MessageParam[] = [
 			{
 				role: "assistant",
@@ -228,8 +228,8 @@ describe("convertToOpenAiMessages", () => {
 			},
 		]
 
-		// With non-Mistral model ID - should NOT normalize
-		const openAiMessages = convertToOpenAiMessages(anthropicMessages, { modelId: "openai/gpt-4" })
+		// Without normalizeToolCallId function - should NOT normalize
+		const openAiMessages = convertToOpenAiMessages(anthropicMessages, {})
 
 		const assistantMessage = openAiMessages[0] as OpenAI.Chat.ChatCompletionAssistantMessageParam
 		expect(assistantMessage.tool_calls![0].id).toBe("call_5019f900a247472bacde0b82")
@@ -238,7 +238,7 @@ describe("convertToOpenAiMessages", () => {
 		expect(toolMessage.tool_call_id).toBe("call_5019f900a247472bacde0b82")
 	})
 
-	it("should be case-insensitive when checking for mistral in modelId", () => {
+	it("should use custom normalization function when provided", () => {
 		const anthropicMessages: Anthropic.Messages.MessageParam[] = [
 			{
 				role: "assistant",
@@ -253,10 +253,11 @@ describe("convertToOpenAiMessages", () => {
 			},
 		]
 
-		// Uppercase MISTRAL should still trigger normalization
-		const openAiMessages = convertToOpenAiMessages(anthropicMessages, { modelId: "MISTRAL-7B" })
+		// Custom normalization function that prefixes with "custom_"
+		const customNormalizer = (id: string) => `custom_${id}`
+		const openAiMessages = convertToOpenAiMessages(anthropicMessages, { normalizeToolCallId: customNormalizer })
 
 		const assistantMessage = openAiMessages[0] as OpenAI.Chat.ChatCompletionAssistantMessageParam
-		expect(assistantMessage.tool_calls![0].id).toBe(normalizeToolCallId("toolu_123"))
+		expect(assistantMessage.tool_calls![0].id).toBe("custom_toolu_123")
 	})
 })

src/api/transform/openai-format.ts

@@ -31,10 +31,11 @@ export function normalizeToolCallId(id: string): string {
  */
 export interface ConvertToOpenAiMessagesOptions {
 	/**
-	 * The model ID being used. If it contains "mistral", tool call IDs will be
-	 * normalized to be compatible with Mistral's strict ID requirements.
+	 * Optional function to normalize tool call IDs for providers with strict ID requirements.
+	 * When provided, this function will be applied to all tool_use IDs and tool_result tool_use_ids.
+	 * This allows callers to declare provider-specific ID format requirements.
 	 */
-	modelId?: string
+	normalizeToolCallId?: (id: string) => string
 }
 
 export function convertToOpenAiMessages(
@@ -43,8 +44,8 @@ export function convertToOpenAiMessages(
 ): OpenAI.Chat.ChatCompletionMessageParam[] {
 	const openAiMessages: OpenAI.Chat.ChatCompletionMessageParam[] = []
 
-	// Check if we need to normalize tool call IDs for Mistral compatibility
-	const shouldNormalizeToolCallIds = options?.modelId?.toLowerCase().includes("mistral") ?? false
+	// Use provided normalization function or identity function
+	const normalizeId = options?.normalizeToolCallId ?? ((id: string) => id)
 
 	for (const anthropicMessage of anthropicMessages) {
 		if (typeof anthropicMessage.content === "string") {
@@ -96,9 +97,7 @@ export function convertToOpenAiMessages(
 					}
 					openAiMessages.push({
 						role: "tool",
-						tool_call_id: shouldNormalizeToolCallIds
-							? normalizeToolCallId(toolMessage.tool_use_id)
-							: toolMessage.tool_use_id,
+						tool_call_id: normalizeId(toolMessage.tool_use_id),
 						content: content,
 					})
 				})
@@ -165,7 +164,7 @@ export function convertToOpenAiMessages(
 
 				// Process tool use messages
 				let tool_calls: OpenAI.Chat.ChatCompletionMessageToolCall[] = toolMessages.map((toolMessage) => ({
-					id: shouldNormalizeToolCallIds ? normalizeToolCallId(toolMessage.id) : toolMessage.id,
+					id: normalizeId(toolMessage.id),
 					type: "function",
 					function: {
 						name: toolMessage.name,