[Fix] LiteLLM + Gemini: tool call id truncation corrupts thought_signature

src/api/providers/__tests__/lite-llm.spec.ts

@@ -1,6 +1,8 @@
 import { Anthropic } from "@anthropic-ai/sdk"
+import type OpenAI from "openai"
 
 import { LiteLLMHandler } from "../lite-llm"
+import type { ApiHandlerCreateMessageMetadata } from "../../index"
 import { ApiHandlerOptions } from "../../../shared/api"
 import { litellmDefaultModelId, litellmDefaultModelInfo } from "@roo-code/types"
 import { asyncStreamFrom, collectStream } from "../../../test-utils/stream"
@@ -754,6 +756,47 @@ describe("LiteLLMHandler", () => {
 				expect(assistantMessage.tool_calls[0].provider_specific_fields.thought_signature).toBe(dummySignature)
 			})
 
+			it("should send tool call ids that carry a thought signature unchanged", async () => {
+				// LiteLLM encodes the Gemini signature into the id; truncating it breaks the signature.
+				const signature = "AY89a18ErUKBAfkTYnDbzq6mGnRG5QS8VFogncpDzYVXzC0i_aDwY5o-0123456789abcdef"
+				const toolCallId = `call_864944__thought__${signature}`
+				expect(toolCallId.length).toBeGreaterThan(64)
+
+				const messages: Anthropic.Messages.MessageParam[] = [
+					{ role: "user", content: "Hello" },
+					{
+						role: "assistant",
+						content: [{ type: "tool_use", id: toolCallId, name: "read_file", input: { path: "test.txt" } }],
+					},
+					{
+						role: "user",
+						content: [{ type: "tool_result", tool_use_id: toolCallId, content: "file contents" }],
+					},
+				]
+				mockCreate.mockReturnValue({
+					withResponse: vi.fn().mockResolvedValue({
+						data: asyncStreamFrom([{ choices: [{ delta: { content: "ok" } }] }]),
+					}),
+				})
+				const metadata: ApiHandlerCreateMessageMetadata = {
+					taskId: "task-1",
+					tools: [
+						{
+							type: "function",
+							function: { name: "read_file", description: "Read a file", parameters: {} },
+						},
+					],
+				}
+
+				await collectStream(handler.createMessage("You are a helpful assistant", messages, metadata))
+
+				const sent: OpenAI.Chat.ChatCompletionMessageParam[] = mockCreate.mock.calls[0][0].messages
+				const assistantMessage = sent.find((msg) => msg.role === "assistant" && msg.tool_calls?.length)
+				const toolMessage = sent.find((msg) => msg.role === "tool")
+				expect(assistantMessage?.role === "assistant" && assistantMessage.tool_calls?.[0].id).toBe(toolCallId)
+				expect(toolMessage?.role === "tool" && toolMessage.tool_call_id).toBe(toolCallId)
+			})
+
 			it("should not inject thought signatures for non-Gemini models", async () => {
 				const optionsWithGPT4: ApiHandlerOptions = {
 					...mockOptions,

src/api/providers/lite-llm.ts

@@ -18,7 +18,7 @@ import { ApiStream, ApiStreamUsageChunk } from "../transform/stream"
 import { convertToOpenAiMessages } from "../transform/openai-format"
 import { convertToR1Format } from "../transform/r1-format"
 import { GEMINI_THOUGHT_SIGNATURE_BYPASS } from "../transform/gemini-format"
-import { sanitizeOpenAiCallId } from "../../utils/tool-id"
+import { sanitizeLiteLlmCallId } from "../../utils/tool-id"
 
 import type {
 	SingleCompletionHandler,
@@ -158,11 +158,11 @@ export class LiteLLMHandler extends RouterProvider implements SingleCompletionHa
 		// never gets inserted mid-turn and causes the model to drop prior reasoning_content.
 		const openAiMessages = info.preserveReasoning
 			? convertToR1Format(messages, {
-					normalizeToolCallId: sanitizeOpenAiCallId,
+					normalizeToolCallId: sanitizeLiteLlmCallId,
 					mergeToolResultText: true,
 				})
 			: convertToOpenAiMessages(messages, {
-					normalizeToolCallId: sanitizeOpenAiCallId,
+					normalizeToolCallId: sanitizeLiteLlmCallId,
 				})
 
 		// Prepare messages with cache control if enabled and supported

src/utils/__tests__/tool-id.spec.ts

@@ -1,4 +1,10 @@
-import { sanitizeToolUseId, truncateOpenAiCallId, sanitizeOpenAiCallId, OPENAI_CALL_ID_MAX_LENGTH } from "../tool-id"
+import {
+	sanitizeToolUseId,
+	truncateOpenAiCallId,
+	sanitizeOpenAiCallId,
+	sanitizeLiteLlmCallId,
+	OPENAI_CALL_ID_MAX_LENGTH,
+} from "../tool-id"
 
 describe("sanitizeToolUseId", () => {
 	describe("valid IDs pass through unchanged", () => {
@@ -184,3 +190,29 @@ describe("OPENAI_CALL_ID_MAX_LENGTH constant", () => {
 		expect(OPENAI_CALL_ID_MAX_LENGTH).toBe(64)
 	})
 })
+
+describe("sanitizeLiteLlmCallId", () => {
+	const signature = "AY89a18ErUKBAfkTYnDbzq6mGnRG5QS8VFogncpDzYVXzC0i_aDwY5o-0123456789abcdef"
+
+	it("keeps an id that carries a thought signature intact, however long", () => {
+		const id = `call_864944__thought__${signature}`
+
+		expect(id.length).toBeGreaterThan(OPENAI_CALL_ID_MAX_LENGTH)
+		expect(sanitizeLiteLlmCallId(id)).toBe(id)
+	})
+
+	it("still replaces invalid characters in an id that carries a thought signature", () => {
+		expect(sanitizeLiteLlmCallId("call_1__thought__ab+c/d=")).toBe("call_1__thought__ab_c_d_")
+	})
+
+	it("truncates other long ids like sanitizeOpenAiCallId", () => {
+		const id = "call_" + "x".repeat(100)
+
+		expect(sanitizeLiteLlmCallId(id)).toBe(sanitizeOpenAiCallId(id))
+		expect(sanitizeLiteLlmCallId(id).length).toBe(OPENAI_CALL_ID_MAX_LENGTH)
+	})
+
+	it("leaves short ids unchanged", () => {
+		expect(sanitizeLiteLlmCallId("toolu_123")).toBe("toolu_123")
+	})
+})

src/utils/tool-id.ts

@@ -54,3 +54,21 @@
 	const sanitized = sanitizeToolUseId(id)
 	return truncateOpenAiCallId(sanitized, maxLength)
 }
+
+/**
+ * LiteLLM carries a Gemini thought signature inside the tool call id, as
+ * `<call id>__thought__<signature>`. Truncating such an id corrupts the signature.
+ */
+export const LITELLM_THOUGHT_SIGNATURE_MARKER = "__thought__"
+
+/**
+ * Normalize a tool call id for LiteLLM. Ids that carry a thought signature are only
+ * character-sanitized, because the signature must reach Gemini intact; every other id
+ * gets the usual OpenAI 64-character treatment.
+ *
+ * @param id - The original call_id
+ * @returns The id to send to LiteLLM
+ */
+export function sanitizeLiteLlmCallId(id: string): string {
+	return id.includes(LITELLM_THOUGHT_SIGNATURE_MARKER) ? sanitizeToolUseId(id) : sanitizeOpenAiCallId(id)
+}