OmniRoute/open-sse/translator/helpers/toolCallHelper.ts

// Tool call helper functions for translator

const ALPHANUM9 = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";

// Generate unique tool call ID (default long form)
export function generateToolCallId() {
  return `call_${Date.now().toString(36)}_${Math.random().toString(36).slice(2, 9)}`;
}

// Generate 9-char [a-zA-Z0-9] id for providers that require it (e.g. Mistral)
function generateToolCallId9(): string {
  let s = "";
  for (let i = 0; i < 9; i++) {
    s += ALPHANUM9[Math.floor(Math.random() * ALPHANUM9.length)];
  }
  return s;
}

/** @param options.use9CharId - When true, normalize ids to 9-char [a-zA-Z0-9] (e.g. Mistral); when false, only fix type/arguments, leave ids as-is */
export function ensureToolCallIds(body, options?: { use9CharId?: boolean }) {
  if (!body.messages || !Array.isArray(body.messages)) return body;

  const use9CharId = options?.use9CharId === true;

  for (let i = 0; i < body.messages.length; i++) {
    const msg = body.messages[i];
    if (msg.role !== "assistant" || !msg.tool_calls || !Array.isArray(msg.tool_calls)) continue;

    const used9 = new Set<string>();
    const newIdsInOrder: string[] = [];

    for (const tc of msg.tool_calls) {
      if (!tc.type) {
        tc.type = "function";
      }
      if (tc.function?.arguments && typeof tc.function.arguments !== "string") {
        tc.function.arguments = JSON.stringify(tc.function.arguments);
      }
      if (use9CharId) {
        let newId: string;
        do {
          newId = generateToolCallId9();
        } while (used9.has(newId));
        used9.add(newId);
        newIdsInOrder.push(newId);
        tc.id = newId;
      } else {
        // Leave id as-is, only ensure it exists for later tool message matching
        const id =
          tc.id != null && String(tc.id).trim() !== "" ? String(tc.id) : generateToolCallId();
        tc.id = id;
        newIdsInOrder.push(id);
      }
    }

    // Tool responses (role "tool") follow in same order as tool_calls; set tool_call_id by index.
    // Stop when we hit another assistant so we only link tool messages that immediately follow this one.
    if (newIdsInOrder.length > 0) {
      let idx = 0;
      for (let j = i + 1; j < body.messages.length; j++) {
        const later = body.messages[j];
        if (later.role === "assistant") break;
        if (later.role !== "tool") continue;
        if (idx < newIdsInOrder.length) {
          later.tool_call_id = newIdsInOrder[idx];
          idx++;
        }
      }
    }
  }

  return body;
}

// Get tool_call ids from assistant message (OpenAI format: tool_calls, Claude format: tool_use in content)
export function getToolCallIds(msg) {
  if (msg.role !== "assistant") return [];

  const ids = [];

  // OpenAI format: tool_calls array
  if (msg.tool_calls && Array.isArray(msg.tool_calls)) {
    for (const tc of msg.tool_calls) {
      if (tc.id) ids.push(tc.id);
    }
  }

  // Claude format: tool_use blocks in content
  if (Array.isArray(msg.content)) {
    for (const block of msg.content) {
      if (block.type === "tool_use" && block.id) {
        ids.push(block.id);
      }
    }
  }

  return ids;
}

// Check if user message has tool_result for given ids (OpenAI format: role=tool, Claude format: tool_result in content)
export function hasToolResults(msg, toolCallIds) {
  if (!msg || !toolCallIds.length) return false;

  // OpenAI format: role = "tool" with tool_call_id
  if (msg.role === "tool" && msg.tool_call_id) {
    return toolCallIds.includes(msg.tool_call_id);
  }

  // Claude format: tool_result blocks in user message content
  if (msg.role === "user" && Array.isArray(msg.content)) {
    for (const block of msg.content) {
      if (block.type === "tool_result" && toolCallIds.includes(block.tool_use_id)) {
        return true;
      }
    }
  }

  return false;
}

// Fix missing tool responses - insert empty tool_result if assistant has tool_use but next message has no tool_result.
// Inserts in the same shape as the opening assistant message: OpenAI tool_calls → role:"tool";
// Claude tool_use blocks → role:"user" with tool_result content blocks.
export function fixMissingToolResponses(body) {
  if (!body.messages || !Array.isArray(body.messages)) return body;

  const newMessages = [];

  for (let i = 0; i < body.messages.length; i++) {
    const msg = body.messages[i];
    const nextMsg = body.messages[i + 1];

    newMessages.push(msg);

    // Check if this is assistant with tool_calls/tool_use
    const toolCallIds = getToolCallIds(msg);
    if (toolCallIds.length === 0) continue;

    // Check if next message has tool_result
    if (nextMsg && !hasToolResults(nextMsg, toolCallIds)) {
      const hasOpenAIToolCalls = Array.isArray(msg.tool_calls) && msg.tool_calls.length > 0;
      if (hasOpenAIToolCalls) {
        for (const id of toolCallIds) {
          newMessages.push({
            role: "tool",
            tool_call_id: id,
            content: "",
          });
        }
      } else {
        newMessages.push({
          role: "user",
          content: toolCallIds.map((id) => ({
            type: "tool_result",
            tool_use_id: id,
            content: "",
          })),
        });
      }
    }
  }

  body.messages = newMessages;
  return body;
}