Function stripUnavailableToolReferencesFromUserMessage

src/utils/messages.ts:1541–1613

* Strips tool_reference blocks for tools that no longer exist from tool_result content. * This handles the case where a session was saved with MCP tools that are no longer * available (e.g., MCP server was disconnected, renamed, or removed). * Without this filtering, the API rejects with "Tool re

(
  message: UserMessage,
  availableToolNames: Set<string>,
)

 * Without this filtering, the API rejects with "Tool reference not found in available tools".
 */
function stripUnavailableToolReferencesFromUserMessage(
  message: UserMessage,
  availableToolNames: Set<string>,
): UserMessage {
  const content = message.message.content
  if (!Array.isArray(content)) {
    return message
  }

  // Check if any tool_reference blocks point to unavailable tools
  const hasUnavailableReference = content.some(
    block =>
      block.type === 'tool_result' &&
      Array.isArray(block.content) &&
      block.content.some(c => {
        if (!isToolReferenceBlock(c)) return false
        const toolName = (c as { tool_name?: string }).tool_name
        return (
          toolName && !availableToolNames.has(normalizeLegacyToolName(toolName))
        )
      }),
  )

  if (!hasUnavailableReference) {
    return message
  }

  return {
    ...message,
    message: {
      ...message.message,
      content: content.map(block => {
        if (block.type !== 'tool_result' || !Array.isArray(block.content)) {
          return block
        }

        // Filter out tool_reference blocks for unavailable tools
        const filteredContent = block.content.filter(c => {
          if (!isToolReferenceBlock(c)) return true
          const rawToolName = (c as { tool_name?: string }).tool_name
          if (!rawToolName) return true
          const toolName = normalizeLegacyToolName(rawToolName)
          const isAvailable = availableToolNames.has(toolName)
          if (!isAvailable) {
            logForDebugging(
              `Filtering out tool_reference for unavailable tool: ${toolName}`,
              { level: 'warn' },
            )
          }
          return isAvailable
        })

        // If all content was filtered out, replace with a placeholder
        if (filteredContent.length === 0) {
          return {
            ...block,
            content: [
              {