Function getMcpInstructionsDeltaAttachment

src/utils/attachments.ts:1559–1585

(
  mcpClients: MCPServerConnection[],
  tools: Tools,
  model: string,
  messages: Message[] | undefined,
)

// Exported for compact.ts / reactiveCompact.ts — single source of truth for the gate.
export function getMcpInstructionsDeltaAttachment(
  mcpClients: MCPServerConnection[],
  tools: Tools,
  model: string,
  messages: Message[] | undefined,
): Attachment[] {
  if (!isMcpInstructionsDeltaEnabled()) return []

  // The chrome ToolSearch hint is client-authored and ToolSearch-conditional;
  // actual server `instructions` are unconditional. Decide the chrome part
  // here, pass it into the pure diff as a synthesized entry.
  const clientSide: ClientSideInstruction[] = []
  if (
    isToolSearchEnabledOptimistic() &&
    modelSupportsToolReference(model) &&
    isToolSearchToolAvailable(tools)
  ) {
    clientSide.push({
      serverName: CLAUDE_IN_CHROME_MCP_SERVER_NAME,
      block: CHROME_TOOL_SEARCH_INSTRUCTIONS,
    })
  }

  const delta = getMcpInstructionsDelta(mcpClients, messages ?? [], clientSide)
  if (!delta) return []
  return [{ type: 'mcp_instructions_delta', ...delta }]
}

function getCriticalSystemReminderAttachment(
  toolUseContext: ToolUseContext,