The Agent Is a New Data Flow AI agents make client document work easier to start and harder to explain. An agency can ask an agent to read a client brief, extract facts, generate a report, and prepare a tracker. That is useful. It is also a new path for client files. The document may move through the agent runtime, the model provider, the MCP client, the tools the agent calls, the review surface, the generated output step, and the logs around all of it. For EU agencies and technical consultancies, that matters because data sovereignty is often part of the pitch. A client does not only ask whether the model endpoint is in Europe. They ask where the document went, which processors saw it, whether content was retained, and whether the agency can prove the workflow is controlled. If the answer is "we connected a few tools and it works," the agency has a trust problem. An EU-hosted agent workflow is not a region checkbox. It is a data-flow design problem.…