Alibaba Cloud open-source (Apache-2.0) white paper distilling enterprise agent deployment experience across the agent lifecycle — architecture, building, runtime, governance and optimization — in 30 Markdown chapters. Core thesis: understand the Model/Harness responsibility boundary instead of attributing everything to model capability. Covers agent loops, task state machines, context builders, action planes, MCP/A2A, sandbox runtimes, AI-gateway governance and evaluation flywheels, plus a 2026 agent developer survey and real cases (ABACI kernel-patch testing, Kitta code review, Bilibili content insights).