The Atmosphere Attack presents the full empirical record of postural manipulation in agentic AI pipelines. This paper documents three-agent propagation findings, Postural Gain, Confidence Laundering, Postural Decay, and a six-layer defensive architecture. It establishes that ordinary non-adversarial context installs a behavioral lean in language models before any task arrives, propagates through agent handoffs, and arrives as confident policy in downstream agents -- without adversarial signature, without log entry, and without detection by current defensive frameworks. Published as part of a coordinated three-paper disclosure on March 30, 2026.