Fixes persistent-identity startup after abrupt MCP client shutdown. Newton now performs one fail-closed, identity-specific stale-lease recovery attempt without requiring unrelated Chrome or Edge windows to close, returns actionable identity recovery errors, and documents the canonical nested session-start observation shape. Verified by 490 deterministic tests, seven real production surfaces, and three unchanged-source release passes across source and exact-packed Chrome and Edge. Artifact SHA-256: 3994de75395c437e5216cdd2ba04d1ac80fb841bbcb691523ae471393071e244.