Claude Code destroys terminal scrollback history every time its output exceeds the viewport height. This affects tmux, GNU screen, every browser-based terminal, VS Code's integrated terminal, and most native terminal emulators. The only surviving environments are raw TTY SSH on iTerm2 (macOS has an opt-out) or pinning Claude Code to 2.1.75 or earlier.
The upstream threads (anthropics/claude-code#16310, #2479) have been open since early 2026 with 25+ interactions. Most workaround proposals fail because they target the wrong layer. This document traces the root cause to its origin and identifies the one fix point that resolves it.