Add compatibility-preserving full-screen ANSI operations, the bounded terminal
screen and input encoders, and a transactional TerminalManager owning one
read-only identity buffer, PTY process, and screen per session.
Drain terminal-owned process events before process.after-tick, retain exact
final output and PID/outcome annotations, reap killed buffers and shutdown
children safely, and enforce buffer-owned read-only checks across ordinary,
host, undo/redo, and CRDT mutation paths.
Cover split parser and grapheme boundaries, screen/reflow/history invariants,
device responses, lifecycle cleanup, and a real adversarial alternate-screen
PTY. Record the fully gated Stage 1 delivery and downstream TUI/GPU contracts.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
