With a real codex login now available, record the one shape the fake-key
lab could never produce: a genuine model reply streaming above the pinned
composer, pushing lines into history (baseY grows) while keystrokes land
mid-stream. The recorder gains an opt-in CODEX_RECORD_REAL=1 scenario
using the user's own ~/.codex (fixture secret-scanned for key/JWT
material before writing; scanned clean). The replay test pins: baseY > 0,
mid-stream predictions painted, exact convergence to the typed text.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>