# Shell input cancellation (K1276–K1280)

Each editing session has an epoch. Input chunks and commit must name the
current epoch. Cancel clears the buffered bytes and advances the epoch, so a
late commit or input from the cancelled session is rejected. Commit copies the
complete UTF-8 line and advances the epoch. Capacity and NUL errors leave the
buffer unchanged. Epoch overflow rejects cancel or commit without mutation.

This is a `no_std` input state model. Keyboard or serial interrupts, actual
EL0 shell integration and product acceptance require separate evidence.