WF-0109: Historical Basis Preview #134

Hill

By the end of this cycle, the Echo History drawer can preview a selected historical basis without mutating the current head, and the UI clearly communicates that the user is viewing history rather than changing canonical editor truth.

Product Role

Part of Jim's signature loop: explain -> preview -> admit -> recover.

Historical basis preview is the foundation for time-travel yank, stale projection truth, current-vs-checkpoint views, and recovery workflows.

Initial Acceptance Shape

• Select a history row.
• Press Enter or the chosen preview command.
• Jim asks for a bounded historical reading.
• The editor reprojects that basis as a view.
• The footer says the current head is unchanged.
• Escape returns to the current head.
• Tests prove current history/head preservation.