Failed Database Migration Error Block for React

Nothing connects to a database. The ledger, the error and the facts are typed in the file, Retry waits a moment and fails again with the same error, and Roll back updates the ledger in the page only. The Copy button is real. To wire it for real, build the ledger from your tool's history table and send the buttons to your tool.

It names the migration, says what its down step does, and says whether that loses data: undoing a rename changes no rows, while undoing a table or a column deletes what is in it, and then the dialog says how many rows and the action turns destructive. It also says the failed migration changed nothing. Cancel is first and has focus when it opens, and Escape closes it.

Because it ran inside a transaction and was rolled back with it. That is true only on databases that can undo schema changes in a transaction, and for statements that can run in one, so check yours before you say the same on a real page.

Because the cause is in the data, not a hiccup: two sessions claim the same user, so the unique constraint fails every time. The demo says so honestly instead of succeeding by accident, and each attempt is counted in the strip.

Yes. Undo is always shown, quiet until there is something to undo, and applies the last rolled-back migration again in the ledger, one at a time. When nothing is applied, Roll back says so instead of opening.

Each ledger row shows its file name with the state under it, the error window scrolls sideways inside itself, the facts are two across and the two buttons stack in a foot that stays pinned to the bottom of the screen.