Mistake: shipping a template change with no way to undo it

Mistake: shipping a template change with no way to undo it

A template tweak goes live across 40k pages, tanks indexation or breaks a schema, and the team realizes there's no clean revert — the old render is gone and the data has moved on. Recovery becomes archaeology.

Rollback SOP:
— Step 1. Owner: dev. Version every template; keep the prior version deployable behind a flag.
— Step 2. Owner: dev. Snapshot rendered HTML for a fixed 500-page canary set before and after each template change.
— Step 3. Owner: SEO. Define the rollback trigger up front: e.g. canary indexation drops >15 percent or schema-valid rate falls below 99 percent within 14 days.
— Step 4. Owner: dev. Rehearse the revert once on staging so it's a flag flip, not an emergency.

Guardrail: no template change ships without a named rollback trigger and a tested revert path.

Ship gate: don't publish until all boxes are checked.