Fix Workbench preview problems
Local preview authorization failed
Close the old Workbench tab, stop old theme preview processes and run upstorr theme dev <theme> again. Open the newly printed URL. Launch values are short-lived and tied to the current local preview.
The editor loads but the storefront stays blank
Read the terminal error and run theme check. Repair the first source error. Missing files, invalid JSON, invalid Liquid or a failed browser bundle can prevent rendering.
Changes do not appear
Confirm you edited the selected theme's theme/ directory and that its current theme dev process is still running. Generated .upstorr-theme/build/ files are outputs, not authored source.
Store data is unexpected
Reconnect only after confirming the store and storefront identity printed by the CLI. Workbench uses permitted data from that connection; it does not invent a sample merchant.
One route fails
Open that route's template and referenced sections. Check the exact Liquid line and variable in the preview error. Do not add a guessed fallback that hides a broken contract.