In which test scenarios would you add a critical path?

In test scenarios representing core, most frequently used, or critically important functional flows of the application.

Examples include:

• Registration / Authorization: Successful creation of an account and login.
• Main transaction / Purchase: The complete process from selecting a product/service to successful payment and confirmation.
• Creation / Editing of core content: Creating, editing, and saving key data elements (e.g., creating an article, adding a record to a database).
• Main search / Filtering: Successful search and application of filters to core data.
• Sending / Receiving of main message / request: For messaging systems or APIs.

These are subject to the strictest requirements for stability and performance, and their failure renders the application unusable.