When Meticulous simulates sessions it is configured to simulate the sessions against a particular base URL - for example the report-diffs-action appUrl or the URL of the Vercel deployment. This URL will normally be different to the URL the session was recorded at. When simulating a session, Meticulous takes the URL the session was recorded at and swaps out the origin with the new base URL. Learn more here.
You'll therefore need to make sure that the base URL you are simulating sessions against serves up the same app under the same configuration as the base URL sessions are recorded on.
If you have multiple URLs that serve different variants of your app, for example, customized for different customers, then you can setup multiple Meticulous projects and multiple Vercel deployments or report-diffs-action calls - one to test each variant of the app using the sessions recorded for that variant. See below for more details.
You'll most likely want to setup multiple Meticulous projects for the same GitHub repo. Each Meticulous project will have it's own recording token, allowing you to setup each app to record sessions in a different Meticulous project.
If you're using Github Actions to run Meticulous in CI you can then setup a seperate call to report-diffs-action for each Meticulous project, passing in the API token of the relevant project, and pointing it to a URL that serves the correct application.
If you're using Vercel, or another service that provides preview URLs, then you'll want to configure Vercel deployments for each application seperately. Navigate to the project settings page for each Meticulous project and configure that project to test against only the relevant Vercel deployments by selecting the appropiate environments in the Environments to Test Against section.
Reach out to eng@meticulous.ai and we'll help you get setup.