My use case and issue:
With the Smartsheet API, I am caching a sheet locally and using the rowsModifiedSince query parameter to only update rows that have been updated since the last time the cache was updated. This is a great performance optimization, however, if a row is deleted from the originating Smartsheet, no information about the deleted row is returned from the query. This means I have no way to know I need to update the cached sheet and remove the deleted row, and degrades the integrity of my cached sheet.
The Get Sheet API call should be able to return information about deleted rows. This could be parameterized in some way (includeDeletedRows in the query or something), and for my purposes it'd be fine if the deleted row was returned as a normal row with entirely blank cells for each column, although this may not be the ideal general solution. Currently the best I can do is retrieve every row for a single column, pull out all the current row IDs, and check this against the cached sheet - it technically works, but it slows things down a lot, hurting my original performance optimization.