Confirmed. :foodndrink:
Wiki does list
some safe containers and some of the categories of containers that are always safe (open top sacks etc).
The following types of containers are always safe: open top grain sacks, torn sacks, lecturns, jewelry boxes, clams, ore deposits. Some corpses or skeleton bodies never disappear - they are also safe.
As far as other individual sacks and chests and barrels etc, there are just far too many to list. For example since you are in the Market District, every single sack of every type outdoors there is safe except for Simplicia the Slow's food bag by her bedroll.
The best thing is to test containers yourself (or look them up on the CS is you know how). Stick something cheap and easy to remember inside the container in question. Most of us use a single iron arrow for this. Leave the area (cell) for at least three game days. Return and check. If the arrow is still there, the container is safe.
When my character was attending the University for example, she lived in the Chironasium with its two beds and nine safe containers - all discovered by iron arrow testing.