Protect topology tool

Sometimes you need to protect your topology from changes at all costs. For example, when working with shape keys or doing retopology by wrapping pre-existed one around target mesh. In some workflows, accident pressing of Extrude of Fill Polygon can remain unnoticed by a modeler and completely wreck the vertex order, destroying hours of work.

I wish there would be a tool, or modifier, by enabling which it would limit all your modeling tools to those that only modify existing geometry data without generating the new one. Or at least a warning message in red, saying something like "Hey man, you altered your topology, are you sure you intended to do that?"