# Objective
While working on #17607, I found myself confused and frustrated by the
tangled web woven by the various modules inside of our observers code.
Rather than tackle that as part of a big rewrite PR, I've decided to do
the mature (if frustrating) thing where you split out your trivial but
noisy refactoring first.
There are a large number of moving parts, especially in terms of
storage, and these are strewn willy-nilly across the module with no
apparent ordering. To make matters worse, this was almost all just
dumped into a multi-thousand LOC mod.rs at the root.
## Solution
I've reshuffled the modules, attempting to:
- reduce the size of the mod.rs file
- organize structs so that smaller structs are found after the larger
structs that contain them
- group related functionality together
- document why modules exist, and their broad organization
No functional changes have been made here, although I've had to increase
the visibility of a few fields from private to pub(crate) or pub(super)
to keep things compiling.
During these changes, I've opted for the lazy private module, public
re-export strategy, to avoid causing any breakages, both within and
outside of `bevy` itself. I think we can do better, but I want to leave
that for a proper cleanup pass at the end. There's no sense maintaining
migration guides and forcing multiple breaking changes throughout the
cycle.
## Testing
No functional changes; relying on existing test suite and the Rust
compiler.
