File	Purpose	When	Required
CACHE/name-version.tar	Cached package	Package download	No
CACHE/name-version.etag	Cache validation	Package download	No
DEP/rebar.config	Dep configuration	After download	Yes
.git/config	Git remote URL	needs_update check	For Git deps

File	Content	When	Location
Package tarball	Hex package	First download	~/.cache/rebar3/hex/.../name-version.tar
ETag file	HTTP ETag	After download	~/.cache/rebar3/hex/.../name-version.etag
Dependency files	Source code	After download	_build/PROFILE/lib/DEPNAME/

Directory	Purpose	When
_build/PROFILE/lib/	Dependency storage	Before first dep download
_build/PROFILE/lib/DEPNAME/	Individual dependency	Per dependency
Temporary directory	Staging area	During download
~/.cache/rebar3/hex/REPO/packages/	Package cache	First Hex download

Directory	When	Why
Old dep version	Before moving new version	Clean old version
Temporary directory	After successful move	Cleanup
Failed download temp	On error	Cleanup