git log <file> stops at the rename — you only see history after the file got its current name.
To follow the file across renames, add --follow:
git log --follow src/auth.ts
Caveats:
--follow works on a single pathspec, not multiple.- For richer rename detection:
git log -M --stat shows similarity scores ("R96 a.ts → b.ts" means 96% similar, treated as a rename).
-C additionally detects code copied between files.
This unlocks "who originally wrote this function?" investigations across years of refactors.