On Tuesday, 21 April 2026 at 3:40 AM, Greg KH <[email protected]> wrote: > I really do not understand, how would this actually be used?
Git history uses email addresses as the de-facto identity key and email addresses aren't stable across a lifetime or a career and, increasingly, aren't meaningful even within a single commit. Contributors move between employers and domains over time; companies rename and migrate their workforce onto new domains; and plenty of commits land with From: lines like blake@desktop or [email protected] because git's username@hostname fallback fired before user.email was set. .mailmap partially fixes the first case inside a single tree but doesn't travel across repositories and can't synthesise an identity where the From: never carried one. A declared Acted-By trailer gives the human a stable key that survives employer changes, domain migrations, misconfigured clients, and cross-tree lookups. > And as you have to have a signed-off-by, why would you use two > different names for yourself this way? Signed-off-by and Acted-By answer different questions. Signed-off-by requires a real name for DCO attestation. Acted-By names the stable working identity the same human operates under across contexts — which for most contributors on a stable setup collapses to the same name, and the trailer adds nothing. They diverge when: - the same human contributes under different employer emails over a long career; - an employer renames and migrates its workforce to a new domain; - a contributor publishes under a stable pseudonym but their DCO Signed-off-by has to carry their legal name; - the From: line is machine-generated noise (blake@desktop, user@hostname) and carries no identity information at all. > And who is asking for this? Who would want to use it? How would > you use it for this very commit? For this very commit I wouldn't need it as Signed-off-by is sufficient. The patch defines a slot in the docs; the commits that benefit from the slot are other commits in other trees where the divergence cases above bite. Pseudonymous contributors and long-career maintainers whose email addresses have changed are the current constituency; anyone writing provenance or review-routing tooling that today falls back on email-fuzzing is the other. If the sense is that optional trailers with narrow audiences don't earn a footnote in coding-assistants.rst, I'm happy to withdraw and keep this out-of-tree. thanks, Blake
