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Break one published citation, on purpose

Claim — you can take a path or symbol cited in a pre-2023 etcd article and show, with a sha or a file:line, either where it lives now or that it is gone. Refuting someone else's citation is the drill; the article is disposable.

Rests on — techniques 4 and 5 of the method — the pickaxe and blame walked backwards — and both previous exercises, whose answers you may not reuse. Pick a third symbol.

Topology — none. forge only; it is not part of any topology and is up regardless.

Do

  1. Find a target. Any etcd storage or watch write-up from 2019–2022 will do; conference slides and vendor blogs are the richest seams because they paste paths. Take one paragraph and extract exactly one claim of the form "X is in path/to/file.go" or "the function F does Y". Write the claim down as a sentence before you check it — an unstated claim is unfalsifiable.

  2. Check the cheap way first:

cd ~/src/etcd
ls path/to/file.go 2>&1
git grep -n 'func F' -- '*.go' | head

If the symbol is there under a different path, you have your answer already and step 3 dates it. If git grep finds nothing, the symbol was renamed or deleted, and the pickaxe is the only thing that will find it.

  1. Pickaxe for the string, across all of history:
git log -S'F(' --oneline -- '*.go' | tail -5     # commits that changed the count of it
git log -G'func F' --oneline -- '*.go' | tail -5 # commits whose diff matched the regex

Read the last lines: git log is newest-first, so the introduction is at the bottom and the removal is at the top.

  1. Take the newest sha R from step 3 and read the diff that ended it:
git show --stat <R>
git show <R> -- '*.go' | grep -E '^[-+].*F\(' | head

  1. State the refutation in the form the standard demands: "the article says F is in A; as of <sha> it is in B at line N", or "as of <sha> it no longer exists, replaced by G".

  2. Confirm your refutation is checkable by someone hostile. Have the exact command that produces the evidence in one line, and run it fresh:

git grep -n 'func G' -- '*.go'

Expect — most 2019–2022 citations into etcd's storage layer are broken by the mvcc/ move alone, and most into consensus are broken by the extraction. That is why the phase asks for a third symbol: the interesting refutations are the ones where the file still exists and the function inside it was renamed, split or inlined, because those are the citations a careless reader will believe.

The failure mode to watch for is refuting the wrong thing. "The path is wrong" is not a refutation if the article's actual claim was about behaviour and the path was incidental — say which of the two you broke.

Write down — the refutation sentence, the command that proves it, and its output. That is the checklist's one broken pre-2023 citation refuted item, and it is the first time in the curriculum the answer is required to be a sha rather than a paragraph.

Teardown — nothing was created; step 2's git grep pulled some blobs into the clone, which is the clone doing its job. Both clones stay for the phase.