ledger: pin the 20-commit snapshot to d4ffaa3 and version the CHECK

wizard-work/ledger/commits.md

@@ -4,6 +4,7 @@ Source: `git -C /root/troupe-standup log -n 20 --format='%x1f%H%x1f%h%x1f%an%x1f
 
 Extract-lane correction: `Files` = number of distinct paths changed in the commit (git show --name-status), re-derived and verified against git in `CHECK`.
 
+Pinned revision: d4ffaa3
 | Rank | Hash | Author | Date | Subject | Files |
 | --- | --- | --- | --- | --- | --- |
 | 1 | d4ffaa3 | spark | 2026-10-25T00:29:29+00:00 | spark: add artifact validation script | 1 |

wizard-work/ledger/verify_commits_check.py

@@ -25,9 +25,12 @@ def git(*args):
     ).stdout
 
 
+PINNED_REV = "d4ffaa3"  # short rev the snapshot was read from (NOT HEAD, which has moved on)
+
+
 def derive_rows():
     fmt = "%H%x1f%h%x1f%an%x1f%aI%x1f%s"
-    commits = [ln for ln in git("log", "-n", str(N), "--format=" + fmt).splitlines() if ln.strip()]
+    commits = [ln for ln in git("log", "-n", str(N), "--format=" + fmt, PINNED_REV).splitlines() if ln.strip()]
     rows = []
     for ln in commits:
         full, short, author, date, subject = ln.split("\x1f")
@@ -87,6 +90,7 @@ def md(rows):
         "Extract-lane correction: `Files` = number of distinct paths changed in the commit "
         "(git show --name-status), re-derived and verified against git in `CHECK`.",
         "",
+        "Pinned revision: d4ffaa3",
         "| Rank | Hash | Author | Date | Subject | Files |",
         "| --- | --- | --- | --- | --- | --- |",
     ]