addendum: the canonical sync check is the lead's, not a member's

I put "the sync script must print in sync: True" in a worker's acceptance
criteria for #455. The worker could not run it and said so, honestly, instead
of inventing a pass. My brief was the defect.

A member's provisioned worktree has wiki/ uninitialized, so the script dies
with FileNotFoundError. Measured in three worker worktrees: git submodule
status printed a leading '-' and wiki/ held 0 entries. The primary's own clone
printed a leading '+' and the file was there.

The note is dated, gives the re-measure command, says what each outcome means,
and says to delete it once it stops reproducing - as this file requires of any
measurement in an addendum.

Canonical block untouched: the sync script itself reports in sync: True.

CLAUDE.md

@@ -392,6 +392,16 @@ print("in sync:", w[i:w.index("\n```\n", i) + 1] == block)
 PY
 ```
 
+**Only the lead can run that check (measured 2026-09-10).** A member's provisioned worktree has
+`wiki/` uninitialized, so the script dies with `FileNotFoundError: wiki/7-Use-Cases.md`. Measured
+in three worker worktrees: `git submodule status` printed a leading `-` and `wiki/` held 0
+entries; the primary's own clone printed a leading `+` and the file was there. So never make this
+check a member's acceptance criterion — it is unsatisfiable for them, and a brief that asks for it
+is asking a worker to invent a pass. A member told to check it must say it could not run it, and
+must never report it as passed. The lead runs it in the main clone before merging. Re-measure with
+`git submodule status` in a member's worktree: a leading `-` means this still applies; once it
+prints a commit with no `-`, delete this paragraph.
+
 ## IDE MCP tools & validation workflow (enforced)
 
 > **Primary only.** Workers have no IDE MCP mount — if you are a worker, skip this section and