docs(playbook): a limitations section lends unearned credibility to the claims above it

Readers take 'what I could not establish' as evidence the rest was held to that
standard. Write the claim the evidence licenses, not the broader one; and when two
items in your own not-established list contradict each other, flag it — that
contradiction is the strongest lead you have, not another unknown.

admin_ui_cleanup.md

@@ -447,6 +447,21 @@ A proof about the container is not a proof about the member, and that substituti
 because the evidence is real and the reasoning feels airtight. Ask explicitly: *does my evidence
 range over exactly the thing I am ruling out, or over something that contains it?*
 
+**A "what I could not establish" section confers unearned credibility on everything above it.**
+Listing your limitations is good practice and this playbook demands it — but be aware of what it does
+to a reader: the presence of a limitations section is taken as evidence that the rest was held to
+that same standard. It usually wasn't. A real example from this round: a `pending.md` entry recorded
+"do not fix this service" on evidence that actually supported only the narrower "a real shutdown does
+not drop events," and its own Not-established section listed two statements that **cannot both be
+true** (the executing task is awaited on stop; the loop never ran before stop returned) without
+flagging the contradiction. Adjacent bullets under an honest heading read as thoroughness and
+function as a dead end for whoever picks it up.
+
+Two habits follow. **State what each piece of evidence licenses, not just what you believe** — if the
+evidence covers a narrower claim than the one you are writing, write the narrower one. And **when two
+items in your own limitations list conflict, say so explicitly**; a contradiction is a lead, and
+burying it in a list of unknowns converts the most informative thing you have into noise.
+
 **A correction is not automatically safer than the claim it replaces.** The first item above was
 corrected to "HistorianGateway has no block, so the bump restyles it" — which was *also* wrong, for a
 new reason: it had no Bootstrap button call sites either, so the kit's rule matches nothing. The