re: propose settle-instant posing -- and my control cannot validate it

The proposal: pose every element at the SCREEN's settle instant rather than
asking each element for its own resting pose. On the 2 249 fallback elements in
settling bundles the visible-pose rate falls 73.6 % -> 34.7 %.

But the control fails twice. Naive, over every plateau element: 46.6 %. That one
was misspecified and I caught it by asking what the number means physically --
rest() finds *a* held pose and many elements hold one during the build-in then
move on, so it answers a different question and disagreement proves nothing.
Restricted to elements HOLDING ACROSS the settle instant: 78.1 %, still not a
pass.

And the residual is ambiguous by construction: rest_plateau() picks one plateau,
so an element with two whose settle instant falls in the other will disagree --
and there pose_at(settle) is RIGHT. The control cannot separate 'the candidate is
wrong' from 'the incumbent is wrong'.

Recorded as the general point: comparing a candidate to the incumbent cannot
adjudicate when the incumbent is the thing under suspicion. It is the wrong shape
of experiment, not a tuning problem.

What does adjudicate is the oracle and it is the port's measurement, not mine --
publisher splash against a committed capture, settle-instant pose RMSE 2.17 /
0.01 % differing against --pose=rest 9.05 / 0.75 %. My numbers describe the
proposal's effect; they do not establish it.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Wuu56cE8vJGTBtn1ppsk8v

docs/re/data/rest-vs-settle.txt

@@ -0,0 +1,52 @@
+# Should the settled pose come from each element's rest(), or from the SCREEN's
+# settle instant? 2026-08-30. examples/rest_vs_settle.rs
+#
+bundles skipped as never-settling (window < 10 units): 896
+
+CONTROL — elements where rest() takes the SOUND plateau path:
+  8171 plateau elements in settling bundles
+  4796 of them HOLD ACROSS the settle instant — the fair control
+  pose_at(settle) agrees with rest() on 3748 of those (78.1 %)
+
+TEST — elements where the unsound dwell fallback decides:
+  2249 elements
+    rest()          returns a VISIBLE pose on 1655 (73.6 %)
+    pose_at(settle) returns a VISIBLE pose on 781 (34.7 %)
+
+--- END (if this line is missing, the run did not finish) ---
+#
+# THE PROPOSAL: pose every element at UiBuild::settle_time() -- the midpoint of
+# the longest keyframe-free interval ACROSS THE BUILD -- instead of asking each
+# element for its own resting pose. That is the port agent's 're-key on the
+# screen's span rather than the element's', and its shipped path already does it.
+#
+# WHAT THE TEST SHOWS: on the 2 249 fallback elements in settling bundles, the
+# visible-pose rate falls 73.6 % -> 34.7 %. Consistent with the proposal
+# removing transient peaks.
+#
+# 🔴 BUT MY CONTROL CANNOT VALIDATE IT, and that is the finding.
+#
+#   naive control, all plateau elements:                46.6 % agreement
+#   fair control, only those HOLDING ACROSS the settle:  78.1 %
+#
+# The naive one was misspecified and I caught it by asking what 46.6 % means
+# physically: rest() finds *a* held pose, many elements hold one during the
+# build-in and then move on, and pose_at(settle) asks what is on screen when
+# the screen has SETTLED. Different questions; disagreement proves nothing.
+#
+# The fair control's 78.1 % is still not a pass -- and worse, its 21.9 %
+# residual is AMBIGUOUS BY CONSTRUCTION. rest_plateau() picks one plateau; an
+# element with two, whose settle instant falls in the other, will disagree --
+# and there pose_at(settle) is RIGHT and rest() is wrong. So the control
+# cannot separate 'the candidate is wrong' from 'the incumbent is wrong'.
+#
+# ⚠️ COMPARING A CANDIDATE TO THE INCUMBENT CANNOT ADJUDICATE WHEN THE
+# INCUMBENT IS THE THING UNDER SUSPICION. No amount of care with this control
+# fixes that; it is the wrong shape of experiment.
+#
+# ✅ WHAT DOES ADJUDICATE IS THE ORACLE, AND IT IS NOT MINE. The port measured
+# its publisher splash against a committed capture in both poses:
+#   timeline (settle-instant) pose   RMSE 2.17   0.01 % differing
+#   --pose=rest                      RMSE 9.05   0.75 % differing
+# 75x the differing area, against the game. That is the evidence for the
+# proposal. My numbers describe its effect; they do not establish it.

docs/re/structures/ui-resting-pose.md

@@ -319,6 +319,45 @@ units brighter.
 **The element has no resting pose.** It is a flash; after it plays there is
 nothing. Neither answer is *derived* — one of them is merely harmless.
 
+### 🟡 A proposal — and my own control cannot validate it
+
+Three iterations have measured how badly the fallback behaves without proposing
+anything. The proposal is **pose every element at the *screen's* settle instant**
+(`UiBuild::settle_time()`, the midpoint of the longest keyframe-free interval across
+the build) rather than asking each element for its own resting pose
+([`../data/rest-vs-settle.txt`](../data/rest-vs-settle.txt)).
+
+**Effect**, on the 2 249 fallback elements in bundles that settle at all: the
+visible-pose rate falls **73.6 % → 34.7 %** — consistent with transient peaks
+disappearing.
+
+🔴 **But the control fails, and then fails better, and still is not a pass:**
+
+| control | agreement |
+|---|---|
+| naive — every plateau element | **46.6 %** |
+| fair — only those **holding across** the settle instant | **78.1 %** |
+
+The naive one was misspecified, caught by asking what 46.6 % means physically:
+`rest()` finds *a* held pose, and many elements hold one during the build-in then
+move on. Different questions; disagreement proves nothing.
+
+⚠️ **And the fair control's 21.9 % residual is ambiguous by construction.**
+`rest_plateau()` picks one plateau; an element with two, whose settle instant falls
+in the *other*, disagrees — and there `pose_at(settle)` is **right** and `rest()`
+wrong. The control cannot separate *"the candidate is wrong"* from *"the incumbent
+is wrong"*.
+
+🔴 **Comparing a candidate to the incumbent cannot adjudicate when the incumbent is
+the thing under suspicion.** No care with this control fixes that; it is the wrong
+shape of experiment.
+
+✅ **What adjudicates is the oracle, and it is the port agent's measurement, not
+mine**: its publisher splash against a committed capture, **settle-instant pose RMSE
+2.17 / 0.01 % differing** against **`--pose=rest` 9.05 / 0.75 %** — 75× the
+differing area, against the game. **That** is the evidence for the proposal; the
+numbers above describe its effect and do not establish it.
+
 ### 🔴 Losing the example did not close the question — it is larger than one element
 
 Disc-wide ([`../data/rest-fallback-census.txt`](../data/rest-fallback-census.txt)):