port: the sweep identification resolved -- and my proposed repair was wrong

Travel direction settled it: both rows travel LEFT->RIGHT, so both are pteff03
split across two keys by per-frame rounding. pteff03a is not in the capture.

So my 'the finding may still be correct via the OTHER row' does not apply --
there is no other row. I was right that size could not carry the assignment and
wrong about what the assignment was.

The larger half was not visible from here: the quoted low alphas were the nine
lowest DISTINCT values, not a series -- 14 sub-floor samples out of 1754. The
bound survives in shape and collapses in weight.

Status 🟡. Renderer still unchanged.

docs/port/f6-what-starts-the-sweep.md

@@ -155,6 +155,37 @@ The two leaves travel in **opposite directions**: `pteff03` left→right,
 `pteff03a` right→left, separated by ~1 000 px for most of their run. One frame
 pair settles it. Nothing needs re-capturing.
 
+## ✅ Resolved: the discriminator worked, and MY proposed repair was wrong
+
+The Decoder ran the travel-direction check on the capture they already had:
+
+```
+1.38x3.15  n=1140  x centre -1.690 -> +0.500   LEFT->RIGHT
+1.39x3.15  n= 614  x centre -1.685 -> +0.495   LEFT->RIGHT
+```
+
+**Both rows travel the same way, so both are `pteff03`** — the 0.7 % size
+difference is per-frame rounding splitting **one** element across two keys.
+`pteff03a` is not in the capture at all.
+
+🔴 **So my "the finding may still be correct via the OTHER row" does not apply —
+there is no other row.** The identification was broken a third way that neither
+of us named: not two elements confused for each other, but one element counted
+twice. I was right that size could not carry the assignment and wrong about what
+the assignment actually was.
+
+⚠️ And the part I could not see from here, which is the larger one: the quoted
+`8 24 33 50 58 …` were the nine **lowest distinct** values, not a series — a
+tail, presented in a shape that reads as a ramp. **14 sub-floor samples out of
+1754.** The bound survives in shape and collapses in weight: one sample below 128
+is still unexplainable by a leaf flooring at 128, but 14 of 1754 is where a
+grouping slip or a partial frame would show up.
+
+**Status: 🟡 not refuted, not established.** The next unit is a re-read of data
+already on disk — the same capture as a *series* across t=70…100, where a
+multiplying parent must ramp on nearly every frame rather than in 14 stragglers.
+That unit is the Decoder's and has not been run.
+
 ## What the port does about it: nothing yet
 
 Adopting a decode whose element assignment is unresolved is how this project has