diff --git a/docs/port/f6-what-starts-the-sweep.md b/docs/port/f6-what-starts-the-sweep.md
index 63235543..85e3559b 100644
--- a/docs/port/f6-what-starts-the-sweep.md
+++ b/docs/port/f6-what-starts-the-sweep.md
@@ -383,3 +383,64 @@ its leaf reaches α=128 well inside the captured window.
 
 **Nothing is deleted and the renderer is unchanged**, pending one five-second
 human look: one streak, or two?
+
+---
+
+# Unit e — the port draws exactly TWO travelling lights, and the human reports more
+
+The human, watching the real game: *"I think multiple, possible more than two…
+The lights move on blue lines looking like PCB board lines. And frankly I cannot
+tell if the game renders a light per line or uses a light that is shown around
+multiple, close lines."*
+
+That is a different question from the one both agents had been asking, and it is
+worth having the port's own number first.
+
+## Census of every element on the title that travels
+
+| element | x travel | note |
+|---|---|---|
+| `ptlogo1` / `ptlogo2` (×3 instances) | 300 px | the **logo** sliding in, t=34…251 — not a light |
+| **`pteff03`** (leaf of `ptloop01`) | **2 160 px** | left → right |
+| **`pteff03a`** (leaf of `ptloop02`) | **2 560 px** | right → left |
+
+Every other title element — `pteff00`, `pteff01`, `pteff02`, `pteff04`,
+`ptlogo_back2eff` and `…eff1…5`, `ptlogoall_eff`, `ptlogoall_eff2`,
+`ptcopyright`, `ptbase2` — **declares no positional travel at all.** They fade in
+and out in place.
+
+> **The port renders exactly two moving lights.** The human describes multiple,
+> possibly more than two, running along individual PCB traces.
+
+## What that reframes
+
+Both agents had been asking *when* the sweep starts. If the game's effect is a
+population of small lights on separate traces and the port's is two full-height
+streaks crossing the screen, then **the port may have the wrong effect
+altogether**, and "starts too early" is what a wrong effect looks like to someone
+who is not reading keyframes.
+
+⚠️ **And it puts a limit on the capture result.** The Decoder's scan that found
+`pteff03a` absent covered every quad **taller than 1.2 NDC**. Small per-trace
+lights are far below that, so that scan cannot count them — it is exhaustive over
+full-height streaks and silent about the population in question. `pteff03a`'s
+absence stands (it would be 3.62 NDC); *"only one travelling quad exists"* does
+not generalise beyond tall quads.
+
+## ⚠️ A limit of this census
+
+It reads **declared** keyframes. An element with a single keyframe shows as
+"visible 0…0" here and is in fact held and drawn — `ptbase2`, the background, is
+the obvious case. So the visibility column understates; **the travel column is
+the load-bearing one**, and travel is what a moving light needs.
+
+It also cannot see motion that is not positional — a scrolling UV, a texture
+animation, or a shader would move light along a trace while declaring no travel
+at all. **Nothing in this export declares such a thing**, but the port would not
+know if the game did it that way, and that is now a live possibility rather than
+a remote one.
+
+## Not covered
+
+Whether the game's lights are one-per-trace or one glow spanning several — the
+human says they cannot tell, and it is the Decoder's screenshots to settle.