handoff: the fade ramp is 10 units decoded, and screen info was stale

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

docs/port/HANDOFF.md

@@ -2533,6 +2533,42 @@ whatever it returns — the same reason a truncated log and a t=0 render both lo
 fine from inside. Template matching against the exported cue with a bed-only
 control has no such knob, which is the right fix rather than a better threshold.
 
+## 🔴 2026-08-30 — your fade ask: the ramp IS 10 units, and my `screen info` was STALE
+
+**Your number survives my attempt to refute it.** `pteff00.prm`'s final ramp on
+build 5 is **70 → 80 = 10 units ≈ 0.167 s**. The `~24 units` HANDOFF told you to
+author is wrong.
+
+🔴 **And the reason it stood so long is a tooling trap you should know about.** The
+`sylpheed-cli` in this container was built **2026-08-29 12:38**, *before* the
+keyframe-record-layout fix. The old parser shifted every time by one slot and could
+not time a group's final pose:
+
+```
+stale  pteff00.prm  4 kf  rest t=70   [12:0,0  70:0,0  80:0,0  -:0,0]
+fresh  pteff00.prm  4 kf  rest t=12   [ 0:0,0  12:0,0  70:0,0  80:0,0]
+```
+
+Both are well-formed; neither announces its age. `screen-transitions.md` argued from
+*"there is exactly one untimed keyframe"* — **the stale parser's artefact**. That
+premise is now marked refuted in place.
+
+⚠️ **`cargo build -p sylpheed-cli` before trusting `screen info`.** ✅ Renders are
+**byte-identical** across the two binaries (max per-channel difference **0**), so
+`screen render` and anything from element identity, pivots or keyframe *counts* is
+unaffected — it is the **times** that move.
+
+### Your actual question, as far as I can take it
+
+✅ **The ~0.4 s is NOT the ramp alone.** 0.4 s is ~24 units against a decoded 10, so
+~14 units belong to something else. That much is decoded-vs-measured and does not
+depend on any decomposition.
+
+🟡 **That the remainder is exactly the black hold is arithmetic that fits, not a
+measurement** — 14 units = 0.233 s, inside this corpus's own 0.17–0.23 s plateau.
+You named this risk yourself and you were right to. **Author nothing from the
+composition.** What you can take is the decoded 10.
+
 ## ✅ 2026-08-30 — `on_cancel` from the MAIN MENU is measured: it goes to the TITLE
 
 You flagged `on_cancel` as still authored. Half of it is now measured — the half