re: the transition is overlap, not ramp-then-hold -- and the fade-in was 5x wrong

screen-transitions.md carried a 14-unit "black hold" that the page itself
flagged as arithmetic rather than measurement. Measured it against the running
game; the guess was wrong, and finding the instrument to measure it turned up a
second, larger error in the same page.

1. fade_quads.py was STALE. It read each pose's time from blk+36 -- the next
record's time word -- the association the keyframe record-layout fix retired in
the crate. sylpheed-cli was rebuilt at the time; the Python helper was never
swept with it. Signature: it cannot time a group's last pose, so it printed a
trailing `t=-`. Fixed, controlled against the rebuilt `screen info` ([0 12 70
80] for build 5's pteff00.prm).

2. Through it, the page labelled the quad's CLEAR-hold as its fade-in and
published 0.87 s / 0.97 s / 4.08 s for a ramp that is 0.20 s / 0.20 s / 0.27 s.
A port pacing its menu fade-in off that would run it 5x too slow.

3. The measurement. fade_decompose.sh boots to the main menu, arms the UI draw
capture there, then presses (B), so one 260-frame window holds the whole screen
change. The fade quad is identified rather than guessed: a .prm carries no
tex[base=] and paints last, so it is the last full-screen untextured quad of a
frame. Control first -- the quad's ramp is decoded at 10 units = 5 frames, and
measures 4 submitted-frame steps with one unlogged frame in the span.

Result: content elements begin fading at frame 34; the black quad first appears
at 40 and is opaque by 43; the menu's last frame is 45; frame 46 has 6 draws
against 12. So the ~14 extra units are the content's own fade-outs OVERLAPPING
the quad's ramp, not a hold after it, and the inter-screen black is one frame.

Refutation attempted: sylpheed-port's entries 13/14 twins. Re-derived off the
disc -- 3.06 / 4.33 / 47.91, identical to two decimals. Recorded as confirming
their addressing and arithmetic, NOT as independent support: same renderer,
same disc, which is their own rule.

Reach: one transition, one run; the frame axis has gaps (232 headers over frames
3..260), so every span is +-1 frame.

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

docs/re/data/fade-envelope-menu-to-title.txt

@@ -0,0 +1,43 @@
+# Menu -> title transition, per-frame, from the running game.
+# tools/re-capture/fade_decompose.sh -> log_ui_draws capture (260 frames)
+# tools/re-capture/fade_envelope.py  (the fade quad = last FULL-SCREEN
+#   UNTEXTURED quad in a frame: a .prm carries no tex[base=], and the fade
+#   quad paints last).
+# Xenia VdSwap frame numbers. 2026-08-30.
+#
+# TIMING CHECK: F10 armed the capture at frame 1; the script sent (B) 1.2 s
+# later. 1.2 s at 30 Hz is frame ~36. The fade begins at 34. The press and
+# the transition agree without either being used to place the other.
+#
+# frame   untextured full-screen quad alphas, in submission order
+   28   [[64]]                     draws= 12 tex= 10
+   29   [[64]]                     draws= 12 tex= 10
+   30   [[64]]                     draws= 12 tex= 10
+   31   [[64]]                     draws= 12 tex= 10
+   32   [[64]]                     draws= 12 tex= 10
+   34   [[64, 255], [64]]          draws= 15 tex= 12   <- content starts fading
+   35   [[64, 223], [64]]          draws= 15 tex= 12
+   36   [[64, 207], [64]]          draws= 15 tex= 12
+   37   [[64, 175], [64]]          draws= 14 tex= 11
+   39   [[64, 95], [64]]           draws= 11 tex=  8
+   40   [[64, 31], [64], [102]]    draws= 12 tex=  6   <- BLACK QUAD APPEARS
+   41   [[64, 15], [64], [127]]    draws= 12 tex=  6
+   43   [[64], [64], [255]]        draws= 12 tex=  6   <- fully black
+   44   [[64], [64], [255]]        draws= 12 tex=  6
+   45   [[64], [64], [255]]        draws= 12 tex=  6
+   46   [[64]]                     draws=  6 tex=  2   <- menu stops drawing (6 draws vs 12); ONE frame of black
+   47   [[64]]                     draws=  8 tex=  6
+   49   [[64]]                     draws=  8 tex=  6
+   50   [[64]]                     draws=  8 tex=  6
+   51   [[64]]                     draws=  8 tex=  6
+   52   [[64]]                     draws=  8 tex=  6
+   53   [[64]]                     draws=  8 tex=  6
+   54   [[64]]                     draws=  8 tex=  6
+   55   [[64]]                     draws=  8 tex=  6
+   56   [[73]]                     draws=  8 tex=  6
+   57   [[93]]                     draws=  8 tex=  6
+   58   [[113]]                    draws=  9 tex=  7
+   59   [[152]]                    draws= 12 tex= 10
+   60   [[172]]                    draws= 12 tex= 10
+
+missing submitted frames in this span: 33->34, 37->39, 41->43, 47->49