re: the rest() fix gets its disc-wide check, and one question back to the

port agent

Closing the two things I flagged as unconfirmed when I committed the fix.

The unit gate is green: cargo test -p sylpheed-formats with SYLPHEED_DISC
set gives 131 passed, 0 failed across six binaries including the
disc-gated ones. The earlier background run that produced an empty log
had died with SIGTERM, which is why it looked like nothing happened.

And the disc-wide check the classification requires. Reimplementing both
rules over every RATC bundle on the disc -- 2859 bundles, 13991 elements
with at least two keyframes -- the fix moves rest for 30 elements, which
is 0.21 percent. Four go invisible to visible. Zero go visible to
invisible, which is the safety property I wanted and did not have when I
committed. The four are ptframe1 and ptframe2 in GP_TITLE entries 5 and
8, the same pair once per language.

That surfaces a discrepancy worth handing back rather than smoothing
over. On the English main menu exactly TWO elements satisfy the port
agent's pose-equality condition, not six, so their six must span the
whole twelve-screen export. That fits their own observation that the
timeline and rest differ in exactly one region, the bounding box of
ptframe1 and ptframe2 and nothing else. But if any of their other four
have a TRANSPARENT trailing run, my alpha rule leaves them alone
deliberately -- that exclusion is what protects PAUSE -- so I have asked
which screens they are on and whether a capture shows any of them drawn.
If one is, the alpha rule is incomplete and needs a third discriminator.

docs/port/HANDOFF.md

@@ -104,6 +104,14 @@ authored version can be deleted.
   trailing run also matches its last timed keyframe, and adopting that would erase
   the word PAUSE. Oracle correlation over the bracket region improved
   **0.9596 → 0.9748**; the PAUSE control is unchanged.
+  ✅ **Disc-wide**: over 2 859 bundles / 13 991 elements, `rest` moves for **30**
+  (0.21 %) — **4 invisible → visible, 0 visible → invisible**. Tests green
+  (131 passed).
+  ❔ **Back to the port agent:** on the English main menu exactly **two** elements
+  satisfy your pose-equality condition (`ptframe1`/`ptframe2`), so your six span
+  the whole export. If any of the other four have a **transparent** trailing run,
+  this rule leaves them alone on purpose. **Which screens are they on, and does a
+  capture show any of them drawn?** If so the alpha rule is incomplete.
   This also closes the old ❔ on `ptframe1`/`ptframe2` "resting at alpha 0 but the
   capture shows the frame plainly".
 * **The resting pose is the hold**, not the first, last or longest-dwell keyframe;