# ✅ Option A implemented — the reference renderer rotates. ⚠️ It does not close the title.

> 🔴 **Two claims below are withdrawn (2026-08-29), and the baseline is
> unreproducible.** See [`ui-settle-time.md`](ui-settle-time.md).
>
> * **"Flat. No minimum."** is explained, not a property of rotation:
>   `ComposeOptions::at` was posing **leaves only**, so the scan moved the light
>   sweeps and never touched the top-level flashes. No `t` could have helped.
>   `at` now poses every element and the scan has a clear optimum.
> * **"our renderer still does not draw `ptlogo1` / `ptlogo2` at all"** is
>   **wrong**. Both are drawn. The four elements the diagnostic reported are kind
>   `0x4` ghost instances, skipped deliberately. Hiding the real ones makes the
>   error *worse*.
> * ❔ The **10.92** baseline is **not reproducible** — the same command gives
>   14.07 at this document's own pre-change tag and 14.07 today — so the "1.7 %
>   better" verdict rests on a recipe that was not recorded.

**Decision:** the human chose **Option A** (2026-08-29) — teach
`sylpheed-formats`' own renderer to draw `rotation_deg`, so it and the port stay
comparable and `verify-screen` keeps meaning *"someone is wrong"*.

**Status:** ✅ implemented and controlled. 🔴 **and it does not measurably improve
the title against the capture we hold** — reported here rather than quietly, because
the improvement was the reason for doing it.

## What changed

Three pieces, because rotation alone does nothing on the title:

1. **`blit` gained a rotated path.** `rotation_deg != 0` draws by **inverse
   mapping** over the rotated bounding box; forward-mapping a rotation leaves
   gaps. Rotation turns about the element's **pivot**, whose absolute position
   `(kf.x + pivot_x, kf.y + pivot_y)` is invariant under scale.
   ✅ `rotation_deg == 0` keeps the original forward-mapped path **byte for
   byte**, so screens that do not rotate cannot regress.
2. **`compose` draws a nested `.rat` leaf when the leaf carries geometry the
   parent does not** — the title's sweeps are exactly that case (parent fixed at
   (441,270) scale 100 %, leaf holding 600 %/800 % and ±30°/−45°).
   ⚠️ Not a blanket rule: a button's leaf *duplicates* its parent and the parent
   wins ([`ui-leaf-vs-parent-alpha.md`](ui-leaf-vs-parent-alpha.md)), so the leaf
   is used only when its pose genuinely differs.
   ⚠️ A leaf element resolves **no sprite of its own** — names resolve against
   the bundle a build was parsed from, and a leaf is parsed from its own slice.
   Its *name* is the sprite name, looked up in the parent bundle's table.
3. **`--at <units>` / `ComposeOptions::at`**, because the sweeps hold off-screen
   at `x = 1521` and a resting composite therefore *omits* them.

## 🔴 A trap this found, and it cost a wrong number first

Posing **everything** at one global time is wrong. A top-level group's final
keyframes are its **exit ramp** — the fade-out played when the screen leaves —
and `rest()` deliberately stops at the last *hold* keyframe before it. Posing the
title at t=358 walked every parent into its exit and drove the disagreement from
**10.92 to 61.74**.

✅ `at` therefore poses **leaves only**; top-level elements keep `rest()`. That
follows the decoded rule directly: the leaf runs on its own timeline and the
parent's does not gate it.

## The controls

| | |
|---|---|
| 0° and **360°** vs the unrotated path | **byte-identical** |
| 90° on a 10×4 sprite | extents swap to **4×10** |
| covered area under rotation | conserved to **< 15 %** |
| centroid under rotation | stays on the pivot (< 1 px) |

`rotation_control_known_angles` pins all four. **116 lib tests pass.**

## 🔴 The verification, which did not show what it was meant to

Rendering the title against
[`live-title-build4-no-plate.png`](../captures/title-builds/live-title-build4-no-plate.png)
and scanning the pose time:

| | mean abs difference |
|---|---|
| before (rest, no leaves, no rotation) | **10.92** |
| after, scanned t = 0 … 600 | **10.73 – 11.17** |
| best (t = 420) | 10.73 — **1.7 %** better |

**Flat. No minimum.** Drawing the sweeps correctly does not measurably improve
this comparison, and two things explain why without rescuing it:

* the whole-frame mean is dominated by the **tone curve**, which
  [`title-residual-tone-vs-geometry.md`](title-residual-tone-vs-geometry.md)
  measures as the larger part of the *level* difference even where geometry is
  right;
* our renderer still **does not draw `ptlogo1` / `ptlogo2` at all** (four
  elements, reported as "not drawn"), and that is a far larger spatial gap than
  two translucent sweeps.

⚠️ **So the honest claim is narrow:** rotation is implemented and correct in
isolation, and no screen regressed. Whether it closes the port's **1.81 % of
pixels differing** is **not established here** — that harness poses deliberately
and counts differing pixels rather than mean level, and it is the place to judge
it. ❔ The sweeps may simply be a small term.

## 🔴 A bug in this change, found by inspection before the tests found it

The leaf branch set its "something was drawn" flag **unconditionally after
calling `blit`** — but `blit` returns early on a **zero scale** (*"collapsed to
nothing", not "unset"*). So a scale-0 leaf would have been treated as drawn, its
parent skipped, and the element **blanked outright**.

⚠️ `pgloading_loop5`'s leaf is scale **(0, 0)**, so this was live on all four
loading screens, and scale-0 is one of the failures this corpus is already named
for. Fixed by skipping a zero-scale leaf pose before it can claim the draw.
Loading builds render afterwards at 4.0 % non-black, unchanged in character.

## No regression

| screen | before | after |
|---|---|---|
| `main_menu` | 9.26 | **9.26** |
| `extras` | — | 9.75 |