docs: record Θ-W7, the arc-and-spline antialiasing fix, and file the scaled-fallback deferral

docs/PLAN.md

@@ -115,8 +115,10 @@ drag/drop defects that block getting captures into it.
 
 **Consolidates items** 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 16.
 
-**All six waves have landed — Phase Θ is complete.** W1 through W6 each carry their own
-landed note above; see `docs/COMPLETED.md` for every track's full narrative.
+**All seven waves have landed — Phase Θ is complete.** W1 through W7 each carry their own
+landed note above; see `docs/COMPLETED.md` for every track's full narrative. Θ-W7 was
+opened after Θ-W6-T1 shipped, to fix two rendering defects Daniel found by eye; it did not
+exist in the plan when this phase was originally scoped.
 
 **The organizing constraint.** Three surfaces in the instrument are single-writer by
 nature and dictate the wave shape:
@@ -283,6 +285,33 @@ All visual outcomes remain pending Daniel's by-eye sign-off on `dev`.
 
 ---
 
+### Θ-W7 — Arc-and-spline antialiasing fix
+
+**Depends on W6 for:** a drawn surface to find a defect on — this wave did not exist in
+the plan; it was opened after Daniel found two rendering defects by eye once Θ-W6-T1
+shipped, so the audit's own output is what surfaced them.
+
+**One track.**
+
+**Θ-W7-T1 has landed** — `arc-and-spline-aa` — see `docs/COMPLETED.md` for the full
+narrative. The stacked-`LICE_Arc` knob and dial rings never reached an opaque core (peak
+alpha measured 138/255), and the staged/spline envelope and velocity-curve traces were
+fully aliased rather than gapped, from integer `cy` quantizing the slope. Both defects,
+plus the two needles, now route through one pure analytic thick-stroke rasterizer —
+coverage in a new `core/ui/stroke_aa`, the single LICE blend in a new
+`shell/instrument/editor_stroke` — replacing `LICE_Arc` and `LICE_ThickFLine` outright.
+Measured: arc peak alpha 138/255 → 255/255, arc perpendicular-weight ripple 67% → 5%,
+spline weight ripple 29% → 3%, at a cost of +0.09 ms per full editor repaint. Daniel then
+ruled every sub-2 px stroker width up to 2 px, since the stroker only guarantees an
+opaque core at width ≥ 2 px; the knob track arc, the inner-dial needle, and the deck's
+mini velocity trace each moved 1.0 → 2.0 px. `docs/product/visual-design-language.md` §8
+is corrected — a false "keeps every ring antialiased" claim is deleted, the rows are
+re-dispositioned with measurements, and the audit's methodological lesson (verifying
+which primitive was called is not verifying what it rasterized) is recorded as a standing
+blockquote. All visual outcomes remain pending Daniel's by-eye sign-off on `dev`.
+
+---
+
 ## Phase Ξ — The resample loop
 
 **Ships:** one consolidated, fully robust provenance/usage tracking system, and on top of
@@ -300,7 +329,7 @@ independent of the editor chain — which is what makes Ξ-W1 concurrency-safe w
 bakes — "filtering, pitching, amp all set up nice" is the instrument items 1, 2, 3, and 14
 build — and its settled reset scope enumerates the filter parameters, the spline contours,
 and the loop points by name. Baking a processing chain that does not exist yet is not a
-schedule preference; the feature is not expressible. Phase Θ landed as of Θ-W6-T1 (see
+schedule preference; the feature is not expressible. Phase Θ landed as of Θ-W7-T1 (see
 `docs/COMPLETED.md`); this gate is satisfied.
 
 ---
@@ -616,8 +645,13 @@ work that did not come from the source doc has no row, and inventing one would w
 proof it exists to give.
 
 - **Θ-W3-T1 — `live-parameter-delivery`** (`pth-w3-t1-live-parameter-delivery`). Arose
-  from Θ-W2-T1's implementation review, not from `TODO-1.0.md`. It is the only such track
-  in this plan today; if others appear, they belong on this list rather than in the table.
+  from Θ-W2-T1's implementation review, not from `TODO-1.0.md`. The first such track in
+  this plan; see Θ-W7-T1 below for the second.
+- **Θ-W7-T1 — `arc-and-spline-aa`** (`pth-w7-t1-arc-and-spline-aa`). Opened after
+  Θ-W6-T1 shipped, when Daniel found two rendering defects by eye in the editor — not
+  from `TODO-1.0.md`, and not a track this plan originally scoped. The second such track
+  in this plan today; if others appear, they belong on this list rather than in the
+  table.
 
 ### Deliberate compressions
 
@@ -672,6 +706,8 @@ Phase Θ — ReaSampler 9000: one parameter set, filter, shapeable envelopes, le
       T1 spline-egs .............................. 3
   W6  Editor legibility pass
       T1 legibility-and-antialiasing ............. 10, 13
+  W7  Arc-and-spline antialiasing fix
+      T1 arc-and-spline-aa ....................... (not one of the seventeen)
 
 Phase Ξ — The resample loop            (W1 concurrency-safe with Θ from Θ-W2 onward)
   W1  Consolidated tracking, and the programmed-note model