Fix deck-UI review findings: right-anchor MASTER's meter column, correct stale/overclaiming comments, split test_deck_groups.cpp on its commit-tier/overlay seam, and pin two width-ceiling assertions.

src/core/instrument/ui/CMakeLists.txt

@@ -79,6 +79,10 @@ reasampler_pure_library(deck_groups
 # assertion needs the band allocator, and the MASTER-reserve identity needs the column width the
 # PRIVATE edge above does not re-export.
 reasampler_test(deck_groups LINK deck_groups sample_bands master_meter)
+# The commit-tier + overlay-selection state machine, split out of deck_groups_tests on the seam
+# those fixtures already had: deckParamCommit/liveCommitFor and the overlay predicates are pure
+# control-id/enum logic that touches no layout, so this target needs no sample_bands/master_meter.
+reasampler_test(deck_groups_state LINK deck_groups)
 
 # The point-editing grammar both spline consumers share, so it links the curve itself (unlike
 # envelope_overlay/envelope_edit, which stay engine-free — the staged envelopes touch no curve).

src/core/instrument/ui/knob_deck.cpp

@@ -8,8 +8,8 @@ namespace reasampler::instrument::ui {
 
 namespace {
 
-// The knob-row width of a group: cells side by side (no inter-cell gap — the 48px cell
-// already carries its own breathing room around the 28px knob), plus the optional row
+// The knob-row width of a group: cells side by side (no inter-cell gap — the 60px cell
+// already carries its own breathing room around the 40px knob), plus the optional row
 // toggle after a kDeckToggleGap. A spanning group's cells stack, so its knob row is one
 // cell wide plus whatever readout column sits beside it.
 int knobRowWidth(const DeckGroupDesc& g) {
@@ -109,8 +109,10 @@ DeckGroupLayout layoutGroup(const DeckGroupDesc& g, const Rect& box) {
             slotTop += kDeckGroupH + kDeckRowGap;
         }
         if (g.column.id >= 0) {
-            // ONE rect spanning every slot, not a readout per row.
-            const int colX = innerLeft + (g.cellIds.empty() ? 0 : kDeckCellW + kDeckColumnGap);
+            // ONE rect spanning every slot, not a readout per row. Right-anchored off
+            // innerRight rather than measured past the cell slot, so a wider caption
+            // reserve on this group can never detach the column from the padding.
+            const int colX = innerRight - g.column.width;
             out.column = DeckColumnLayout{
                 g.column.id, Rect::ltrb(colX, cellTop, colX + g.column.width,
                                         box.bottom() - kDeckGroupPadY)};
@@ -156,7 +158,7 @@ std::vector<int> justifyGutters(int count, int total, int blockW) {
     const int slack = blockW - total;
     if (slack < gutters * kDeckGroupGap) {
         // The block cannot hold the row: minimum gutters, and the row overruns to the right
-        // rather than wrapping. Unreachable in the editor — see layoutDeck's header note.
+        // rather than wrapping — see layoutDeck's header note for when this degrade applies.
         return std::vector<int>(static_cast<std::size_t>(gutters), kDeckGroupGap);
     }
     const int base = slack / gutters;

src/core/instrument/ui/knob_deck.h

@@ -1,12 +1,8 @@
 // knob_deck.h — knob-deck layout + hit-test for the Sample-face knob deck. Engine-free
 // like param_slider: cells and toggles carry opaque shell-owned control ids. Mirror of
 // action_bar/param_slider; the knob primitive itself (value<->needle-angle, drag) is
-// param_slider's — a knob cell here is just a rect the shell composes it into.
-//
-// A group is a fenced box: caption row (caption left, toggles and a corner radio
-// right-anchored) over a knob row of equal-width cells, optionally followed by one row
-// toggle. Row membership is a PROPERTY OF THE GROUP (DeckRow), never a wrap outcome — see
-// the justification law at layoutDeck.
+// param_slider's — a knob cell here is just a rect the shell composes it into. Group/row
+// composition and the justification law are this directory's own CLAUDE.md's to describe.
 
 #pragma once
 
@@ -31,7 +27,8 @@ inline constexpr int kDeckGroupPadY = 4;      // group box vertical inner paddin
 inline constexpr int kDeckCaptionGap = 2;     // caption row -> knob row gap
 inline constexpr int kDeckToggleGap = 4;      // caption text -> toggle / cells -> row toggle gap
 inline constexpr int kDeckGroupGap = 12;      // gap between groups on a row
-inline constexpr int kDeckRowGap = 8;         // gap between wrapped deck rows
+inline constexpr int kDeckRowGap = 8;         // gap between the deck's two categorical rows,
+                                               // and between the spanning deck's stacked slots
 inline constexpr int kDeckRadioSize = 12;     // the caption-row corner radio square
 inline constexpr int kDeckColumnGap = 8;      // the spanning deck's cell column -> its readout column
 // The knob cell's INNER dial: a concentric sub-disc that edits a second, related value while
@@ -181,7 +178,8 @@ int deckHeight(const std::vector<DeckGroupDesc>& groups);
 // divided equally with the integer residue going to the leftmost ones. Decks are never
 // stretched. Below the width the block needs, every gutter sits at kDeckGroupGap and the row
 // overflows right rather than wrapping — the shell clamps the window to a floor that fits
-// (sample_bands' kEditorMinWidth), so that degrade is unreachable in the editor.
+// (sample_bands' kEditorMinWidth) via checkSizeConstraint, a host-honoured clamp rather than a
+// guarantee, so this degrade is defined and tested rather than assumed impossible.
 DeckLayout layoutDeck(const std::vector<DeckGroupDesc>& groups, int left, int top,
                       int availWidth);