diff --git a/docs/proposals/mockups/wtc-rebuild/SPEC-wtc-rebuild.md b/docs/proposals/mockups/wtc-rebuild/SPEC-wtc-rebuild.md
index 4614e89d2..c7ae6786e 100644
--- a/docs/proposals/mockups/wtc-rebuild/SPEC-wtc-rebuild.md
+++ b/docs/proposals/mockups/wtc-rebuild/SPEC-wtc-rebuild.md
@@ -177,6 +177,17 @@ above rather than proposing anything new):**
     its ActionGrid siblings now — hierarchy comes from position (its own row, above the grid)
     and colour (`.primary`, orange) rather than from being a larger control.
 
+14. **A14: Exclusion-group chip width + group boundary (#742/#743).** `ChipGroup`
+    (`attributeChipRender.tsx`) gets an explicit `width: fit-content` — its containing row
+    switches to `flex-direction: column` once there's room to form (A10's still-present `@media (min-width: 576px)`), and a flex container's default `align-items: stretch` then stretches
+    any child with no definite cross-size to that column's full width; a definite width makes
+    the chip immune to that stretch regardless of which axis the ancestor row happens to run on.
+    `AttributeChipPanel.tsx`'s flat-stack `LeftArea`/`RightArea` (`BORDER_COLOR_GROUP`/
+    `FRAME_STYLE_GROUP`, two independent axes) now render each group's existing `label` field as
+    a heading above its chip row, plus a divider between them — previously the two groups' rows
+    ran together as one unlabelled list, so a collapse that correctly affects only one group's
+    siblings read as a bug affecting a supposedly single list.
+
 D-number scope note: D-numbers are per-proposal in this repo (proposal-h owns
 its own D1–D19; the old WTC round used W4–W7). The decisions below are the
 **WTC-rebuild round's** ledger, numbered WD1.. to avoid collision with either.
diff --git a/frontend/src/features/attributeChips/AttributeChipPanel.tsx b/frontend/src/features/attributeChips/AttributeChipPanel.tsx
index a49d4d63d..130df8399 100644
--- a/frontend/src/features/attributeChips/AttributeChipPanel.tsx
+++ b/frontend/src/features/attributeChips/AttributeChipPanel.tsx
@@ -73,25 +73,48 @@ const TopArea = styled(ChipRow)`
   grid-area: top;
 `;
 
+// Issue #743: BORDER_COLOR_GROUP and FRAME_STYLE_GROUP are independent axes (a card's border
+// colour and its frame era don't imply each other), but nothing previously rendered their
+// `ExclusionGroup.label` - the two groups' chip rows ran together as one unlabelled list, so a
+// user reasonably read a correct half-collapse (one group's siblings dimming, the other
+// untouched) as a bug. Renders the label that already existed as data.
+const GroupHeading = styled.p`
+  margin: 0 0 0.3rem;
+  font-size: 0.75rem;
+  font-weight: 600;
+  letter-spacing: 0.04em;
+  text-transform: uppercase;
+  color: rgba(0, 0, 0, 0.55);
+  text-align: center;
+`;
+
+// A divider between the two exclusion groups (flat-stack layout only, see the `cardSlot == null`
+// branch below) - the ring layout already keeps them apart spatially (left/right of the card),
+// so it doesn't need one.
+const GroupDivider = styled.hr`
+  width: 100%;
+  margin: 0;
+  border: none;
+  border-top: 1px solid rgba(0, 0, 0, 0.12);
+`;
+
 // Row+wrap below `sm` (matching TopArea, since the ring hasn't formed yet and there's no
 // flanking column to stack vertically inside) - becomes a genuine vertical column only once
 // the ring itself forms at `sm` and up.
-const LeftArea = styled(ChipRow)`
-  grid-area: left;
-
+const ExclusionChipRow = styled(ChipRow)`
   @media (min-width: 576px) {
     flex-direction: column;
-    align-items: stretch;
   }
 `;
 
-const RightArea = styled(ChipRow)`
-  grid-area: right;
+// Wraps a heading plus its `ExclusionChipRow` as one unit, so `ChipRing`'s grid can still
+// position the whole group (heading + chips together) as a single "left"/"right" cell.
+const LeftArea = styled.div`
+  grid-area: left;
+`;
 
-  @media (min-width: 576px) {
-    flex-direction: column;
-    align-items: stretch;
-  }
+const RightArea = styled.div`
+  grid-area: right;
 `;
 
 // position: relative so an absolutely-positioned burst rendered as part of `cardSlot` (see
@@ -183,16 +206,22 @@ export function AttributeChipPanel({
   );
   const leftArea = leftGroup != null && (
     <LeftArea>
-      {leftGroup.chips.map((chip) =>
-        renderAttributeChip(chipArgs, chip.tagName, chip.label)
-      )}
+      <GroupHeading>{leftGroup.label}</GroupHeading>
+      <ExclusionChipRow>
+        {leftGroup.chips.map((chip) =>
+          renderAttributeChip(chipArgs, chip.tagName, chip.label)
+        )}
+      </ExclusionChipRow>
     </LeftArea>
   );
   const rightArea = rightGroup != null && (
     <RightArea>
-      {rightGroup.chips.map((chip) =>
-        renderAttributeChip(chipArgs, chip.tagName, chip.label)
-      )}
+      <GroupHeading>{rightGroup.label}</GroupHeading>
+      <ExclusionChipRow>
+        {rightGroup.chips.map((chip) =>
+          renderAttributeChip(chipArgs, chip.tagName, chip.label)
+        )}
+      </ExclusionChipRow>
     </RightArea>
   );
 
@@ -203,6 +232,7 @@ export function AttributeChipPanel({
         <FlatChipStack data-testid="attribute-chip-panel">
           {topArea}
           {leftArea}
+          {leftArea != null && rightArea != null && <GroupDivider />}
           {rightArea}
         </FlatChipStack>
       </>
diff --git a/frontend/src/features/attributeChips/attributeChipRender.tsx b/frontend/src/features/attributeChips/attributeChipRender.tsx
index b16cfa0cd..5fa043965 100644
--- a/frontend/src/features/attributeChips/attributeChipRender.tsx
+++ b/frontend/src/features/attributeChips/attributeChipRender.tsx
@@ -40,6 +40,13 @@ import {
 // reclaim the row space the owner reported as dead. Height/tap-targets are unchanged (still the
 // full 44px buttons, still directly tappable to override the implied state - see this file's
 // header comment).
+// `width: fit-content` (issue #742): an exclusion-group chip renders inside a container
+// (`LeftArea`/`RightArea`, AttributeChipPanel.tsx) that switches to `flex-direction: column`
+// once the ring/flat-stack has room to form; the flex spec's default `align-items: stretch`
+// then stretches any child with no definite cross-size to the column's full width, which is how
+// a chip meant to be a small label+buttons pill ended up spanning the whole panel with its Yes/
+// No buttons stranded far from the label. A definite width makes the chip immune to that stretch
+// regardless of an ancestor's flex-direction.
 export const ChipGroup = styled.div<{ impliedNegative: boolean }>`
   border: 2px solid rgba(0, 0, 0, 0.25);
   border-radius: 0.5rem;
@@ -48,6 +55,7 @@ export const ChipGroup = styled.div<{ impliedNegative: boolean }>`
   font-size: 0.85rem;
   white-space: nowrap;
   min-height: 44px;
+  width: fit-content;
   display: inline-flex;
   align-items: stretch;
   overflow: hidden;