diff --git a/DESIGN.md b/DESIGN.md
index 7eaceec028..30ef7a682a 100644
--- a/DESIGN.md
+++ b/DESIGN.md
@@ -126,11 +126,12 @@ Nothing interactive is square. One ladder, assigned monotonically by box height:
 | Radius | Maka tier | Astryx tier | Assign to |
 |---|---|---|---|
 | 6px | control | inner | chips, keycaps, nested inlays, and product-drawn compact controls |
-| 10px | card | element | cards, rows-as-cards, list containers, chat bubbles; Astryx `Button`, `Input`, `SegmentedControl` |
+| 10px | card | element | cards, rows-as-cards, list containers; Astryx `Button`, `Input`, `SegmentedControl` |
 | 12px | container | container | modals, panels, portal surfaces; Astryx `Card`, `Dialog`, `DropdownMenu` |
+| 28px | chat | chat | the conversation surface as one shape: user bubble, assistant bubble, composer dock. Sourced from Astryx's `--radius-chat` by `ChatMessageBubble` and `ChatComposer` themselves; product CSS never restates it |
 | full | pill (999px) | full (9999px) | badges, pills, circular controls |
 
-- **The Two-Name Rule.** These are one ladder under two vocabularies, and the names never line up: Maka's `control` is Astryx's `inner`, Maka's `card` is Astryx's `element`, Maka's `modal` is Astryx's `container`. Resolve a tier from the box, never from the token name that sounds right. The paired values agree *today* but are independent literals, not aliases — an Astryx upgrade can move one side silently, so a mismatch is a real failure mode rather than an impossibility. Astryx's `--radius-page` (28px) has no Maka tier and no product consumer; anything reaching for a page-level radius is inventing a rung.
+- **The Two-Name Rule.** These are one ladder under two vocabularies, and the names never line up: Maka's `control` is Astryx's `inner`, Maka's `card` is Astryx's `element`, Maka's `modal` is Astryx's `container`. Resolve a tier from the box, never from the token name that sounds right. The paired values agree *today* but are independent literals, not aliases — an Astryx upgrade can move one side silently, so a mismatch is a real failure mode rather than an impossibility. The chat rung is the one tier the product does not assign: `ChatMessageBubble` and `ChatComposer` both resolve `--radius-chat` on their own, which is why the bubble and the dock round together, and why setting a bubble radius or a non-default `density` in product code silently breaks the pair. Astryx's `--radius-page` carries the same 28px literal but is a different token with no Maka tier and no product consumer; reaching for it to match the chat surface is inventing a rung.
 - **The Full-Bleed Rule.** `border-radius: 0` is legal only on true full-bleed rows — an element flush with its container on both sides. Radius and gap move together: if it has breathing room, it has corners.
 - **Proportional marks.** Product-drawn icon plates use ratio-owned radius (~25–27% of the box edge), recorded in prose because Stitch accepts only absolute units.
 
diff --git a/apps/desktop/e2e/session-workbar.spec.ts b/apps/desktop/e2e/session-workbar.spec.ts
index 6f754ba4fb..e5d69d2fb6 100644
--- a/apps/desktop/e2e/session-workbar.spec.ts
+++ b/apps/desktop/e2e/session-workbar.spec.ts
@@ -70,6 +70,32 @@ test('narrow right workbar keeps launcher shortcuts and side-chat send button in
   const composerCard = companion.locator('.maka-composer-astryx');
   // Keep ChatComposer's inner elevation visible.
   await expect(composerCard).toHaveCSS('overflow', 'visible');
+
+  // #3452: Side Chat is a branch of the main conversation, not a second
+  // conversation surface, so its dock rounds like the main dock. Both resolve
+  // Astryx's `--radius-chat`, the same token `ChatMessageBubble` defaults to —
+  // a side-only `--_chat-composer-radius` split the bubble from the dock the
+  // moment the bubbles moved back to that default. Compared against the main
+  // composer rather than a literal so an upstream token change moves both or
+  // fails here.
+  const composerRadii = await page.evaluate(() => {
+    const wrappers = [...document.querySelectorAll('.maka-composer-astryx')];
+    const inCompanion = (element: Element) => element.closest('.maka-quote-companion') !== null;
+    const effectiveRadius = (element: Element | undefined) => {
+      if (!element) return null;
+      const styles = getComputedStyle(element);
+      return (
+        styles.getPropertyValue('--_chat-composer-radius').trim() ||
+        styles.getPropertyValue('--radius-chat').trim()
+      );
+    };
+    return {
+      side: effectiveRadius(wrappers.find(inCompanion)),
+      main: effectiveRadius(wrappers.find((element) => !inCompanion(element))),
+    };
+  });
+  expect(composerRadii.side).toBeTruthy();
+  expect(composerRadii.side).toBe(composerRadii.main);
   // Match the long model-label pressure from the reported side-chat screenshot
   // without coupling the fixture's globally useful default model to this test.
   await companion.locator('.maka-composer-model-chip-text').evaluate((element) => {
diff --git a/apps/desktop/src/renderer/styles/chat-message.css b/apps/desktop/src/renderer/styles/chat-message.css
index d9c12e890e..fcb71e4d87 100644
--- a/apps/desktop/src/renderer/styles/chat-message.css
+++ b/apps/desktop/src/renderer/styles/chat-message.css
@@ -62,26 +62,23 @@
   font: var(--maka-text-body);
 }
 
-/* Padding and max-width belong to ChatMessageBubble; re-declaring those here
-   only forks the primitive. What stays is the product tint, the verbatim-text
-   rule (Maka renders user input as typed, which the primitive has no opinion
-   about) — and, since Visual System 2.0 (T3), the radius TIER.
-
-   The primitive resolves `--radius-container` (12px). DESIGN.md §6 assigns
-   radius by box height, and container is scoped to "modals, panels, portal
-   surfaces" — a message bubble is none of those. Measured in the chat fixture
-   the filled user bubble is 44px tall, which lands it in the card tier (10px,
-   "cards, rows-as-cards, list containers"). Astryx publishes no radius prop on
-   this component (only `variant`), so the tier is expressed on Maka's own
-   class rather than by reaching into the primitive's internals.
+/* Padding, max-width and radius belong to ChatMessageBubble; re-declaring any
+   of them here only forks the primitive. What stays is the product tint and the
+   verbatim-text rule (Maka renders user input as typed, which the primitive has
+   no opinion about).
+
+   Radius is absent on purpose. The primitive resolves `--radius-chat` (28px),
+   the same token `ChatComposer` reads through `--_chat-composer-radius`, so the
+   bubble and the dock round together as one conversation surface — DESIGN.md §6
+   records that as the chat rung. Astryx publishes no radius prop on this
+   component (only `variant`), so a product radius could only fight the
+   primitive, never configure it.
 
    Scoped to the filled bubble on purpose: the assistant bubble is `ghost` (no
-   fill, measured transparent), so it has no corner to round and inherits
-   nothing it needs to override. */
+   fill, measured transparent), so it carries no tint to override. */
 .maka-chat-message-bubble-user {
   background: var(--chat-user-bg);
   color: var(--chat-user-foreground, var(--foreground));
-  border-radius: var(--radius-surface);
   white-space: pre-wrap;
 }
 
diff --git a/apps/desktop/src/renderer/styles/quote-side-panel.css b/apps/desktop/src/renderer/styles/quote-side-panel.css
index e79dcc2be7..f473005fa7 100644
--- a/apps/desktop/src/renderer/styles/quote-side-panel.css
+++ b/apps/desktop/src/renderer/styles/quote-side-panel.css
@@ -78,14 +78,13 @@
   padding-bottom: var(--space-2);
 }
 
-.maka-session-workbar-panel[data-placement="right"]
-  .maka-quote-companion
-  .maka-composer-astryx {
-  --_chat-composer-radius: var(--radius-surface);
-
-  /* Let ChatComposer paint its own radius and elevation. Clipping this wrapper
-     hides the body's hover/focus shadow against the white side panel. */
-}
+/* `.maka-composer-astryx` is deliberately unstyled on this surface. Side Chat is
+   a branch of the main conversation, not a second one, so the composer resolves
+   `--radius-chat` here exactly as it does at full width and pairs with the
+   bubble; a side-only radius token forked the pair the moment the bubbles moved
+   to the primitive's default. The wrapper is also left unclipped — `overflow:
+   hidden` here would hide the body's hover/focus shadow against the white side
+   panel, and `session-workbar.spec.ts` asserts `overflow: visible`. */
 
 .maka-session-workbar-panel[data-placement="right"]
   .maka-quote-companion
diff --git a/packages/ui/src/chat-view.tsx b/packages/ui/src/chat-view.tsx
index 6d1358e9c9..d45637cddd 100644
--- a/packages/ui/src/chat-view.tsx
+++ b/packages/ui/src/chat-view.tsx
@@ -483,8 +483,6 @@ export function ChatView(props: {
             owns. */}
         <ChatMessageList
           className="maka-chat-message-list maka-chatContent"
-          density="compact"
-          gap={4}
           emptyState={conversationItems.length === 0 ? emptyContent : undefined}
         >
           {conversationItems.length > 0 ? (
@@ -589,8 +587,6 @@ export function ChatView(props: {
         <ChatMessageList
           className="maka-chat-message-list maka-chatContent"
           data-turn-source-count={turns.length}
-          density="compact"
-          gap={4}
           isStreaming={streamingActive}
           emptyState={showEmptyState ? emptyContent : undefined}
         >