diff --git a/src/__tests__/baselines/version-stamp-comments.json b/src/__tests__/baselines/version-stamp-comments.json
index 10a8c80c5..105c8dc14 100644
--- a/src/__tests__/baselines/version-stamp-comments.json
+++ b/src/__tests__/baselines/version-stamp-comments.json
@@ -1,7 +1,7 @@
 {
   "$comment": "Comment lines that open with a release version, per file under src/. Maintained by src/__tests__/version-stamp-ratchet.test.ts.",
   "count": 2876,
-  "total": 9164,
+  "total": 9161,
   "entries": {
     "__tests__/account-payload-consumer-guard.test.ts": 2,
     "__tests__/acting-account-boundary-guard.test.ts": 7,
@@ -925,7 +925,7 @@
     "components/insights/coach-panel/guided-questions-card.tsx": 1,
     "components/insights/coach-panel/guided-questions-machine.ts": 2,
     "components/insights/coach-panel/memory-note.tsx": 1,
-    "components/insights/coach-panel/message-thread.tsx": 31,
+    "components/insights/coach-panel/message-thread.tsx": 28,
     "components/insights/coach-panel/method-line.tsx": 1,
     "components/insights/coach-panel/mobile-rail-tray.tsx": 2,
     "components/insights/coach-panel/read-aloud.tsx": 8,
diff --git a/src/components/insights/coach-panel/__tests__/message-thread.test.tsx b/src/components/insights/coach-panel/__tests__/message-thread.test.tsx
index 9c28c40b1..ea843d1aa 100644
--- a/src/components/insights/coach-panel/__tests__/message-thread.test.tsx
+++ b/src/components/insights/coach-panel/__tests__/message-thread.test.tsx
@@ -252,6 +252,16 @@ describe("<MessageThread>", () => {
     );
   });
 
+  it("keeps the floating New conversation button's height free below the last message", () => {
+    const html = render(<MessageThread conversation={baseConversation} />);
+    const scroller =
+      html.match(/<div[^>]*data-slot="coach-message-thread"[^>]*>/)?.[0] ?? "";
+
+    expect(scroller).toContain("pb-20");
+    // Back to the plain gutter once the button sits beside the composer.
+    expect(scroller).toContain("@min-[57rem]/coach-thread:pb-6");
+  });
+
   it("folds an older message's provenance into the thought-process row, never a raw key", () => {
     const html = render(<MessageThread conversation={baseConversation} />);
     expect(html).toContain('data-slot="coach-turn-steps-done"');
diff --git a/src/components/insights/coach-panel/message-thread.tsx b/src/components/insights/coach-panel/message-thread.tsx
index 941d4c55c..d61fa1c4e 100644
--- a/src/components/insights/coach-panel/message-thread.tsx
+++ b/src/components/insights/coach-panel/message-thread.tsx
@@ -640,27 +640,25 @@ export function MessageThread({
           one scroll container. */}
       <div
         data-slot="coach-message-thread-frame"
-        className="relative flex min-h-0 flex-1 flex-col"
+        className="@container/coach-thread relative flex min-h-0 flex-1 flex-col"
       >
         <div
           ref={scrollerRef}
           data-slot="coach-message-thread"
           className={cn(
-            // v1.18.6.1 — `min-h-0 flex-1` (not `h-full`) so the scroll region
-            // resolves its height from the flex parent rather than a 100%-of-auto
-            // chain that let the thread grow instead of scroll.
-            // v1.18.7 — calmer vertical rhythm (gap-6) and more generous top/
-            // bottom breathing room so the conversation reads like a document,
-            // not a chat log packed against the chrome.
+            // `min-h-0 flex-1`, not `h-full`: the region takes its height from
+            // the flex parent, so the thread scrolls instead of growing.
             "flex min-h-0 flex-1 flex-col gap-6 overflow-y-auto px-4 py-6 sm:px-6",
-            // v1.18.6 v1.18.7 — on the wide page surface an edge-to-
-            // edge thread sprawled the prose past a readable measure. Centre the
-            // content on a narrower, calmer Claude/ChatGPT-like column
-            // (`max-w-2xl`) via an `mx-auto` inner gutter; the scrollbar still
-            // rides the surface edge. The drawer surface is already narrow, so
-            // the cap only bites on the wide page surface.
+            // A readable measure on the wide page; the scrollbar stays on the
+            // surface edge.
             "[&>*]:mx-auto [&>*]:w-full [&>*]:max-w-2xl",
             "scroll-smooth",
+            // Every surface with a thread floats New conversation over its
+            // bottom edge while the composer fills the column (`NewChatFab`),
+            // so the last message keeps the button's height free, as the
+            // shell clears the Coach button. The button moves beside a 54rem
+            // composer, which the column is at 57rem with its padding.
+            "pb-20 @min-[57rem]/coach-thread:pb-6",
           )}
         >
           {[
diff --git a/src/components/insights/coach-panel/new-chat-fab.tsx b/src/components/insights/coach-panel/new-chat-fab.tsx
index 97fb69c9b..0d94e6379 100644
--- a/src/components/insights/coach-panel/new-chat-fab.tsx
+++ b/src/components/insights/coach-panel/new-chat-fab.tsx
@@ -16,7 +16,8 @@ import { cn } from "@/lib/utils";
  * column is wide enough, it takes the bottom right corner beside the
  * composer, where the Coach button sits on other pages; where the composer
  * fills the width (a phone, the drawer, a narrow column), it rises just
- * above the composer's top edge so it never covers the field.
+ * above the composer's top edge so it never covers the field, and the thread
+ * keeps its height free below the last message.
  *
  * The parent is the composer's wrapper and must be `relative` and an
  * `@container/composer`.