diff --git a/src/ui/useSelectionBoundary.test.tsx b/src/ui/useSelectionBoundary.test.tsx
index 442d16038..643cf294c 100644
--- a/src/ui/useSelectionBoundary.test.tsx
+++ b/src/ui/useSelectionBoundary.test.tsx
@@ -121,8 +121,10 @@ it("selects only the pane's text on primary+A", () => {
   const event = fireEvent.keyDown(pane, { key: "a", ctrlKey: true, metaKey: true });
   expect(event).toBe(false);
   const range = window.getSelection()!.getRangeAt(0);
-  expect(range.startContainer).toBe(pane);
-  expect(range.endContainer).toBe(pane);
+  expect(range.startContainer).toBe(view.getByText("GET /data.json").firstChild);
+  expect(range.startOffset).toBe(0);
+  expect(range.endContainer).toBe(view.getByText("GET /data.json").firstChild);
+  expect(range.endOffset).toBe("GET /data.json".length);
   expect(window.getSelection()!.toString()).not.toContain("Request history");
 });
 
@@ -133,3 +135,13 @@ it("leaves Select All in an editable field to the field", () => {
   expect(selectReadingPane(input)).toBe(false);
   expect(selectReadingPane(document.body)).toBe(false);
 });
+
+it("ends Select All in the pane's last selectable text, not on its edge before the composer", () => {
+  const view = fixture();
+  expect(selectReadingPane(view.getByText("First message"))).toBe(true);
+  const range = window.getSelection()!.getRangeAt(0);
+  expect(range.startContainer).toBe(view.text("First message"));
+  expect(range.endContainer).toBe(view.text("Last message"));
+  expect(range.endOffset).toBe("Last message".length);
+  expect(window.getSelection()!.toString()).not.toContain("Reply to the agent");
+});
diff --git a/src/ui/useSelectionBoundary.ts b/src/ui/useSelectionBoundary.ts
index 1234f92e5..8c880db51 100644
--- a/src/ui/useSelectionBoundary.ts
+++ b/src/ui/useSelectionBoundary.ts
@@ -120,9 +120,10 @@ export function selectReadingPane(focused: Element | null): boolean {
   const pane = focused.closest<HTMLElement>("[data-selection-scope]");
   const selection = pane?.ownerDocument.getSelection();
   if (!pane || !selection) return false;
-  const range = pane.ownerDocument.createRange();
-  range.selectNodeContents(pane);
-  selection.removeAllRanges();
-  selection.addRange(range);
+  // From the first to the last text, not the pane's own boundaries, which WebKit paints into
+  // the field after the pane (the composer).
+  const start = textEdge(pane, "start");
+  const end = textEdge(pane, "end");
+  selection.setBaseAndExtent(start.node, start.offset, end.node, end.offset);
   return true;
 }