diff --git a/apps/web/src/components/chat/ChatComposer.tsx b/apps/web/src/components/chat/ChatComposer.tsx
index b89521a932d..ab31c4bfd8b 100644
--- a/apps/web/src/components/chat/ChatComposer.tsx
+++ b/apps/web/src/components/chat/ChatComposer.tsx
@@ -425,6 +425,7 @@ const ComposerFooterPrimaryActions = memo(function ComposerFooterPrimaryActions(
   isEnvironmentUnavailable: boolean;
   hasSendableContent: boolean;
   preserveComposerFocusOnPointerDown?: boolean;
+  showSendWhileRunning?: boolean;
   onPreviousPendingQuestion: () => void;
   onInterrupt: () => void;
   onImplementPlanInNewThread: () => void;
@@ -453,6 +454,7 @@ const ComposerFooterPrimaryActions = memo(function ComposerFooterPrimaryActions(
         isPreparingWorktree={props.isPreparingWorktree}
         hasSendableContent={props.hasSendableContent}
         preserveComposerFocusOnPointerDown={props.preserveComposerFocusOnPointerDown ?? false}
+        showSendWhileRunning={props.showSendWhileRunning ?? false}
         onPreviousPendingQuestion={props.onPreviousPendingQuestion}
         onInterrupt={props.onInterrupt}
         onImplementPlanInNewThread={props.onImplementPlanInNewThread}
@@ -3164,6 +3166,7 @@ export const ChatComposer = memo(function ChatComposer(props: ChatComposerProps)
                   isPreparingWorktree={isPreparingWorktree}
                   hasSendableContent={composerSendState.hasSendableContent}
                   preserveComposerFocusOnPointerDown={isMobileViewport}
+                  showSendWhileRunning={isMobileViewport}
                   onPreviousPendingQuestion={onPreviousActivePendingUserInputQuestion}
                   onInterrupt={handleInterruptPrimaryAction}
                   onImplementPlanInNewThread={handleImplementPlanInNewThreadPrimaryAction}
diff --git a/apps/web/src/components/chat/ComposerPrimaryActions.test.ts b/apps/web/src/components/chat/ComposerPrimaryActions.test.tsx
similarity index 55%
rename from apps/web/src/components/chat/ComposerPrimaryActions.test.ts
rename to apps/web/src/components/chat/ComposerPrimaryActions.test.tsx
index b7624db0a8f..14ee2e092d5 100644
--- a/apps/web/src/components/chat/ComposerPrimaryActions.test.ts
+++ b/apps/web/src/components/chat/ComposerPrimaryActions.test.tsx
@@ -1,6 +1,29 @@
+import { renderToStaticMarkup } from "react-dom/server";
 import { describe, expect, it } from "vite-plus/test";
 
-import { formatPendingPrimaryActionLabel } from "./ComposerPrimaryActions";
+import { ComposerPrimaryActions, formatPendingPrimaryActionLabel } from "./ComposerPrimaryActions";
+
+const renderPrimaryActions = (
+  overrides: Partial<Parameters<typeof ComposerPrimaryActions>[0]> = {},
+) =>
+  renderToStaticMarkup(
+    <ComposerPrimaryActions
+      compact={false}
+      pendingAction={null}
+      isRunning={false}
+      showPlanFollowUpPrompt={false}
+      promptHasText={false}
+      isSendBusy={false}
+      isConnecting={false}
+      isEnvironmentUnavailable={false}
+      isPreparingWorktree={false}
+      hasSendableContent={false}
+      onPreviousPendingQuestion={() => {}}
+      onInterrupt={() => {}}
+      onImplementPlanInNewThread={() => {}}
+      {...overrides}
+    />,
+  );
 
 describe("formatPendingPrimaryActionLabel", () => {
   it("returns 'Submitting...' while responding", () => {
@@ -91,3 +114,35 @@ describe("formatPendingPrimaryActionLabel", () => {
     ).toBe("Submit answers");
   });
 });
+
+describe("ComposerPrimaryActions send-while-running", () => {
+  it("only renders stop while running when Enter-to-send is available", () => {
+    const markup = renderPrimaryActions({ isRunning: true, hasSendableContent: true });
+
+    expect(markup).toContain('aria-label="Stop generation"');
+    expect(markup).not.toContain('aria-label="Send message"');
+  });
+
+  it("renders send alongside stop while running when Enter-to-send is unavailable", () => {
+    const markup = renderPrimaryActions({
+      isRunning: true,
+      hasSendableContent: true,
+      showSendWhileRunning: true,
+    });
+
+    expect(markup).toContain('aria-label="Stop generation"');
+    expect(markup).toContain('aria-label="Send message"');
+    expect(markup).toContain('type="submit"');
+  });
+
+  it("keeps stop as the only action while running with an empty composer", () => {
+    const markup = renderPrimaryActions({
+      isRunning: true,
+      hasSendableContent: false,
+      showSendWhileRunning: true,
+    });
+
+    expect(markup).toContain('aria-label="Stop generation"');
+    expect(markup).not.toContain('aria-label="Send message"');
+  });
+});
diff --git a/apps/web/src/components/chat/ComposerPrimaryActions.tsx b/apps/web/src/components/chat/ComposerPrimaryActions.tsx
index 504b7e1cc44..4e9b5d7b13b 100644
--- a/apps/web/src/components/chat/ComposerPrimaryActions.tsx
+++ b/apps/web/src/components/chat/ComposerPrimaryActions.tsx
@@ -28,6 +28,9 @@ interface ComposerPrimaryActionsProps {
   isPreparingWorktree: boolean;
   hasSendableContent: boolean;
   preserveComposerFocusOnPointerDown?: boolean;
+  /** Enter-to-send is disabled on mobile viewports, where stop would otherwise
+   * be the only primary action and a running turn could not be steered. */
+  showSendWhileRunning?: boolean;
   onPreviousPendingQuestion: () => void;
   onInterrupt: () => void;
   onImplementPlanInNewThread: () => void;
@@ -68,6 +71,7 @@ export const ComposerPrimaryActions = memo(function ComposerPrimaryActions({
   isPreparingWorktree,
   hasSendableContent,
   preserveComposerFocusOnPointerDown = false,
+  showSendWhileRunning = false,
   onPreviousPendingQuestion,
   onInterrupt,
   onImplementPlanInNewThread,
@@ -132,22 +136,6 @@ export const ComposerPrimaryActions = memo(function ComposerPrimaryActions({
     );
   }
 
-  if (isRunning) {
-    return (
-      <button
-        type="button"
-        className="flex size-8 cursor-pointer items-center justify-center rounded-full bg-destructive/90 text-white shadow-xs shadow-destructive/24 inset-shadow-[0_1px_--theme(--color-white/16%)] transition-all duration-150 hover:bg-destructive hover:scale-105 active:inset-shadow-[0_1px_--theme(--color-black/8%)] active:shadow-none sm:h-8 sm:w-8"
-        {...pointerFocusProps}
-        onClick={onInterrupt}
-        aria-label="Stop generation"
-      >
-        <svg width="12" height="12" viewBox="0 0 12 12" fill="currentColor" aria-hidden="true">
-          <rect x="2" y="2" width="8" height="8" rx="1.5" />
-        </svg>
-      </button>
-    );
-  }
-
   if (showPlanFollowUpPrompt) {
     if (promptHasText) {
       return (
@@ -202,7 +190,7 @@ export const ComposerPrimaryActions = memo(function ComposerPrimaryActions({
     );
   }
 
-  return (
+  const sendButton = (
     <button
       type="submit"
       className={cn(
@@ -253,4 +241,25 @@ export const ComposerPrimaryActions = memo(function ComposerPrimaryActions({
       )}
     </button>
   );
+
+  if (!isRunning) {
+    return sendButton;
+  }
+
+  return (
+    <>
+      <button
+        type="button"
+        className="flex size-8 cursor-pointer items-center justify-center rounded-full bg-destructive/90 text-white shadow-xs shadow-destructive/24 inset-shadow-[0_1px_--theme(--color-white/16%)] transition-all duration-150 hover:bg-destructive hover:scale-105 active:inset-shadow-[0_1px_--theme(--color-black/8%)] active:shadow-none sm:h-8 sm:w-8"
+        {...pointerFocusProps}
+        onClick={onInterrupt}
+        aria-label="Stop generation"
+      >
+        <svg width="12" height="12" viewBox="0 0 12 12" fill="currentColor" aria-hidden="true">
+          <rect x="2" y="2" width="8" height="8" rx="1.5" />
+        </svg>
+      </button>
+      {showSendWhileRunning && hasSendableContent ? sendButton : null}
+    </>
+  );
 });