diff --git a/ui/src/e2e/chat-flow.e2e.test.ts b/ui/src/e2e/chat-flow.e2e.test.ts
index b327ba8d58c9..3fa6b0b57fd9 100644
--- a/ui/src/e2e/chat-flow.e2e.test.ts
+++ b/ui/src/e2e/chat-flow.e2e.test.ts
@@ -482,6 +482,12 @@ describeControlUiE2e("Control UI mocked Gateway E2E", () => {
       expect(await gateway.getRequests("sessions.files.list")).toHaveLength(0);
       expect(await page.locator(".chat-workspace-rail__file").count()).toBe(0);
       expect(await page.locator(".chat-workspace-rail__collapsed-icon svg").count()).toBe(1);
+      // The rail docks flush to the window edge in both states (no content gutter).
+      const railEdgeGap = () =>
+        page.locator(".chat-workspace-rail").evaluate((element) => {
+          return window.innerWidth - element.getBoundingClientRect().right;
+        });
+      expect(await railEdgeGap()).toBe(0);
 
       await page.getByRole("button", { name: "Expand session workspace" }).click();
       await page.getByRole("button", { name: "Collapse session workspace" }).waitFor({
@@ -495,6 +501,7 @@ describeControlUiE2e("Control UI mocked Gateway E2E", () => {
       });
       expect(await gateway.getRequests("sessions.files.list")).toHaveLength(1);
       expect(await gateway.getRequests("artifacts.list")).toHaveLength(1);
+      expect(await railEdgeGap()).toBe(0);
 
       await page.getByRole("button", { name: "Collapse session workspace" }).click();
       await page.getByRole("button", { name: "Expand session workspace" }).waitFor({
diff --git a/ui/src/styles/chat/sidebar.css b/ui/src/styles/chat/sidebar.css
index dff9167130a1..db6c57c05fca 100644
--- a/ui/src/styles/chat/sidebar.css
+++ b/ui/src/styles/chat/sidebar.css
@@ -9,7 +9,24 @@
 }
 
 .chat-workbench--workspace-collapsed {
-  grid-template-columns: minmax(0, 1fr) 52px;
+  /* Collapsed rail is a slim always-visible icon strip (Cursor-style); it
+     stays in layout so it never overlays or floats over chat content. */
+  grid-template-columns: minmax(0, 1fr) 44px;
+}
+
+/* The workspace rail docks flush to the window edge like the terminal panel:
+   drop the chat content's right gutter and square the card's right corners in
+   both rail states. Guarded to viewports where the rail actually renders
+   (it is display:none <=1120px, where the gutter should stay). */
+@media (min-width: 1121px) {
+  .content--chat:has(.chat-workbench) {
+    padding-right: 0;
+  }
+
+  .content--chat:has(.chat-workbench) .chat {
+    border-top-right-radius: 0;
+    border-bottom-right-radius: 0;
+  }
 }
 
 .chat-split-container {
@@ -54,7 +71,7 @@
 .chat-workspace-rail--collapsed {
   align-items: center;
   gap: 10px;
-  padding: 12px 8px;
+  padding: 12px 6px;
 }
 
 .chat-workspace-rail__header {