diff --git a/ui/src/components/EntityRow.test.tsx b/ui/src/components/EntityRow.test.tsx
index 5845a9d33e8..5b94343405b 100644
--- a/ui/src/components/EntityRow.test.tsx
+++ b/ui/src/components/EntityRow.test.tsx
@@ -70,7 +70,7 @@ describe("EntityRow", () => {
     );
 
     // The name keeps a usable floor instead of collapsing to zero...
-    expect(markup).toContain("min-w-(--sz-7rem)");
+    expect(markup).toContain("min-w-(--sz-6rem)");
     // ...and the meta cluster is the item that yields (shrinks), not the title.
     expect(markup).toContain("min-w-0 shrink");
     expect(markup).not.toContain('class="flex items-center gap-2 shrink-0"');
diff --git a/ui/src/components/EntityRow.tsx b/ui/src/components/EntityRow.tsx
index b03208295a9..43009093d45 100644
--- a/ui/src/components/EntityRow.tsx
+++ b/ui/src/components/EntityRow.tsx
@@ -77,7 +77,7 @@ export function EntityRow({
         className={cn(
           // `titlePriority` gives the name a floor so it ellipsizes instead of
           // collapsing to zero; otherwise the title may shrink to nothing.
-          titlePriority ? "min-w-(--sz-7rem)" : "min-w-0",
+          titlePriority ? "min-w-(--sz-6rem)" : "min-w-0",
           !meta && "flex-1",
           titleClassName,
         )}
diff --git a/ui/src/components/SidebarAgents.tsx b/ui/src/components/SidebarAgents.tsx
index 4def4ef4080..ffa7eb2e410 100644
--- a/ui/src/components/SidebarAgents.tsx
+++ b/ui/src/components/SidebarAgents.tsx
@@ -165,6 +165,7 @@ function SidebarAgentItem({
       iconNode={<AgentIcon icon={agent.icon} className="shrink-0 h-4 w-4" />}
       active={isActive}
       liveCount={runCount}
+      labelClassName={builtInStatus ? "min-w-(--sz-4_5rem) flex-initial" : undefined}
       className={cn(
         "min-w-0 flex-1",
         // Reserve room for the hover ⋯ menu; starred rows widen it for the
diff --git a/ui/src/components/SidebarNavItem.tsx b/ui/src/components/SidebarNavItem.tsx
index e7d7619afa3..b9856e2ad7e 100644
--- a/ui/src/components/SidebarNavItem.tsx
+++ b/ui/src/components/SidebarNavItem.tsx
@@ -44,6 +44,7 @@ interface SidebarNavItemProps {
   iconNode?: ReactNode;
   end?: boolean;
   className?: string;
+  labelClassName?: string;
   badge?: number;
   badgeTone?: "default" | "danger";
   /**
@@ -75,6 +76,7 @@ export function SidebarNavItem({
   iconNode,
   end,
   className,
+  labelClassName,
   badge,
   badgeTone = "default",
   badgeLabel,
@@ -156,7 +158,7 @@ export function SidebarNavItem({
           />
         )}
       </span>
-      <span className={rail ? SIDEBAR_RAIL_HIDDEN_LABEL : "flex-1 truncate"}>{label}</span>
+      <span className={rail ? SIDEBAR_RAIL_HIDDEN_LABEL : cn("min-w-0 flex-1 truncate", labelClassName)}>{label}</span>
       {!rail && trailing}
       {!rail && textBadge && (
         <Badge variant="ghost"
diff --git a/ui/src/index.css b/ui/src/index.css
index 950418dd740..2c0e3fb0da5 100644
--- a/ui/src/index.css
+++ b/ui/src/index.css
@@ -1565,6 +1565,7 @@ span.paperclip-mention-chip[data-mention-kind="external-object"] {
   --sz-80vh: 80vh; /* Extracted from ui/src/components/DocumentAnnotationPanel.tsx (max-h-[80vh]). */
   --sz-360px: 360px; /* Extracted from ui/src/components/DocumentAnnotationPanel.tsx (w-[360px]). */
   --sz-85vh: 85vh; /* Extracted from ui/src/components/DocumentDiffModal.tsx (max-h-[85vh]). */
+  --sz-6rem: 6rem; /* Extracted from ui/src/components/EntityRow.tsx (min-w-[6rem]). */
   --sz-1px: 1px; /* Extracted from ui/src/components/EntityRow.tsx (top-[1px]). */
   --sz-100px: 100px; /* Extracted from ui/src/components/ExecutionParticipantPicker.tsx (max-w-[100px]). */
   --sz-calc-3: min(840px,calc(100dvh - 2rem)); /* Extracted from ui/src/components/FileViewerSheet.tsx (h-[min(840px,calc(100dvh-2rem))]). */
@@ -1618,6 +1619,7 @@ span.paperclip-mention-chip[data-mention-kind="external-object"] {
   --sz-calc-23: min(32rem,calc(100vw - 2rem)); /* Extracted from ui/src/components/SearchableSelect.tsx (max-w-[min(32rem,calc(100vw-2rem))]). */
   --sz-277px: 277px; /* Extracted from ui/src/components/SidebarAccountMenu.test.tsx (w-[277px]). */
   --sz-calc-24: calc(100vw - 1rem); /* Extracted from ui/src/components/SidebarAccountMenu.tsx (max-w-[calc(100vw-1rem)]). */
+  --sz-4_5rem: 4.5rem; /* Extracted from ui/src/components/SidebarAgents.tsx (min-w-[4.5rem]). */
   --sz-36px: 36px; /* Extracted from ui/src/components/WorkspaceFileBrowser.tsx (min-h-[36px]). */
   --sz-32px: 32px; /* Extracted from ui/src/components/WorkspaceFileBrowser.tsx (min-h-[32px]). */
   --sz-30px: 30px; /* Extracted from ui/src/components/WorkspaceFileBrowser.tsx (min-h-[30px]). */