fix(webapp): fade overflowing side menu selector labels (#4412)

Long organization, project, and environment names in the side menu were
cut off mid-character. They now fade out at the right edge like the rest
of the side menu items already did.

### Example of faded long names:
<img width="246" height="200" alt="CleanShot 2026-07-28 at 22 59 24"
src="https://github.com/user-attachments/assets/efa60b87-286f-4ab0-9d4e-490ef2de53e5"
/>

apps/webapp/app/components/environments/EnvironmentLabel.tsx

@@ -6,6 +6,7 @@ import {
 } from "~/assets/icons/EnvironmentIcons";
 import type { RuntimeEnvironment } from "~/models/runtimeEnvironment.server";
 import { cn } from "~/utils/cn";
+import { labelOverflowFadeStyle } from "~/components/primitives/labelOverflowFade";
 import { SimpleTooltip } from "~/components/primitives/Tooltip";
 import { useEffect, useRef, useState } from "react";
 
@@ -88,7 +89,7 @@ export function EnvironmentLabel({
   tooltipSideOffset?: number;
   tooltipSide?: "top" | "right" | "bottom" | "left";
   disableTooltip?: boolean;
-  /** When false, the label clips without an ellipsis (side menu fades it in place). Defaults true. */
+  /** When false, an overflowing label fades at its right edge instead of ending in an ellipsis. */
   truncate?: boolean;
 }) {
   const spanRef = useRef<HTMLSpanElement>(null);
@@ -122,6 +123,7 @@ export function EnvironmentLabel({
         environmentTextClassName(environment),
         className
       )}
+      style={labelOverflowFadeStyle(!truncate && isTruncated)}
     >
       {text}
     </span>

apps/webapp/app/components/navigation/EnvironmentSelector.tsx

@@ -94,7 +94,7 @@ export function EnvironmentSelector({
                 fades in place and scales its width to 0 so it never holds width mid-drag. The
                 selector is also reused outside the side menu (BlankStatePanels, limits) where the var
                 is unset — the 0.2 max-width fallback pins a ~200px cap (0.2 * 1000px) so long names
-                ellipsis-truncate there instead of widening the control, while opacity stays 1.
+                fade out there instead of widening the control, while opacity stays 1.
               */}
               <span
                 className="flex min-w-0 items-center overflow-hidden"
@@ -105,7 +105,7 @@ export function EnvironmentSelector({
               >
                 <EnvironmentLabel
                   environment={environment}
-                  className="text-ellipsis text-[0.90625rem] font-medium tracking-[-0.01em]"
+                  className="text-[0.90625rem] font-medium tracking-[-0.01em]"
                   disableTooltip
                   truncate={false}
                 />

apps/webapp/app/components/navigation/SideMenu.tsx

@@ -1682,9 +1682,9 @@ function OrgSelector({
                 className="flex min-w-0 items-center gap-1.5 overflow-hidden"
                 style={SIDE_MENU_SELECTOR_LABEL_STYLE}
               >
-                <span className="overflow-hidden whitespace-nowrap text-[0.90625rem] font-medium tracking-[-0.01em] text-text-bright">
+                <SideMenuLabel className="text-[0.90625rem] font-medium tracking-[-0.01em] text-text-bright">
                   {organization.title}
-                </span>
+                </SideMenuLabel>
               </span>
             </span>
             <span
@@ -1987,9 +1987,9 @@ function ProjectSelector({
                 className="flex min-w-0 items-center overflow-hidden"
                 style={SIDE_MENU_SELECTOR_LABEL_STYLE}
               >
-                <span className="overflow-hidden whitespace-nowrap text-[0.90625rem] font-medium tracking-[-0.01em] text-text-bright">
+                <SideMenuLabel className="text-[0.90625rem] font-medium tracking-[-0.01em] text-text-bright">
                   {project.name ?? "Select a project"}
-                </span>
+                </SideMenuLabel>
               </span>
             </span>
             <span
@@ -2041,7 +2041,7 @@ function ProjectSelector({
                 to={v3ProjectPath(organization, p)}
                 title={
                   <div className="flex w-full items-center justify-between text-text-bright">
-                    <span className="grow truncate text-left">{p.name}</span>
+                    <SideMenuLabel className="min-w-0 grow text-left">{p.name}</SideMenuLabel>
                   </div>
                 }
                 isSelected={isSelected}

apps/webapp/app/components/navigation/SideMenuItem.tsx

@@ -12,12 +12,10 @@ import { motion } from "framer-motion";
 import { usePathName } from "~/hooks/usePathName";
 import { cn } from "~/utils/cn";
 import { type RenderIcon, Icon } from "../primitives/Icon";
+import { labelOverflowFadeStyle } from "../primitives/labelOverflowFade";
 import { SimpleTooltip } from "../primitives/Tooltip";
 import { useActiveFavoriteId } from "./favoritePages";
 
-/** Right-edge fade shown instead of a hard clip, only while the label actually overflows. */
-const LABEL_OVERFLOW_MASK = "linear-gradient(to right, black calc(100% - 1.5rem), transparent)";
-
 /**
  * A menu label that fades out at its right edge when (and only when) the text overflows. Text
  * that fits renders exactly as before, with no mask. Overflow is re-measured when the element
@@ -56,12 +54,7 @@ export function SideMenuLabel({
     <span
       ref={ref}
       className={cn("overflow-hidden whitespace-nowrap", className)}
-      style={{
-        ...style,
-        ...(isOverflowing
-          ? { maskImage: LABEL_OVERFLOW_MASK, WebkitMaskImage: LABEL_OVERFLOW_MASK }
-          : undefined),
-      }}
+      style={{ ...style, ...labelOverflowFadeStyle(isOverflowing) }}
     >
       {children}
     </span>

apps/webapp/app/components/primitives/labelOverflowFade.ts

@@ -0,0 +1,7 @@
+const LABEL_OVERFLOW_MASK = "linear-gradient(to right, black calc(100% - 1.5rem), transparent)";
+
+export function labelOverflowFadeStyle(isOverflowing: boolean) {
+  return isOverflowing
+    ? { maskImage: LABEL_OVERFLOW_MASK, WebkitMaskImage: LABEL_OVERFLOW_MASK }
+    : undefined;
+}