diff --git a/CHANGELOG.md b/CHANGELOG.md
index ea29cc24..c8ec9465 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,13 @@
 
 ## [Unreleased]
 
+## [v0.51.171] — 2026-05-30 — Release EQ (stage-batch53 — tool-output card badge + Neon opt-in skin)
+
+### Added
+
+- Tool-call output cards now carry a persistent "Tool output" badge and accent rail so tool output stays visually distinct from final assistant responses without requiring hover (#2867).
+- New opt-in "Neon" cyberpunk skin (dark-first, purple/cyan accents). Default-off; select it from the skin list like Catppuccin or Nous.
+
 ## [v0.51.170] — 2026-05-30 — Release EP (stage-batch52 — run-aware SSE replay cursors)
 
 ### Fixed
diff --git a/static/boot.js b/static/boot.js
index 3835e261..9136a028 100644
--- a/static/boot.js
+++ b/static/boot.js
@@ -1343,6 +1343,7 @@ const _SKINS=[
   {name:'Catppuccin',colors:['#CBA6F7','#B4BEFE','#8839EF']},
   {name:'Hepburn',   colors:['#c6246a','#ec5597','#f2abca']},
   {name:'Nous',     colors:['#4682B4','#3A6E9A','#2C5F88']},
+  {name:'Neon',     colors:['#B347FF','#C76BFF','#00DDFF']},
   {name:'Geist Contrast', value:'geist-contrast', colors:['#000000','#ffffff','#FFF175']},
 ];
 const _VALID_THEMES=new Set((_THEMES||[]).map(t=>t.value));
diff --git a/static/index.html b/static/index.html
index ccd2a344..5969bde2 100644
--- a/static/index.html
+++ b/static/index.html
@@ -17,7 +17,7 @@
 <meta name="apple-mobile-web-app-status-bar-style" content="black-translucent">
 <meta name="apple-mobile-web-app-title" content="Hermes">
 <link rel="apple-touch-icon" sizes="512x512" href="static/apple-touch-icon.png">
-<script>(function(){try{var themes={light:1,dark:1,system:1},skins={default:1,ares:1,mono:1,slate:1,poseidon:1,sisyphus:1,charizard:1,sienna:1,catppuccin:1,hepburn:1,nous:1,'geist-contrast':1},legacy={slate:['dark','slate'],solarized:['dark','poseidon'],monokai:['dark','sisyphus'],nord:['dark','slate'],oled:['dark','default']},t=(localStorage.getItem('hermes-theme')||'dark').toLowerCase(),s=(localStorage.getItem('hermes-skin')||'').toLowerCase(),m=legacy[t],theme=m?m[0]:(themes[t]?t:'dark'),skin=skins[s]?s:(m?m[1]:'default');localStorage.setItem('hermes-theme',theme);localStorage.setItem('hermes-skin',skin);if(theme==='system')theme=window.matchMedia('(prefers-color-scheme:dark)').matches?'dark':'light';if(theme==='dark')document.documentElement.classList.add('dark');if(skin!=='default')document.documentElement.dataset.skin=skin;}catch(e){document.documentElement.classList.add('dark');}})()</script>
+<script>(function(){try{var themes={light:1,dark:1,system:1},skins={default:1,ares:1,mono:1,slate:1,poseidon:1,sisyphus:1,charizard:1,sienna:1,catppuccin:1,hepburn:1,nous:1,'geist-contrast':1,neon:1},legacy={slate:['dark','slate'],solarized:['dark','poseidon'],monokai:['dark','sisyphus'],nord:['dark','slate'],oled:['dark','default']},t=(localStorage.getItem('hermes-theme')||'dark').toLowerCase(),s=(localStorage.getItem('hermes-skin')||'').toLowerCase(),m=legacy[t],theme=m?m[0]:(themes[t]?t:'dark'),skin=skins[s]?s:(m?m[1]:'default');localStorage.setItem('hermes-theme',theme);localStorage.setItem('hermes-skin',skin);if(theme==='system')theme=window.matchMedia('(prefers-color-scheme:dark)').matches?'dark':'light';if(theme==='dark')document.documentElement.classList.add('dark');if(skin!=='default')document.documentElement.dataset.skin=skin;}catch(e){document.documentElement.classList.add('dark');}})()</script>
 <script>(function(){try{var fs=localStorage.getItem('hermes-font-size');if(fs&&fs!=='default')document.documentElement.dataset.fontSize=fs;}catch(e){}})()</script>
 <!-- theme-color: surfaces the active app chrome color to native status bars (Safari status bar, PWA, native WKWebView wrappers). Updated dynamically by boot.js when theme/skin changes. The light/dark default values match style.css :root --sidebar / :root.dark --sidebar. -->
 <meta name="theme-color" content="#FAF7F0" media="(prefers-color-scheme: light)">
diff --git a/static/style.css b/static/style.css
index 90b36834..f1a97f79 100644
--- a/static/style.css
+++ b/static/style.css
@@ -345,6 +345,86 @@
   :root.dark[data-skin="nous"] .mcp-http{color:#7EB6E0;}
   :root.dark[data-skin="nous"] .mcp-status-active{color:#7EB6E0;}
 
+  /* ═══ NEON — cyberpunk theme (dark-first) ═══ */
+  :root[data-skin="neon"]{
+    --bg:#F8F7FC;--sidebar:#F0EEF8;--border:#D8D4EC;--border2:rgba(0,0,0,0.12);
+    --text:#1E1B2E;--muted:#6E6888;--accent:#9333EA;--blue:#7C3AED;--gold:#A855F7;--code-bg:#F0EDF8;
+    --surface:#FFFFFF;--topbar-bg:rgba(248,247,252,.98);--main-bg:rgba(248,247,252,0.5);
+    --focus-ring:rgba(147,51,234,.3);--focus-glow:rgba(147,51,234,.08);
+    --input-bg:rgba(147,51,234,.03);--hover-bg:rgba(147,51,234,.05);
+    --strong:#0D0B14;--em:#7C3AED;--code-text:#6D28D9;--code-inline-bg:rgba(147,51,234,.08);--pre-text:#1E1B2E;
+    --accent-hover:#7E22CE;--accent-bg:rgba(147,51,234,0.06);--accent-bg-strong:rgba(147,51,234,0.12);--accent-text:#6D28D9;
+    --error:#DC2626;--success:#059669;--warning:#D97706;--info:#7C3AED;
+    --radius-sm:2px;--radius-md:4px;--radius-card:4px;--radius-lg:6px;
+    --font-ui:system-ui,-apple-system,sans-serif;
+    --surface-subtle:rgba(147,51,234,.025);--surface-subtle-hover:rgba(147,51,234,.05);
+    --border-subtle:rgba(147,51,234,.08);--border-muted:rgba(147,51,234,.12);
+    --purple:#9333EA;
+  }
+  :root.dark[data-skin="neon"]{
+    --bg:#08060d;--sidebar:#06040a;--border:#1c1633;--border2:rgba(179,71,255,0.15);
+    --text:#d8d6f0;--muted:#6a6588;--accent:#b347ff;--blue:#a78bfa;--gold:#c084fc;--code-bg:#050308;
+    --surface:#0f0d1a;--topbar-bg:rgba(8,6,13,.98);--main-bg:rgba(8,6,13,0.5);
+    --focus-ring:rgba(179,71,255,.35);--focus-glow:rgba(179,71,255,.10);
+    --input-bg:rgba(179,71,255,.04);--hover-bg:rgba(179,71,255,.06);
+    --strong:#f0edff;--em:#00ddff;--code-text:#c8c0f0;--code-inline-bg:rgba(179,71,255,.10);--pre-text:#d8d6f0;
+    --accent-hover:#c76bff;--accent-bg:rgba(179,71,255,0.10);--accent-bg-strong:rgba(179,71,255,0.20);--accent-text:#c8a0ff;
+    --error:#ff4466;--success:#00dd88;--warning:#ffaa33;--info:#00ddff;
+    --surface-subtle:rgba(179,71,255,.03);--surface-subtle-hover:rgba(179,71,255,.06);
+    --border-subtle:rgba(179,71,255,.08);--border-muted:rgba(179,71,255,.12);
+    --purple:#b347ff;
+  }
+  /* ── Neon skin: component-level overrides ── */
+  /* Selection glow */
+  :root.dark[data-skin="neon"] ::selection{background:rgba(179,71,255,0.35);color:#fff;}
+  /* Topbar: purple bottom border with glow */
+  :root.dark[data-skin="neon"] .app-titlebar{border-bottom-color:rgba(179,71,255,0.2);}
+  /* Sidebar: subtle purple inset shadow */
+  :root.dark[data-skin="neon"] .sidebar{box-shadow:inset -1px 0 30px rgba(179,71,255,0.03);}
+  /* Inputs: purple glow on focus */
+  :root.dark[data-skin="neon"] textarea:focus,
+  :root.dark[data-skin="neon"] input[type="text"]:focus,
+  :root.dark[data-skin="neon"] input[type="password"]:focus,
+  :root.dark[data-skin="neon"] select:focus{box-shadow:0 0 16px rgba(179,71,255,0.2);}
+  /* Send button: neon glow */
+  :root.dark[data-skin="neon"] button.send-btn{box-shadow:0 0 14px rgba(179,71,255,0.25);}
+  :root.dark[data-skin="neon"] button.send-btn:hover{box-shadow:0 0 24px rgba(179,71,255,0.45);}
+  /* New chat button: purple gradient */
+  :root.dark[data-skin="neon"] .new-chat-btn{background:var(--accent);border-color:var(--accent);color:#fff;font-weight:600;box-shadow:0 0 12px rgba(179,71,255,0.2);}
+  :root.dark[data-skin="neon"] .new-chat-btn:hover{background:var(--accent-hover);border-color:var(--accent-hover);color:#fff;box-shadow:0 0 20px rgba(179,71,255,0.35);}
+  /* Scrollbar: purple */
+  :root.dark[data-skin="neon"]::-webkit-scrollbar-thumb{background:rgba(179,71,255,.18);border-radius:3px;}
+  :root.dark[data-skin="neon"]::-webkit-scrollbar-thumb:hover{background:rgba(179,71,255,.30);}
+  :root.dark[data-skin="neon"]{scrollbar-width:thin;scrollbar-color:rgba(179,71,255,.18) transparent;}
+  /* Tool cards */
+  :root.dark[data-skin="neon"] .tool-card{background:rgba(179,71,255,0.03);border-color:rgba(179,71,255,0.08);}
+  :root.dark[data-skin="neon"] .tool-card:hover{border-color:rgba(179,71,255,0.2);}
+  :root.dark[data-skin="neon"] .tool-card-running{background:var(--accent-bg);border-color:var(--accent-bg-strong);}
+  :root.dark[data-skin="neon"] .tool-card-name{color:var(--muted);font-weight:500;}
+  :root.dark[data-skin="neon"] .tool-arg-key,
+  :root.dark[data-skin="neon"] .tool-card-more{color:var(--accent-text);}
+  :root.dark[data-skin="neon"] .tool-card-running-dot{background:var(--accent);}
+  /* Tree viewer: purple family */
+  :root.dark[data-skin="neon"] .tree-key{color:#b347ff;}
+  :root.dark[data-skin="neon"] .tree-str{color:#c8a0ff;}
+  :root.dark[data-skin="neon"] .tree-num{color:#00ddff;}
+  :root.dark[data-skin="neon"] .tree-bool{color:#b347ff;}
+  /* Session badges/tags */
+  :root.dark[data-skin="neon"] .session-child-count{background:rgba(179,71,255,.16);color:#c8a0ff;}
+  :root.dark[data-skin="neon"] .session-child-count:hover{background:rgba(179,71,255,.26);color:#d8c0ff;}
+  :root.dark[data-skin="neon"] .session-tree-badge{background:rgba(179,71,255,.2);color:#c8a0ff;}
+  :root.dark[data-skin="neon"] .session-tag{background:rgba(179,71,255,.2);color:#c8a0ff;}
+  /* Diff blocks */
+  :root.dark[data-skin="neon"] .diff-block .diff-plus{color:#b347ff;}
+  /* MCP status */
+  :root.dark[data-skin="neon"] .mcp-http{color:#c8a0ff;}
+  :root.dark[data-skin="neon"] .mcp-status-active{color:#00dd88;}
+  /* Image lightbox */
+  :root.dark[data-skin="neon"] .img-lightbox-close:hover{background:rgba(179,71,255,.35);}
+  /* Links: cyan with hover glow */
+  :root.dark[data-skin="neon"] a{color:var(--info);transition:text-shadow 0.2s;}
+  :root.dark[data-skin="neon"] a:hover{text-shadow:0 0 8px rgba(0,221,255,0.4);}
+
   /* ── Skin: Geist Contrast (Geist-inspired neutral precision) ──
      Dark mode uses a #FFF175 accent; solid accent controls use black
      foreground, while selected/navigation states stay neutral and restrained. */
@@ -2544,11 +2624,12 @@ body.resizing .sidebar{transition:none!important;}
     display:none;
   }
 }
-.tool-card{background:var(--surface-subtle);border:1px solid var(--border-muted);border-left:2px solid var(--border-muted);border-radius:var(--radius-card);margin:2px 0;overflow:hidden;transition:border-color .15s,background-color .15s;}
+.tool-card{background:var(--surface-subtle);border:1px solid var(--border-muted);border-left:3px solid var(--accent-bg-strong);border-radius:var(--radius-card);margin:2px 0;overflow:hidden;transition:border-color .15s,background-color .15s;}
 .tool-card:hover{border-color:var(--border2);background:var(--surface-subtle-hover);}
 .tool-card-running{border-color:var(--accent-bg-strong);background:var(--accent-bg);}
 .tool-card-header{display:flex;align-items:center;gap:var(--space-2);padding:var(--space-1) var(--space-3);cursor:pointer;user-select:none;}
 .tool-card-icon{font-size:13px;flex-shrink:0;opacity:.65;}
+.tool-card-badge{flex-shrink:0;font-size:10px;line-height:1.2;text-transform:uppercase;letter-spacing:.045em;font-weight:700;color:var(--accent-text);background:var(--accent-bg);border:1px solid var(--accent-bg-strong);border-radius:999px;padding:1px 6px;}
 .tool-card-name{font-size:var(--font-size-xs);font-weight:600;color:var(--muted);font-family:'SF Mono',ui-monospace,monospace;flex-shrink:0;}
 .tool-card-preview{font-size:var(--font-size-xs);color:var(--muted);opacity:.62;flex:1;overflow:hidden;text-overflow:ellipsis;white-space:nowrap;}
 .tool-card-toggle{font-size:10px;color:var(--muted);opacity:.45;flex-shrink:0;display:inline-flex;align-items:center;justify-content:center;transform-origin:center;transition:transform .18s ease;will-change:transform;}
diff --git a/static/ui.js b/static/ui.js
index 50ffce78..5f2a9360 100644
--- a/static/ui.js
+++ b/static/ui.js
@@ -6987,6 +6987,7 @@ function buildToolCard(tc){
       <div class="tool-card-header" onclick="this.closest('.tool-card').classList.toggle('open')">
         ${runIndicator}
         <span class="tool-card-icon">${icon}</span>
+        <span class="tool-card-badge">Tool output</span>
         <span class="tool-card-name">${esc(displayName)}</span>
         <span class="tool-card-preview">${esc(previewText)}</span>
         ${hasDetail?`<span class="tool-card-toggle">${li('chevron-right',12)}</span>`:''}
diff --git a/tests/test_issue2867_tool_output_visual_distinction.py b/tests/test_issue2867_tool_output_visual_distinction.py
new file mode 100644
index 00000000..f8daca29
--- /dev/null
+++ b/tests/test_issue2867_tool_output_visual_distinction.py
@@ -0,0 +1,33 @@
+from pathlib import Path
+
+ROOT = Path(__file__).resolve().parent.parent
+UI_JS = (ROOT / "static" / "ui.js").read_text(encoding="utf-8")
+STYLE_CSS = (ROOT / "static" / "style.css").read_text(encoding="utf-8")
+
+
+def test_tool_cards_render_persistent_tool_output_badge():
+    """Tool output must remain distinguishable without relying on hover state."""
+    build_start = UI_JS.index('function buildToolCard(tc){')
+    build_end = UI_JS.index('function _syncToolCallGroupSummary', build_start)
+    build_tool_card = UI_JS[build_start:build_end]
+
+    assert '<span class="tool-card-badge">Tool output</span>' in build_tool_card
+    assert '<span class="tool-card-name">${esc(displayName)}</span>' in build_tool_card
+    assert build_tool_card.index('class="tool-card-badge"') < build_tool_card.index('class="tool-card-name"')
+
+
+def test_tool_card_badge_style_is_not_hover_only():
+    badge_rule_start = STYLE_CSS.index('.tool-card-badge{')
+    badge_rule_end = STYLE_CSS.index('}', badge_rule_start)
+    badge_rule = STYLE_CSS[badge_rule_start:badge_rule_end]
+
+    assert '.tool-card:hover .tool-card-badge' not in STYLE_CSS
+    assert 'text-transform:uppercase' in badge_rule
+    assert 'background:var(--accent-bg)' in badge_rule
+    assert 'border:1px solid var(--accent-bg-strong)' in badge_rule
+    assert 'color:var(--accent-text)' in badge_rule
+
+
+def test_tool_cards_have_persistent_accent_rail():
+    assert '.tool-card{background:var(--surface-subtle);' in STYLE_CSS
+    assert 'border-left:3px solid var(--accent-bg-strong)' in STYLE_CSS
diff --git a/tests/test_mobile_layout.py b/tests/test_mobile_layout.py
index 21a0656e..49d68630 100644
--- a/tests/test_mobile_layout.py
+++ b/tests/test_mobile_layout.py
@@ -681,7 +681,11 @@ def test_pwa_safe_area_top_stays_scoped_to_installed_modes():
 
 def test_titlebar_safe_area_top_uses_scoped_variable():
     """The titlebar must use the safe-area variable instead of direct env()."""
-    m = re.search(r'\.app-titlebar\{(?P<body>[^}]*)\}', CSS)
+    # Match the GLOBAL `.app-titlebar{...}` rule, not skin-scoped variants like
+    # `:root.dark[data-skin="neon"] .app-titlebar{...}` (#3164) which can appear
+    # earlier in the file. Require the selector to start the line (optionally
+    # indented) with no `[data-skin=` scope prefix.
+    m = re.search(r'(?m)^\s*\.app-titlebar\{(?P<body>[^}]*)\}', CSS)
     assert m, ".app-titlebar rule missing from style.css"
     rule = m.group("body")
     assert "padding-top:var(--app-titlebar-safe-top)" in rule, (
diff --git a/tests/test_sprint20b.py b/tests/test_sprint20b.py
index 13aad7b7..ee41488a 100644
--- a/tests/test_sprint20b.py
+++ b/tests/test_sprint20b.py
@@ -31,7 +31,10 @@ def _find_global_selector(css, selector):
             return -1
         line_start = css.rfind('\n', 0, idx) + 1
         line_prefix = css[line_start:idx]
-        if ':root[data-skin=' not in line_prefix:
+        # Skip skin-scoped rules. Skins use both `:root[data-skin="x"]` and the
+        # dark-variant `:root.dark[data-skin="x"]` (#3164 Neon), so match the
+        # `[data-skin=` marker generically rather than the bare `:root[` form.
+        if '[data-skin=' not in line_prefix:
             return idx
         pos = idx + 1