diff --git a/README.md b/README.md
index 2bd1bd875..fef1ea596 100644
--- a/README.md
+++ b/README.md
@@ -1,5 +1,7 @@
 # AgentV
 
+> **Deprecated:** AgentV has been replaced by [oh-my-promptfoo](https://github.com/allagentsdev/oh-my-promptfoo) and [Promptfoo](https://github.com/promptfoo/promptfoo). Use oh-my-promptfoo for workspace setup, and migrate your YAML configs to `promptfooconfig.yaml` for Promptfoo.
+
 Test AI providers on real repo tasks and measure what actually works.
 
 ## Why?
diff --git a/apps/web/src/components/DeprecationBanner.astro b/apps/web/src/components/DeprecationBanner.astro
new file mode 100644
index 000000000..7f73ab5b8
--- /dev/null
+++ b/apps/web/src/components/DeprecationBanner.astro
@@ -0,0 +1,38 @@
+<aside class="deprecation-banner" aria-label="AgentV deprecation notice">
+  <p>
+    <strong>AgentV is deprecated.</strong>
+    Use <a href="https://github.com/allagentsdev/oh-my-promptfoo">oh-my-promptfoo</a> for workspace setup;
+    migrate eval YAML to <a href="https://github.com/promptfoo/promptfoo">Promptfoo</a>'s
+    <code>promptfooconfig.yaml</code>.
+  </p>
+</aside>
+
+<style>
+  .deprecation-banner {
+    box-sizing: border-box;
+    display: flex;
+    align-items: center;
+    flex: 0 0 var(--av-deprecation-banner-height);
+    padding: 0.375rem max(1rem, calc((100% - 76rem) / 2));
+    border-bottom: 1px solid var(--sl-color-gray-5);
+    color: var(--sl-color-text);
+    background: var(--sl-color-accent-low);
+    font-size: 0.8125rem;
+    line-height: 1.35;
+  }
+
+  p {
+    margin: 0;
+  }
+
+  a {
+    color: var(--sl-color-accent-high);
+    text-decoration: underline;
+    text-underline-offset: 0.15em;
+  }
+
+  a:focus-visible {
+    outline: 2px solid var(--sl-color-accent-high);
+    outline-offset: 2px;
+  }
+</style>
diff --git a/apps/web/src/components/Header.astro b/apps/web/src/components/Header.astro
index fd5d79ede..16f61ec54 100644
--- a/apps/web/src/components/Header.astro
+++ b/apps/web/src/components/Header.astro
@@ -5,38 +5,48 @@ import SiteTitle from 'virtual:starlight/components/SiteTitle';
 import SocialIcons from 'virtual:starlight/components/SocialIcons';
 import ThemeSelect from 'virtual:starlight/components/ThemeSelect';
 import config from 'virtual:starlight/user-config';
+import DeprecationBanner from './DeprecationBanner.astro';
 
 const shouldRenderSearch =
   config.pagefind || config.components.Search !== '@astrojs/starlight/components/Search.astro';
 ---
 
-<div class="header">
-  <div class="title-wrapper sl-flex">
-    <SiteTitle />
-  </div>
-  <div class="mobile-version md:sl-hidden print:hidden">
-    <LanguageSelect />
-  </div>
-  <div class="sl-flex print:hidden">
-    {shouldRenderSearch && <Search />}
-  </div>
-  <div class="sl-hidden md:sl-flex print:hidden right-group">
-    <div class="sl-flex social-icons">
-      <SocialIcons />
+<div class="header-shell">
+  <DeprecationBanner />
+  <div class="header">
+    <div class="title-wrapper sl-flex">
+      <SiteTitle />
+    </div>
+    <div class="mobile-version md:sl-hidden print:hidden">
+      <LanguageSelect />
+    </div>
+    <div class="sl-flex print:hidden">
+      {shouldRenderSearch && <Search />}
+    </div>
+    <div class="sl-hidden md:sl-flex print:hidden right-group">
+      <div class="sl-flex social-icons">
+        <SocialIcons />
+      </div>
+      <ThemeSelect />
+      <LanguageSelect />
     </div>
-    <ThemeSelect />
-    <LanguageSelect />
   </div>
 </div>
 
 <style>
   @layer starlight.core {
+    .header-shell {
+      display: flex;
+      flex-direction: column;
+      height: 100%;
+    }
+
     .header {
       display: flex;
+      flex: 1;
       gap: 0.625rem;
       justify-content: space-between;
       align-items: center;
-      height: 100%;
     }
 
     .title-wrapper {
diff --git a/apps/web/src/styles/custom.css b/apps/web/src/styles/custom.css
index 637e10372..fe74404cc 100644
--- a/apps/web/src/styles/custom.css
+++ b/apps/web/src/styles/custom.css
@@ -5,6 +5,8 @@
 /* Design tokens */
 :root {
   --av-font-mono: "JetBrains Mono", ui-monospace, "Cascadia Code", "Fira Code", monospace;
+  --av-deprecation-banner-height: 2.75rem;
+  --av-docs-top-offset: calc(var(--sl-nav-height) + var(--av-deprecation-banner-height));
   --av-indigo: #06b6d4;
   --av-indigo-dark: #0891b2;
   --av-violet: #22d3ee;
@@ -16,6 +18,38 @@
   --av-radius: 4px;
 }
 
+@media (max-width: 49.999rem) {
+  :root {
+    --av-deprecation-banner-height: 4.25rem;
+  }
+
+  starlight-menu-button button {
+    top: calc(
+      var(--av-deprecation-banner-height) +
+      (var(--sl-nav-height) - var(--sl-menu-button-size)) /
+      2
+    );
+  }
+}
+
+@media (max-width: 23.5rem) {
+  :root {
+    --av-deprecation-banner-height: 6.25rem;
+  }
+}
+
+.page > header.header {
+  height: var(--av-docs-top-offset);
+}
+
+.main-frame {
+  padding-top: calc(var(--av-docs-top-offset) + var(--sl-mobile-toc-height));
+}
+
+.sidebar-pane {
+  inset-block-start: var(--av-docs-top-offset);
+}
+
 /* Light mode */
 :root {
   --sl-color-accent-low: hsl(185, 60%, 92%);