🎨 docs: Document the Deployment Theme, Appearance Scales and ClickHouse Theme

content/docs/configuration/dotenv.mdx

@@ -3549,6 +3549,26 @@ Properly setting cache headers is crucial for optimizing the performance and eff
 
 > **Markdown example:** `CUSTOM_FOOTER=[Link 1](http://example1.com) | [Link 2](http://example2.com)`
 
+#### Theme Colors
+
+<OptionTable
+  options={[
+    [
+      'REACT_APP_THEME_<TOKEN>',
+      'string',
+      'Overrides one theme color token at build time. The value is a space-separated `R G B` triplet.',
+      '# REACT_APP_THEME_SURFACE_SUBMIT=4 120 87',
+    ],
+  ]}
+/>
+
+**Behaviour:**
+
+- Every color token in the theme engine can be set this way: drop the `rgb-` prefix from the token name and upper-snake-case the rest, so `rgb-surface-submit` becomes `REACT_APP_THEME_SURFACE_SUBMIT` and `rgb-status-error-border` becomes `REACT_APP_THEME_STATUS_ERROR_BORDER`. The token list is the `IThemeRGB` interface in [`packages/client/src/theme/types/index.ts`](https://github.com/LibreChat-AI/LibreChat/blob/canary/packages/client/src/theme/types/index.ts).
+- Values are inlined into the client when it is built, so the client has to be rebuilt after changing them. Setting them on a prebuilt Docker image has no effect.
+- The same colors apply in light and dark mode, and they only change colors, not shape.
+- [`interface.theme`](/docs/configuration/librechat_yaml/object_structure/theme) in `librechat.yaml` outranks these colors, and the high-contrast modes outrank both. `interface.theme` also needs no rebuild and can change shape, so prefer it for new deployments.
+
 #### Birthday Hat
 
 <OptionTable

content/docs/configuration/librechat_yaml/object_structure/interface.mdx

@@ -9,6 +9,7 @@ The `interface` object allows for customization of various user interface elemen
 
 These are fields under `interface`:
 
+- `theme`
 - `mcpServers`
 - `privacyPolicy`
 - `termsOfService`
@@ -63,6 +64,7 @@ See [Access Control](/docs/features/access_control) for the full permission mode
 
 ```yaml filename="interface"
 interface:
+  theme: librechat
   mcpServers:
     placeholder: 'MCP Servers'
     use: true
@@ -136,6 +138,36 @@ interface:
     - mcp
 ```
 
+## theme
+
+Sets the deployment theme applied to every user, in both light and dark mode. Either the name of a bundled theme (`librechat` or `clickhouse`) or an inline theme definition with its own colors, radii, fonts, shadows and motion.
+
+It outranks the `REACT_APP_THEME_*` build-time colors and users' stored themes, yields to the high-contrast modes, and is never saved to the user's browser. Removing it restores each user's own stored theme, or the `REACT_APP_THEME_*` colors when the client was built with them.
+
+**Key:**
+
+<OptionTable
+  options={[
+    [
+      'theme',
+      'String or Object',
+      'A bundled theme name, or an inline theme definition with `version`, `name`, `modes` and `brands`.',
+      'theme: clickhouse',
+    ],
+  ]}
+/>
+
+**Default:** _None (the default LibreChat theme, or the user's own theme)_
+
+**Example:**
+
+```yaml filename="interface / theme"
+interface:
+  theme: clickhouse
+```
+
+See [Theme](/docs/configuration/librechat_yaml/object_structure/theme) for the inline definition format, every appearance key with its default, the ClickHouse reference theme and how shared links pick their theme.
+
 ## mcpServers
 
 > **Deprecated for permission management.** The `use`, `create`, `share`, and `public` sub-keys seed role permissions at startup. Prefer the [Admin Panel](/docs/features/admin_panel) for managing MCP server permissions per role/group/user. The `placeholder` and `trustCheckbox` sub-keys are unaffected.

content/docs/configuration/librechat_yaml/object_structure/meta.json

@@ -5,6 +5,7 @@
     "---General---",
     "config",
     "interface",
+    "theme",
     "registration",
     "turnstile",
     "---Models & Specs---",