docs: document folder-title-source global setting in docs.yml

fern/products/docs/pages/changelog/2026-02-06.mdx

@@ -1,5 +1,25 @@
+---
+tags: ["ai", "search", "navigation", "configuration", "docs.yml"]
+---
+
 ## Deep linking for Ask Fern
 
 Open Ask Fern or the search dialog directly from a URL using query parameters. Append `?searchType=ai&query={prompt}` to open Ask AI with a prompt, or `?query={search}` for regular search. Parameters are removed from the URL after the search opens.
 
 Learn more about [deep linking](/learn/docs/ai-features/ask-fern/features#deep-linking).
+
+## Global folder title source setting
+
+Set a default `title-source` for all folder navigations using the new `folder-title-source` option in `settings`. Individual folders can still override this value with their own `title-source`.
+
+```yaml docs.yml
+settings:
+  folder-title-source: frontmatter
+
+navigation:
+  - folder: ./pages/guides         # uses frontmatter (from global setting)
+  - folder: ./pages/reference
+    title-source: filename          # overrides global setting
+```
+
+Learn more about [folder title source](/learn/docs/configuration/site-level-settings#settingsfolder-title-source).

fern/products/docs/pages/customization/site-level-settings.mdx

@@ -654,6 +654,7 @@ settings:
   http-snippets: false
   hide-404-page: true
   use-javascript-as-typescript: false
+  folder-title-source: frontmatter
   substitute-env-vars: true
 ```
 
@@ -712,6 +713,10 @@ settings:
   If set to true, all analytics integrations configured in the [`analytics` configuration](#analytics-configuration) will be disabled. This includes Google Analytics 4, Google Tag Manager, PostHog, and any other analytics providers you have configured.
 </ParamField>
 
+<ParamField path="settings.folder-title-source" type="'filename' | 'frontmatter'" required={false} default="filename" toc={true}>
+  Sets the default method for deriving page and section titles across all [folder navigations](/learn/docs/configuration/navigation#add-a-folder). By default (`filename`), titles are derived from file names. Set to `frontmatter` to use the `title` field from each file's frontmatter instead (falls back to filename if not set). Individual folders can override this global default using the per-folder [`title-source`](/learn/docs/configuration/navigation#title-source) setting.
+</ParamField>
+
 <ParamField path="settings.substitute-env-vars" type="boolean" required={false} default="false" toc={true}>
   If set to true, replaces `${ENV_VAR}` expressions with environment variable values at build time. Useful for injecting API keys, base URLs, or version numbers into your docs.
 

fern/products/docs/pages/navigation/overview.mdx

@@ -162,7 +162,7 @@ navigation:
 </ParamField>
 
 <ParamField path="title-source" type="'filename' | 'frontmatter'" required={false} default="filename" toc={true}>
-  Determines how page and section titles with the folder are derived. By default (`filename`), titles are derived from file names. Set to `frontmatter` to use the `title` field from each file's frontmatter instead (falls back to filename if not set).
+  Determines how page and section titles within the folder are derived. By default (`filename`), titles are derived from file names. Set to `frontmatter` to use the `title` field from each file's frontmatter instead (falls back to filename if not set). This per-folder setting overrides the global [`settings.folder-title-source`](/learn/docs/configuration/site-level-settings#settingsfolder-title-source) value.
 </ParamField>
 
 <ParamField path="slug" type="string" required={false} toc={true}>