feat: add frontMatter.file.slugSeparator setting

Allows users to configure the word separator used when generating slugs
and file names from titles. Defaults to `-` (hyphen) to preserve existing
behavior. Set to `_` for underscore-separated file names.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

package.json

@@ -965,6 +965,12 @@
           "markdownDescription": "%setting.frontMatter.file.preserveCasing.markdownDescription%",
           "scope": "File"
         },
+        "frontMatter.file.slugSeparator": {
+          "type": "string",
+          "default": "-",
+          "markdownDescription": "%setting.frontMatter.file.slugSeparator.markdownDescription%",
+          "scope": "File"
+        },
         "frontMatter.framework.id": {
           "type": "string",
           "default": "",

package.nls.json

@@ -155,6 +155,7 @@
   "setting.frontMatter.data.types.markdownDescription": "Specify the data types. These types can be used in for your data files. [Docs](https://frontmatter.codes/docs/settings/overview#frontmatter.data.types) - [View in VS Code](command:simpleBrowser.show?%5B%22https://frontmatter.codes/docs/settings/overview%23frontmatter.data.types%22%5D)",
   "setting.frontMatter.data.types.items.properties.id.description": "Your unique ID you want to use for your data type.",
   "setting.frontMatter.file.preserveCasing.markdownDescription": "Specify if you want to preserve the casing of your file names from the title. [Docs](https://frontmatter.codes/docs/settings/overview#frontmatter.file.preservecasing) - [View in VS Code](command:simpleBrowser.show?%5B%22https://frontmatter.codes/docs/settings/overview%23frontmatter.file.preservecasing%22%5D)",
+  "setting.frontMatter.file.slugSeparator.markdownDescription": "Specify the separator character used between words when generating slugs and file names from titles. Default is `-` (hyphen). Use `_` for underscores.",
   "setting.frontMatter.framework.id.markdownDescription": "Specify the ID of your static site generator or framework you are using for your website. [Docs](https://frontmatter.codes/docs/settings/overview#frontmatter.framework.id) - [View in VS Code](command:simpleBrowser.show?%5B%22https://frontmatter.codes/docs/settings/overview%23frontmatter.framework.id%22%5D)",
   "setting.frontMatter.framework.startCommand.markdownDescription": "Specify the command you want to use to start your static site generator or framework. [Docs](https://frontmatter.codes/docs/settings/overview#frontmatter.framework.startcommand) - [View in VS Code](command:simpleBrowser.show?%5B%22https://frontmatter.codes/docs/settings/overview%23frontmatter.framework.startcommand%22%5D)",
   "setting.frontMatter.git.enabled.markdownDescription": "Specify if you want to use the Git actions for your website. [Docs](https://frontmatter.codes/docs/settings/overview#frontmatter.git.enabled) - [View in VS Code](command:simpleBrowser.show?%5B%22https://frontmatter.codes/docs/settings/overview%23frontmatter.git.enabled%22%5D)",

src/constants/settings.ts

@@ -97,6 +97,7 @@ export const SETTING_DATA_FOLDERS = 'data.folders';
 export const SETTING_DATA_TYPES = 'data.types';
 
 export const SETTING_FILE_PRESERVE_CASING = 'file.preserveCasing';
+export const SETTING_FILE_SLUG_SEPARATOR = 'file.slugSeparator';
 
 export const SETTING_FRAMEWORK_ID = 'framework.id';
 export const SETTING_FRAMEWORK_START = 'framework.startCommand';

src/helpers/ArticleHelper.ts

@@ -10,6 +10,7 @@ import {
   SETTING_CONTENT_PLACEHOLDERS,
   SETTING_CONTENT_SUPPORTED_FILETYPES,
   SETTING_FILE_PRESERVE_CASING,
+  SETTING_FILE_SLUG_SEPARATOR,
   SETTING_COMMA_SEPARATED_FIELDS,
   SETTING_DATE_FIELD,
   SETTING_DATE_FORMAT,
@@ -660,7 +661,8 @@ export class ArticleHelper {
    */
   public static sanitize(value: string): string {
     const preserveCasing = Settings.get(SETTING_FILE_PRESERVE_CASING) as boolean;
-    return sanitize((preserveCasing ? value : value.toLowerCase()).replace(/ /g, '-'));
+    const separator = (Settings.get(SETTING_FILE_SLUG_SEPARATOR) as string) || '-';
+    return sanitize((preserveCasing ? value : value.toLowerCase()).replace(/ /g, separator));
   }
 
   /**

src/helpers/SlugHelper.ts

@@ -1,5 +1,5 @@
 import { parseWinPath, Settings } from '.';
-import { stopWords, charMap, SETTING_DATE_FORMAT, SETTING_SLUG_TEMPLATE } from '../constants';
+import { stopWords, charMap, SETTING_DATE_FORMAT, SETTING_SLUG_TEMPLATE, SETTING_FILE_SLUG_SEPARATOR } from '../constants';
 import { processTimePlaceholders, processFmPlaceholders } from '.';
 import { parse } from 'path';
 
@@ -26,7 +26,8 @@ export class SlugHelper {
     if (typeof slugTemplate === 'string') {
       if (slugTemplate.includes('{{title}}')) {
         const regex = new RegExp('{{title}}', 'g');
-        slugTemplate = slugTemplate.replace(regex, articleTitle.toLowerCase().replace(/\s/g, '-'));
+        const separator = (Settings.get(SETTING_FILE_SLUG_SEPARATOR) as string) || '-';
+        slugTemplate = slugTemplate.replace(regex, articleTitle.toLowerCase().replace(/\s/g, separator));
       } else if (slugTemplate.includes('{{seoTitle}}')) {
         const regex = new RegExp('{{seoTitle}}', 'g');
         slugTemplate = slugTemplate.replace(regex, SlugHelper.slugify(articleTitle));
@@ -69,7 +70,8 @@ export class SlugHelper {
       let words = cleanTitle.split(/\s/);
       // Removing stop words
       words = this.removeStopWords(words);
-      cleanTitle = words.join('-');
+      const separator = (Settings.get(SETTING_FILE_SLUG_SEPARATOR) as string) || '-';
+      cleanTitle = words.join(separator);
       cleanTitle = this.replaceCharacters(cleanTitle);
       return cleanTitle;
     }