Using deep data merge (post tag is inherited from posts/posts.json) and updates to use 0.7.0.

.eleventy.js

@@ -5,6 +5,7 @@ const pluginSyntaxHighlight = require("@11ty/eleventy-plugin-syntaxhighlight");
 module.exports = function(eleventyConfig) {
   eleventyConfig.addPlugin(pluginRss);
   eleventyConfig.addPlugin(pluginSyntaxHighlight);
+  eleventyConfig.setDataDeepMerge(true);
 
   eleventyConfig.addLayoutAlias("post", "layouts/post.njk");
 
@@ -12,6 +13,11 @@ module.exports = function(eleventyConfig) {
     return DateTime.fromJSDate(dateObj, {zone: 'utc'}).toFormat("dd LLL yyyy");
   });
 
+  // https://html.spec.whatwg.org/multipage/common-microsyntaxes.html#valid-date-string
+  eleventyConfig.addFilter('htmlDateString', (dateObj) => {
+    return DateTime.fromJSDate(dateObj).toFormat('yyyy-LL-dd');
+  });
+
   // Get the first `n` elements of a collection.
   eleventyConfig.addFilter("head", (array, n) => {
     if( n < 0 ) {
@@ -21,18 +27,6 @@ module.exports = function(eleventyConfig) {
     return array.slice(0, n);
   });
 
-  // https://html.spec.whatwg.org/multipage/common-microsyntaxes.html#valid-date-string
-  eleventyConfig.addFilter('htmlDateString', (dateObj) => {
-    return DateTime.fromJSDate(dateObj).toFormat('yyyy-LL-dd');
-  });
-
-  // only content in the `posts/` directory
-  eleventyConfig.addCollection("posts", function(collection) {
-    return collection.getFilteredByGlob("./posts/*").sort(function(a, b) {
-      return a.date - b.date;
-    });
-  });
-
   eleventyConfig.addCollection("tagList", require("./_11ty/getTagList"));
 
   eleventyConfig.addPassthroughCopy("img");