Speed up yarn develop on warm restart

data/onCreateNode/index.ts

@@ -1,5 +1,16 @@
 import { GatsbyNode, Node } from 'gatsby';
 
+// Touch existing derived nodes on every build so Gatsby's stale-node GC
+// does not delete them on warm restart. Derived nodes created via
+// `createNode` from inside `onCreateNode` are not re-created when their
+// parent File nodes are cached unchanged, so without this hook the
+// ExampleFile nodes disappear between dev runs and `allExampleFile`
+// returns undefined in createPages.
+export const sourceNodes: GatsbyNode['sourceNodes'] = ({ actions, getNodesByType }) => {
+  const { touchNode } = actions;
+  getNodesByType('ExampleFile').forEach((node) => touchNode(node));
+};
+
 export const onCreateNode: GatsbyNode['onCreateNode'] = async ({
   node,
   actions: { createNode, createParentChildLink },

gatsby-config.ts

@@ -67,7 +67,16 @@ const headerLinkIcon = `<svg aria-hidden="true" height="20" version="1.1" viewBo
 export const plugins = [
   'gatsby-plugin-postcss',
   'gatsby-plugin-image',
-  'gatsby-plugin-sharp',
+  process.env.NODE_ENV === 'production'
+    ? 'gatsby-plugin-sharp'
+    : {
+        resolve: 'gatsby-plugin-sharp',
+        options: {
+          defaults: {
+            formats: ['auto'],
+          },
+        },
+      },
   'gatsby-transformer-yaml',
   {
     resolve: 'gatsby-transformer-sharp',

gatsby-node.ts

@@ -1,5 +1,5 @@
 export { createPages } from './data/createPages';
-export { onCreateNode } from './data/onCreateNode';
+export { onCreateNode, sourceNodes } from './data/onCreateNode';
 export { onCreatePage } from './data/onCreatePage';
 export { createSchemaCustomization } from './data/onCreateNode/create-graphql-schema-customization';
 export { onCreateBabelConfig } from './gatsby-overwrite-config';

package.json

@@ -16,10 +16,11 @@
     "node": "^22.19.0"
   },
   "scripts": {
-    "develop": "export EDITOR_WARNINGS_OFF='true' && gatsby clean && gatsby develop",
+    "develop": "export EDITOR_WARNINGS_OFF='true' GATSBY_CPU_COUNT='physical_cores' GATSBY_EXPERIMENTAL_DEV_SSR='true' && gatsby develop",
+    "develop:clean": "export EDITOR_WARNINGS_OFF='true' GATSBY_CPU_COUNT='physical_cores' GATSBY_EXPERIMENTAL_DEV_SSR='true' && gatsby clean && gatsby develop",
     "develop:env-setup": "cp .env.example .env.development",
     "start": "yarn clean && yarn develop",
-    "edit": "unset EDITOR_WARNINGS_OFF && export ENABLE_GATSBY_REFRESH_ENDPOINT='true' && gatsby clean && gatsby develop",
+    "edit": "unset EDITOR_WARNINGS_OFF && export ENABLE_GATSBY_REFRESH_ENDPOINT='true' GATSBY_CPU_COUNT='physical_cores' GATSBY_EXPERIMENTAL_DEV_SSR='true' && gatsby develop",
     "refresh": "curl -X POST http://localhost:8000/__refresh",
     "build": "yarn clean && gatsby build --prefix-paths",
     "build:cli": "tsc -p .",