fix(gatsby): Add DEV_SSR note to 95312 error

docs/docs/debugging-html-builds.md

@@ -35,7 +35,7 @@ Errors while building static HTML files (the build-time React SSR process) or wh
 
 5. Some other reason :-) #1 is the most common reason building static files
    fail. If it's another reason, you have to be a bit more creative in figuring
-   out the problem.
+   out the problem. The [`DEV_SSR` feature](#ssr-during-gatsby-develop) can help you with this.
 
 ## How to check if `window` is defined
 
@@ -106,3 +106,20 @@ exports.onCreateWebpackConfig = ({ stage, loaders, actions }) => {
 ```
 
 Another solution is to use a package like [loadable-components](https://github.com/gregberge/loadable-components). The module that tries to use `window` will be dynamically loaded only on the client side (and not during SSR).
+
+## SSR during `gatsby develop`
+
+Server-Side render (SSR) pages on full reloads during `gatsby develop`. This helps you detect SSR bugs and fix them without needing to do full builds with `gatsby build`. Once enabled, go to your desired page and do a full reload (e.g. Ctrl + R or F5).
+
+Add the `DEV_SSR` flag to your `gatsby-config.js`:
+
+```js:title=gatsby-config.js
+module.exports = {
+  flags: {
+    DEV_SSR: true
+  },
+  plugins: [...]
+}
+```
+
+Please give feedback in the [DEV_SSR umbrella discussion](https://github.com/gatsbyjs/gatsby/discussions/28138).

docs/docs/glossary/server-side-rendering.md

@@ -1,5 +1,5 @@
 ---
-title: Server Side Rendering
+title: Server-Side Rendering
 disableTableOfContents: true
 ---
 

docs/docs/how-to/local-development/troubleshooting-common-errors.md

@@ -91,12 +91,12 @@ The following errors are related to styles in your site, using CSS, preprocessor
 
 ### Inconsistent CSS styles between develop and build using styled-components or emotion
 
-_NOTE: We're in process of adding SSR support to the develop server. To use it now, enable the `DEV_SSR` flag in your gatsby-config.js — https://github.com/gatsbyjs/gatsby/discussions/28138_
-
 A common problem that trips up users that install and begin to use styled-components or emotion is not including the related plugin in the config. Because `gatsby develop` doesn't run server-side rendering, the build may look different if the plugin is not included to tell Gatsby to server-side render the styles for the CSS-in-JS solution being used.
 
 Adding `gatsby-plugin-styled-components` (in the case of styled-components) or `gatsby-plugin-emotion` (in the case of emotion) to `gatsby-config.js` will inform Gatsby to process the styles server-side so they display correctly in the final build.
 
+You can use the [`DEV_SSR` feature flag](/docs/debugging-html-builds#ssr-during-gatsby-develop) inside your `gatsby-config` to enable SSR support during `gatsby develop` which can help you debug such issues.
+
 ## Errors with GraphQL
 
 Gatsby's GraphQL data layer provides access to build time data, there are sometimes errors you may encounter while implementing plugins that are sourcing data or adding nodes to the schema yourself.

integration-tests/gatsby-cli/__tests__/build-ssr-errors.js

@@ -16,7 +16,7 @@ describe(`gatsby build (SSR errors)`, () => {
     logs.should.contain(`failed Building static HTML for pages`)
     logs.should.contain(`ERROR #95312`)
     logs.should.contain(
-      `"window" is not available during server side rendering.`
+      `"window" is not available during Server-Side Rendering.`
     )
     logs.should.contain(
       `See our docs page for more info on this error: https://gatsby.dev/debug-html`

packages/gatsby-cli/src/reporter/__tests__/__snapshots__/index.ts.snap

@@ -130,7 +130,7 @@ Object {
   "docsUrl": "https://gatsby.dev/debug-html",
   "level": "ERROR",
   "stack": Array [],
-  "text": "\\"navigator\\" is not available during server side rendering.",
+  "text": "\\"navigator\\" is not available during Server-Side Rendering. Enable \\"DEV_SSR\\" to debug this during \\"gatsby develop\\".",
 }
 `;
 

packages/gatsby-cli/src/structured-errors/error-map.ts

@@ -34,7 +34,7 @@ const errors = {
   },
   "95312": {
     text: (context): string =>
-      `"${context.ref}" is not available during server side rendering.`,
+      `"${context.ref}" is not available during Server-Side Rendering. Enable "DEV_SSR" to debug this during "gatsby develop".`,
     level: Level.ERROR,
     docsUrl: `https://gatsby.dev/debug-html`,
     category: ErrorCategory.USER,

packages/gatsby/src/utils/flags.ts

@@ -97,7 +97,7 @@ const activeFlags: Array<IFlag> = [
     command: `develop`,
     telemetryId: `DevSsr`,
     experimental: false,
-    description: `Server Side Render (SSR) pages on full reloads during develop. Helps you detect SSR bugs and fix them without needing to do full builds. See umbrella issue for how to update custom webpack config.`,
+    description: `Server Side Render (SSR) pages on full reloads during develop. Helps you detect SSR bugs and fix them without needing to do full builds.`,
     umbrellaIssue: `https://gatsby.dev/dev-ssr-feedback`,
     testFitness: (): fitnessEnum => true,
   },