Tighten up includes/excludes (#15813)

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## DESCRIBE YOUR PR
Slight reconfiguration to the allowlist and blocklist of files that are
or are not needed by the vercel serverless functions. This is tightening
up changes made in #15452
and some subsequent updates to these lists.

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Author: jaffrepaul

next.config.ts

@@ -9,6 +9,9 @@ import {redirects} from './redirects.js';
 // needed during the build process to compile MDX and optimize assets. The compiled
 // output is used at runtime, so bundling these ~150-200MB of dependencies would bloat
 // functions unnecessarily and cause deployment failures.
+//
+// Note: mdx-bundler/client (getMDXComponent) is a tiny runtime module needed by
+// app/[[...path]]/page.tsx, so we exclude only the build parts (dist/!(client)*).
 const outputFileTracingExcludes = process.env.NEXT_PUBLIC_DEVELOPER_DOCS
   ? {
       '/**/*': [
@@ -27,8 +30,9 @@ const outputFileTracingExcludes = process.env.NEXT_PUBLIC_DEVELOPER_DOCS
         'node_modules/@prettier/**/*',
         'node_modules/sharp/**/*',
         'node_modules/mermaid/**/*',
-        // Exclude MDX processing dependencies
-        'node_modules/mdx-bundler/**/*',
+        // Exclude MDX processing dependencies (but keep mdx-bundler/client for runtime)
+        'node_modules/mdx-bundler/dist/!(client*)',
+        'node_modules/mdx-bundler/node_modules/**/*',
         'node_modules/rehype-preset-minify/**/*',
         'node_modules/rehype-prism-plus/**/*',
         'node_modules/rehype-prism-diff/**/*',
@@ -55,8 +59,9 @@ const outputFileTracingExcludes = process.env.NEXT_PUBLIC_DEVELOPER_DOCS
         'node_modules/@prettier/**/*',
         'node_modules/sharp/**/*',
         'node_modules/mermaid/**/*',
-        // Exclude MDX processing dependencies
-        'node_modules/mdx-bundler/**/*',
+        // Exclude MDX processing dependencies (but keep mdx-bundler/client for runtime)
+        'node_modules/mdx-bundler/dist/!(client*)',
+        'node_modules/mdx-bundler/node_modules/**/*',
         'node_modules/rehype-preset-minify/**/*',
         'node_modules/rehype-prism-plus/**/*',
         'node_modules/rehype-prism-diff/**/*',
@@ -72,6 +77,8 @@ const outputFileTracingExcludes = process.env.NEXT_PUBLIC_DEVELOPER_DOCS
         '**/*.pdf',
       ],
       '\\[\\[\\.\\.\\.path\\]\\]': [
+        // Exclude docs to save ~156MB, but allow specific files via outputFileTracingIncludes
+        // for pages that may be accessed at runtime (error pages, cold starts, etc.)
         'docs/**/*',
         'node_modules/prettier/plugins',
         'node_modules/rollup/dist',
@@ -90,17 +97,24 @@ const outputFileTracingExcludes = process.env.NEXT_PUBLIC_DEVELOPER_DOCS
 // Both platform-redirect and [[...path]] need the doctree at runtime:
 // - platform-redirect: dynamic route with searchParams
 // - [[...path]]: calls getDocsRootNode() during prerendering (even though force-static)
-// Additionally, [[...path]] needs source files for pages using ISR (Incremental Static Regeneration):
-// - changelog.mdx: uses ISR with 1-hour revalidation to fetch fresh content (user docs only)
-// Other routes read frontmatter from source files instead of using doctree (sitemap, api/source-map)
+//
+// Additionally, include specific doc files that may be accessed at runtime due to:
+// - Error page rendering (when a static page fails to load)
+// - Cold start edge cases during deployment
+// - On-demand revalidation requests
+// These are whitelisted individually to avoid including the entire docs/ directory.
 const outputFileTracingIncludes = process.env.NEXT_PUBLIC_DEVELOPER_DOCS
   ? {
       '/platform-redirect': ['public/doctree-dev.json'],
       '\\[\\[\\.\\.\\.path\\]\\]': ['public/doctree-dev.json'],
     }
   : {
       '/platform-redirect': ['public/doctree.json'],
-      '\\[\\[\\.\\.\\.path\\]\\]': ['public/doctree.json', 'docs/changelog.mdx'],
+      '\\[\\[\\.\\.\\.path\\]\\]': [
+        'public/doctree.json',
+        'docs/changelog.mdx',
+        'docs/platforms/index.mdx',
+      ],
     };
 
 if (process.env.NODE_ENV !== 'development' && !process.env.NEXT_PUBLIC_SENTRY_DSN) {