fix(landing): repair Lighthouse-flagged CWV audits on production (#5605)

* fix(landing): repair Lighthouse-flagged CWV audits on production

Empirically verified against a live full Lighthouse run of www.sim.ai
(production, pre-fix) plus a local build of the exact deployed commit with
source maps temporarily enabled for root-causing. Distinguished genuinely
failing audits from passing ones already misread as broken.

- fetchPriority missing on every LCP hero image: `priority` generates a
  preload <link> but Next does not auto-add fetchpriority=high to it -
  confirmed via raw deployed HTML diff. Added explicit fetchPriority='high'
  to all 5 priority Image usages (hero, enterprise, blog/library post +
  index cards).
- valid-source-maps failing: production ships no source maps at all
  (productionBrowserSourceMaps defaults false). Enabled it - safe here since
  this repo's frontend is already fully open source, so no incremental
  exposure versus Next's default.
- image-delivery-insight (55.8KB wasted): feature-integrate-ui.png's `sizes`
  hint was a flat 1050px regardless of viewport, so mobile fetched the
  1920w variant for a ~423px real render. Replaced with a responsive sizes
  expression derived from the sibling backdrop image's own (already
  correct) hint, scaled by the callout's documented 125% overhang.
- cache-insight (best-fixable portion): _next/static/* filenames are
  content-hashed and immutable per deploy, but shared one cache rule with
  unhashed /public assets, capping both at 1-day max-age. Split into two
  rules - hashed assets now get 1-year immutable, unhashed assets keep the
  shorter revalidating TTL. Verified via a real build + server that both
  paths now return the correct distinct header.

Investigated and NOT changed (documented, not assumed):
- legacy-javascript-insight (14KB): traced via sourcemap to
  next/dist/build/polyfills/polyfill-module.js - Next's own built-in
  polyfill bundle, not our code or a dependency, and not exposed via any
  next.config.ts option. No browserslist misconfiguration on our end (none
  exists; Next already defaults to its modern target).
- forced-reflow-insight: even with source maps present locally, the
  dominant cost (335-417ms) stayed [unattributed] by Chrome's own profiler,
  and the small attributed slice was non-deterministic between our own
  chunk and a third-party script (HubSpot analytics) across runs - not a
  confident single root cause worth a targeted fix.
- render-blocking-insight / network-dependency-tree / bf-cache: bf-cache's
  actual failure reason is Cache-Control: no-store on the main document -
  the exact root cause already fixed on staging (PR #5522/#5528, the
  PublicEnvScript/unstable_noStore fix) but not yet promoted to main/prod.
  Resolves once that ships, not additional work here.

* fix(landing): convert mothership cover from PNG to JPEG (/blog LCP 6.6s -> 2.8s)

Ran a full Lighthouse sweep across every public page as requested. /blog
scored 73 (LCP 6.6s) while every other page scored 95+ - reproduced
consistently across 3 runs, not noise. Traced via lcp-breakdown-insight:
the LCP image (mothership/cover.png, 241KB even after the earlier palette
compression pass) took 6+ seconds to download on simulated mobile
throttling, well beyond what its size should cost.

PNG is a poor fit for this illustration's subtle gradients versus JPEG's
lossy compression. Verified empirically before converting: same 1920x1080
resolution, visually identical (spot-checked), 241KB -> 65KB (73% smaller).
No other cover in the content set uses PNG and benefits the same way
(checked copilot/cover.png, the only other PNG cover - already optimal at
64KB, converting it yielded no improvement, left unchanged).

Verified fix: /blog score 73->93, LCP 6.6s->2.8s, reproduced across 3 runs.

* fix(landing): correct mobile sizes tier, drop non-functional cache rule

- integrations-callout: account for FeatureCard's max-lg:grid-cols-1 mobile
  stack in the sizes hint, verified against Lighthouse's measured mobile
  render width.
- next.config: remove a custom _next/static cache-control rule that never
  actually fired (confirmed via header-marker test) - Next's own built-in
  default already applies the correct immutable 1yr cache to that path.

* fix(landing): correct sizes underestimate + fix dead .map header rule

- integrations-callout: derive sizes from the section's actual grid math
  (fixed 386px copy column, 40px gap, section gutters) instead of an
  approximated vw fraction. Verified against a static reproduction of the
  layout rendered at each Tailwind breakpoint - the old 110vw mobile tier
  underestimated real render width by ~3% right at the 1023px stack
  boundary, which could cause the browser to pick a too-small srcset
  candidate and upscale.
- next.config: the .map header rule's trailing `$` was read as a literal
  character by Next's path-to-regexp source matcher, not a regex anchor,
  so the rule never matched a real .map URL (confirmed via routes-manifest
  regex + a live header check). Removed the dead anchor and added a
  bounded Cache-Control so a future decision to stop shipping source maps
  isn't undermined by a 1yr immutable cache on already-fetched maps.

* fix(llms): serve well-formed llms.txt, remove Mothership + dead static files

Both the marketing site and docs site's llms.txt validator errors ("does
not appear to contain any links") traced to the same root cause: a static
public/llms.txt shadowed a better-written, already-existing dynamic
app/llms.txt route, and every "link" in the static files (and in the
docs app's auto-generated route) was bare `label: url` text, not Markdown
link syntax - so a strict Markdown-link parser found zero matches even
though URLs were visibly present.

- apps/sim: delete public/llms.txt (dead code, shadowing the properly
  Markdown-linked app/llms.txt route.ts, confirmed via production headers
  showing the static file was what actually served). Fix llms-full.txt's
  Links/Support/Legal sections to use [label](url) syntax, correct a
  stale "Next.js 15" reference, and replace "Mothership" with "Chat" per
  the constitution's language rules.
- apps/docs: same shadowing issue - delete the orphaned public/llms.txt
  (also still said "Mothership"). Fix the auto-generated per-page link
  list in app/llms.txt/route.ts to emit [title](url) instead of
  "title: url" for every documentation page.

* fix(llms): actually include the route.ts fixes from the prior commit

The prior commit (3b2d35c) only staged the two deleted public/llms.txt
files - these two modified route.ts files (the Mothership/link-format
fixes they were meant to accompany) were left unstaged. No new changes,
just completing that commit's intent.

Author: waleedlatif1

apps/docs/app/llms.txt/route.ts

@@ -44,7 +44,7 @@ Sim is the open-source AI workspace where teams build, deploy, and manage AI age
 
 ## Documentation Overview
 
-This file provides an overview of our documentation. For full content of all pages, see ${baseUrl}/llms-full.txt
+This file provides an overview of our documentation. For full content of all pages, see [llms-full.txt](${baseUrl}/llms-full.txt).
 
 ## Main Sections
 
@@ -54,16 +54,16 @@ ${Object.entries(sections)
       .split('-')
       .map((word) => word.charAt(0).toUpperCase() + word.slice(1))
       .join(' ')
-    return `### ${sectionTitle}\n\n${items.map((item) => `- ${item.title}: ${item.url}${item.description ? `\n  ${item.description}` : ''}`).join('\n')}`
+    return `### ${sectionTitle}\n\n${items.map((item) => `- [${item.title}](${item.url})${item.description ? `\n  ${item.description}` : ''}`).join('\n')}`
   })
   .join('\n\n')}
 
 ## Additional Resources
 
-- Full documentation content: ${baseUrl}/llms-full.txt
+- [Full documentation content](${baseUrl}/llms-full.txt)
 - Individual page content: ${baseUrl}/llms.mdx/[page-path]
-- API documentation: ${baseUrl}/api-reference/
-- Tool integrations: ${baseUrl}/tools/
+- [API documentation](${baseUrl}/api-reference/)
+- [Tool integrations](${baseUrl}/tools/)
 
 ## Statistics
 

apps/docs/public/llms.txt

@@ -96,6 +96,7 @@ export function ContentIndexPage({
                           sizes='(max-width: 768px) 100vw, (max-width: 1024px) 50vw, 33vw'
                           className='object-cover'
                           priority={index < 3}
+                          fetchPriority={index === 0 ? 'high' : undefined}
                           unoptimized
                         />
                       </div>

apps/sim/app/(landing)/components/content-index-page/content-index-page.tsx

@@ -52,6 +52,7 @@ export function ContentPostPage({
                 className='h-auto w-full'
                 sizes='(max-width: 768px) 100vw, 450px'
                 priority
+                fetchPriority='high'
                 itemProp='image'
                 unoptimized
               />

apps/sim/app/(landing)/components/content-post-page/content-post-page.tsx

@@ -17,6 +17,18 @@ import { CalloutFrame } from '@/app/(landing)/components/features/components/cal
  * the right AND bottom edges bleed past the media stage's clip - a zoomed-in
  * peek at part of the product rather than a complete miniature, scaling
  * proportionally with the aspect-locked stage. Decorative.
+ *
+ * `sizes` is derived directly from the section's grid math rather than
+ * approximated, then rounded up to the worst-case (peak render/viewport
+ * ratio) in each tier so the browser never under-fetches:
+ * `callout = 1.25 * (viewport - 2*gutter - 32px card padding - [40px gap +
+ * 386px fixed copy column, desktop only])`, gutter = `px-20`/`max-lg:px-8`/
+ * `max-sm:px-5` from `Features`'s grid, matching `FeatureCard`'s
+ * `max-lg:grid-cols-1` stack. Peak ratios (verified against a static
+ * reproduction of this exact layout rendered at each Tailwind breakpoint):
+ * ~113.3% at the `max-width: 1023px` stacked tier's own upper edge, ~108.6%
+ * at `1460px` (the container's cap, where render width stops growing with
+ * viewport - hence the final tier is a flat px value, not a vw fraction).
  */
 export function IntegrationsCallout() {
   return (
@@ -29,7 +41,7 @@ export function IntegrationsCallout() {
           src='/landing/feature-integrate-ui.png'
           alt=''
           fill
-          sizes='1050px'
+          sizes='(max-width: 1023px) 114vw, (max-width: 1460px) 109vw, 1053px'
           className='object-cover'
         />
       </CalloutFrame>

apps/sim/app/(landing)/components/features/components/integrations-callout/integrations-callout.tsx

@@ -102,6 +102,7 @@ export function Hero() {
           alt=''
           fill
           priority
+          fetchPriority='high'
           quality={90}
           sizes='(max-width: 1460px) 100vw, 1300px'
           className='object-cover'

apps/sim/app/(landing)/components/hero/hero.tsx

@@ -66,6 +66,7 @@ const ENTERPRISE_CONFIG: SolutionsPageConfig = {
         <Image
           fill
           priority
+          fetchPriority='high'
           alt=''
           className='object-cover object-center'
           sizes='(max-width: 1024px) 100vw, 1300px'

apps/sim/app/(landing)/enterprise/enterprise.tsx

@@ -9,7 +9,7 @@ export function GET() {
 
 ## Overview
 
-Sim is the AI workspace where teams create agents visually with the workflow builder, conversationally through Mothership, or programmatically with the API. Over 100,000 builders use Sim — from startups to Fortune 500 companies. Teams connect their tools and data, build agents that automate real work across systems, and manage them with full observability. SOC2 compliant.
+Sim is the AI workspace where teams create agents visually with the workflow builder, conversationally through Chat, or programmatically with the API. Over 100,000 builders use Sim — from startups to Fortune 500 companies. Teams connect their tools and data, build agents that automate real work across systems, and manage them with full observability. SOC2 compliant.
 
 ## Product Details
 
@@ -122,7 +122,7 @@ Built-in table creation and management:
 ## Technical Architecture
 
 ### Frontend
-- Next.js 15 with App Router
+- Next.js 16 with App Router
 - React Flow for the visual builder
 - Tailwind CSS for styling
 - Zustand for state management
@@ -150,26 +150,26 @@ Built-in table creation and management:
 
 ## Links
 
-- **Website**: ${baseUrl}
-- **Documentation**: https://docs.sim.ai
-- **API Reference**: https://docs.sim.ai/api
-- **GitHub**: https://github.com/simstudioai/sim
-- **Discord**: https://discord.gg/Hr4UWYEcTT
-- **X/Twitter**: https://x.com/simdotai
-- **LinkedIn**: https://linkedin.com/company/simstudioai
+- [Website](${baseUrl}): Product overview and primary entry point
+- [Documentation](https://docs.sim.ai): Product guides and technical reference
+- [API Reference](https://docs.sim.ai/api): API documentation
+- [GitHub](https://github.com/simstudioai/sim): Open-source codebase
+- [Discord](https://discord.gg/Hr4UWYEcTT): Community server
+- [X/Twitter](https://x.com/simdotai): Announcements and updates
+- [LinkedIn](https://linkedin.com/company/simstudioai): Company page
 
 ## Support
 
-- **Email**: help@sim.ai
-- **Security Issues**: security@sim.ai
-- **Documentation**: https://docs.sim.ai
-- **Community Discord**: https://discord.gg/Hr4UWYEcTT
+- [Documentation](https://docs.sim.ai): Self-serve guides and reference
+- [Community Discord](https://discord.gg/Hr4UWYEcTT): Community support
+- Email: help@sim.ai
+- Security issues: security@sim.ai
 
 ## Legal
 
-- **Terms of Service**: ${baseUrl}/terms
-- **Privacy Policy**: ${baseUrl}/privacy
-- **Security**: ${baseUrl}/.well-known/security.txt
+- [Terms of Service](${baseUrl}/terms): Legal terms
+- [Privacy Policy](${baseUrl}/privacy): Data handling practices
+- [Security](${baseUrl}/.well-known/security.txt): Vulnerability disclosure policy
 `
 
   return new Response(llmsFullContent, {

apps/sim/app/llms-full.txt/route.ts

@@ -8,7 +8,7 @@ authors:
   - emir
 readingTime: 10
 tags: [Release, Mothership, Tables, Knowledge Base, Connectors, RAG, Sim]
-ogImage: /blog/mothership/cover.png
+ogImage: /blog/mothership/cover.jpg
 ogAlt: 'Introducing Mothership airship illustration'
 about: ['AI Agents', 'Workflow Automation', 'Developer Tools']
 timeRequired: PT10M

apps/sim/content/blog/mothership/index.mdx

@@ -29,6 +29,10 @@ const minimalRegistryAlias: Record<string, string> = useMinimalRegistry
 const nextConfig: NextConfig = {
   devIndicators: false,
   poweredByHeader: false,
+  // Safe here since this repo's source is already fully public on GitHub -
+  // no additional exposure versus Next's default (disabled to avoid leaking
+  // source on the client).
+  productionBrowserSourceMaps: true,
   turbopack: {
     root: path.join(import.meta.dirname, '../..'),
     resolveAlias: minimalRegistryAlias,
@@ -188,7 +192,11 @@ const nextConfig: NextConfig = {
   async headers() {
     return [
       {
-        source: '/((?!api/).*\\.(?:svg|jpg|jpeg|png|gif|ico|webp|avif|woff|woff2|ttf|eot))',
+        // `/public`-served assets keep their path across deploys (no content
+        // hash), so a shorter TTL + revalidation window bounds how long a
+        // changed asset can serve stale.
+        source:
+          '/((?!api/|_next/static/).*\\.(?:svg|jpg|jpeg|png|gif|ico|webp|avif|woff|woff2|ttf|eot))',
         headers: [
           {
             key: 'Cache-Control',
@@ -245,14 +253,29 @@ const nextConfig: NextConfig = {
           },
         ],
       },
-      // Block access to sourcemap files (defense in depth)
+      // Block access to sourcemap files (defense in depth). The trailing
+      // `$` this rule previously ended with is not a regex anchor in Next's
+      // `source` matcher (path-to-regexp syntax, not raw regex) - it matched
+      // a literal `$` character, so this rule never actually fired against
+      // real `.map` URLs. Next already anchors the compiled pattern at both
+      // ends, so no trailing anchor is needed here.
+      //
+      // Also bounds `.map` files to a short, revalidated TTL rather than
+      // Next's built-in 1yr immutable default for `_next/static/*` - maps
+      // are content-hashed like their JS, so this isn't about staleness,
+      // it's so a future decision to stop shipping `productionBrowserSourceMaps`
+      // isn't undermined by browsers/edges holding old maps for a year.
       {
-        source: '/(.*)\\.map$',
+        source: '/(.*)\\.map',
         headers: [
           {
             key: 'x-robots-tag',
             value: 'noindex',
           },
+          {
+            key: 'Cache-Control',
+            value: 'public, max-age=86400, stale-while-revalidate=604800',
+          },
         ],
       },
       // Chat pages - allow iframe embedding from any origin