chore: import upstream snapshot with attribution

apps/sim/app/ingest/[[...path]]/route.ts

@@ -0,0 +1,74 @@
+import { createLogger } from '@sim/logger'
+import { toError } from '@sim/utils/errors'
+import { type NextRequest, NextResponse } from 'next/server'
+
+const logger = createLogger('PostHogProxy')
+
+const API_HOST = 'us.i.posthog.com'
+const ASSET_HOST = 'us-assets.i.posthog.com'
+
+/**
+ * Builds the target PostHog URL from the incoming request path.
+ * Routes /ingest/static/* to the asset host, everything else to the API host.
+ */
+function buildTargetUrl(pathname: string, search: string): { url: string; hostname: string } {
+  const strippedPath = pathname.replace(/^\/ingest/, '')
+  const hostname = strippedPath.startsWith('/static/') ? ASSET_HOST : API_HOST
+  return {
+    url: `https://${hostname}${strippedPath}${search}`,
+    hostname,
+  }
+}
+
+/**
+ * Builds forwarding headers for the PostHog request.
+ * Sets the Host header and strips cookies/connection headers
+ * that shouldn't be forwarded.
+ */
+function buildHeaders(request: NextRequest, hostname: string): Headers {
+  const headers = new Headers(request.headers)
+  headers.set('host', hostname)
+  headers.delete('cookie')
+  headers.delete('connection')
+
+  return headers
+}
+
+async function handler(request: NextRequest) {
+  const { url, hostname } = buildTargetUrl(request.nextUrl.pathname, request.nextUrl.search)
+  const headers = buildHeaders(request, hostname)
+
+  const hasBody = !['GET', 'HEAD'].includes(request.method)
+
+  try {
+    const response = await fetch(url, {
+      method: request.method,
+      headers,
+      ...(hasBody ? { body: request.body, duplex: 'half' } : {}),
+    } as RequestInit)
+
+    const responseHeaders = new Headers(response.headers)
+    responseHeaders.delete('content-encoding')
+    responseHeaders.delete('content-length')
+    responseHeaders.delete('transfer-encoding')
+
+    return new NextResponse(response.body, {
+      status: response.status,
+      headers: responseHeaders,
+    })
+  } catch (error) {
+    logger.error('PostHog proxy error', {
+      url,
+      method: request.method,
+      error: toError(error).message,
+    })
+    return new NextResponse(null, { status: 502 })
+  }
+}
+
+export const GET = handler
+export const POST = handler
+export const PUT = handler
+export const PATCH = handler
+export const DELETE = handler
+export const OPTIONS = handler