refactor: modularize chat backend, update docs for .m4s segments

infrastructure/cloudflare/cache-rules.md

@@ -1,25 +1,25 @@
 # Cloudflare Cache Rules for Linear Void (per ADR-001)
 
-## Recommended Cache Rules for media.example.com
+## Recommended Cache Rules for media.linearvoid.tv
 
-1. **.ts segments (immutable)**
-   - Expression: (http.host eq "media.example.com" and http.request.uri.path contains ".ts")
+1. **.m4s and .ts segments (immutable)**
+   - Expression: (http.host eq "media.linearvoid.tv" and (http.request.uri.path contains ".ts" or http.request.uri.path contains ".m4s"))
    - Cache status: Eligible for cache
    - Edge Cache TTL: 1 month (or `Cache-Control: public, max-age=31536000, immutable` from origin)
    - Cache Everything: Yes
 
 2. **.m3u8 manifests (live)**
-   - Expression: (http.host eq "media.example.com" and http.request.uri.path contains ".m3u8")
+   - Expression: (http.host eq "media.linearvoid.tv" and http.request.uri.path contains ".m3u8")
    - Cache status: Eligible for cache
-   - Edge Cache TTL: 10 seconds
-   - Cache-Control: public, max-age=10, must-revalidate
+   - Edge Cache TTL: 2 seconds
+   - Cache-Control: public, max-age=2, must-revalidate
 
 3. **Static assets**
-   - Expression: (http.host eq "example.com" and http.request.uri.path contains ".js" or http.request.uri.path contains ".css")
+   - Expression: (http.host eq "linearvoid.tv" and http.request.uri.path contains ".js" or http.request.uri.path contains ".css")
    - Edge Cache TTL: 1 year (with hash in filename for immutable caching)
 
 **Tiered Cache**: Enable Smart Tiered Cache for R2 custom domain to reduce origin requests.
 
 **WAF**: Enable basic rate limiting and bot management for /ws and admin routes.
 
-These rules ensure high cache hit ratio for .ts segments while keeping live manifests fresh. Monitor cache hit ratio in Cloudflare analytics.
+These rules ensure high cache hit ratio for .m4s and .ts segments while keeping live manifests fresh. Monitor cache hit ratio in Cloudflare analytics.

infrastructure/cloudflare/worker.js

@@ -6,8 +6,8 @@ addEventListener("fetch", (event) => {
 async function handleRequest(request) {
   const url = new URL(request.url);
 
-  // Add immutable cache headers for .ts segments
-  if (url.pathname.endsWith(".ts")) {
+  // Add immutable cache headers for .m4s segments
+  if (url.pathname.endsWith(".m4s")) {
     const response = await fetch(request);
     const headers = new Headers(response.headers);
     headers.set("Cache-Control", "public, max-age=31536000, immutable");