# PSR vs Edge Delivery

Two distinct layers that prior conversations have conflated. They are
independent.

## PSR — Preemptive Static Rendering

**Protocol feature.** Render HTML on mutation, not on request.

Mechanism: `@client` fires mutation → backend adapter triggers local
render runtime → HTML stored locally.

Works on a $5 VPS with local Bun. **No Edge required.** PSR is part
of the protocol; it's available to every Mizan deployment regardless
of hosting.

## Edge Delivery — Mizan Render (Paid Product)

Pre-rendered HTML cached globally on Cloudflare CDN.

Uses `fetch()` to a render Worker on a separate domain
(`render.mizan.cloud`) instead of `cache.put()`, because Workers
Cache API is per-datacenter only. `fetch()` across zones goes through
the global CDN cache path with Tiered Cache.

This layer is the paid Mizan Render product.

## Caching modes

- **Public content** — preemptive (render on mutation)
- **User-scoped content** — reactive only (purge on mutation, render
  on next request)

## Invariant

PSR logic must not couple to Cloudflare-specific APIs. PSR must work
without any cloud infrastructure. Edge delivery extends PSR; it does
not replace it.