Allocate elastic Cloudflare sites through a D1 registry and wildcard hostnames

[chubes4]

Parent: #1970

Goal

Replace the finite WORDPRESS_SITE_CONTEXTS allocation pool with an elastic site identity contract that can create N isolated preview sites without deploying a Worker or editing Worker configuration per site.

Architecture

• Use one configured preview-domain suffix and derive canonical site_id directly from {siteId}.<preview-domain> before coordinator or storage access.
• Keep anonymous published reads coordinator- and D1-free: deterministic wildcard parsing yields the R2 namespace, and absent publication state fails closed.
• Store allocation, ownership, lifecycle state, canonical hostname, aliases, timestamps, and generation in D1.
• Allocate collision-resistant site IDs and wildcard origins transactionally during POST /v1/sites.
• Preserve the existing production hostname as the explicit default compatibility mapping.
• Treat custom-domain aliases as a separate registry projection; they must not weaken deterministic preview-host routing.

Acceptance criteria

• POST /v1/sites allocates a new site without a predeclared context entry or Worker redeployment.
• Concurrent allocation is collision-safe and idempotent across isolates.
• The same Worker serves at least 100 dynamically allocated hostnames with strict D1/R2/cache/credential isolation.
• Unknown, malformed, mixed-case, suffix-confused, and generation-stale hostnames fail before state access.
• Anonymous publication reads for the wildcard hostname do not query D1 or construct a coordinator.
• Existing default production state remains byte- and namespace-compatible.
• Local D1 gates prove allocation, import, publication, restart, edit, and cross-site denial for dynamically created sites.
• No deployment is performed by this issue.

Current limitation

The current allocator selects only from WORDPRESS_SITE_CONTEXTS. Capacity therefore equals the number of contexts embedded in Worker environment configuration.

Related

• Expose an authenticated idempotent Cloudflare site provisioning API #1971 authenticated provisioning API
• Scope Cloudflare WordPress state by site identity #1972 site-scoped state
• Add a durable Cloudflare site registry and operation lifecycle #1973 durable operations
• Import a pinned static website artifact into the Cloudflare runtime #1975 production artifact import

AI assistance

OpenAI GPT-5.6 Sol via OpenCode inspected the current allocation and public-reader contracts and drafted this elastic identity slice with Chris Huber.