feat(cloudflare)!: Durable Object-managed Containers

[Butch78]

Model Cloudflare's Durable Object-managed Containers (scheduling_policy: "durable_object", public beta), where a container's images move from the application to the Worker upload and the Durable Object picks one at runtime. None of it is in the API reference yet, so the shapes are transcribed from wrangler 4.144.0 (deploy-helpers container-metadata.ts and durable-object-container-applications.ts).

// workers / workers_for_platforms: every metadata.containers entry (script upload + beta versions)
{ className: "Sandbox", name: "sandbox", images: { node: "registry.cloudflare.com/<acct>/node@sha256:…" } }

// containers: new operation, polled until "ready" before an image may be uploaded
yield* Containers.prepareContainerImage({ accountId, image }) // { status: "pending" | "ready" | "error", reason? }

// containers: a DO-managed application has no image, instances or configuration
yield* Containers.createContainerApplication({
  accountId, name, schedulingPolicy: "durable_object",
  durableObjects: { namespaceId }, observability: { logs: { enabled: true } },
})

• Breaking: ContainerConfiguration.image, CreateContainerApplicationRequest.maxInstances / .configuration, and ContainerApplicationItem.instances / .maxInstances / .configuration are now optional.
• configuration gains experimentalFlags, wranglerSsh and authorizedKeys. Create, update and the item gain top-level observability.
• fix(core): mapKeys no longer renames keys that an index signature admits. They are map data, and before this fix an image named className went on the wire as class_name.

These shapes were exercised live through alchemy's Durable Object-managed container support: image preparation, the upload's containers[].images, and creating the image-less application. A Durable Object started each named image by ctx.container.images.

🤖 Generated with Claude Code

[Butch78]

Closing: this was the distilled half of alchemy-run/alchemy#1904, which is closed in favour of alchemy-run/alchemy#1905. Its distilled counterpart is #685.