April 23, 2026 ·

Cella Sandbox: fast enough to throw away, durable enough to keep

April 23, 2026

We are announcing Latere Cella: a named sandbox you mint in one API call, ephemeral or persistent, your choice at create time. Cella is Latin for inner chamber: a small, private room for your work. Warm starts are under 500ms, so it is fast enough to use once and throw away. The workspace (files, caches, git clone, half-built container image) survives stops, restarts, and idle auto-shutdown for as long as you want it to, so it is durable enough to keep.

Cella is in private beta today. Request access.

What it is for

Cella exists for work that does not fit the two shapes most cloud compute is sold in: neither a request-scoped function that dies at the end of the call, nor a long-lived machine you have to operate yourself.

Four concrete use cases shaped the design:

Background compute workloads. Jobs that take minutes to hours: a test suite across a large matrix, a data transformation, a model fine-tune, a long-running scrape. You want to fire them off, walk away, and come back to logs and artifacts. You do not want to keep a WebSocket alive for ninety minutes or babysit a process on a server.

Environments for experimentation. A scratch space with a real filesystem, a real shell, real tools. Somewhere to try a library, reproduce a bug against a specific commit, or let a coding agent work on a repo for an hour. The setup cost is paid once; the cella remembers.

Ad-hoc allocation. Compute you mint in one API call and discard when you are done, at the scale where that makes sense: a handful of cellas, not a fleet. No infrastructure to provision, no cluster to operate. Quotas are enforced per user, per organisation, and at a global cap.

Named, persistent workspaces. Every cella has a slug. Stop it and the cella is still there tomorrow, with the same files, the same caches, the same git state. Ephemeral cellas are available too; persistence is a choice you make at create time.

The primitive

The separation of concerns is the whole idea:

  • A persistent workspace. Default 1Gi, capped at 10Gi per user. It survives restarts and idle auto-stop.
  • Compute that is replaceable. Auto-stopped when idle. Warm starts in under 500ms, cold in seconds.
  • A hardened runtime. Isolated, (non-)root, minimal capabilities. The cella runs with no ambient privilege.
  • Clear egress control. Default-deny. An allowlist, attached to the credential that signs out cellas, governs what any cella under that credential can reach. Consistent behaviour across every workspace, visible and auditable.
  • One API. POST /v1/sandboxes to mint. POST /v1/sandboxes/:id/commands to run. POST /commands?detach=true for background jobs. A tailable log cursor. File import and export.

That is the whole primitive. Everything else is policy.

Three consumer shapes

The harder question is not what is a cella. It is who is allowed to hold one, and how do credentials get into it. Three shapes cover the workloads we have seen.

Agents, via a trust plane. A server app mints cellas on a user's behalf. Real secrets (LLM keys, git tokens) never enter the cella. A per-client broker runs alongside the workload on a local address and hands out scoped, audience-narrow tokens on demand. The agent inside has no ambient authority; it has a token that lets it talk to one broker. If the cella is compromised, the blast radius is the broker's allowlist, not the credential vault.

Developers, direct. Browser login, a latere CLI, a dashboard, Go and TypeScript SDKs. Create, rename, start, stop, exec against your own cellas. Persistent or ephemeral, chosen at create time.

MCP, background workloads. A reference sandbox-mcp server lets MCP clients like Claude Code fire long-running jobs, detach, and come back later for logs and artifacts. POST /commands?detach=true returns a command ID; a tailable cursor streams output; files round-trip through /files. The unit of work is a task that may outlive the conversation.

What is next

Cella is in private beta with a small set of design partners. Pricing tiers are being finalised with them. The pricing page has the shape; numbers are not locked.

If any of the above reads like it removes a problem you are currently solving by hand, we would like to talk. Request beta access.

Cella is a product of Latere. Founded by Dr. Changkun Ou.