wursor/docs/decisions/0013-docker-boundary-mock.md

13. Sandbox orchestration mocks the Docker boundary; real daemon client deferred

• Status: Accepted
• Date: 2026-08-15

Context

The development machine has no Docker daemon (the Phase 0 spikes already hit this). Sprint 1 still had to build and test the sandbox services: DB subset, media proxy, manifest delta, GC, and orchestration.

Decision

Implement the pure-logic sandbox services (subset, media-proxy, manifest, gc) and test them directly. Define a DockerClient interface and a SandboxManager orchestrator that depends on it, tested with a fake client. Defer the real Docker daemon HTTP client.

Options considered

• Block on a Docker host.
• Mock at the boundary (chosen).

Rejected

• Block on Docker — IMPLEMENTATION §7 already specifies "mocks at boundaries"; blocking would stall the slice for a reason that doesn't change the logic.

Consequences

• subset and media-proxy logic is promoted from the golden harness (e2e/golden/src/) into api/src/sandbox/.
• The Docker wire-up (DockerClient daemon implementation, image-manager, warm-pool) is an explicit Sprint 1 follow-up and remains unverified until a Docker host exists.