BranchBox · Open-source engineering
Isolating the whole runtime, not just the branch.
BranchBox gives each feature—and each human or AI coding agent working on it—an isolated development environment with its own runtime state, rather than only a separate Git branch.
Live · Open source · MIT
The problem
A branch can be isolated while the runtime still collides.
Parallel development gets fragile when supposedly separate work still shares ports, databases, Docker networks, environment state, credentials, or cleanup assumptions.
Git isolates source history. It does not isolate the system the code actually runs inside. As more work happens concurrently—especially with coding agents—that distinction becomes operational.
Key decision
A branch is not an environment. Runtime state has to be isolated too.
Starting a feature provisions the surrounding runtime as well as the worktree: devcontainer, Compose project and network, database, ports, environment variables, and optional tunnel.
A Rust core and stack-adapter model keep the workflow consistent across application types. A local agent adds durable machine state and creates a foundation for orchestration without weakening the isolation boundary.
Architecture
The system around the decision.
- 01Rust CLI + core library
- 02Stack adapters + modules
- 03Worktree + devcontainer
- 04Docker / database / ports
- 05Local agent + optional control plane
What this demonstrates
What this work demonstrates.
BranchBox shows the infrastructure side of Amidship’s AI thesis. More capable coding agents increase parallelism; safe parallelism depends on environments, state boundaries, credentials, recoverability, and observability. The AI capability is only useful when the operating system around it is designed for concurrency.
- Developer-platform product thinking rather than one-off automation
- Runtime isolation for parallel human and AI-assisted development
- Rust CLI and agent engineering integrated with conventional application infrastructure
- Explicit handling of credentials, state, teardown, recovery, and observability
- Productizing a recurring internal engineering failure mode into reusable software
Inspectable evidence
Inspect it directly.
Evidence boundary
BranchBox is public open-source engineering proof. No adoption, download, productivity, or time-saved metrics are claimed, and future distribution or control-plane concepts are not presented as shipped capability.