ADR 0002 — One agent = one branch = one git worktree

- **Status:** Accepted - **Date:** 2026-07-23

Context

Any team member can submit a request, and several may submit at once. Each submission runs its own agent that reads and writes files in the repo. Parallel agents sharing a single working copy would clobber each other.

Decision

The orchestrator keeps a single clone and creates a **git worktree per active agent session**, each on its own `ourai/<slug>` branch. Worktrees let many branches be checked out simultaneously from one clone, cheaply. Concurrency is capped (`MAX_CONCURRENT_AGENTS`, default 3); submissions beyond the cap queue.

Consequences

- Parallel submissions never collide — isolation is physical. - **Branches outstanding ≠ agents running.** Many branches can sit in the review queue while only a few agents burn tokens — this is also the cost control (see [ADR 0003](./0003-open-core-license-split.md) is separate; cost detail in the plan §7). - Nothing reaches the default branch without a human clicking merge (no auto-merge in Phase 1). - The orchestrator is stateful and long-running — it runs on an always-on host (Fly.io / Railway), never serverless.