Project Artifacts

Project artifacts live under .oat/projects/<scope>/<project>/.

Core artifacts

• state.md: lifecycle state and checkpoint metadata
• discovery.md: problem framing, constraints, solution space exploration (for exploratory requests), and discovery outcomes
• spec.md: requirements + acceptance criteria
• design.md: architecture and implementation approach (full in spec-driven mode; optional lightweight version in quick mode covering architecture, components, and testing strategy)
• plan.md: phase/task breakdown and review tracking
• implementation.md: execution log, verification, final summary
• summary.md: institutional memory artifact — generated from project artifacts at closeout, used as PR description source and archive cover page

Mode-sensitive notes:

• state.md includes workflow mode metadata (spec-driven, quick, import) for routing.
• spec.md and design.md are required in spec-driven mode, optional in quick/import mode. Quick mode offers a lightweight design.md (architecture, components, testing strategy) at a post-discovery decision point.
• plan.md remains canonical execution artifact across all modes.

Supporting artifacts

• summary.md: generated by oat-project-summary — re-runnable, tracks its own state via frontmatter for incremental updates after revisions
• reviews/*.md: phase/final review files
• pr/*.md: generated PR descriptions
• references/imported-plan.md: preserved source plan for import mode
• references/split-plan.json: persisted split plan for a coordination parent, used as the durable resume source when oat-project-split is interrupted

Gate review frontmatter

Review artifacts produced by oat gate review use the normal review fields plus an exact copy of the gate-owned configured invocation:

oat_review_invocation: gate
oat_project: .oat/projects/shared/example
oat_gate_run_id: 00000000-0000-0000-0000-000000000000
oat_gate_target: codex-sol-max
oat_gate_runtime: codex
oat_invocation_model: gpt-5.6-sol
oat_invocation_reasoning_effort: max
oat_invocation_source: exec-target-config

oat_invocation_model and oat_invocation_reasoning_effort may be provider-default when OAT deliberately leaves a control to the provider, or unknown when the target does not declare it. These fields are configured invocation metadata, not runtime-confirmed or self-reported model identity. Manual and auto review artifacts do not require the gate-only fields.

Contract

Artifacts are the project system of record; automation and routing should derive from these files, not memory.

Coordination parents

Project splitting introduces a coordination-only parent artifact. It records shared context and child relationships, but it is not an executable lifecycle project.

A coordination parent uses:

• oat_kind: coordination
• oat_phase: decomposition
• oat_phase_status: complete

Coordination parents do not contain executable phase files. spec.md, design.md, plan.md, and implementation.md are removed from the parent and represented in state prose as not applicable.

The parent still keeps state.md, discovery.md, and references/split-plan.json. Child projects are flat siblings and link back to the parent through state metadata. Each child starts from a distilled discovery seed and must revalidate inherited context before moving beyond discovery/design.

See Project Splitting for the full parent/child model.

plan.md frontmatter

plan.md carries frontmatter that the implementation skill consumes. Notable fields:

• oat_plan_hill_phases — list of phase IDs to pause at for HiLL checkpoints.
• oat_plan_parallel_groups — declares which phases may execute concurrently in worktrees. See below.
• oat_phase_review_gate — opt-in non-pausing external review gate that runs after a phase's standard reviewer passes. See below.

oat_plan_parallel_groups

Declare phase groups that run in parallel during oat-project-implement:

oat_plan_parallel_groups: [['p02', 'p03'], ['p04', 'p05']]

Each inner array is a group of phases that execute concurrently in their own worktrees and merge back to the orchestration branch in plan order. Phases not listed in any group run sequentially.

Semantics:

• Empty or missing field → fully sequential, no worktrees created (default).
• Each group must contain 2 or more phases — singleton groups are rejected.
• Every phase ID must exist in the plan body.
• No phase may appear in more than one group.
• Parallelism is only honored at Tier 1 (native subagents). Tier 2 degrades parallel groups to sequential target-preserving execution, not unconditional inline review. Concrete managed Claude and Cursor reviewers retain the exact resolver-returned dispatchArgs.model in the actual invocation and every retry; Codex retains its exact role or pinned child. Inline review requires verified equivalent host controls or an explicit inherit/default or managed-uncapped base-role exception, and otherwise blocks.

Authoring responsibility:

• oat-project-plan proposes parallel groups when phases have file-disjoint task sets; it never infers parallelism silently.
• Phases listed in a group should have no file-level overlap. Overlap will produce merge conflicts during fan-in that stop the run.

Validation:

Before dispatching, oat-project-implement invokes oat project validate-plan --project-path "${PROJECT_PATH}". Non-zero exit blocks the run. See CLI Reference and Implementation Execution for details.

oat_phase_review_gate

Enable an optional, non-pausing external review gate that runs after each selected phase's standard reviewer passes and its bookkeeping is committed:

Planning offers this setting after stable phase IDs exist and before the plan artifact review. The read-only target probe qualifies only an explicitly configured, enabled, and available target, then offers all phases, selected phases, or disabled. An explicit oat_phase_review_gate value from a resumed or imported plan is preserved unchanged without re-prompting. If the probe fails, no target qualifies, the run is non-interactive, or the user declines, planning leaves phase review disabled.

oat_phase_review_gate:
  enabled: true
  phases: [] # empty or omitted = every implementation phase
  review_type: code
  exit_nonzero_on: important

Semantics:

• Missing, null, or enabled: false → disabled (default). enabled: true activates the gate.
• phases → optional. Empty or missing runs the gate after every implementation phase; a populated list restricts it to those phase IDs, each of which must exist in the plan body.
• review_type → optional, defaults to code. Only code is supported for phase gates.
• exit_nonzero_on → optional, defaults to important. One of critical, important, medium, minor. This is the blocking threshold: findings at or above it stop the phase; sub-threshold findings are dispositioned by the judgment sweep rather than ignored.

A malformed gate stops the run before task execution rather than being silently disabled. The gate is independent of HiLL checkpoints and reuses the existing oat gate review target config — it does not hardcode a --target. See Reviews → Phase review gate for the runtime behavior and disposition rules.

Reference artifacts

• .oat/templates/*.md
• .oat/projects/<scope>/<project>/spec.md
• .oat/projects/<scope>/<project>/design.md
• .oat/projects/<scope>/<project>/plan.md
• .oat/projects/<scope>/<project>/implementation.md
• .oat/projects/<scope>/<project>/summary.md