---
title: Project Artifacts
description: 'Project artifact contracts: state.md, spec.md, design.md, plan.md, and implementation.md.'
---

# 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

### Explainer artifacts

[Explainer Kit](../skills/explainer-kit.md) writes project runs under
`<resolved-project-path>/explainers/<slug>/`. The two project products have
different retention contracts:

- A `project-explainer` is a working artifact. In a shared project it can be
  tracked while the project is active, but project completion removes it from
  the tracked branch with the active project tree. It remains only in the local
  archived project.
- A selected final `project-recap` is a durable completion record. Before a
  shared project is removed, archive copies the complete selected run to
  `.oat/repo/reference/project-recaps/<YYYYMMDD-project-slug>/`, verifies its
  immutable package hashes, and reports that tracked export path. Summary and
  PR links use this export, never the gitignored local archive. Lifecycle
  callers identify the selected project-relative run with:

  ```bash
  oat project archive <project-path> \
    --project-recap-run explainers/<recap-slug>
  ```

The archive exports at most one selected recap package. It preserves structured
failure outcomes and successful intermediates, rejects an existing dated
destination, and requires the selected path to stay under the project's
`explainers/` directory with a `project-recap` manifest. Verification covers
the exact retained bytes for the privacy-safe request, content approval, fact
base JSON and Markdown, declared author results, authored Markdown, resolved
theme, and every built artifact. Canonical fact-base and theme hashes remain
normalized-object identities; `manifest.immutableHashes` independently covers
serialized file bytes. Missing, stale, or tampered coverage fails before the
active project is deleted.

Local-scope projects are not archived through this export path. Their explainer
packages inherit the local project's untracked posture and remain
`built-not-durable` unless independent publish evidence exists. Non-project OAT
explainer runs use `.oat/repo/reference/explainers/<slug>/`; direct core callers
must provide their own explicit output root.

### 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:

```yaml
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.

### Formatting and verification hygiene

Tracked artifacts are part of the repository diff, so artifact writers format
them before finishing or committing. During plan authoring, OAT resolves the
repository's documented write/fix command from applicable `AGENTS.md` /
`CLAUDE.md` instructions and relevant package manifests. Each task that writes
an artifact receives a concrete invocation, scoped to that task's files when
the command supports paths.

Downstream implementers execute that supplied command without repeating
discovery. Roles and lifecycle skills that write outside a planned task,
including reviewers and documentation, summary, PR, and quick-start flows, use
the same discovery procedure as a fallback. Gate-originated review prompts also
carry the contract so review artifacts follow the same rule across runtimes.

Writers must:

- prefer a documented write/fix command over a check-only command;
- avoid inferring or hardcoding a formatter;
- scope the write to created or edited files when supported;
- avoid whole-tree rewrites that could absorb unrelated changes; and
- warn once with
  `no format command discovered in repo instructions; skipping` when no command
  is discoverable, then continue.

Formatting supplements the applicable verification contract. Phase
implementation runs repository gates over its produced diff, including
artifact writes. Prose-only lifecycle work runs only checks relevant to the
files it changed.

## 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](splitting.md) 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`:

```yaml
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 reviewers retain the exact resolver-returned `dispatchArgs.model`; Cursor reviewers retain the exact `providers.cursor.dispatchArgs.variant` native agent type; Codex retains its exact role or pinned child. Every retry preserves the complete target. 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](../../reference/cli-reference.md) and [Implementation Execution](implementation-execution.md) 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.

```yaml
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](reviews.md#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`
