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 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:
```
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 complete mode-aware package:

privacy-safe request and content approval;
fact-base JSON and Markdown;
the five immutable set-plan records and authored drafts;
declared author results and authored content;
resolved theme and every built artifact;
canonical mobile, tablet, and desktop screenshots;
paired browser-evidence/v2 metrics with launched Chromium name, version, and capture identity;
cohesion observations and each visual-review request/result; and
the bounded revision record when a correction occurred.

Canonical object hashes identify normalized fact-base, theme, runtime, and capture objects; manifest.immutableHashes independently covers serialized file bytes. The archive requires one complete, internally consistent browser and review chain for a successful unattended recap. Missing, stale, forged, cross-record-mismatched, or tampered coverage fails before the active project is deleted.

built-needs-review is a terminal review-gate outcome, not a non-durable success. Its partial evidence remains available for diagnosis, but it cannot be finalized, exported, attested, archived, or pushed. Review and rebuild the recap to a passing visual-review outcome first.

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:

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 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 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 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

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