schema orchestration

---

title: Schema-Based Orchestration category: concepts tags: [harness, orchestration, archon, dag, layer-7] status: developing created: 2026-04-28 updated: 2026-04-28 sources:

• "harness-implementation-plan" related:
• "agentic-harness"
• "persistent-memory"
• "structured-planning" layer: "Layer_7" summary: Layer 7 composes all other layers into a coherent pipeline using Archon's YAML workflow engine. DAG execution, loop nodes, human approval gates, worktree isolation, and run persistence come from Archon — no custom orchestration code. provenance: extracted: 0.85 inferred: 0.15 ambiguous: 0.0

---

Schema-Based Orchestration via Archon

Origin Principle

Human coordination is narrative (Slack, PRs, standups). Agent coordination should be structured data passing. Each agent publishes typed schemas; orchestration routes work based on declared capabilities. No "asking" — only task routing based on capability declaration.

Architecture: Archon as Workflow Engine

Rather than building custom orchestration, Layer 7 uses Archon's YAML workflow engine:

Need	Archon provides	Alternative build cost
DAG execution	YAML workflow nodes with dependencies	Custom task graph executor
Loop nodes	loop: { until: CONDITION }	Custom rework loop logic
Human approval gates	loop: { until: APPROVED, interactive: true }	Custom approval UI
Worktree isolation	Auto git worktree per run	Custom branch management
Run persistence	SQLite/PostgreSQL	Custom state storage
Multi-platform invocation	CLI, Web UI, Slack, Telegram, GitHub	Custom API layer
Parallel nodes	Concurrent independent nodes	Custom parallel dispatch

pi.dev extensions implement intelligence (spec hardening, planning, critic review, grounding, memory). Archon implements orchestration (sequencing, looping, isolation, persistence).

Primary Workflow: harness-pipeline.yaml

The workflow defines nodes for each layer:

1. harden-spec → Spec hardening using harden-spec tool
2. resolve-ambiguities → Loop until no blocking ambiguities (interactive)
3. create-plan → Plan from hardened spec
4. review-plan → Adversarial review of plan
5. approve-plan → Loop until approved (interactive, max 3 iterations)
6. execute-plan → Loop until all tasks complete (fresh_context: true, max 100 iterations)
7. capture-memory → Store results via wiki-ingest skill

Additional Workflows

• harness-fix-issue.yaml — GitHub issue → full pipeline
• harness-quick-review.yaml — Standalone critic review on latest diff

Terminal State Model

State	Meaning
completed	All control objectives passed
blocked	Mandatory gate/dependency unresolved
replan_required	Drift, failed critics, or spec change
cancelled	Precondition not met
failed	Retries/limits exhausted

Failure & Resume Policy

• Node retries for transient errors only; fatal errors fail closed
• Every interactive loop has bounded max_iterations and gate message
• Compensation is a harness responsibility, not Archon's
• Resume only from last verified checkpoint, only if prior run ended in resumable state

Extension Interface

Type	Name	Description
Event consumed	plan_approved	Begin orchestrated execution
Event consumed	subtask_verified	Task passed critics, advance wave
Event consumed	subtask_failed	Task failed, mark dependents blocked
Event emitted	execution_complete	All tasks done or failed
Tool	orchestrate-plan	Begin orchestrated execution
Tool	register-agent-capability	Declare agent capabilities
Command	/harness-orchestration-status	Agents, capabilities, wave progress

Config

{
  "orchestration": {
    "max_parallel": 2
  }
}

Files

• lib/harness-orchestrator.ts — Orchestrator class, schema validation, wave tracking
• extensions/harness-orchestrator.ts — pi.dev extension registration
• .archon/workflows/harness-pipeline.yaml
• .archon/workflows/harness-fix-issue.yaml
• .archon/workflows/harness-quick-review.yaml