Architecture invariants (spec)

These invariants preserve the system boundary and auditability.

Separation of concerns

• Orchestration MUST live in the pipeline runner, not in agents.
• Agents MUST be pure workers: given an input contract, return an output contract.

Artifact ownership

• Final artifacts (final_result.json, run_trace.json) MUST be written by the orchestrator/finalize layer.
• Agents MUST NOT write or mutate run artifacts directly.

Statelessness

• The system MUST NOT require persistent state across runs.
• Any optional caching MUST be explicitly documented and must not change semantics when absent.

Schema discipline

• Trace schema and agent output schema are compatibility gates; breaking changes require version bumps.