ADR 055 — Orchestrator pub/sub coordination by plan

Status

Proposed (2026-10-03), not scheduled.

Context

Orchestrator agents working on related plans across projects currently coordinate by appending dated notes to a shared plain-text exchange file (for example, between snodo-public and snodo-cloud during a cloud interface change). This works, but requires a shared folder and provides neither structure nor a delivery guarantee. The cloud repository has proposed cloud-hosted, per-organisation streams; this record captures the client-side counterpart.

Decision

Direction only: snodo would offer publish/subscribe for orchestrator messages scoped to a plan id, using the cloud as shared transport and a local file as a fallback. Messages would identify who sent them and the plan, task, job or commit they refer to.

The following remain open for a later decision: message types; whether messages ever enter the audit trail (the state machine and audit vocabulary are closed, so this requires an explicit decision); retention; and authentication.

Consequences

Related orchestrators could coordinate without a shared folder, while a local fallback remains available. No implementation or protocol change is scheduled by this proposal.

Alternatives

Keep the shared plain-text exchange file as the only coordination mechanism; it works today but retains its shared-folder, structure and delivery limits.