ADR-0012: Separate editable drafts from immutable revisions

Status: Accepted Date: 2026-10-07

Context #

A visual editor needs to save work without accumulating a published-history snapshot for every adjustment. Concurrent editors must not silently overwrite each other.

Decision #

Store a validated draft definition and optimistic version on the tenant-owned Estimator. Saving checks the version. Publishing captures a new immutable revision in a serializable transaction and changes the publication pointer. Reuse the latest snapshot when its canonical content hash matches the draft.

This replaces the editing behavior in ADR-0005. Its immutable revision and estimate snapshot guarantees remain in force. Existing candidate revisions remain available for rollback and export.

Alternatives considered #

Creating snapshots on every save produces noisy history. Updating a published revision breaks historical calculations. A separate draft table adds a join for a single workspace per estimator without improving isolation.

Consequences #

Draft saves cannot affect live pricing. Stale saves return a conflict. Publication and rollback remain explicit. Empty or invalid intermediate edits stay local until they satisfy the portable schema. Deleted unused estimators are tombstoned; retained snapshots are never physically deleted by the application.