Reference: Database schema

PostgreSQL is the source of truth for human-task state, business data, and the audit log. The authoritative model is specs/001-document-approval-engine/data-model.md; the live schema is defined by the Flyway migrations in adapters/persistence-postgres/src/main/resources/db/migration/.

Tables (first deliverable)

Table	Holds
flow_definition	data-defined templates (states/transitions/initiator+candidate groups), immutable per version
flow_instance	a running flow (current state, status, terminal outcome, document ref, submitter)
task	human work item (status, owner, version for optimistic concurrency)
decision	recorded approve/reject on a task
person, group, group_membership	minimal identity for assignment & authorization
audit_entry	append-only ordered history of every change
outbox_event	transactional outbox for CloudEvents publication

Notes

• Append-only: audit_entry is never updated or deleted (Principle III). A flow's lifecycle is reconstructable from its ordered entries (SC-003).
• Concurrency: claim/release/decide are conditional updates on task (status, version) — exactly one effective outcome (FR-013, SC-004).
• jOOQ: typed SQL is generated from the migrated schema during the build (T016).
• step is not in the schema — Steps are out of scope for the first deliverable.