Constraint Validation

SQL constraints are checked on Origin at sync time, not on the device. This keeps local writes fast (no network round-trip) while preserving global consistency.

Enforced Constraints

• UNIQUE — Duplicate key → CompensationHint::UniqueViolation
• FOREIGN KEY — Dangling reference → CompensationHint::ForeignKeyMissing
• CHECK / schema — Type or CHECK violation → CompensationHint::SchemaViolation
• Integrity — Other integrity-rule violation → CompensationHint::IntegrityViolation
• Permission — Insufficient privilege → CompensationHint::PermissionDenied
• Rate limit — Quota exceeded → CompensationHint::RateLimited
• Custom — Application-defined handling → CompensationHint::Custom

Compensation Hints

When a local write violates a constraint on Origin, a typed CompensationHint is sent back to the device. The application handles the conflict:

• UniqueViolation — The document ID or key already exists. Offer the user to rename or merge.
• ForeignKeyMissing — A FK target doesn't exist. Offer to create it or discard the child.
• SchemaViolation — A CHECK constraint or type rule failed. Show the violation and let the user fix it.
• IntegrityViolation — Another integrity rule was violated. Surface the error for manual resolution.
• PermissionDenied — The operation exceeds the user's role. Show the denial and suggest re-authentication.
• RateLimited — A quota or rate limit was exceeded. Retry after cooldown.
• Custom — Application-specific handling via custom compensation logic.

No silent data loss — the application always decides.

State Constraints

ALTER COLLECTION invoices ADD CONSTRAINT invoice_flow
    ON COLUMN status TRANSITIONS (
        'draft'     -> 'submitted',
        'submitted' -> 'approved' BY ROLE 'manager',
        'approved'  -> 'issued'   BY ROLE 'accountant'
    );

State transitions are validated at sync time. Invalid transitions (e.g., draft -> issued) are rejected with a compensation hint.