Data Layer Contracts

Purpose

Defines the contract chain from migration schema to factory to seeder, and prevents drift between them.

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Schema Contract

Every NOT NULL column defined in a migration must be supported by:

• a factory definition, or
• a seeder definition (only for seed data), or
• an explicit DB default in the migration

This is a schema-only rule, not a validation rule. MySQL/MariaDB is the canonical database — SQLite differences are invalid for schema validation assumptions.

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Factory Rules

Factories MUST:

• satisfy all NOT NULL columns
• reflect migration constraints
• represent the smallest valid persisted entity — not random data, not business scenarios, only valid schema state

Factories MUST NOT:

• enforce business rules or validation rules
• replace service-layer creation logic
• define seeder logic, or depend on seeders

If a migration introduces a NOT NULL column, the factory MUST be updated immediately — omission is invalid state.

Factories SHOULD align with service-layer expectations but do NOT depend on it: service layer = behavior, factory = valid structure.

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Seeder Rules

Seeders MUST:

• rely on factories for object creation — factories are the source of truth for valid model state
• orchestrate dependency order between models, optionally via helpers (findOrCreateClient, findOrCreateProject, findOrCreateUser — convenience utilities, not business logic)
• only insert schema-valid data, with no reliance on implicit database defaults

Seeders MUST NOT:

• define validation rules, factory structure, or schema constraints
• contain business logic

Seeders assemble data. They do not define data correctness.

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Drift Triggers

The following indicate schema drift: migration changes, factory mismatch, seeder mismatch, SQLSTATE constraint violations, CI vs local DB mismatch.

Schema validation requires migrate:fresh + seed before running test suites.

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Identity Rule

Primary keys are non-deterministic. Tests MUST NOT rely on hardcoded IDs.