MigrationInterface

A single reversible schema/data migration. Implementations apply forward changes in {@see up()} and must be able to undo them in {@see down()}. Discovery/ordering convention: migrations of this kind live as flat PHP classes directly under the root `migrations/` directory (namespace `Milpa\Migrations`), one class per file, with the class short-name equal to the file's basename (e.g. `migrations/CreateUsersTable.php` → `CreateUsersTable`). {@see \Milpa\app\Commands\MigrateCommand} discovers them via `glob('migrations/*.php')` and applies `sort()` on the file list — i.e. execution order is the ASCII-sort of the class short-name, not a timestamp or semver embedded in the name. This is a *different* migration kind than plugin-versioned migrations (`Version_X_Y_Z.php`, see {@see \Milpa\app\Interfaces\PluginMigrationInterface}), which sort by semver instead.

abstract public function up(): void

Applies the migration.

abstract public function down(): void

Reverts the migration applied by {@see up()}.

abstract public function getDescription(): string

Returns a human-readable description of what this migration does.

abstract public function getId(): string

Returns a stable, unique key identifying this migration for ordering and dedup purposes across plugins. Per the discovery convention documented on this interface, this is the migration class's short name (e.g. `CreateUsersTable`) — already unique within the `migrations/` directory, since the runner keys applied migrations by fully-qualified class name.

abstract public function getVersion(): string

Returns a version/ordering token for this migration. There is no timestamp or semver embedded in the naming convention for this migration kind (unlike `Version_X_Y_Z.php` plugin migrations), so this defaults to the same value as {@see getId()} — the class short-name — which is exactly the token the runner's `sort()` over `glob()` results already orders by.