feat: single-file project import/export (.ocp)

fflate zip container: project.json (serialized project incl. schema
version) + media files with a manifest. Export gathers all project
media (missing blobs warn, never abort) after save-flush; import
validates everything before any write, migrates older archives through
the storage migration registry, remaps media ids, and creates a new
project with rollback on failure. Entry points: projects page
import/export, editor header menu, export-project-archive action.
29 tests incl. full round-trip.

1 files changed, 75 insertions, 0 deletions

diff --git a/apps/web/src/project/transfer/migrate.ts b/apps/web/src/project/transfer/migrate.ts
new file mode 100644
index 00000000..14f59790
--- /dev/null
+++ b/apps/web/src/project/transfer/migrate.ts
@@ -0,0 +1,75 @@
+import type { StorageMigration } from "@/services/storage/migrations/base";
+import type { ProjectRecord } from "@/services/storage/migrations/transformers/types";
+import { getProjectId } from "@/services/storage/migrations/transformers/utils";
+
+/**
+ * In-memory counterpart to `runStorageMigrations`: applies the same migration
+ * registry to a single project record (e.g. parsed from an imported project
+ * archive) without touching IndexedDB.
+ */
+
+export function getRecordVersion({
+	project,
+}: {
+	project: ProjectRecord;
+}): number {
+	const versionValue = project.version;
+	if (typeof versionValue === "number") {
+		return versionValue;
+	}
+
+	const scenesValue = project.scenes;
+	if (Array.isArray(scenesValue) && scenesValue.length > 0) {
+		return 1;
+	}
+
+	return 0;
+}
+
+export interface MigratedProjectRecord {
+	project: ProjectRecord;
+	fromVersion: number;
+	toVersion: number;
+	complete: boolean;
+}
+
+export async function migrateProjectRecord({
+	project,
+	migrations,
+}: {
+	project: ProjectRecord;
+	migrations: StorageMigration[];
+}): Promise<MigratedProjectRecord> {
+	const orderedMigrations = [...migrations].sort((a, b) => a.from - b.from);
+	const fromVersion = getRecordVersion({ project });
+	const targetVersion = orderedMigrations.at(-1)?.to ?? fromVersion;
+
+	let currentVersion = fromVersion;
+	let record = project;
+	const projectId = getProjectId({ project: record }) ?? "imported-project";
+
+	for (const migration of orderedMigrations) {
+		if (migration.from !== currentVersion) {
+			continue;
+		}
+
+		const result = await migration.run({
+			projectId,
+			project: record,
+		});
+
+		if (result.skipped) {
+			break;
+		}
+
+		record = result.project;
+		currentVersion = migration.to;
+	}
+
+	return {
+		project: record,
+		fromVersion,
+		toVersion: currentVersion,
+		complete: currentVersion >= targetVersion,
+	};
+}