fix(hub-projects): make generated data table migrations idempotent

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

frontend/src/lib/components/datatableSchemaSql.ts

@@ -172,14 +172,26 @@ export function generateMigrationSql(
 		const pkLine = pkCols.length > 0 ? `,\n  PRIMARY KEY (${pkCols.join(', ')})` : ''
 		const qualifiedName = `"${change.schemaName}"."${change.tableName}"`
 		const createKeyword = options?.ifNotExists ? 'CREATE TABLE IF NOT EXISTS' : 'CREATE TABLE'
-		let sql = `BEGIN;\n${createKeyword} ${qualifiedName} (\n  ${colDefs}${pkLine}\n);`
+		// The target may not have the schema at all (fresh data table import).
+		const schemaDdl =
+			change.schemaName !== 'public' ? `CREATE SCHEMA IF NOT EXISTS "${change.schemaName}";\n` : ''
+		let sql = `BEGIN;\n${schemaDdl}${createKeyword} ${qualifiedName} (\n  ${colDefs}${pkLine}\n);`
 		for (const fk of table.foreignKeys ?? []) {
 			const fkSql = renderForeignKey(fk, {
 				useSchema: true,
 				dbType: 'postgresql',
 				tableName: change.tableName
 			})
-			sql += `\nALTER TABLE ${qualifiedName} ADD ${fkSql};`
+			// With IF NOT EXISTS the table may pre-exist with this FK already in
+			// place; an unconditional ADD would then abort the whole transaction.
+			// The constraint name is emitted unquoted, so Postgres folds it to
+			// lowercase — compare against the folded form.
+			const fkName = options?.ifNotExists
+				? fkSql.match(/^CONSTRAINT\s+(\S+)/)?.[1]?.toLowerCase()
+				: undefined
+			sql += fkName
+				? `\nDO $$\nBEGIN\n  IF NOT EXISTS (\n    SELECT 1 FROM pg_constraint\n    WHERE conname = '${fkName}' AND conrelid = '${qualifiedName}'::regclass\n  ) THEN\n    ALTER TABLE ${qualifiedName} ADD ${fkSql};\n  END IF;\nEND $$;`
+				: `\nALTER TABLE ${qualifiedName} ADD ${fkSql};`
 		}
 		sql += '\nCOMMIT;'
 		return sql

frontend/src/lib/components/workspaceSettings/projectMigrations.test.ts

@@ -160,6 +160,40 @@ describe('generateDatatableMigrations', () => {
 		expect(migrations[0].sql).toContain('"public"."customers"')
 	})
 
+	it('guards FK creation so re-running on an existing table does not abort', async () => {
+		getDatatableFullSchemaMock.mockResolvedValue(schema)
+		const usage = new Map([['main', new Set(['orders'])]])
+		const migrations = await generateDatatableMigrations('ws', usage)
+		const sql = migrations[0].sql
+		// The ADD CONSTRAINT must be wrapped in a pg_constraint existence check.
+		expect(sql).toContain('DO $$')
+		expect(sql).toContain('SELECT 1 FROM pg_constraint')
+		expect(sql).toContain(`conrelid = '"public"."orders"'::regclass`)
+		// No unguarded ALTER TABLE ... ADD at the start of a line.
+		expect(/^ALTER TABLE .* ADD CONSTRAINT/m.test(sql)).toBe(false)
+	})
+
+	it('creates non-public schemas before their tables', async () => {
+		const appSchema = {
+			app: {
+				customers: {
+					name: 'customers',
+					columns: [{ name: 'id', datatype: 'integer', primary_key: true, nullable: false }],
+					foreign_keys: []
+				}
+			}
+		}
+		getDatatableFullSchemaMock.mockResolvedValue(appSchema)
+		const usage = new Map([['main', new Set(['app.customers'])]])
+		const migrations = await generateDatatableMigrations('ws', usage)
+		const sql = migrations[0].sql
+		expect(sql).toContain('CREATE SCHEMA IF NOT EXISTS "app";')
+		expect(sql.indexOf('CREATE SCHEMA IF NOT EXISTS "app";')).toBeLessThan(
+			sql.indexOf('CREATE TABLE IF NOT EXISTS "app"."customers"')
+		)
+		expect(sql).not.toContain('CREATE SCHEMA IF NOT EXISTS "public"')
+	})
+
 	it('keeps same-named tables from different schemas both created', async () => {
 		const twoSchemas = {
 			public: {