fix(polls): canonicalize transaction lock order

src/features/housekeeping/domains/content/services/mutations-production.test.ts

@@ -101,6 +101,28 @@ describe("Content production mutation adapter", () => {
 		);
 	});
 
+	it("uses read committed isolation only for poll mutations", async () => {
+		const pollDeps = dependencies();
+		await pollDeps.adapter.execute(
+			"poll.change",
+			{ action: "delete", id: 7 },
+			mutationContext,
+		);
+		expect(pollDeps.transaction).toHaveBeenCalledWith(expect.any(Function), {
+			isolationLevel: "read committed",
+		});
+
+		const articleDeps = dependencies();
+		await articleDeps.adapter.execute(
+			"article.change",
+			{ action: "update", id: 7 },
+			mutationContext,
+		);
+		expect(articleDeps.transaction).toHaveBeenCalledWith(
+			expect.any(Function),
+			undefined,
+		);
+	});
 	it("persists correlated intent and truthful outcome around external storage writes", async () => {
 		const deps = dependencies();
 		await deps.adapter.execute(

src/features/housekeeping/domains/content/services/mutations-production.ts

@@ -46,9 +46,14 @@ export const CONTENT_MIXED_OPERATIONS = [
 
 type TransactionToken = unknown;
 
+interface ContentTransactionOptions {
+	isolationLevel: "read committed";
+}
+
 export interface ContentProductionMutationDependencies {
 	transaction<T>(
 		run: (transaction: TransactionToken) => Promise<T>,
+		options?: ContentTransactionOptions,
 	): Promise<T>;
 	writeAudit(entry: AuditEntry, transaction?: TransactionToken): Promise<void>;
 	executeOperation(
@@ -126,6 +131,10 @@ export function createContentProductionMutationAdapter(
 	return {
 		async execute(operation, input, context) {
 			if (includesOperation(CONTENT_DATABASE_OPERATIONS, operation)) {
+				const transactionOptions =
+					operation === "poll.change"
+						? ({ isolationLevel: "read committed" } as const)
+						: undefined;
 				return dependencies.transaction(async (transaction) => {
 					const snapshot = await dependencies.executeOperation(
 						operation,
@@ -138,7 +147,7 @@ export function createContentProductionMutationAdapter(
 						transaction,
 					);
 					return snapshot;
-				});
+				}, transactionOptions);
 			}
 
 			await dependencies.writeAudit(auditEntry(operation, context, "intent"));
@@ -192,9 +201,9 @@ export function createContentProductionMutationAdapter(
 
 export const contentProductionMutationAdapter =
 	createContentProductionMutationAdapter({
-		async transaction(run) {
+		async transaction(run, options) {
 			const { db } = await import("@/lib/db");
-			return db.transaction((transaction) => run(transaction));
+			return db.transaction((transaction) => run(transaction), options);
 		},
 		async writeAudit(entry, transaction) {
 			const { logAudit } = await import("@/lib/services/audit");