fix(polls): canonicalize transaction lock order

src/actions/polls.test.ts

@@ -1,22 +1,127 @@
 // @ts-nocheck
 import { beforeEach, describe, expect, it, vi } from "vitest";
 
-const { selectLimit, updateSet, updateWhere } = vi.hoisted(() => ({
-	selectLimit: vi.fn(),
-	updateSet: vi.fn(() => ({ where: updateWhere })),
-	updateWhere: vi.fn(),
+const database = vi.hoisted(() => {
+	let selectedQueue: unknown[][] = [];
+	let mutationSteps: string[] = [];
+	let validationVoteQuestionIds: number[] = [];
+	let insertedVoteQuestionIds: number[] = [];
+
+	const nextSelected = () => selectedQueue.shift() ?? [];
+	const conditionPart = (condition: unknown, key: "column" | "value") => {
+		if (!condition || typeof condition !== "object") return "none";
+		return String((condition as Record<string, unknown>)[key] ?? "none");
+	};
+	const conditionOperator = (condition: unknown) => {
+		if (!condition || typeof condition !== "object") return "none";
+		return String((condition as Record<string, unknown>).operator ?? "none");
+	};
+	const select = vi.fn(() => ({
+		from: vi.fn((table: { tableName?: string }) => ({
+			where: vi.fn((condition: unknown) => {
+				const tableName = table.tableName ?? "unknown";
+				const run = async () => nextSelected();
+				return {
+					limit: vi.fn(async () => {
+						if (tableName === "WebsitePollVote") {
+							const clauses =
+								(condition as { clauses?: Array<Record<string, unknown>> })
+									?.clauses ?? [];
+							const question = clauses.find(
+								(clause) => clause.column === "questionId",
+							);
+							if (question) {
+								validationVoteQuestionIds.push(Number(question.value));
+							}
+						}
+						return run();
+					}),
+					for: vi.fn(async (strength: string) => {
+						mutationSteps.push(
+							`lock:${tableName}:${conditionOperator(condition)}:${conditionPart(condition, "column")}:${conditionPart(condition, "value")}:${strength}`,
+						);
+						return run();
+					}),
+					orderBy: vi.fn(async (column: unknown) => {
+						mutationSteps.push(
+							`read:${tableName}:${conditionOperator(condition)}:${conditionPart(condition, "column")}:orderBy:${String(column)}`,
+						);
+						return run();
+					}),
+					// biome-ignore lint/suspicious/noThenProperty: This query-builder mock must be awaitable like Drizzle.
+					then(
+						resolve: (value: unknown[]) => unknown,
+						reject: (error: unknown) => unknown,
+					) {
+						return run().then(resolve, reject);
+					},
+				};
+			}),
+		})),
+	}));
+	const updateWhere = vi.fn();
+	const updateSet = vi.fn(() => ({ where: updateWhere }));
+	const update = vi.fn(() => ({ set: updateSet }));
+	const insert = vi.fn((table: { tableName?: string }) => ({
+		values: vi.fn(async (values: Record<string, unknown>) => {
+			mutationSteps.push(`insert:${table.tableName ?? "unknown"}`);
+			if (table.tableName === "WebsitePollVote") {
+				insertedVoteQuestionIds.push(Number(values.questionId));
+			}
+			return [{ insertId: 1 }];
+		}),
+	}));
+	const deleteFrom = vi.fn((table: { tableName?: string }) => ({
+		where: vi.fn(async () => {
+			mutationSteps.push(`delete:${table.tableName ?? "unknown"}`);
+		}),
+	}));
+	const tx = { select, insert, delete: deleteFrom };
+	const transaction = vi.fn(
+		async (
+			run: (transaction: typeof tx) => Promise<unknown>,
+			_config?: unknown,
+		) => run(tx),
+	);
+
+	return {
+		db: { select, update, insert, delete: deleteFrom, transaction },
+		updateSet,
+		updateWhere,
+		transaction,
+		queueSelected(...values: unknown[][]) {
+			selectedQueue = [...values];
+		},
+		mutationSteps: () => [...mutationSteps],
+		validationVoteQuestionIds: () => [...validationVoteQuestionIds],
+		insertedVoteQuestionIds: () => [...insertedVoteQuestionIds],
+		reset() {
+			selectedQueue = [];
+			mutationSteps = [];
+			validationVoteQuestionIds = [];
+			insertedVoteQuestionIds = [];
+		},
+	};
+});
+
+vi.mock("drizzle-orm", () => ({
+	and: vi.fn((...clauses: unknown[]) => ({ operator: "and", clauses })),
+	eq: vi.fn((column: unknown, value: unknown) => ({
+		operator: "eq",
+		column,
+		value,
+	})),
+	inArray: vi.fn((column: unknown, value: unknown) => ({
+		operator: "inArray",
+		column,
+		value,
+	})),
 }));
 
 vi.mock("@/lib/db", () => ({
-	db: {
-		select: vi.fn(() => ({
-			from: vi.fn(() => ({
-				where: vi.fn(() => ({ limit: selectLimit })),
-			})),
-		})),
-		update: vi.fn(() => ({ set: updateSet })),
-	},
+	db: database.db,
 	WebsitePoll: {
+		tableName: "WebsitePoll",
 		id: "id",
 		title: "title",
 		description: "description",
@@ -27,6 +132,7 @@ vi.mock("@/lib/db", () => ({
 		endsAt: "endsAt",
 	},
 	WebsitePollQuestion: {
+		tableName: "WebsitePollQuestion",
 		id: "id",
 		pollId: "pollId",
 		question: "question",
@@ -34,14 +140,19 @@ vi.mock("@/lib/db", () => ({
 		sortOrder: "sortOrder",
 		options: "options",
 	},
-	WebsitePollVote: { id: "id", questionId: "questionId", userId: "userId" },
+	WebsitePollVote: {
+		tableName: "WebsitePollVote",
+		id: "id",
+		questionId: "questionId",
+		userId: "userId",
+	},
 }));
 
 vi.mock("@/lib/permissions", () => ({ PERMS: { POLLS_EDIT: "polls.edit" } }));
 vi.mock("@/lib/services/audit", () => ({ logAudit: vi.fn() }));
 vi.mock("next/cache", () => ({ revalidatePath: vi.fn() }));
-vi.mock("@/lib/safe-action", () => ({
-	adminAction: (options, handler) => async (input) => {
+vi.mock("@/lib/safe-action", () => {
+	const wrap = (options, handler) => async (input) => {
 		const parsed = options.schema.safeParse(input);
 		if (!parsed.success) return { ok: false, error: "Validation failed" };
 		try {
@@ -55,9 +166,9 @@ vi.mock("@/lib/safe-action", () => ({
 				error: error instanceof Error ? error.message : "Internal server error",
 			};
 		}
-	},
-	authAction: vi.fn(),
-}));
+	};
+	return { adminAction: wrap, authAction: wrap };
+});
 
 vi.mock("@/lib/safe-action-shared", () => ({
 	actionOk: (data) => ({ ok: true, data: data ?? {} }),
@@ -70,18 +181,21 @@ vi.mock("@/lib/safe-action-shared", () => ({
 	},
 }));
 
-import { updatePoll, updatePollQuestion } from "./polls";
+import {
+	deletePoll,
+	updatePoll,
+	updatePollQuestion,
+	voteOnPoll,
+} from "./polls";
 
 beforeEach(() => {
 	vi.clearAllMocks();
-	selectLimit.mockReset();
-	updateSet.mockClear();
-	updateWhere.mockClear();
+	database.reset();
 });
 
 describe("poll update merge validation", () => {
 	it("rejects a partial end time before the persisted start without updating", async () => {
-		selectLimit.mockResolvedValueOnce([
+		database.queueSelected([
 			{
 				id: 1,
 				title: "Schedule",
@@ -100,11 +214,11 @@ describe("poll update merge validation", () => {
 		});
 
 		expect(result).toEqual({ ok: false, error: "Invalid poll schedule" });
-		expect(updateSet).not.toHaveBeenCalled();
+		expect(database.updateSet).not.toHaveBeenCalled();
 	});
 
 	it("rejects a partial options patch for a persisted text question without updating", async () => {
-		selectLimit.mockResolvedValueOnce([
+		database.queueSelected([
 			{
 				pollId: 1,
 				question: "Why?",
@@ -117,6 +231,66 @@ describe("poll update merge validation", () => {
 		const result = await updatePollQuestion({ id: 1, options: "Not allowed" });
 
 		expect(result).toEqual({ ok: false, error: "Invalid poll question" });
-		expect(updateSet).not.toHaveBeenCalled();
+		expect(database.updateSet).not.toHaveBeenCalled();
+	});
+});
+
+describe("poll transaction lock order", () => {
+	it("deletes a legacy poll through ordered primary-key locks and child-first writes", async () => {
+		database.queueSelected(
+			[{ id: 7, title: "Legacy poll" }],
+			[{ id: 4 }, { id: 9 }],
+			[{ id: 4 }],
+			[{ id: 9 }],
+		);
+
+		const result = await deletePoll({ id: 7 });
+
+		expect(result).toEqual({ ok: true, data: {} });
+		expect(database.transaction).toHaveBeenCalledWith(expect.any(Function), {
+			isolationLevel: "read committed",
+		});
+		expect(database.mutationSteps()).toEqual([
+			"lock:WebsitePoll:eq:id:7:update",
+			"read:WebsitePollQuestion:eq:pollId:orderBy:id",
+			"lock:WebsitePollQuestion:eq:id:4:update",
+			"lock:WebsitePollQuestion:eq:id:9:update",
+			"delete:WebsitePollVote",
+			"delete:WebsitePollQuestion",
+			"delete:WebsitePoll",
+		]);
+	});
+
+	it("validates votes in request order but inserts a sorted copy", async () => {
+		database.queueSelected(
+			[
+				{
+					id: 7,
+					status: "active",
+					startsAt: null,
+					endsAt: null,
+				},
+			],
+			[
+				{ id: 9, pollId: 7, type: "single", options: "A\nB" },
+				{ id: 4, pollId: 7, type: "single", options: "A\nB" },
+			],
+			[],
+			[],
+		);
+		const input = {
+			pollId: 7,
+			votes: [
+				{ questionId: 9, answer: " A " },
+				{ questionId: 4, answer: "B" },
+			],
+		};
+
+		const result = await voteOnPoll(input);
+
+		expect(result).toEqual({ ok: true, data: { pollId: 7 } });
+		expect(database.validationVoteQuestionIds()).toEqual([9, 4]);
+		expect(database.insertedVoteQuestionIds()).toEqual([4, 9]);
+		expect(input.votes.map(({ questionId }) => questionId)).toEqual([9, 4]);
 	});
 });

src/actions/polls.ts

@@ -1,6 +1,6 @@
 "use server";
 
-import { and, eq } from "drizzle-orm";
+import { and, eq, inArray } from "drizzle-orm";
 import { revalidatePath } from "next/cache";
 import { z } from "zod";
 import {
@@ -97,14 +97,43 @@ const deletePollInput = z.object({
 export const deletePoll = adminAction(
 	{ permission: PERMS.POLLS_EDIT, schema: deletePollInput },
 	async (ctx) => {
-		const [existing] = await db
-			.select({ id: WebsitePoll.id, title: WebsitePoll.title })
-			.from(WebsitePoll)
-			.where(eq(WebsitePoll.id, ctx.data.id))
-			.limit(1);
-		if (!existing) throw new ActionError("Poll not found");
+		const existing = await db.transaction(
+			async (tx) => {
+				const [poll] = await tx
+					.select({ id: WebsitePoll.id, title: WebsitePoll.title })
+					.from(WebsitePoll)
+					.where(eq(WebsitePoll.id, ctx.data.id))
+					.for("update");
+				if (!poll) throw new ActionError("Poll not found");
+
+				const questionRows = await tx
+					.select({ id: WebsitePollQuestion.id })
+					.from(WebsitePollQuestion)
+					.where(eq(WebsitePollQuestion.pollId, poll.id))
+					.orderBy(WebsitePollQuestion.id);
+				for (const question of questionRows) {
+					await tx
+						.select({ id: WebsitePollQuestion.id })
+						.from(WebsitePollQuestion)
+						.where(eq(WebsitePollQuestion.id, question.id))
+						.for("update");
+				}
+
+				const questionIds = questionRows.map(({ id }) => id);
+				if (questionIds.length > 0) {
+					await tx
+						.delete(WebsitePollVote)
+						.where(inArray(WebsitePollVote.questionId, questionIds));
+				}
+				await tx
+					.delete(WebsitePollQuestion)
+					.where(eq(WebsitePollQuestion.pollId, poll.id));
+				await tx.delete(WebsitePoll).where(eq(WebsitePoll.id, poll.id));
+				return poll;
+			},
+			{ isolationLevel: "read committed" },
+		);
 
-		await db.delete(WebsitePoll).where(eq(WebsitePoll.id, ctx.data.id));
 		logAudit({
 			userId: ctx.session.user.id,
 			action: "poll_delete",
@@ -272,8 +301,11 @@ export const voteOnPoll = authAction(
 			}
 		}
 
+		const votesToInsert = [...ctx.data.votes].sort(
+			(left, right) => left.questionId - right.questionId,
+		);
 		await db.transaction(async (tx) => {
-			for (const vote of ctx.data.votes) {
+			for (const vote of votesToInsert) {
 				await tx.insert(WebsitePollVote).values({
 					questionId: vote.questionId,
 					userId,

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");