fix(workshop): enforce atomic revisions

apps/workshop/pb_migrations/1784240000_workshop_widgets.js

@@ -106,6 +106,18 @@ migrate(
     submissions.addIndex("idx_submissions_author", false, "author", "");
     submissions.addIndex("idx_submissions_created", false, "created", "");
     app.save(submissions);
+    app
+      .db()
+      .newQuery(
+        `CREATE TRIGGER submissions_revision_cas
+         BEFORE UPDATE ON submissions
+         FOR EACH ROW
+         WHEN NEW.revision != OLD.revision + 1
+         BEGIN
+           SELECT RAISE(ABORT, 'submission revision must increment exactly once');
+         END`,
+      )
+      .execute();
 
     const votes = new Collection({
       type: "base",

apps/workshop/tests/workshop-contracts.mjs

@@ -24,6 +24,7 @@ const migration = await read("apps/workshop/pb_migrations/1784240000_workshop_wi
 for (const required of [
   "workshop_migration_state",
   "addedUserFields",
+  "CREATE TRIGGER submissions_revision_cas",
   "state.rateLimits.enabled",
   "users.passwordAuth = state.users.passwordAuth",
   "users.oauth2 = state.users.oauth2",

apps/workshop/tests/workshop-migration.mjs

@@ -67,7 +67,19 @@ Object.assign(users, original.rules);
 const settings = { rateLimits: structuredClone(original.rateLimits) };
 const collections = new Map([[users.id, users]]);
 const records = new Map();
+const rawQueries = [];
 const app = {
+  db() {
+    return {
+      newQuery(sql) {
+        return {
+          execute() {
+            rawQueries.push(sql);
+          },
+        };
+      },
+    };
+  },
   findCollectionByNameOrId(name) {
     const collection = collections.get(name);
     if (!collection) throw new Error(`Missing collection ${name}`);
@@ -113,6 +125,9 @@ migration.up(app);
 if (!collections.has("workshop_migration_state") || settings.rateLimits.enabled !== true) {
   throw new Error("Workshop migration did not capture state before applying changes");
 }
+if (!rawQueries.some((query) => query.includes("CREATE TRIGGER submissions_revision_cas"))) {
+  throw new Error("Workshop migration did not install the atomic submission revision guard");
+}
 migration.down(app);
 
 if (JSON.stringify(users.passwordAuth) !== JSON.stringify(original.passwordAuth))

apps/workshop/tests/workshop.integration.mjs

@@ -178,17 +178,20 @@ if (!outdatedSubmission.outdated || outdatedSubmission.revision !== 3) {
   throw new Error("PocketBase must own submission revision increments");
 }
 
-const concurrentUpdates = await Promise.all(
-  ["Concurrent first", "Concurrent second"].map((title) =>
-    fetch(`${baseUrl}/api/collections/submissions/records/${submission.id}`, {
-      method: "PATCH",
-      headers: { "content-type": "application/json", ...authorSession.headers },
-      body: JSON.stringify({ title, expectedRevision: 3 }),
-    }),
-  ),
-);
-if (concurrentUpdates.filter((response) => response.ok).length !== 1) {
-  throw new Error("Exactly one update may consume an expected submission revision");
+for (let attempt = 0; attempt < 5; attempt += 1) {
+  const expectedRevision = 3 + attempt;
+  const concurrentUpdates = await Promise.all(
+    ["Concurrent first", "Concurrent second"].map((title) =>
+      fetch(`${baseUrl}/api/collections/submissions/records/${submission.id}`, {
+        method: "PATCH",
+        headers: { "content-type": "application/json", ...authorSession.headers },
+        body: JSON.stringify({ title: `${title} ${attempt}`, expectedRevision }),
+      }),
+    ),
+  );
+  if (concurrentUpdates.filter((response) => response.ok).length !== 1) {
+    throw new Error("Exactly one update may consume an expected submission revision");
+  }
 }
 
 await expectStatus(