feat: add project-wide i18n support

backend/db/migration-i18n-utils.js

@@ -0,0 +1,25 @@
+'use strict';
+
+/**
+ * Helpers for Sequelize migrations that store i18n keys in the database.
+ * Down migrations resolve English source strings from en locale JSON.
+ *
+ * @author Andrii Nikitin
+ */
+const { t, hasKey } = require('../utils/i18n');
+
+/**
+ * @param {string} i18nKey
+ * @returns {string|null} English text, or `null` if the key is missing from `en` JSON.
+ *   Callers that skip updates on `null` leave i18n keys in the DB; the frontend then
+ *   typically shows that raw key string (e.g. `translateMaybeKey` passes it through when
+ *   there is no translation).
+ */
+function resolveEnText(i18nKey) {
+  if (typeof i18nKey !== 'string' || !hasKey(i18nKey, 'en')) {
+    return null;
+  }
+  return t(i18nKey, {}, 'en');
+}
+
+module.exports = { resolveEnText, t, hasKey };

backend/db/migrations/20260525220113-transform-placeholder-i18n-keys.js

@@ -0,0 +1,87 @@
+"use strict";
+
+const { resolveEnText } = require("../migration-i18n-utils");
+
+/**
+ * Replace English placeholderLabel / placeholderDescription with i18n keys.
+ * Help tooltips stay in templates.json (frontend derives help key from description key).
+ *
+ * @type {import('sequelize-cli').Migration}
+ */
+
+const TYPE_SLUG = {
+  1: "emailGeneral",
+  2: "emailStudySession",
+  3: "emailAssignment",
+  6: "emailStudyClose",
+};
+
+const PLACEHOLDER_ROWS = [
+  { type: 1, placeholderKey: "username" },
+  { type: 1, placeholderKey: "firstName" },
+  { type: 1, placeholderKey: "lastName" },
+  { type: 1, placeholderKey: "link" },
+  { type: 1, placeholderKey: "otp" },
+  { type: 1, placeholderKey: "tokenExpiry" },
+  { type: 2, placeholderKey: "username" },
+  { type: 2, placeholderKey: "link" },
+  { type: 3, placeholderKey: "username" },
+  { type: 3, placeholderKey: "assignmentType" },
+  { type: 3, placeholderKey: "assignmentName" },
+  { type: 3, placeholderKey: "link" },
+  { type: 6, placeholderKey: "username" },
+  { type: 6, placeholderKey: "studyName" },
+];
+
+function keysFor(type, placeholderKey) {
+  const slug = TYPE_SLUG[type];
+  const base = "templates.placeholders";
+  return {
+    placeholderLabel: `${base}.labels.${slug}.${placeholderKey}`,
+    placeholderDescription: `${base}.descriptions.${slug}.${placeholderKey}`,
+  };
+}
+
+/** @type {import('sequelize-cli').Migration} */
+module.exports = {
+  async up(queryInterface, Sequelize) {
+    for (const row of PLACEHOLDER_ROWS) {
+      await queryInterface.bulkUpdate(
+        "placeholder",
+        {
+          ...keysFor(row.type, row.placeholderKey),
+          updatedAt: new Date(),
+        },
+        {
+          type: row.type,
+          placeholderKey: row.placeholderKey,
+        },
+        {},
+      );
+    }
+  },
+
+  async down(queryInterface) {
+    for (const row of PLACEHOLDER_ROWS) {
+      const keys = keysFor(row.type, row.placeholderKey);
+      const placeholderLabel = resolveEnText(keys.placeholderLabel);
+      const placeholderDescription = resolveEnText(keys.placeholderDescription);
+      if (!placeholderLabel || !placeholderDescription) {
+        continue;
+      }
+      await queryInterface.bulkUpdate(
+        "placeholder",
+        {
+          placeholderLabel,
+          placeholderDescription,
+          updatedAt: new Date(),
+        },
+        {
+          type: row.type,
+          placeholderKey: row.placeholderKey,
+        },
+        {}
+      );
+    }
+  },
+};

backend/db/migrations/20260601120000-transform-email-submission-upload-placeholder-i18n-keys.js

@@ -0,0 +1,72 @@
+"use strict";
+
+const { resolveEnText } = require("../migration-i18n-utils");
+
+/**
+ * Replace English placeholderLabel / placeholderDescription for email template type 7.
+ *
+ * @type {import('sequelize-cli').Migration}
+ */
+
+const TYPE_SLUG = "emailSubmissionUpload";
+
+const PLACEHOLDER_ROWS = [
+  { type: 7, placeholderKey: "username" },
+  { type: 7, placeholderKey: "assignmentName" },
+  { type: 7, placeholderKey: "eventType" },
+  { type: 7, placeholderKey: "assignmentId" },
+  { type: 7, placeholderKey: "submissionId" },
+  { type: 7, placeholderKey: "timestamp" },
+];
+
+function keysFor(placeholderKey) {
+  const base = "templates.placeholders";
+  return {
+    placeholderLabel: `${base}.labels.${TYPE_SLUG}.${placeholderKey}`,
+    placeholderDescription: `${base}.descriptions.${TYPE_SLUG}.${placeholderKey}`,
+  };
+}
+
+/** @type {import('sequelize-cli').Migration} */
+module.exports = {
+  async up(queryInterface) {
+    for (const row of PLACEHOLDER_ROWS) {
+      await queryInterface.bulkUpdate(
+        "placeholder",
+        {
+          ...keysFor(row.placeholderKey),
+          updatedAt: new Date(),
+        },
+        {
+          type: row.type,
+          placeholderKey: row.placeholderKey,
+        },
+        {}
+      );
+    }
+  },
+
+  async down(queryInterface) {
+    for (const row of PLACEHOLDER_ROWS) {
+      const keys = keysFor(row.placeholderKey);
+      const placeholderLabel = resolveEnText(keys.placeholderLabel);
+      const placeholderDescription = resolveEnText(keys.placeholderDescription);
+      if (!placeholderLabel || !placeholderDescription) {
+        continue;
+      }
+      await queryInterface.bulkUpdate(
+        "placeholder",
+        {
+          placeholderLabel,
+          placeholderDescription,
+          updatedAt: new Date(),
+        },
+        {
+          type: row.type,
+          placeholderKey: row.placeholderKey,
+        },
+        {}
+      );
+    }
+  },
+};

backend/db/models/assignment.js

@@ -14,54 +14,54 @@ module.exports = (sequelize, DataTypes) => {
 		static fields = [
 			{
 				key: "name",
-				label: "Assignment Name:",
-				placeholder: "Assignment 1",
+				label: "assignments.fields.name.label",
+				placeholder: "assignments.fields.name.placeholder",
 				type: "text",
 				required: true,
 				default: "",
 			},
 			{
 				key: "description",
-				label: "Description:",
-				help: "Optional description shown for this assignment.",
+				label: "assignments.fields.description.label",
+				help: "assignments.fields.description.help",
 				type: "textarea",
 				required: false,
 			},
 			{
 				key: "maxRevisions",
-				label: "Maximum Revisions:",
+				label: "assignments.fields.maxRevisions.label",
 				type: "slider",
 				class: "custom-slider-class",
 				min: 1,
 				max: 20,
 				step: 1,
-				unit: "revision(s)",
+				unit: "assignments.fields.maxRevisions.unit",
 				unlimitedAtMax: true,
-				unlimitedLabel: "unlimited",
+				unlimitedLabel: "assignments.fields.maxRevisions.unlimitedLabel",
 				unlimitedStoredValue: 0,
 				required: true,
 				default: 1,
-				help: "Maximum number of allowed revision copies for this assignment. Move to the end for unlimited.",
+				help: "assignments.fields.maxRevisions.help",
 			},
 			{
 				key: "start",
-				label: "Start Time:",
+				label: "assignments.fields.start.label",
 				type: "datetime",
 				size: 6,
 				default: null,
 				required: false,
 			},
 			{
 				key: "end",
-				label: "End Time:",
+				label: "assignments.fields.end.label",
 				type: "datetime",
 				size: 6,
 				default: null,
 				required: false,
 			},
 			{
 				key: "validationConfigurationId",
-				label: "Validation Configuration:",
+				label: "assignments.fields.validationConfigurationId.label",
 				type: "select",
 				options: {
 					table: "configuration",
@@ -72,23 +72,23 @@ module.exports = (sequelize, DataTypes) => {
 					],
 				},
 				required: true,
-				help: "Validation is applied before submission upload.",
+				help: "assignments.fields.validationConfigurationId.help",
 			},
 			{
 				key: "allowReUpload",
-				label: "Allow Re-Upload:",
+				label: "assignments.fields.allowReUpload.label",
 				type: "switch",
 				default: false,
 				required: false,
-				help: "If enabled, users can replace or delete uploaded submissions.",
+				help: "assignments.fields.allowReUpload.help",
 			},
 			{
 				key: "notifyOnSubmissionUpload",
-				label: "Notify on Submission Upload:",
+				label: "assignments.fields.notifyOnSubmissionUpload.label",
 				type: "switch",
 				default: false,
 				required: false,
-				help: "If enabled, sends an email when a student uploads or re-uploads a submission.",
+				help: "assignments.fields.notifyOnSubmissionUpload.help",
 			},
 		];
 

backend/db/models/configuration.js

@@ -13,49 +13,49 @@ module.exports = (sequelize, DataTypes) => {
         static fields = [
             {
                 key: "name",
-                label: "Name",
-                placeholder: "Configuration name",
+                label: "basic.configuration.fields.name.label",
+                placeholder: "basic.configuration.fields.name.placeholder",
                 type: "text",
                 required: true,
                 default: "",
             },
             {
                 key: "description",
-                label: "Description",
-                placeholder: "Optional description",
+                label: "basic.configuration.fields.description.label",
+                placeholder: "basic.configuration.fields.description.placeholder",
                 type: "text",
                 required: false,
                 default: "",
             },
             {
                 key: "userId",
-                label: "User ID",
+                label: "basic.configuration.fields.userId.label",
                 placeholder: "#",
                 type: "text",
                 required: true,
 
             },
             {
                 key: "hideInFrontend",
-                label: "Hide in Frontend",
+                label: "basic.configuration.fields.hideInFrontend.label",
                 type: "switch",
                 required: false,
                 default: false,
             },
             {
                 key: "type",
-                label: "Type",
+                label: "basic.configuration.fields.type.label",
                 placeholder: "0",
                 type: "select",
                 options: [
-                    { name: "Assessment", value: 0 },
-                    { name: "Validation", value: 1 },
+                    { name: "basic.configuration.types.assessment", value: 0 },
+                    { name: "basic.configuration.types.validation", value: 1 },
                 ],
                 required: true,
             },
             {
                 key: "content",
-                label: "Config (JSON)",
+                label: "basic.configuration.fields.content.label",
                 placeholder: "{ }",
                 type: "json",
                 required: true,