diff --git a/src/common/translationCatalogue.unit.spec.ts b/src/common/translationCatalogue.unit.spec.ts
new file mode 100644
index 00000000..04c081ab
--- /dev/null
+++ b/src/common/translationCatalogue.unit.spec.ts
@@ -0,0 +1,57 @@
+import { afterEach, describe, expect, it } from "vitest";
+import { allMessages } from "./messages/combinedMessages.prod";
+import { $msg, setLang } from "./translation";
+
+function interpolationNames(message: string): string[] {
+    return [...message.matchAll(/\$\{([^}]+)\}/g)].map((match) => match[1]).sort();
+}
+
+describe("Russian catalogue interpolation", () => {
+    afterEach(() => setLang("def"));
+
+    it("retains the English interpolation values in each translated message", () => {
+        const mismatches = Object.entries(allMessages).flatMap(([key, messages]) => {
+            if (!messages.def || !messages.ru) return [];
+            const expected = interpolationNames(messages.def);
+            const actual = interpolationNames(messages.ru);
+            return JSON.stringify(actual) === JSON.stringify(expected) ? [] : [{ key, expected, actual }];
+        });
+
+        expect(mismatches).toEqual([]);
+    });
+
+    it("renders the generated QR image inside its display container", () => {
+        setLang("ru");
+        const qrImage = '<img src="data:image/png;base64,cXI=" alt="Fixture QR code">';
+
+        const message = $msg("Setup.QRCode", { qr_image: qrImage });
+
+        expect(message).toContain(`<div class="sls-qr">${qrImage}</div>`);
+        expect(message).not.toContain("${qr_image}");
+    });
+
+    it("shows both generated keys in their individual and combined copy areas", () => {
+        setLang("ru");
+        const publicKey = "PUBLIC-KEY-FIXTURE";
+        const privateKey = "PRIVATE-KEY-FIXTURE";
+
+        const message = $msg("Setting.GenerateKeyPair.Desc", { public_key: publicKey, private_key: privateKey });
+
+        expect(message.split(publicKey)).toHaveLength(3);
+        expect(message.split(privateKey)).toHaveLength(3);
+        expect(message).toContain(`${publicKey}\n${privateKey}`);
+        expect(message).not.toMatch(/\$\{(?:public_key|private_key)\}/);
+    });
+
+    it("keeps the measured and configured database sizes in the comparison table", () => {
+        setLang("ru");
+
+        const message = $msg("moduleCheckRemoteSize.msgDatabaseGrowing", {
+            estimatedSize: "123 MB",
+            maxSize: "456 MB",
+        });
+
+        expect(message).toContain("| 123 MB | 456 MB |");
+        expect(message).not.toMatch(/\$\{(?:estimatedSize|maxSize)\}/);
+    });
+});