Validate and deduplicate custom difficulty presets

tests/service-error.test.ts

@@ -1,18 +1,58 @@
 import { test } from "node:test";
 import assert from "node:assert/strict";
-import { checkServiceError, ServiceError } from "../lib/service-error";
+import {
+  checkServiceError,
+  checkDifficultyPresetError,
+  ServiceError,
+} from "../lib/service-error";
+
+test("expected preset validation and duplicate-name errors return 400/409 without database log noise", (t) => {
+  const log = t.mock.method(console, "error", () => {});
+  for (const [code, status] of [
+    ["23514", 400],
+    ["23505", 409],
+  ] as const)
+    assert.throws(
+      () =>
+        checkDifficultyPresetError({
+          code,
+          message: "private database constraint details",
+        }),
+      (error) => {
+        assert.ok(error instanceof ServiceError);
+        assert.equal(error.status, status);
+        assert.doesNotMatch(error.message, /private database|constraint/);
+        return true;
+      },
+    );
+  assert.equal(log.mock.callCount(), 0);
+  assert.doesNotThrow(() => checkDifficultyPresetError(null));
+});
 
 test("backend failures use 503 and keep database internals out of browser errors", (t) => {
   t.mock.method(console, "error", () => {});
-  assert.throws(() => checkServiceError({ code: "42P01", message: 'relation "private_table" does not exist' }), (error) => {
-    assert.ok(error instanceof ServiceError);
-    assert.equal(error.status, 503);
-    assert.doesNotMatch(error.message, /private_table|42P01/);
-    return true;
-  });
+  assert.throws(
+    () =>
+      checkServiceError({
+        code: "42P01",
+        message: 'relation "private_table" does not exist',
+      }),
+    (error) => {
+      assert.ok(error instanceof ServiceError);
+      assert.equal(error.status, 503);
+      assert.doesNotMatch(error.message, /private_table|42P01/);
+      return true;
+    },
+  );
 });
 test("missing records and expected RPC validation keep actionable statuses and messages", () => {
-  assert.throws(() => checkServiceError({ code: "PGRST116", message: "no rows" }), (error) => error instanceof ServiceError && error.status === 404);
-  assert.throws(() => checkServiceError({ code: "P0001", message: "Guess outside map" }), /Guess outside map/);
+  assert.throws(
+    () => checkServiceError({ code: "PGRST116", message: "no rows" }),
+    (error) => error instanceof ServiceError && error.status === 404,
+  );
+  assert.throws(
+    () => checkServiceError({ code: "P0001", message: "Guess outside map" }),
+    /Guess outside map/,
+  );
   assert.doesNotThrow(() => checkServiceError(null));
 });