Require distinct panorama locations for rounds and captures

tests/protocol.test.ts

@@ -1,7 +1,53 @@
 import { test } from "node:test";
 import assert from "node:assert/strict";
-import { boundsSchema, datasetSchema, scoreGuess } from "../shared/protocol";
+import {
+  boundsSchema,
+  datasetSchema,
+  parseUploadManifest,
+  scoreGuess,
+} from "../shared/protocol";
 const bounds = { minX: -512, minZ: -256, maxX: 512, maxZ: 256 };
+test("new maps need five distinct positions, while older captures can retain duplicates", () => {
+  const manifest = {
+    format: "minegeo-dataset/v1",
+    minecraftVersion: "1.21.11",
+    dimension: "minecraft:overworld",
+    source: "plugin",
+    name: "Distinct location fixture",
+    serverName: "Fixture",
+    north: "-z",
+    bounds,
+    viewpoints: Array.from({ length: 5 }, (_, i) => ({
+      id: `p${i}`,
+      x: i - 4,
+      y: 65,
+      z: i - 4,
+    })),
+    assets: [{ path: "terrain.json.gz", sha256: "a".repeat(64), bytes: 100 }],
+  };
+  assert.equal(parseUploadManifest(manifest).viewpoints.length, 5);
+  const repeated = {
+    ...manifest,
+    viewpoints: [
+      ...manifest.viewpoints,
+      { id: "repeat", x: -3.9, y: 65.5, z: -3.9 },
+    ],
+  };
+  // Keep older exports usable when they already contain five distinct locations.
+  assert.equal(datasetSchema.safeParse(repeated).success, true);
+  assert.equal(parseUploadManifest(repeated).viewpoints.length, 6);
+  assert.throws(
+    () =>
+      parseUploadManifest({
+        ...manifest,
+        viewpoints: [
+          ...manifest.viewpoints.slice(0, 4),
+          repeated.viewpoints[5],
+        ],
+      }),
+    /five panoramas from different block positions/,
+  );
+});
 test("horizontal scoring ignores elevation and handles negative coordinates", () => {
   assert.equal(
     scoreGuess({ x: -13, z: -25 }, { x: -13, z: -25 }, bounds).score,