diff --git a/frontend/packages/swarm-ui/test/tryout-types.test.mjs b/frontend/packages/swarm-ui/test/tryout-types.test.mjs
new file mode 100644
index 00000000..95fa18af
--- /dev/null
+++ b/frontend/packages/swarm-ui/test/tryout-types.test.mjs
@@ -0,0 +1,132 @@
+// The review try-out form's pure logic: the repo and row checks, the gate on
+// opening a PR from the rows, and the request body each row becomes. Run by
+// `npm test`, which Node runs with its built-in test runner and type
+// stripping, so the `.ts` module is imported as it is.
+import assert from "node:assert/strict";
+import { test } from "node:test";
+import {
+  draftFromRule,
+  draftProblem,
+  duplicateName,
+  hasTypedText,
+  prNumber,
+  repoProblem,
+  rowsProblem,
+  thresholdValue,
+  toBody,
+} from "../src/pages/review-tryout/TryOutTypes.ts";
+
+// A row ready to send, with `over` replacing any of its fields.
+function row(over = {}) {
+  return {
+    key: 0,
+    name: "no-ads",
+    description: "No ads.",
+    polarity: "negative",
+    threshold: "80",
+    ...over,
+  };
+}
+
+test("a repo is owner/name with forge-safe characters in each part", () => {
+  assert.equal(repoProblem("hyperhive/hyperhive"), null);
+  assert.equal(repoProblem("  o/r.name_x-1  "), null);
+  for (const bad of ["", "o", "o/", "/r", "o/r/x", "o/..", "./r", "o/r s"]) {
+    assert.match(repoProblem(bad), /owner\/name/, bad);
+  }
+});
+
+test("a row needs a name, then a description, then a whole 0-100 threshold", () => {
+  assert.equal(draftProblem(row()), null);
+  assert.match(draftProblem(row({ name: " " })), /a name/);
+  assert.match(
+    draftProblem(row({ name: " ", description: "" })),
+    /a name/,
+    "the name is checked first",
+  );
+  assert.match(
+    draftProblem(row({ description: "  " })),
+    /no-ads needs a description/,
+  );
+  assert.match(
+    draftProblem(row({ description: "", threshold: "x" })),
+    /description/,
+    "the description is checked before the threshold",
+  );
+  for (const bad of ["", "101", "-1", "1.5", "x"]) {
+    assert.match(draftProblem(row({ threshold: bad })), /threshold/, bad);
+  }
+  assert.equal(draftProblem(row({ threshold: " 100 " })), null);
+  assert.equal(draftProblem(row({ threshold: "0" })), null);
+});
+
+test("two rows with one trimmed name are refused", () => {
+  assert.equal(duplicateName([row(), row({ name: "other" })]), null);
+  assert.match(
+    duplicateName([row(), row({ name: " no-ads " })]),
+    /two classifications are named no-ads/,
+  );
+});
+
+test("opening a PR is gated by the repo, then each row, then a shared name", () => {
+  const good = [row(), row({ name: "other" })];
+  assert.equal(rowsProblem("o/r", good), null);
+
+  // Each check on its own.
+  assert.match(rowsProblem("", good), /owner\/name/);
+  assert.match(rowsProblem("o/r", [row(), row({ name: "" })]), /a name/);
+  assert.match(rowsProblem("o/r", [row(), row()]), /two classifications/);
+
+  // The order: a bad repo wins over a bad row, and a bad row over a shared
+  // name.
+  assert.match(rowsProblem("o", [row({ name: "" })]), /owner\/name/);
+  assert.match(
+    rowsProblem("o/r", [row(), row({ threshold: "x" }), row()]),
+    /threshold/,
+  );
+  // Rows are checked in their order.
+  assert.match(
+    rowsProblem("o/r", [row({ description: "" }), row({ name: "" })]),
+    /no-ads needs a description/,
+  );
+});
+
+test("opening a PR needs no PR number, which a run does", () => {
+  assert.equal(prNumber(""), null);
+  assert.equal(rowsProblem("o/r", [row()]), null);
+  assert.equal(prNumber(" 7 "), 7);
+  assert.equal(prNumber("0"), null);
+  assert.equal(prNumber("7a"), null);
+});
+
+test("a row becomes the request's classification", () => {
+  assert.deepEqual(
+    toBody(
+      row({ name: " no-ads ", description: " No ads. ", threshold: " 60 " }),
+    ),
+    {
+      name: "no-ads",
+      description: " No ads. ",
+      polarity: "negative",
+      threshold: 60,
+    },
+  );
+  assert.equal(thresholdValue("101"), null);
+});
+
+test("a loaded rule becomes a row that sends back the same rule", () => {
+  const rule = {
+    name: "no-ads",
+    description: "No ads.",
+    polarity: "negative",
+    threshold: 80,
+  };
+  const d = draftFromRule(rule, 3);
+  assert.deepEqual(d, { key: 3, ...rule, threshold: "80" });
+  assert.deepEqual(toBody(d), rule);
+});
+
+test("only a typed name or description counts as the user's work", () => {
+  assert.equal(hasTypedText([row({ name: " ", description: "" })]), false);
+  assert.equal(hasTypedText([row({ name: "", description: "x" })]), true);
+});