diff --git a/frontend/user/modules/opportunity-board.js b/frontend/user/modules/opportunity-board.js
index 0fe601d..85cc9bd 100644
--- a/frontend/user/modules/opportunity-board.js
+++ b/frontend/user/modules/opportunity-board.js
@@ -195,15 +195,19 @@ function emptyMessageFor(modeId) {
   }[modeId] || "当前筛选下暂无结果，可放宽条件后再试。";
 }
 
-function sortItems(items, sortSpec) {
+function isMissingSortValue(value) {
+  return value === null || value === undefined || Number.isNaN(value);
+}
+
+export function sortItems(items, sortSpec) {
   if (!sortSpec) return items;
   const dir = sortSpec.direction === "asc" ? 1 : -1;
   return [...items].sort((a, b) => {
     const av = a[sortSpec.key];
     const bv = b[sortSpec.key];
     if (av === bv) return 0;
-    if (av === null || av === undefined) return 1;
-    if (bv === null || bv === undefined) return -1;
+    if (isMissingSortValue(av)) return 1;
+    if (isMissingSortValue(bv)) return -1;
     return av > bv ? dir : -dir;
   });
 }
diff --git a/tests/frontend/test_opportunity_board_sort.mjs b/tests/frontend/test_opportunity_board_sort.mjs
new file mode 100644
index 0000000..2e7cc78
--- /dev/null
+++ b/tests/frontend/test_opportunity_board_sort.mjs
@@ -0,0 +1,100 @@
+import { test } from "node:test";
+import assert from "node:assert/strict";
+
+import { sortItems } from "../../frontend/user/modules/opportunity-board.js";
+
+test("sortItems: descending sort orders numeric values from high to low", () => {
+  const items = [
+    { id: "a", yield: 3 },
+    { id: "b", yield: 7 },
+    { id: "c", yield: 5 },
+  ];
+  const sorted = sortItems(items, { key: "yield", direction: "desc" });
+  assert.deepEqual(sorted.map((i) => i.id), ["b", "c", "a"]);
+});
+
+test("sortItems: explicit 0 is a real value, not a missing marker", () => {
+  // The board sorts by yield/score; rows with an explicit zero should keep
+  // their numeric position relative to other numbers — not be lumped in with
+  // null/undefined as "no data".
+  const items = [
+    { id: "neg", yield: -1 },
+    { id: "zero", yield: 0 },
+    { id: "pos", yield: 4 },
+    { id: "missing", yield: null },
+  ];
+  const desc = sortItems(items, { key: "yield", direction: "desc" });
+  assert.deepEqual(
+    desc.map((i) => i.id),
+    ["pos", "zero", "neg", "missing"],
+    "desc: 0 sits between positive and negative; null goes to the end",
+  );
+  const asc = sortItems(items, { key: "yield", direction: "asc" });
+  assert.deepEqual(
+    asc.map((i) => i.id),
+    ["neg", "zero", "pos", "missing"],
+    "asc: 0 sits between negative and positive; null still goes to the end",
+  );
+});
+
+test("sortItems: null and undefined values sort to the end regardless of direction", () => {
+  const items = [
+    { id: "n", yield: null },
+    { id: "u", yield: undefined },
+    { id: "a", yield: 4 },
+    { id: "b", yield: 1 },
+  ];
+  const desc = sortItems(items, { key: "yield", direction: "desc" });
+  assert.deepEqual(desc.slice(0, 2).map((i) => i.id), ["a", "b"]);
+  assert.ok(["n", "u"].includes(desc[2].id) && ["n", "u"].includes(desc[3].id));
+
+  const asc = sortItems(items, { key: "yield", direction: "asc" });
+  assert.deepEqual(asc.slice(0, 2).map((i) => i.id), ["b", "a"]);
+  assert.ok(["n", "u"].includes(asc[2].id) && ["n", "u"].includes(asc[3].id));
+});
+
+test("sortItems: NaN values sort to the end like null (no silent reordering)", () => {
+  // NaN sneaks through Number() when upstream data is malformed; the board
+  // should treat it as 'no data' and push it to the end, not float it to the
+  // top because of how IEEE-754 NaN comparisons return false.
+  const items = [
+    { id: "nan", yield: Number.NaN },
+    { id: "low", yield: 1 },
+    { id: "high", yield: 9 },
+  ];
+  const desc = sortItems(items, { key: "yield", direction: "desc" });
+  assert.deepEqual(
+    desc.map((i) => i.id),
+    ["high", "low", "nan"],
+    "desc: NaN must go to the end, not the top",
+  );
+  const asc = sortItems(items, { key: "yield", direction: "asc" });
+  assert.deepEqual(
+    asc.map((i) => i.id),
+    ["low", "high", "nan"],
+    "asc: NaN must go to the end, not the top",
+  );
+});
+
+test("sortItems: mixed null/NaN/numbers — all missing markers cluster at the end", () => {
+  const items = [
+    { id: "a", score: 50 },
+    { id: "nan", score: Number.NaN },
+    { id: "null", score: null },
+    { id: "b", score: 10 },
+    { id: "undef", score: undefined },
+    { id: "zero", score: 0 },
+  ];
+  const sorted = sortItems(items, { key: "score", direction: "desc" });
+  // First three are the numeric values, in desc order; last three are the
+  // missing markers (any order is fine).
+  assert.deepEqual(sorted.slice(0, 3).map((i) => i.id), ["a", "b", "zero"]);
+  const tail = sorted.slice(3).map((i) => i.id).sort();
+  assert.deepEqual(tail, ["nan", "null", "undef"]);
+});
+
+test("sortItems: returns the original list when no sortSpec is supplied", () => {
+  const items = [{ id: "a" }, { id: "b" }];
+  assert.equal(sortItems(items, null), items);
+  assert.equal(sortItems(items, undefined), items);
+});