diff --git a/web/src/app/(main)/function/tasks/detail/_tabs/findings-tab.tsx b/web/src/app/(main)/function/tasks/detail/_tabs/findings-tab.tsx
index 3ae1876..91f355e 100644
--- a/web/src/app/(main)/function/tasks/detail/_tabs/findings-tab.tsx
+++ b/web/src/app/(main)/function/tasks/detail/_tabs/findings-tab.tsx
@@ -222,7 +222,7 @@ export function FindingsTab({ taskId }: { taskId: string }) {
           type="button"
           variant="outline"
           size="sm"
-          aria-label={`${sortPreference.field === "severity" ? "同等级" : "全部"}发现时间当前${sortPreference.direction === "asc" ? "正序" : "倒序"}，点击切换排序方向`}
+          aria-label={`${sortPreference.field === "severity" ? "同严重度" : "全部"}发现时间当前${sortPreference.direction === "asc" ? "正序" : "倒序"}，点击切换排序方向`}
           onClick={() =>
             setSortPreference((current) => ({
               ...current,
@@ -235,8 +235,8 @@ export function FindingsTab({ taskId }: { taskId: string }) {
           ) : (
             <ArrowDownIcon aria-hidden="true" />
           )}
-          {sortPreference.field === "severity" ? "同等级" : ""}
-          {sortPreference.direction === "asc" ? "最早在前" : "最新在前"}
+          {sortPreference.field === "severity" ? "同严重度：" : ""}
+          {sortPreference.direction === "asc" ? "最早优先" : "最新优先"}
         </Button>
         <form
           className="flex w-full items-center gap-2 sm:w-auto"
@@ -304,7 +304,7 @@ export function FindingsTab({ taskId }: { taskId: string }) {
                 漏洞（{sortPreference.field === "severity" ? "按严重度排序" : "按时间排序"}）
               </span>
               <span className="inline-flex items-center gap-1">
-                <span>{sortPreference.field === "severity" ? "同等级发现时间" : "发现时间"}</span>
+                <span>{sortPreference.field === "severity" ? "同严重度发现时间" : "发现时间"}</span>
                 {sortPreference.direction === "asc" ? (
                   <ArrowUpIcon className="size-3.5" />
                 ) : (
diff --git a/web/src/lib/mock/finding-time-sort.test.cjs b/web/src/lib/mock/finding-time-sort.test.cjs
new file mode 100644
index 0000000..b1b52cb
--- /dev/null
+++ b/web/src/lib/mock/finding-time-sort.test.cjs
@@ -0,0 +1,134 @@
+const assert = require("node:assert/strict");
+const test = require("node:test");
+
+// Use the existing TypeScript dev dependency to exercise the real mock routes,
+// including their extensionless imports, without adding a test runtime.
+require("ts-node").register({
+  skipProject: true,
+  transpileOnly: true,
+  compilerOptions: { target: "ES2022", module: "CommonJS", moduleResolution: "Node" },
+});
+const data = require("./data.ts");
+const finding = (id, task, severity, day, status = "pending") => ({
+  id,
+  task_id: task,
+  severity,
+  ts: `2026-01-${String(day).padStart(2, "0")}T12:00:00Z`,
+  status,
+  name: "needle",
+  vulnclass: "Demo",
+  summary: "Synthetic sorting fixture",
+  evidence: "",
+  assets: [],
+});
+const fixtures = [
+  finding("1", "2", "low", 2),
+  finding("2", "2", "high", 4),
+  finding("10", "10", "high", 4),
+  finding("11", "10", "critical", 1),
+  finding("12", "20", "high", 4),
+  finding("13", undefined, "high", 4),
+  finding("14", "30", "low", 5),
+  finding("15", "40", "critical", 1),
+  finding("16", "10", "high", 3, "resolved"),
+];
+// handler.ts snapshots fixtures on import. Restore exported demo data immediately;
+// node:test runs this test file in its own process, separate from the application.
+const original = data.findings.slice();
+let mockHandle;
+try {
+  data.findings.splice(0, data.findings.length, ...fixtures);
+  ({ mockHandle } = require("./handler.ts"));
+} finally {
+  data.findings.splice(0, data.findings.length, ...original);
+}
+
+const rowOrders = {
+  time: {
+    asc: ["15", "11", "1", "16", "13", "12", "10", "2", "14"],
+    desc: ["14", "13", "12", "10", "2", "16", "1", "15", "11"],
+  },
+  severity: {
+    asc: ["15", "11", "16", "13", "12", "10", "2", "1", "14"],
+    desc: ["15", "11", "13", "12", "10", "2", "16", "14", "1"],
+  },
+};
+const groupOrders = {
+  time: {
+    asc: ["40", "20", "10", "2", null, "30"],
+    desc: ["30", "20", "10", "2", null, "40"],
+  },
+  severity: {
+    asc: ["40", "10", "20", "2", null, "30"],
+    desc: ["10", "40", "20", "2", null, "30"],
+  },
+};
+const routes = [
+  { path: "/exploration/findings", key: (row) => row.id, orders: rowOrders },
+  { path: "/exploration/finding-cases", key: (row) => row.finding.id, orders: rowOrders },
+  { path: "/exploration/findings/groups", key: (row) => row.task_id, orders: groupOrders },
+];
+const read = (route, query = {}) =>
+  mockHandle("GET", `${route.path}?${new URLSearchParams({ page: "1", limit: "100", ...query })}`);
+
+for (const route of routes) {
+  for (const sort of ["time", "severity"]) {
+    for (const direction of ["asc", "desc"]) {
+      test(`${route.path}: ${sort}/${direction} sorts before pagination with stable ID ties`, async () => {
+        const expected = route.orders[sort][direction];
+        const full = await read(route, { sort, time_direction: direction });
+        assert.deepEqual(full.items.map(route.key), expected);
+        assert.equal(full.total, expected.length);
+        const paged = [];
+        for (let page = 1; page <= Math.ceil(expected.length / 2); page++) {
+          const result = await read(route, { sort, time_direction: direction, page: String(page), limit: "2" });
+          assert.equal(result.total, expected.length);
+          assert.equal(result.page, page);
+          assert.equal(result.page_size, 2);
+          paged.push(...result.items.map(route.key));
+        }
+        assert.deepEqual(paged, expected);
+      });
+    }
+  }
+
+  test(`${route.path}: missing or invalid direction defaults to descending`, async () => {
+    for (const sort of ["time", "severity"]) {
+      for (const direction of [undefined, "", "ASC", "invalid", "asc; DROP TABLE findings"]) {
+        const query = { sort, ...(direction === undefined ? {} : { time_direction: direction }) };
+        assert.deepEqual((await read(route, query)).items.map(route.key), route.orders[sort].desc);
+      }
+    }
+  });
+
+  test(`${route.path}: direction preserves combined filters and leaves the snapshot unchanged`, async () => {
+    const before = await read(route, { sort: "time", time_direction: "desc" });
+    const grouped = route.path.endsWith("/groups");
+    for (const direction of ["asc", "desc"]) {
+      const result = await read(route, {
+        sort: "time",
+        time_direction: direction,
+        severity: "high",
+        status: "pending",
+        q: "needle",
+      });
+      assert.deepEqual(result.items.map(route.key), grouped ? ["20", "10", "2", null] : ["13", "12", "10", "2"]);
+      assert.equal(result.total, 4);
+      if (grouped) assert.equal(result.finding_total, 4);
+      const empty = await read(route, { time_direction: direction, q: "absent fixture text" });
+      assert.deepEqual(empty.items, []);
+      assert.equal(empty.total, 0);
+    }
+    const after = await read(route, { sort: "time", time_direction: "desc" });
+    assert.deepEqual(after, before);
+  });
+}
+
+test("group dates use the latest matching finding after filters", async () => {
+  const route = routes[2];
+  const result = await read(route, { status: "resolved", time_direction: "asc" });
+  assert.equal(result.total, 1);
+  assert.equal(result.finding_total, 1);
+  assert.equal(result.items[0].task_id, "10");
+  assert.equal(result.items[0].last_found_at, fixtures[8].ts);
+});
diff --git a/web/src/lib/mock/handler.ts b/web/src/lib/mock/handler.ts
index 85b1882..e45af0f 100644
--- a/web/src/lib/mock/handler.ts
+++ b/web/src/lib/mock/handler.ts
@@ -1972,14 +1972,10 @@ function route(m: string, path: string, seg: string[], q: URLSearchParams, b: Re
   if (path === "/exploration/finding-case-review" && m === "POST")
     throw new Error("演示模式不执行 Reporter 整理，请在已配置模型的实例中使用");
   if (path === "/exploration/finding-cases" && m === "GET") {
-    const list = filterAndSortFindings(
-      mockApplyAssetScope(mockFilterFindings(q), q.get("asset_scope")),
-      "all",
-      {
-        field: q.get("sort") === "severity" ? "severity" : "time",
-        direction: q.get("time_direction") === "asc" ? "asc" : "desc",
-      },
-    );
+    const list = filterAndSortFindings(mockApplyAssetScope(mockFilterFindings(q), q.get("asset_scope")), "all", {
+      field: q.get("sort") === "severity" ? "severity" : "time",
+      direction: q.get("time_direction") === "asc" ? "asc" : "desc",
+    });
     const page = Math.max(1, Number(q.get("page")) || 1);
     const size = Math.min(100, Math.max(1, Number(q.get("limit")) || 20));
     const scoped = mockFindings.filter((f) => !q.get("task_id") || f.task_id === q.get("task_id"));
@@ -2055,11 +2051,16 @@ function route(m: string, path: string, seg: string[], q: URLSearchParams, b: Re
         max_severity: Math.max(...items.map((finding) => severityOrder[finding.severity])),
       };
     });
-    groups.sort((left, right) =>
-      q.get("sort") === "severity"
-        ? right.max_severity - left.max_severity || right.last_found_at.localeCompare(left.last_found_at)
-        : right.last_found_at.localeCompare(left.last_found_at),
-    );
+    groups.sort((left, right) => {
+      const severityCompared = right.max_severity - left.max_severity;
+      if (q.get("sort") === "severity" && severityCompared !== 0) return severityCompared;
+      const timeCompared = Date.parse(left.last_found_at) - Date.parse(right.last_found_at);
+      if (timeCompared !== 0) return q.get("time_direction") === "asc" ? timeCompared : -timeCompared;
+      // Match the backend's task ID DESC NULLS LAST tie-breaker.
+      if (left.task_id === null) return right.task_id === null ? 0 : 1;
+      if (right.task_id === null) return -1;
+      return right.task_id.localeCompare(left.task_id, undefined, { numeric: true });
+    });
     const rawPage = Number(q.get("page") ?? 1);
     const rawPageSize = Number(q.get("limit") ?? 10);
     const page = Number.isFinite(rawPage) && rawPage > 0 ? Math.floor(rawPage) : 1;
@@ -2273,13 +2274,10 @@ function route(m: string, path: string, seg: string[], q: URLSearchParams, b: Re
     }
     // 全局:带 page/limit → 分页对象;否则裸数组(dashboard)。
     if (!q.has("page") && !q.has("limit")) return mockFindings.map(withFid);
-    const sev = { critical: 4, high: 3, medium: 2, low: 1 } as const;
-    const list = mockApplyAssetScope(mockFilterFindings(q), q.get("asset_scope"));
-    list.sort((a, b) =>
-      q.get("sort") === "severity"
-        ? sev[b.severity] - sev[a.severity] || +new Date(b.ts) - +new Date(a.ts)
-        : +new Date(b.ts) - +new Date(a.ts),
-    );
+    const list = filterAndSortFindings(mockApplyAssetScope(mockFilterFindings(q), q.get("asset_scope")), "all", {
+      field: q.get("sort") === "severity" ? "severity" : "time",
+      direction: q.get("time_direction") === "asc" ? "asc" : "desc",
+    });
     const rawPage = Number(q.get("page") ?? 1);
     const rawPageSize = Number(q.get("limit") ?? 20);
     const page = Number.isFinite(rawPage) && rawPage > 0 ? Math.floor(rawPage) : 1;