diff --git a/changelog.d/maintenance/router-eval-test-assert-strengthen.md b/changelog.d/maintenance/router-eval-test-assert-strengthen.md
new file mode 100644
index 0000000000..c6f6e86046
--- /dev/null
+++ b/changelog.d/maintenance/router-eval-test-assert-strengthen.md
@@ -0,0 +1 @@
+- Strengthen the `compareRouterEvalRuns` regression test to assert the actual AIQ and cost regression reasons instead of counting entries, clearing the weakened-assert (test-masking) gate on the release tip.
diff --git a/tests/unit/router-eval.test.ts b/tests/unit/router-eval.test.ts
index ba520a6c86..4d6527704f 100644
--- a/tests/unit/router-eval.test.ts
+++ b/tests/unit/router-eval.test.ts
@@ -73,7 +73,14 @@ test("compareRouterEvalRuns captures AIQ and cost regressions", () => {
     relativeCostIncrease: 1.2,
   });
 
-  assert.equal(comparison.regressions.length > 0, true);
+  assert.ok(
+    comparison.regressions.some((reason) => reason.startsWith("AIQ dropped by")),
+    "expected an AIQ regression to be reported"
+  );
+  assert.ok(
+    comparison.regressions.some((reason) => reason.startsWith("cost increased by")),
+    "expected a cost regression to be reported"
+  );
   assert.equal(comparison.delta.aiq <= 0, true);
   assert.equal(comparison.delta.costUsd > 0, true);
 });