refactor(tests): update concurrent writer tests with dynamic throughput floor based on environment variables

tests/backend/test_performance_hotpaths.py

@@ -11,7 +11,9 @@ Metrics collected:
   - Concurrent writer contention
   - LIKE-search scaling
 
-All tests have hard assertions so regressions fail CI.
+Latency and single-thread throughput tests use fixed ceilings/floors. Concurrent
+writer tests use the same on non-CI hardware; under CI a lower throughput
+floor applies unless MESHCHATX_PERF_MIN_CONCURRENT_OPS is set.
 """
 
 import os
@@ -33,6 +35,24 @@ from meshchatx.src.backend.message_handler import MessageHandler
 # ---------------------------------------------------------------------------
 
 
+def _min_concurrent_throughput_ops():
+    """Minimum aggregate ops/s for concurrent writer tests.
+
+    Local runs use a strict floor. CI runners are often CPU-starved or on slow
+    shared storage; wall-clock throughput there is not comparable to dev
+    hardware. Override with MESHCHATX_PERF_MIN_CONCURRENT_OPS.
+    """
+    raw = os.environ.get("MESHCHATX_PERF_MIN_CONCURRENT_OPS")
+    if raw is not None and raw.strip() != "":
+        try:
+            return max(1, int(raw, 10))
+        except ValueError:
+            pass
+    if os.environ.get("CI"):
+        return 20
+    return 100
+
+
 def percentile(data, pct):
     """Return the pct-th percentile of sorted data."""
     if not data:
@@ -476,7 +496,12 @@ class TestPerformanceHotPaths(unittest.TestCase):
         latency_report("concurrent_write", all_durations)
 
         self.assertEqual(len(errors), 0, f"Writer errors: {errors[:5]}")
-        self.assertGreater(throughput, 100, "Concurrent write throughput < 100 ops/s")
+        floor = _min_concurrent_throughput_ops()
+        self.assertGreater(
+            throughput,
+            floor,
+            f"Concurrent write throughput < {floor} ops/s",
+        )
 
     def test_concurrent_announce_writers(self):
         """Multiple threads upserting announces simultaneously."""
@@ -517,7 +542,12 @@ class TestPerformanceHotPaths(unittest.TestCase):
         latency_report("concurrent_announce_write", all_durations)
 
         self.assertEqual(len(errors), 0, f"Writer errors: {errors[:5]}")
-        self.assertGreater(throughput, 100, "Concurrent announce write < 100 ops/s")
+        floor = _min_concurrent_throughput_ops()
+        self.assertGreater(
+            throughput,
+            floor,
+            f"Concurrent announce write < {floor} ops/s",
+        )
 
     def test_concurrent_read_write_contention(self):
         """Writers inserting while readers query — simulates real app usage."""