diff --git a/src/central/gui/resend.py b/src/central/gui/resend.py
index 33f953d..2fe3ebe 100644
--- a/src/central/gui/resend.py
+++ b/src/central/gui/resend.py
@@ -42,9 +42,15 @@ logger = logging.getLogger(__name__)
 
 # Pull-fetch tuning. The ephemeral consumer's inactive_threshold guarantees
 # JetStream auto-cleans the temp consumer if anything kills our iterator.
+# v0.10.5.1 fix: ``inactive_threshold`` is expected as float SECONDS by
+# nats-py (which then multiplies by 1e9 internally to form the nanosecond
+# value sent to the server). v0.10.5 passed ``int(30e9)`` thinking it was
+# already in ns, which got re-multiplied to 30e18 -- out of int64 range,
+# rejected by the server with err_code=10025. Use the documented float-
+# seconds API and let the library handle the unit conversion.
 _FETCH_BATCH = 200
 _FETCH_TIMEOUT_S = 2.0
-_INACTIVE_THRESHOLD_NS = int(30e9)
+_INACTIVE_THRESHOLD_S = 30.0
 
 # Hard cap per stream per operation. 24h * worst-case CENTRAL_TRAFFIC_FLOW
 # volume is still well under this; bump if a legitimate operator action
@@ -103,7 +109,7 @@ async def _iter_window(
         deliver_policy=DeliverPolicy.BY_START_TIME,
         opt_start_time=cutoff.isoformat(),
         ack_policy=AckPolicy.NONE,
-        inactive_threshold=_INACTIVE_THRESHOLD_NS,
+        inactive_threshold=_INACTIVE_THRESHOLD_S,
         filter_subject=subject_filter,
     )
     try:
diff --git a/tests/test_resend.py b/tests/test_resend.py
index 3a9ccc5..a4a781e 100644
--- a/tests/test_resend.py
+++ b/tests/test_resend.py
@@ -250,6 +250,56 @@ async def test_execute_rejects_invalid_window():
     nc.publish.assert_not_called()
 
 
+# --- ConsumerConfig regression guard (v0.10.5.1) -----------------------------
+
+
+@pytest.mark.asyncio
+async def test_pull_subscribe_inactive_threshold_within_nats_range():
+    """v0.10.5.1 regression guard: ``inactive_threshold`` on the ephemeral
+    consumer must be a number nats-py can serialise as a Go ``time.Duration``.
+
+    v0.10.5 passed ``int(30e9)`` thinking it was nanoseconds. nats-py treats
+    the value as float SECONDS and multiplies by 1e9 internally, so the
+    server received 30e18 -- out of int64 range. NATS rejected the consumer
+    with ``err_code=10025``; preview_resend caught the exception per-stream
+    and returned 0 events across the board (silent verification failure).
+
+    Assert the captured config has:
+      - ``inactive_threshold`` in [1, 3600] seconds (operator sanity range)
+      - the nanosecond-equivalent (value * 1e9) fits within int64
+    The ``int64`` ceiling is 9_223_372_036_854_775_807 -- anything above that
+    triggers the same JSON unmarshal error that broke v0.10.5.
+    """
+    captured_configs: list = []
+
+    async def _capture_config(filter_subj, durable=None, stream=None, config=None):
+        captured_configs.append(config)
+        sub = MagicMock()
+        sub.fetch = AsyncMock(return_value=[])
+        sub.unsubscribe = AsyncMock()
+        return sub
+
+    js = MagicMock()
+    js.pull_subscribe = AsyncMock(side_effect=_capture_config)
+    await preview_resend(js, minutes=60)
+
+    INT64_MAX_NS = 9_223_372_036_854_775_807
+    assert captured_configs, "expected at least one pull_subscribe call"
+    for cfg in captured_configs:
+        threshold = cfg.inactive_threshold
+        assert threshold is not None, "inactive_threshold must be set"
+        assert 1 <= threshold <= 3600, (
+            f"inactive_threshold={threshold!r}s outside [1, 3600] sanity range"
+        )
+        ns = threshold * 1_000_000_000
+        assert ns < INT64_MAX_NS, (
+            f"inactive_threshold={threshold!r} would produce ns={ns}, "
+            f"overflowing int64 ({INT64_MAX_NS}). This is the exact v0.10.5 "
+            f"bug -- a unit confusion that produced 30e18 and triggered "
+            f"err_code=10025 from NATS."
+        )
+
+
 # --- stream-set safety -------------------------------------------------------