diff --git a/py/api/prompts.py b/py/api/prompts.py
index 2914616..22b2b3d 100644
--- a/py/api/prompts.py
+++ b/py/api/prompts.py
@@ -25,16 +25,20 @@ EXPORT_PAGE_SIZE = 1000
 # The most prompts one bulk category request may change.
 BULK_CATEGORY_MAX_PROMPTS = 1000
 
+# The largest value SQLite's INTEGER can bind; a larger id raises OverflowError.
+MAX_SQLITE_INT = 2**63 - 1
+
 
 def parse_bulk_prompt_ids(value, cap=BULK_CATEGORY_MAX_PROMPTS):
     """A bulk request's ``prompt_ids``: distinct positive ints, first-seen order.
 
     Raises ``ValueError`` unless ``value`` is a non-empty list of at most
-    ``cap`` distinct positive integers (booleans are not integers here).
+    ``cap`` distinct positive integers no larger than SQLite's INTEGER
+    (booleans are not integers here).
     """
     if not isinstance(value, list) or not value:
         raise ValueError("prompt_ids must be a non-empty list")
-    if any(type(pid) is not int or pid < 1 for pid in value):
+    if any(type(pid) is not int or not 1 <= pid <= MAX_SQLITE_INT for pid in value):
         raise ValueError("prompt_ids must be positive integers")
     ids = list(dict.fromkeys(value))
     if len(ids) > cap:
diff --git a/tests/test_api_prompts.py b/tests/test_api_prompts.py
index 1265183..2cfb7a0 100644
--- a/tests/test_api_prompts.py
+++ b/tests/test_api_prompts.py
@@ -926,6 +926,9 @@ class TestBulkRoutes(RouteCoverageCase):
             [pid, 1.5],
             [True],
             [pid, None],
+            # Beyond SQLite's INTEGER range: binding it would raise OverflowError.
+            [pid, 2**63],
+            [2**64],
             list(range(1, BULK_CATEGORY_MAX_PROMPTS + 2)),
         )
         for prompt_ids in cases: