From 519ab59d7121a21e78a5b6018a253269a13e5f9c Mon Sep 17 00:00:00 2001
From: Vito Sansevero <vito.sansevero@gmail.com>
Date: Fri, 23 Oct 2026 07:45:57 -0700
Subject: [PATCH] fix(system): answer the Overview and Statistics only after
 every read ended

asyncio.gather answered at the first failed read while its sibling
executor reads were still inside SQLite. In the suite the test teardown
then deleted the database under the running read, and py3.10 on Ubuntu
segfaulted in get_statistics (test_statistics_failure_is_an_error_envelope).
Both routes now wait for all their reads before answering.
---
 py/api/system.py         | 18 +++++++++++++--
 tests/test_system_api.py | 48 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 64 insertions(+), 2 deletions(-)

diff --git a/py/api/system.py b/py/api/system.py
index 2362b32..605334e 100644
--- a/py/api/system.py
+++ b/py/api/system.py
@@ -41,6 +41,20 @@ _HEALTH_STATUS_LINES = {
 _StoredReport = namedtuple("_StoredReport", "generation report")
 
 
+async def _settled(*reads):
+    """Every read's result once all of them ended; the first error raises.
+
+    ``asyncio.gather`` answers at the first error while the other executor
+    reads still run, so a route could answer (and its caller replace or
+    delete the database) with a sibling read still inside SQLite.
+    """
+    results = await asyncio.gather(*reads, return_exceptions=True)
+    for result in results:
+        if isinstance(result, BaseException):
+            raise result
+    return results
+
+
 def _failure(message, status=500, code=None):
     return web.json_response(
         {"success": False, "code": code, "error": message}, status=status
@@ -155,7 +169,7 @@ class SystemRoutesMixin:
         from ..config import GalleryConfig
 
         try:
-            (output_dirs, auto_detected), counts = await asyncio.gather(
+            (output_dirs, auto_detected), counts = await _settled(
                 self._run_in_executor(self._output_dirs_with_origin),
                 self._run_in_executor(self.db.library_counts),
             )
@@ -189,7 +203,7 @@ class SystemRoutesMixin:
 
     async def get_system_statistics(self, request):
         try:
-            by_category, totals, counts = await asyncio.gather(
+            by_category, totals, counts = await _settled(
                 self._run_in_executor(self.db.usage_by_category),
                 self._run_in_executor(self.db.get_statistics),
                 self._run_in_executor(self.db.library_counts),
diff --git a/tests/test_system_api.py b/tests/test_system_api.py
index 7af1955..3d649fe 100644
--- a/tests/test_system_api.py
+++ b/tests/test_system_api.py
@@ -416,6 +416,54 @@ class TestStatisticsRoute(SystemAPITestCase):
         )
 
 
+class TestReadsSettleBeforeTheAnswer(SystemAPITestCase):
+    """A failed read answers only after its sibling reads ended.
+
+    ``asyncio.gather`` does not stop executor work, so an early answer left a
+    sibling read on the database while the caller went on (in the suite, the
+    test's teardown deleted the database under it: a segfault on py3.10).
+    """
+
+    def _slow(self, target, name):
+        real = getattr(target, name)
+        finished = threading.Event()
+
+        def slow(*args, **kwargs):
+            threading.Event().wait(0.3)  # still reading when the sibling fails
+            try:
+                return real(*args, **kwargs)
+            finally:
+                finished.set()
+
+        return patch.object(target, name, side_effect=slow), finished
+
+    async def _failing(self, url, failing, slow_target, slow_name):
+        slow, finished = self._slow(slow_target, slow_name)
+        with (
+            slow,
+            patch.object(self.api.db, failing, side_effect=RuntimeError("secret")),
+            self.assertLogs("prompt_manager.api", "ERROR"),
+        ):
+            await self.json("GET", url, 500)
+            self.assertTrue(finished.is_set(), "a sibling read outlived the answer")
+
+    async def test_statistics_failure_waits_for_its_sibling_reads(self):
+        await self._failing(
+            "/prompt_manager/system/statistics",
+            "usage_by_category",
+            self.api.db,
+            "get_statistics",
+        )
+
+    async def test_overview_failure_waits_for_its_sibling_reads(self):
+        await self._failing(
+            "/prompt_manager/system/overview",
+            "library_counts",
+            self.api,
+            "_output_dirs_with_origin",
+        )
+
+
 if __name__ == "__main__":
     import unittest