From 0d214e6a6b3586b71ec83e7ff2c509bc9a74e33f Mon Sep 17 00:00:00 2001
From: HardMax71 <maxymazatyan@gmail.com>
Date: Sat, 3 Oct 2026 01:34:23 +0200
Subject: [PATCH 1/2] fix(crons): Return `None` from `capture_checkin` when
 nothing is sent

Return None when capture_event does not send the check-in, because there
is no active client or before_send drops the event. Previously the
generated or passed-in id came back either way, so a caller that hands
the id to another process could not tell that the check-in never reached
Sentry.

Fixes GH-7845
---
 sentry_sdk/crons/api.py |  5 +++--
 tests/test_crons.py     | 12 +++++++++++-
 2 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/sentry_sdk/crons/api.py b/sentry_sdk/crons/api.py
index 6ea3e36b6d..1d81582db6 100644
--- a/sentry_sdk/crons/api.py
+++ b/sentry_sdk/crons/api.py
@@ -42,7 +42,7 @@ def capture_checkin(
     status: "Optional[str]" = None,
     duration: "Optional[float]" = None,
     monitor_config: "Optional[MonitorConfig]" = None,
-) -> str:
+) -> "Optional[str]":
     check_in_event = _create_check_in_event(
         monitor_slug=monitor_slug,
         check_in_id=check_in_id,
@@ -51,7 +51,8 @@ def capture_checkin(
         monitor_config=monitor_config,
     )
 
-    sentry_sdk.capture_event(check_in_event)
+    if sentry_sdk.capture_event(check_in_event) is None:
+        return None
 
     logger.debug(
         f"[Crons] Captured check-in ({check_in_event.get('check_in_id')}): {check_in_event.get('monitor_slug')} -> {check_in_event.get('status')}"
diff --git a/tests/test_crons.py b/tests/test_crons.py
index 30031db6e1..8a7ee32ec6 100644
--- a/tests/test_crons.py
+++ b/tests/test_crons.py
@@ -321,7 +321,17 @@ def test_capture_checkin_sdk_not_initialized():
         status=None,
         duration=None,
     )
-    assert check_in_id == "112233"
+    assert check_in_id is None
+
+
+def test_capture_checkin_dropped_by_before_send(sentry_init, capture_envelopes):
+    sentry_init(before_send=lambda event, hint: None)
+    envelopes = capture_envelopes()
+
+    check_in_id = capture_checkin(monitor_slug="abc123", status="in_progress")
+
+    assert check_in_id is None
+    assert envelopes == []
 
 
 def test_scope_data_in_checkin(sentry_init, capture_envelopes):

From 99ec2d842f06630d0ab68caaab11ca3f421ba2bb Mon Sep 17 00:00:00 2001
From: HardMax71 <maxymazatyan@gmail.com>
Date: Mon, 5 Oct 2026 18:54:40 +0200
Subject: [PATCH 2/2] test(crons): Cover the monitor exit check-in after a
 dropped enter

Test written by ericapisani in review.
---
 tests/test_crons.py | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/tests/test_crons.py b/tests/test_crons.py
index 8a7ee32ec6..035b0df801 100644
--- a/tests/test_crons.py
+++ b/tests/test_crons.py
@@ -334,6 +334,31 @@ def test_capture_checkin_dropped_by_before_send(sentry_init, capture_envelopes):
     assert envelopes == []
 
 
+def test_context_monitor_exit_successfully_sends_checkin_when_enter_checkin_dropped(
+    sentry_init, capture_envelopes
+):
+    sentry_init(
+        before_send=lambda event, hint: (
+            None if event.get("status") == "in_progress" else event
+        )
+    )
+    envelopes = capture_envelopes()
+
+    monitor = sentry_sdk.monitor(monitor_slug="abc123")
+    with monitor:
+        # Confirms that the check in was dropped in the `__enter__`
+        assert monitor.check_in_id is None
+
+    (envelope,) = envelopes
+    check_in = envelope.items[0].payload.json
+
+    # Confirms that the second check in in `__exit__` works correctly
+    assert check_in["monitor_slug"] == "abc123"
+    assert check_in["check_in_id"]
+    assert check_in["status"] == "ok"
+    assert check_in["duration"] > 0
+
+
 def test_scope_data_in_checkin(sentry_init, capture_envelopes):
     sentry_init()
     envelopes = capture_envelopes()