feat(seer-slack): Only show missing scope footer on first thread response

Use cache.add() to atomically track whether the missing-scope footer
has already been shown in a given thread. Subsequent Seer Explorer
responses in the same thread no longer repeat the warning.

Author: alexsohn1126

src/sentry/seer/entrypoints/slack/messaging.py

@@ -29,6 +29,7 @@
 from sentry.shared_integrations.exceptions import IntegrationConfigurationError, IntegrationError
 from sentry.tasks.base import instrumented_task
 from sentry.taskworker.namespaces import integrations_tasks
+from sentry.utils.cache import cache
 from sentry.utils.registry import NoRegistrationExistsError
 
 if TYPE_CHECKING:
@@ -37,9 +38,16 @@
     from sentry.seer.entrypoints.slack.entrypoint import SlackThreadDetails
 
 
+# TTL for the "missing scope footer already shown" cache key (24 hours).
+MISSING_SCOPE_FOOTER_CACHE_TIMEOUT = 60 * 60 * 24
+
 logger = logging.getLogger(__name__)
 
 
+def _missing_scope_footer_cache_key(integration_id: int, channel_id: str, thread_ts: str) -> str:
+    return f"seer:explorer:scope_footer:{integration_id}:{channel_id}:{thread_ts}"
+
+
 def send_thread_update(
     *,
     install: SlackIntegration,
@@ -70,10 +78,17 @@ def send_thread_update(
         if isinstance(data, SeerExplorerResponse) and not install.has_history_scope(
             thread["channel_id"]
         ):
-            settings_url = install.organization.absolute_url(
-                f"/settings/{install.organization.slug}/integrations/slack/"
+            footer_key = _missing_scope_footer_cache_key(
+                install.model.id, thread["channel_id"], thread["thread_ts"]
             )
-            renderable["blocks"].extend(SeerSlackRenderer.render_missing_scope_footer(settings_url))
+            # cache.add is atomic: returns True only the first time (key didn't exist).
+            if cache.add(footer_key, True, timeout=MISSING_SCOPE_FOOTER_CACHE_TIMEOUT):
+                settings_url = install.organization.absolute_url(
+                    f"/settings/{install.organization.slug}/integrations/slack/"
+                )
+                renderable["blocks"].extend(
+                    SeerSlackRenderer.render_missing_scope_footer(settings_url)
+                )
 
         try:
             if ephemeral_user_id:

tests/sentry/seer/entrypoints/slack/test_slack.py

@@ -669,6 +669,64 @@ def test_send_thread_update_explorer_response_missing_scope_has_footer(
         assert "Reinstall" in footer_text
         assert "Thread context is unavailable" in footer_text
 
+    @patch("sentry.integrations.slack.integration.SlackIntegration.send_threaded_message")
+    @patch(
+        "sentry.integrations.slack.integration.SlackIntegration.has_history_scope",
+        return_value=False,
+    )
+    def test_send_thread_update_explorer_response_missing_scope_no_footer_on_second_message(
+        self, mock_has_history_scope, mock_send_threaded_message
+    ):
+        """Subsequent explorer responses in the same thread should not repeat the footer."""
+        data = SeerExplorerResponse(
+            run_id=12345,
+            organization_id=self.organization.id,
+            summary="Test summary",
+        )
+        install = self.integration.get_installation(organization_id=self.organization.id)
+        thread = SlackThreadDetails(thread_ts=self.thread_ts, channel_id=self.channel_id)
+
+        # First call — footer should be present
+        send_thread_update(install=install, thread=thread, data=data)
+        renderable_first = mock_send_threaded_message.call_args.kwargs["renderable"]
+        assert renderable_first["blocks"][-1].type == "context"
+
+        mock_send_threaded_message.reset_mock()
+
+        # Second call in same thread — footer should be absent
+        send_thread_update(install=install, thread=thread, data=data)
+        renderable_second = mock_send_threaded_message.call_args.kwargs["renderable"]
+        for block in renderable_second["blocks"]:
+            assert block.type != "context"
+
+    @patch("sentry.integrations.slack.integration.SlackIntegration.send_threaded_message")
+    @patch(
+        "sentry.integrations.slack.integration.SlackIntegration.has_history_scope",
+        return_value=False,
+    )
+    def test_send_thread_update_explorer_response_missing_scope_different_thread_gets_footer(
+        self, mock_has_history_scope, mock_send_threaded_message
+    ):
+        """Different threads should each get their own first-time footer."""
+        data = SeerExplorerResponse(
+            run_id=12345,
+            organization_id=self.organization.id,
+            summary="Test summary",
+        )
+        install = self.integration.get_installation(organization_id=self.organization.id)
+        thread_a = SlackThreadDetails(thread_ts=self.thread_ts, channel_id=self.channel_id)
+        thread_b = SlackThreadDetails(thread_ts="9999999999.999999", channel_id=self.channel_id)
+
+        send_thread_update(install=install, thread=thread_a, data=data)
+        renderable_a = mock_send_threaded_message.call_args.kwargs["renderable"]
+        assert renderable_a["blocks"][-1].type == "context"
+
+        mock_send_threaded_message.reset_mock()
+
+        send_thread_update(install=install, thread=thread_b, data=data)
+        renderable_b = mock_send_threaded_message.call_args.kwargs["renderable"]
+        assert renderable_b["blocks"][-1].type == "context"
+
     @patch("sentry.integrations.slack.integration.SlackIntegration.send_threaded_message")
     @patch(
         "sentry.integrations.slack.integration.SlackIntegration.has_history_scope",