test(multi-agent): pin first-wins assumption on pending subagent interrupts

surfsense_backend/tests/unit/agents/multi_agent_chat/middleware/checkpointed_subagent_middleware/test_pending_interrupt.py

@@ -0,0 +1,55 @@
+"""Pins the first-wins assumption of ``get_first_pending_subagent_interrupt``.
+
+The bridge currently relies on at-most-one pending interrupt per snapshot
+(sequential tool nodes). If parallel tool calls are ever enabled, the bridge
+needs an id-aware lookup; these tests will need to be revisited at that point.
+"""
+
+from __future__ import annotations
+
+from types import SimpleNamespace
+
+from app.agents.multi_agent_chat.middleware.main_agent.checkpointed_subagent_middleware.resume import (
+    get_first_pending_subagent_interrupt,
+)
+
+
+class TestGetFirstPendingSubagentInterrupt:
+    def test_returns_first_when_multiple_top_level_interrupts_pending(self):
+        first = SimpleNamespace(id="i-1", value={"decision": "approve"})
+        second = SimpleNamespace(id="i-2", value={"decision": "reject"})
+        state = SimpleNamespace(interrupts=(first, second), tasks=())
+
+        assert get_first_pending_subagent_interrupt(state) == (
+            "i-1",
+            {"decision": "approve"},
+        )
+
+    def test_returns_first_when_multiple_subtask_interrupts_pending(self):
+        first = SimpleNamespace(id="i-A", value="approve")
+        second = SimpleNamespace(id="i-B", value="reject")
+        sub_task = SimpleNamespace(interrupts=(first, second))
+        state = SimpleNamespace(interrupts=(), tasks=(sub_task,))
+
+        assert get_first_pending_subagent_interrupt(state) == ("i-A", "approve")
+
+    def test_returns_none_when_no_interrupts(self):
+        state = SimpleNamespace(interrupts=(), tasks=())
+
+        assert get_first_pending_subagent_interrupt(state) == (None, None)
+
+    def test_returns_none_when_state_is_none(self):
+        assert get_first_pending_subagent_interrupt(None) == (None, None)
+
+    def test_skips_interrupts_with_none_value(self):
+        empty = SimpleNamespace(id="i-empty", value=None)
+        real = SimpleNamespace(id="i-real", value="approve")
+        state = SimpleNamespace(interrupts=(empty, real), tasks=())
+
+        assert get_first_pending_subagent_interrupt(state) == ("i-real", "approve")
+
+    def test_normalizes_non_string_id_to_none(self):
+        interrupt = SimpleNamespace(id=12345, value="approve")
+        state = SimpleNamespace(interrupts=(interrupt,), tasks=())
+
+        assert get_first_pending_subagent_interrupt(state) == (None, "approve")