Fix WhatsApp overlap by serial queue, typing, and outbound delivery.

Serialize per-session inbound turns and merge follow-ups after the active run; show composing while busy and enqueue final replies so long agent runs still reach the group.

Co-authored-by: Cursor <cursoragent@cursor.com>

tests/test_channel_turn_gate.py

@@ -0,0 +1,63 @@
+from __future__ import annotations
+
+from runtime.application.gateway.channel_turn_gate import (
+    ChannelTurnGate,
+    merge_channel_pending_jobs,
+    reset_channel_turn_gate_for_tests,
+)
+
+
+def test_try_begin_enqueues_when_busy() -> None:
+    gate = ChannelTurnGate()
+    first = gate.try_begin("sess-a", {"user_text": "A"})
+    assert first is not None
+    second = gate.try_begin("sess-a", {"user_text": "B"})
+    assert second is None
+    assert gate.pending_count("sess-a") == 1
+    third = gate.try_begin("sess-a", {"user_text": "C"})
+    assert third is None
+    assert gate.pending_count("sess-a") == 2
+
+
+def test_end_and_take_merged_combines_pending() -> None:
+    gate = ChannelTurnGate()
+    first = gate.try_begin("sess-a", {"user_text": "A", "lang": "en"})
+    assert first is not None
+    assert gate.try_begin("sess-a", {"user_text": "B question", "lang": "en", "attachments": [{"n": 1}]}) is None
+    assert gate.try_begin("sess-a", {"user_text": "C question", "lang": "en", "attachments": [{"n": 2}]}) is None
+
+    merged, nxt = gate.end_and_take_merged(first)
+    assert nxt is not None
+    assert merged is not None
+    assert int(merged.get("merged_count") or 0) == 2
+    text = str(merged.get("user_text") or "")
+    assert "B question" in text
+    assert "C question" in text
+    assert "follow-up" in text.lower() or "Several" in text
+    assert len(merged.get("attachments") or []) == 2
+    assert gate.pending_count("sess-a") == 0
+
+    done, nxt2 = gate.end_and_take_merged(nxt)
+    assert done is None and nxt2 is None
+
+
+def test_merge_channel_pending_jobs_zh_header() -> None:
+    merged = merge_channel_pending_jobs(
+        [
+            {"user_text": "光功率？", "lang": "zh"},
+            {"user_text": "还有告警吗？", "lang": "zh"},
+        ]
+    )
+    assert "一并回答" in str(merged.get("user_text") or "")
+    assert "1) 光功率？" in str(merged.get("user_text") or "")
+    assert "2) 还有告警吗？" in str(merged.get("user_text") or "")
+
+
+def test_isolated_sessions_and_reset() -> None:
+    g1 = reset_channel_turn_gate_for_tests()
+    a = g1.try_begin("a", {"user_text": "1"})
+    b = g1.try_begin("b", {"user_text": "2"})
+    assert a is not None and b is not None
+    g2 = reset_channel_turn_gate_for_tests()
+    assert g1 is not g2
+    assert g2.pending_count("a") == 0