refactor(agent): let runner own context compaction (#5568)

* refactor(agent): consolidate accepted history under pressure

* fix(agent): align provider and session compaction

* refactor(agent): simplify runner context compaction

* refactor(agent): remove background token consolidation

* fix(agent): keep injected transcript messages distinct

* refactor(agent): unify native compaction summaries

* fix(agent): preserve native compaction boundary

* fix(agent): unify context compaction paths

* fix(agent): preserve exact compaction request boundaries

tests/agent/test_loop_save_turn.py

@@ -45,6 +45,10 @@ from nanobot.session.recovery import (
     RUNTIME_CHECKPOINT_KEY,
     restore_runtime_checkpoint,
 )
+from nanobot.session.summary import (
+    SUMMARY_CONTINUATION_TEXT,
+    SessionSummaryCheckpoint,
+)
 from nanobot.session.turn_continuation import (
     INTERNAL_CONTINUATION_META,
     INTERNAL_CONTINUATION_RUN_STARTED_AT_META,
@@ -506,6 +510,60 @@ def test_save_turn_keeps_multimodal_runtime_context_for_model_replay() -> None:
     assert public_history_message(session.messages[0])["content"] == []
 
 
+def test_save_turn_commits_summary_boundary_without_rewriting_raw_history() -> None:
+    loop = _mk_loop()
+    session = Session(key="test:summary-checkpoint")
+    session.add_message("user", "inspect the project")
+    messages = [
+        {"role": "system", "content": "system"},
+        {"role": "user", "content": "inspect the project"},
+        {
+            "role": "assistant",
+            "content": "",
+            "tool_calls": [{
+                "id": "call-1",
+                "type": "function",
+                "function": {"name": "inspect", "arguments": "{}"},
+            }],
+        },
+        {
+            "role": "tool",
+            "tool_call_id": "call-1",
+            "name": "inspect",
+            "content": "full current result",
+        },
+        {"role": "assistant", "content": "done"},
+    ]
+
+    loop._save_turn(
+        session,
+        messages,
+        skip=2,
+        summary_checkpoint=SessionSummaryCheckpoint(
+            summary="Current working-memory checkpoint.",
+            transcript_boundary=2,
+        ),
+        input_persisted_early=True,
+    )
+
+    assert [message["role"] for message in session.messages] == [
+        "user", "user", "assistant", "tool", "assistant",
+    ]
+    assert session.messages[0]["content"] == "inspect the project"
+    assert session.messages[1]["content"] == SUMMARY_CONTINUATION_TEXT
+    assert session.messages[1]["_hidden_history"] is True
+    assert session.last_archived == 1
+    assert session.metadata["_last_summary"]["text"] == (
+        "Current working-memory checkpoint."
+    )
+    assert [message["content"] for message in session.get_history()] == [
+        SUMMARY_CONTINUATION_TEXT,
+        "",
+        "full current result",
+        "done",
+    ]
+
+
 def test_save_turn_acknowledges_every_merged_recovery_followup() -> None:
     """Persisting a merged injected row retires every durable follow-up ID."""
     loop = _mk_loop()
@@ -966,7 +1024,6 @@ async def test_runtime_checkpoint_keeps_provider_state_out_of_public_metadata(
 @pytest.mark.asyncio
 async def test_process_message_persists_user_message_before_turn_completes(tmp_path: Path) -> None:
     loop = _make_full_loop(tmp_path)
-    loop.consolidator.maybe_consolidate_by_tokens = AsyncMock(return_value=False)  # type: ignore[method-assign]
     loop._run_agent_loop = AsyncMock(side_effect=RuntimeError("boom"))  # type: ignore[method-assign]
 
     msg = InboundMessage(channel="feishu", sender_id="u1", chat_id="c1", content="persist me")
@@ -986,7 +1043,6 @@ async def test_subagent_followup_stages_provider_state_before_turn_runs(
     tmp_path: Path,
 ) -> None:
     loop = _make_full_loop(tmp_path)
-    loop.consolidator.maybe_consolidate_by_tokens = AsyncMock(return_value=False)  # type: ignore[method-assign]
     loop._run_agent_loop = AsyncMock(side_effect=RuntimeError("boom"))  # type: ignore[method-assign]
     loop.provider.can_resume_conversation_state.return_value = True
     session = loop.sessions.get_or_create("cli:subagent-crash")
@@ -1016,7 +1072,6 @@ async def test_subagent_followup_state_is_durable_before_prompt_assembly(
     tmp_path: Path,
 ) -> None:
     loop = _make_full_loop(tmp_path)
-    loop.consolidator.maybe_consolidate_by_tokens = AsyncMock(return_value=False)  # type: ignore[method-assign]
     loop.provider.can_resume_conversation_state.return_value = True
     loop.context.build_system_prompt = MagicMock(  # type: ignore[method-assign]
         side_effect=RuntimeError("prompt boom"),
@@ -1049,7 +1104,6 @@ async def test_subagent_redelivery_does_not_duplicate_staged_provider_input(
     tmp_path: Path,
 ) -> None:
     loop = _make_full_loop(tmp_path)
-    loop.consolidator.maybe_consolidate_by_tokens = AsyncMock(return_value=False)  # type: ignore[method-assign]
     loop.provider.can_resume_conversation_state.return_value = True
     build_system_prompt = loop.context.build_system_prompt
     loop.context.build_system_prompt = MagicMock(  # type: ignore[method-assign]
@@ -1101,7 +1155,6 @@ async def test_subagent_followup_clears_state_before_compatibility_failure(
     tmp_path: Path,
 ) -> None:
     loop = _make_full_loop(tmp_path)
-    loop.consolidator.maybe_consolidate_by_tokens = AsyncMock(return_value=False)  # type: ignore[method-assign]
     loop.provider.can_resume_conversation_state.side_effect = RuntimeError(
         "compatibility boom"
     )
@@ -1129,7 +1182,6 @@ async def test_subagent_followup_clears_state_before_compatibility_failure(
 async def test_process_message_persists_unified_session_delivery_route(tmp_path: Path) -> None:
     loop = _make_full_loop(tmp_path)
     loop._unified_session = True
-    loop.consolidator.maybe_consolidate_by_tokens = AsyncMock(return_value=False)  # type: ignore[method-assign]
     loop._run_agent_loop = AsyncMock(side_effect=RuntimeError("boom"))  # type: ignore[method-assign]
 
     msg = InboundMessage(
@@ -1230,7 +1282,6 @@ async def test_process_message_persists_media_paths_on_user_turn(tmp_path: Path)
     img_b.write_bytes(_PNG_1X1)
 
     loop = _make_full_loop(tmp_path)
-    loop.consolidator.maybe_consolidate_by_tokens = AsyncMock(return_value=False)  # type: ignore[method-assign]
     loop._run_agent_loop = AsyncMock(side_effect=RuntimeError("interrupt"))  # type: ignore[method-assign]
 
     msg = InboundMessage(
@@ -1262,7 +1313,6 @@ async def test_process_message_persists_media_only_turn_without_text(tmp_path: P
     img.write_bytes(_PNG_1X1)
 
     loop = _make_full_loop(tmp_path)
-    loop.consolidator.maybe_consolidate_by_tokens = AsyncMock(return_value=False)  # type: ignore[method-assign]
     loop._run_agent_loop = AsyncMock(side_effect=RuntimeError("boom"))  # type: ignore[method-assign]
 
     msg = InboundMessage(
@@ -1286,7 +1336,6 @@ async def test_process_message_persists_media_only_turn_without_text(tmp_path: P
 @pytest.mark.asyncio
 async def test_process_message_does_not_duplicate_early_persisted_user_message(tmp_path: Path) -> None:
     loop = _make_full_loop(tmp_path)
-    loop.consolidator.maybe_consolidate_by_tokens = AsyncMock(return_value=False)  # type: ignore[method-assign]
     loop._run_agent_loop = AsyncMock(return_value=_agent_run_result(
         "done",
         [
@@ -1319,7 +1368,6 @@ async def test_internal_continuation_queues_turn_without_fake_user_history(
     tmp_path: Path,
 ) -> None:
     loop = _make_full_loop(tmp_path)
-    loop.consolidator.maybe_consolidate_by_tokens = AsyncMock(return_value=False)  # type: ignore[method-assign]
     session = loop.sessions.get_or_create("feishu:c-auto")
     session.metadata[GOAL_STATE_KEY] = {
         "status": "active",
@@ -1388,7 +1436,6 @@ async def test_internal_continuation_preserves_streaming_route_metadata(
     tmp_path: Path,
 ) -> None:
     loop = _make_full_loop(tmp_path)
-    loop.consolidator.maybe_consolidate_by_tokens = AsyncMock(return_value=False)  # type: ignore[method-assign]
     session = loop.sessions.get_or_create("feishu:c-stream")
     session.metadata[GOAL_STATE_KEY] = {
         "status": "active",
@@ -1462,7 +1509,6 @@ async def test_websocket_internal_continuation_keeps_single_visible_run(
     tmp_path: Path,
 ) -> None:
     loop = _make_full_loop(tmp_path)
-    loop.consolidator.maybe_consolidate_by_tokens = AsyncMock(return_value=False)  # type: ignore[method-assign]
     session = loop.sessions.get_or_create("websocket:c-auto")
     session.metadata[GOAL_STATE_KEY] = {
         "status": "active",
@@ -1526,7 +1572,6 @@ async def test_websocket_internal_continuation_keeps_single_visible_run(
 @pytest.mark.asyncio
 async def test_process_message_keeps_delivery_chat_for_thread_session(tmp_path: Path) -> None:
     loop = _make_full_loop(tmp_path)
-    loop.consolidator.maybe_consolidate_by_tokens = AsyncMock(return_value=False)  # type: ignore[method-assign]
     loop.context.build_messages = MagicMock(  # type: ignore[method-assign]
         return_value=[
             {"role": "system", "content": "system"},
@@ -1565,7 +1610,6 @@ async def test_process_message_uses_explicit_session_for_goal_context(
     tmp_path: Path,
 ) -> None:
     loop = _make_full_loop(tmp_path)
-    loop.consolidator.maybe_consolidate_by_tokens = AsyncMock(return_value=False)  # type: ignore[method-assign]
     chat_session = loop.sessions.get_or_create("websocket:chat-with-goal")
     chat_session.metadata[GOAL_STATE_KEY] = {
         "status": "active",
@@ -1713,7 +1757,6 @@ async def test_request_context_uses_effective_key_for_spawn_tool(tmp_path: Path)
 @pytest.mark.asyncio
 async def test_next_turn_after_crash_closes_pending_user_turn_before_new_input(tmp_path: Path) -> None:
     loop = _make_full_loop(tmp_path)
-    loop.consolidator.maybe_consolidate_by_tokens = AsyncMock(return_value=False)  # type: ignore[method-assign]
     loop.provider.chat_with_retry = AsyncMock(return_value=MagicMock())  # unused because _run_agent_loop is stubbed
 
     session = loop.sessions.get_or_create("feishu:c3")
@@ -1762,7 +1805,6 @@ async def test_stop_preserves_runtime_checkpoint_for_next_turn(tmp_path: Path) -
     from nanobot.command.router import CommandContext
 
     loop = _make_full_loop(tmp_path)
-    loop.consolidator.maybe_consolidate_by_tokens = AsyncMock(return_value=False)  # type: ignore[method-assign]
 
     checkpoint_saved = asyncio.Event()
 
@@ -1866,7 +1908,6 @@ async def test_stop_preserves_runtime_checkpoint_for_next_turn(tmp_path: Path) -
 @pytest.mark.asyncio
 async def test_system_subagent_followup_is_persisted_before_prompt_assembly(tmp_path: Path) -> None:
     loop = _make_full_loop(tmp_path)
-    loop.consolidator.maybe_consolidate_by_tokens = AsyncMock(return_value=False)  # type: ignore[method-assign]
 
     session = loop.sessions.get_or_create("cli:test")
     session.add_message("user", "question")
@@ -1913,11 +1954,6 @@ async def test_system_subagent_followup_is_persisted_before_prompt_assembly(tmp_
     assert request.metadata == {"subagent_task_id": "sub-1"}
     assert request.turn_id
     record_runtime.assert_called_once_with("cli:test", runtime)
-    assert len(loop.consolidator.maybe_consolidate_by_tokens.call_args_list) == 2
-    assert all(
-        call.kwargs["runtime"] is runtime
-        for call in loop.consolidator.maybe_consolidate_by_tokens.call_args_list
-    )
     initial_messages = seen["initial_messages"]
     assert isinstance(initial_messages, list)
     non_system = [m for m in initial_messages if m.get("role") != "system"]
@@ -1952,7 +1988,6 @@ async def test_system_subagent_followup_is_persisted_before_prompt_assembly(tmp_
 @pytest.mark.asyncio
 async def test_turn_usage_is_persisted_with_the_saved_session(tmp_path: Path) -> None:
     loop = _make_full_loop(tmp_path)
-    loop.consolidator.maybe_consolidate_by_tokens = AsyncMock(return_value=False)  # type: ignore[method-assign]
     turn_usage = LLMUsage.reported(input_tokens=64, output_tokens=9)
 
     async def fake_run_agent_loop(transcript_input, **_kwargs):
@@ -1978,9 +2013,6 @@ async def test_turn_usage_is_persisted_with_the_saved_session(tmp_path: Path) ->
 @pytest.mark.asyncio
 async def test_system_subagent_followup_does_not_log_content(tmp_path: Path) -> None:
     loop = _make_full_loop(tmp_path)
-    loop.consolidator.maybe_consolidate_by_tokens = AsyncMock(  # type: ignore[method-assign]
-        return_value=False
-    )
 
     async def fake_run_agent_loop(transcript_input, **_kwargs):
         initial_messages = _assembled_messages(loop.context, transcript_input)
@@ -2017,9 +2049,6 @@ async def test_system_subagent_followup_does_not_log_content(tmp_path: Path) ->
 @pytest.mark.asyncio
 async def test_system_subagent_followup_uses_common_turn_lifecycle(tmp_path: Path) -> None:
     loop = _make_full_loop(tmp_path)
-    loop.consolidator.maybe_consolidate_by_tokens = AsyncMock(  # type: ignore[method-assign]
-        return_value=False
-    )
     visited: list[str] = []
 
     for name in (
@@ -2081,7 +2110,6 @@ async def test_system_subagent_followup_uses_common_turn_lifecycle(tmp_path: Pat
 @pytest.mark.asyncio
 async def test_multiple_subagent_followups_all_persist_as_standalone_history(tmp_path: Path) -> None:
     loop = _make_full_loop(tmp_path)
-    loop.consolidator.maybe_consolidate_by_tokens = AsyncMock(return_value=False)  # type: ignore[method-assign]
 
     async def fake_run_agent_loop(transcript_input, **_kwargs):
         initial_messages = _assembled_messages(loop.context, transcript_input)
@@ -2207,7 +2235,6 @@ async def test_request_context_passes_thread_session_key_to_spawn(tmp_path: Path
 @pytest.mark.asyncio
 async def test_system_subagent_followup_uses_thread_session_and_slack_metadata(tmp_path: Path) -> None:
     loop = _make_full_loop(tmp_path)
-    loop.consolidator.maybe_consolidate_by_tokens = AsyncMock(return_value=False)  # type: ignore[method-assign]
 
     thread_session = loop.sessions.get_or_create("slack:C123:1700.42")
     thread_session.add_message("user", "thread question")
@@ -2266,7 +2293,6 @@ async def test_system_subagent_followup_uses_thread_session_and_slack_metadata(t
 @pytest.mark.asyncio
 async def test_turn_after_unanswered_user_keeps_tool_call_pairing(tmp_path: Path) -> None:
     loop = _make_full_loop(tmp_path)
-    loop.consolidator.maybe_consolidate_by_tokens = AsyncMock(return_value=False)  # type: ignore[method-assign]
 
     session = loop.sessions.get_or_create("feishu:c-merge")
     session.add_message("user", "earlier question that never got an answer")