fix(session): preserve complete transcripts

tests/agent/test_history_replay.py

@@ -0,0 +1,120 @@
+"""Tests for token-bounded session history replay."""
+
+from __future__ import annotations
+
+from pathlib import Path
+from unittest.mock import AsyncMock, MagicMock, patch
+
+import pytest
+
+from nanobot.agent.loop import AgentLoop
+from nanobot.bus.events import InboundMessage
+from nanobot.bus.queue import MessageBus
+from nanobot.providers.base import LLMResponse
+from nanobot.session.manager import Session
+
+
+def _make_loop(tmp_path: Path, context_window_tokens: int = 200_000) -> AgentLoop:
+    provider = MagicMock()
+    provider.get_default_model.return_value = "test-model"
+    provider.generation.max_tokens = 4096
+    return AgentLoop(
+        bus=MessageBus(),
+        provider=provider,
+        workspace=tmp_path,
+        model="test-model",
+        context_window_tokens=context_window_tokens,
+    )
+
+
+def _populated_session(turns: int) -> Session:
+    session = Session(key="test:populated")
+    for index in range(turns):
+        session.add_message("user", f"msg-{index}")
+        session.add_message("assistant", f"reply-{index}")
+    return session
+
+
+def _tool_round(call_id: str) -> list[dict]:
+    return [
+        {
+            "role": "assistant",
+            "content": None,
+            "tool_calls": [
+                {"id": call_id, "type": "function", "function": {"name": "x", "arguments": "{}"}}
+            ],
+        },
+        {"role": "tool", "tool_call_id": call_id, "name": "x", "content": "ok"},
+    ]
+
+
+def test_default_history_has_no_message_count_limit() -> None:
+    session = _populated_session(1_001)
+
+    history = session.get_history()
+
+    assert len(history) == 2_002
+    assert history[0]["content"] == "msg-0"
+    assert history[-1]["content"] == "reply-1000"
+
+
+def test_explicit_message_limit_still_starts_at_user_turn() -> None:
+    history = _populated_session(30).get_history(max_messages=25)
+
+    assert len(history) <= 25
+    assert history[0]["role"] == "user"
+
+
+@pytest.mark.asyncio
+async def test_process_message_replays_with_token_budget_only(tmp_path: Path) -> None:
+    loop = _make_loop(tmp_path, context_window_tokens=32_768)
+    loop.provider.chat_with_retry = AsyncMock(
+        return_value=LLMResponse(content="ok", tool_calls=[], usage={})
+    )
+    loop.tools.get_definitions = MagicMock(return_value=[])
+    loop.consolidator.maybe_consolidate_by_tokens = AsyncMock(return_value=False)  # type: ignore[method-assign]
+
+    session = loop.sessions.get_or_create("cli:test")
+    with patch.object(session, "get_history", wraps=session.get_history) as get_history:
+        result = await loop._process_message(
+            InboundMessage(channel="cli", sender_id="user", chat_id="test", content="hello")
+        )
+
+    assert result is not None
+    assert get_history.call_args.kwargs == {
+        "max_tokens": loop._replay_token_budget(loop.llm_runtime()),
+        "extend_to_user": False,
+    }
+
+
+@pytest.mark.asyncio
+async def test_token_budget_keeps_current_user_as_replay_boundary(tmp_path: Path) -> None:
+    loop = _make_loop(tmp_path, context_window_tokens=8_000)
+    loop.provider.chat_with_retry = AsyncMock(
+        return_value=LLMResponse(content="ok", tool_calls=[], usage={})
+    )
+    loop.tools.get_definitions = MagicMock(return_value=[])
+    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", "old")
+    session.add_message("assistant", "old answer")
+    session.add_message("user", "long older turn")
+    for index in range(70):
+        session.messages.extend(_tool_round(f"older-{index}"))
+    session.add_message("assistant", "older final")
+
+    result = await loop._process_message(
+        InboundMessage(
+            channel="cli",
+            sender_id="user",
+            chat_id="test",
+            content="new question",
+        )
+    )
+
+    assert result is not None
+    sent_messages = loop.provider.chat_with_retry.await_args.kwargs["messages"]
+    sent_text = "\n".join(str(message.get("content")) for message in sent_messages)
+    assert "new question" in sent_text
+    assert "long older turn" not in sent_text