core/cli+agent: /compact and resume latest by workspace recency

Soft-compact history, model-summarize without tools, seed a new session;
/resume with no id loads the lately-used session for this workspace.

tests/test_cli/test_compact_cmd.py

@@ -0,0 +1,133 @@
+from __future__ import annotations
+
+from typing import TYPE_CHECKING, Literal, overload
+
+import pytest
+import tomlkit
+
+from plyngent.agent import ChatAgent
+from plyngent.cli.state import ReplState
+from plyngent.config.models import DatabaseConfig, OpenAIProvider
+from plyngent.config.store import ConfigStore
+from plyngent.lmproto.openai_compatible.model import (
+    AssistantChatMessage,
+    ChatCompletionChoice,
+    ChatCompletionChunk,
+    ChatCompletionResponse,
+    ChatCompletionsParam,
+    UserChatMessage,
+)
+from plyngent.memory import MemoryStore
+from plyngent.tools import set_workspace_root
+
+if TYPE_CHECKING:
+    from collections.abc import AsyncIterator
+    from pathlib import Path
+
+
+class SummaryClient:
+    @overload
+    async def chat_completions(
+        self, param: ChatCompletionsParam, *, stream: Literal[False] = False
+    ) -> ChatCompletionResponse: ...
+
+    @overload
+    async def chat_completions(
+        self, param: ChatCompletionsParam, *, stream: Literal[True]
+    ) -> AsyncIterator[ChatCompletionChunk]: ...
+
+    async def chat_completions(
+        self, param: ChatCompletionsParam, *, stream: bool = False
+    ) -> ChatCompletionResponse | AsyncIterator[ChatCompletionChunk]:
+        del param, stream
+        return ChatCompletionResponse(
+            id="1",
+            object="chat.completion",
+            created=0,
+            model="m",
+            choices=[
+                ChatCompletionChoice(
+                    index=0,
+                    message=AssistantChatMessage(content="compacted goals: ship feature"),
+                    logprobs={},
+                    finish_reason="stop",
+                )
+            ],
+            system_fingerprint="",
+            usage={},
+        )
+
+
+async def test_compact_to_new_session(tmp_path: Path) -> None:
+    _ = set_workspace_root(tmp_path)
+    memory = await MemoryStore.open(DatabaseConfig())
+    try:
+        provider = OpenAIProvider(access_key_or_token="sk-test")
+        config = ConfigStore(path=tmp_path / "plyngent.toml", document=tomlkit.document())
+        config.providers = {"local": provider}
+        state = ReplState(
+            config=config,
+            memory=memory,
+            workspace=tmp_path,
+            provider_name="local",
+            provider=provider,
+            model="gpt-test",
+            tools_enabled=False,
+        )
+        state.client = SummaryClient()
+        await state.new_session("orig")
+        old_id = state.session_id
+        assert old_id is not None
+        state.agent = ChatAgent(
+            state.client,
+            model=state.model,
+            memory=state.memory,
+            session_id=old_id,
+            system_prompt="Be brief.",
+        )
+        state.agent.messages = [
+            UserChatMessage(content="do work"),
+            AssistantChatMessage(content="done lots of stuff"),
+        ]
+        for msg in state.agent.messages:
+            _ = await memory.append_message(old_id, msg)
+
+        new_old, new_id, summary = await state.compact_to_new_session()
+        assert new_old == old_id
+        assert new_id != old_id
+        assert state.session_id == new_id
+        assert "compacted goals" in summary
+        loaded = await memory.list_messages(new_id)
+        assert any("compacted goals" in getattr(m, "content", "") for m in loaded)
+        # Old session still exists and is listable
+        sessions = await memory.list_sessions(workspace=tmp_path)
+        ids = {s.sid for s in sessions}
+        assert old_id in ids
+        assert new_id in ids
+    finally:
+        await memory.close()
+
+
+async def test_compact_empty_fails(tmp_path: Path) -> None:
+    _ = set_workspace_root(tmp_path)
+    memory = await MemoryStore.open(DatabaseConfig())
+    try:
+        provider = OpenAIProvider(access_key_or_token="sk-test")
+        config = ConfigStore(path=tmp_path / "plyngent.toml", document=tomlkit.document())
+        config.providers = {"local": provider}
+        state = ReplState(
+            config=config,
+            memory=memory,
+            workspace=tmp_path,
+            provider_name="local",
+            provider=provider,
+            model="gpt-test",
+            tools_enabled=False,
+        )
+        state.client = SummaryClient()
+        await state.new_session("empty")
+        state.agent.messages = []
+        with pytest.raises(ValueError, match="nothing to compact"):
+            _ = await state.compact_to_new_session()
+    finally:
+        await memory.close()