cli/state: cancel a compact's summary instead of hanging on it

tests/test_cli/test_compact_cmd.py

@@ -1,5 +1,6 @@
 from __future__ import annotations
 
+import asyncio
 from typing import TYPE_CHECKING, Literal, overload
 
 import pytest
@@ -57,6 +58,31 @@ class SummaryClient:
         )
 
 
+class HangingClient:
+    """A summarizer that never answers until the request is cancelled."""
+
+    def __init__(self) -> None:
+        self.entered = asyncio.Event()
+
+    @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
+        self.entered.set()
+        await asyncio.Event().wait()  # until the caller cancels
+        raise AssertionError("the summary request should have been cancelled")
+
+
 async def test_compact_to_new_session(tmp_path: Path) -> None:
     memory = await MemoryStore.open(DatabaseConfig())
     try:
@@ -128,6 +154,50 @@ async def test_compact_to_new_session(tmp_path: Path) -> None:
         await memory.close()
 
 
+async def test_compact_cancel_leaves_the_session_untouched(tmp_path: Path) -> None:
+    """Ctrl+C during the summary drops the request before anything is created."""
+    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,
+        )
+        await state.new_session("orig")
+        old_id = state.session_id
+        assert old_id is not None
+        client = HangingClient()
+        state.client = client
+        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")]
+        before = {row.sid for row in await memory.list_sessions(workspace=tmp_path)}
+
+        task = asyncio.ensure_future(state.compact_to_new_session())
+        await asyncio.wait_for(client.entered.wait(), timeout=5)
+        _ = task.cancel()
+        with pytest.raises(ValueError, match="compaction cancelled"):
+            await task
+
+        assert state.session_id == old_id
+        after = {row.sid for row in await memory.list_sessions(workspace=tmp_path)}
+        assert after == before
+    finally:
+        await memory.close()
+
+
 async def test_rebuild_client_preserves_persist_cursor(tmp_path: Path) -> None:
     memory = await MemoryStore.open(DatabaseConfig())
     try: