clai: Add ability to continue last conversation

clai/README.md

@@ -54,7 +54,7 @@ Either way, running `clai` will start an interactive session where you can chat
 ## Help
 
 ```
-usage: clai [-h] [-m [MODEL]] [-a AGENT] [-l] [-t [CODE_THEME]] [--no-stream] [--version] [prompt]
+usage: clai [-h] [-m [MODEL]] [-a AGENT] [-l] [-t [CODE_THEME]] [-c] [--no-stream] [--version] [prompt]
 
 Pydantic AI CLI v...
 
@@ -76,6 +76,7 @@ options:
   -l, --list-models     List all available models and exit
   -t [CODE_THEME], --code-theme [CODE_THEME]
                         Which colors to use for code, can be "dark", "light" or any theme from pygments.org/styles/. Defaults to "dark" which works well on dark terminals.
+  -c, --continue        Continue last conversation, if any, instead of starting a new one.
   --no-stream           Disable streaming from the model
   --version             Show version and exit
 ```

pydantic_ai_slim/pydantic_ai/_cli.py

@@ -12,13 +12,14 @@
 from pathlib import Path
 from typing import Any, cast
 
+from pydantic import ValidationError
 from typing_inspection.introspection import get_literal_values
 
 from . import __version__
 from ._run_context import AgentDepsT
 from .agent import AbstractAgent, Agent
 from .exceptions import UserError
-from .messages import ModelMessage, ModelResponse
+from .messages import ModelMessage, ModelMessagesTypeAdapter, ModelResponse
 from .models import KnownModelName, infer_model
 from .output import OutputDataT
 
@@ -54,6 +55,7 @@
 """
 
 PROMPT_HISTORY_FILENAME = 'prompt-history.txt'
+LAST_CONVERSATION_FILENAME = 'last-conversation.json'
 
 
 class SimpleCodeBlock(CodeBlock):
@@ -148,6 +150,13 @@ def cli(  # noqa: C901
         help='Which colors to use for code, can be "dark", "light" or any theme from pygments.org/styles/. Defaults to "dark" which works well on dark terminals.',
         default='dark',
     )
+    parser.add_argument(
+        '-c',
+        '--continue',
+        dest='continue_',
+        action='store_true',
+        help='Continue last conversation, if any, instead of starting a new one.',
+    )
     parser.add_argument('--no-stream', action='store_true', help='Disable streaming from the model')
     parser.add_argument('--version', action='store_true', help='Show version and exit')
 
@@ -207,19 +216,42 @@ def cli(  # noqa: C901
     else:
         code_theme = args.code_theme  # pragma: no cover
 
+    try:
+        history = load_last_conversation() if args.continue_ else None
+    except ValidationError:
+        console.print(
+            '[red]Error loading last conversation, it is corrupted or invalid.\nStarting a new conversation.[/red]'
+        )
+        history = None
+
     if prompt := cast(str, args.prompt):
         try:
-            asyncio.run(ask_agent(agent, prompt, stream, console, code_theme))
+            asyncio.run(ask_agent(agent, prompt, stream, console, code_theme, messages=history))
         except KeyboardInterrupt:
             pass
         return 0
 
     try:
-        return asyncio.run(run_chat(stream, agent, console, code_theme, prog_name))
+        return asyncio.run(run_chat(stream, agent, console, code_theme, prog_name, message_history=history))
     except KeyboardInterrupt:  # pragma: no cover
         return 0
 
 
+def store_last_conversation(messages: list[ModelMessage], config_dir: Path | None = None) -> None:
+    last_conversation_path = (config_dir or PYDANTIC_AI_HOME) / LAST_CONVERSATION_FILENAME
+    last_conversation_path.parent.mkdir(parents=True, exist_ok=True)
+    last_conversation_path.write_bytes(ModelMessagesTypeAdapter.dump_json(messages))
+
+
+def load_last_conversation(config_dir: Path | None = None) -> list[ModelMessage] | None:
+    last_conversation_path = (config_dir or PYDANTIC_AI_HOME) / LAST_CONVERSATION_FILENAME
+
+    if not last_conversation_path.exists():
+        return None
+
+    return ModelMessagesTypeAdapter.validate_json(last_conversation_path.read_bytes())
+
+
 async def run_chat(
     stream: bool,
     agent: AbstractAgent[AgentDepsT, OutputDataT],
@@ -255,7 +287,7 @@ async def run_chat(
                 return exit_value
         else:
             try:
-                messages = await ask_agent(agent, text, stream, console, code_theme, deps, messages)
+                messages = await ask_agent(agent, text, stream, console, code_theme, deps, messages, config_dir)
             except CancelledError:  # pragma: no cover
                 console.print('[dim]Interrupted[/dim]')
             except Exception as e:  # pragma: no cover
@@ -273,6 +305,7 @@ async def ask_agent(
     code_theme: str,
     deps: AgentDepsT = None,
     messages: Sequence[ModelMessage] | None = None,
+    config_dir: Path | None = None,
 ) -> list[ModelMessage]:
     status = Status('[dim]Working on it…[/dim]', console=console)
 
@@ -281,7 +314,10 @@ async def ask_agent(
             result = await agent.run(prompt, message_history=messages, deps=deps)
         content = str(result.output)
         console.print(Markdown(content, code_theme=code_theme))
-        return result.all_messages()
+        result_messages = result.all_messages()
+        store_last_conversation(result_messages, config_dir)
+
+        return result_messages
 
     with status, ExitStack() as stack:
         async with agent.iter(prompt, message_history=messages, deps=deps) as agent_run:
@@ -296,7 +332,10 @@ async def ask_agent(
                             live.update(Markdown(str(content), code_theme=code_theme))
 
         assert agent_run.result is not None
-        return agent_run.result.all_messages()
+        result_messages = agent_run.result.all_messages()
+        store_last_conversation(result_messages, config_dir)
+
+        return result_messages
 
 
 class CustomAutoSuggest(AutoSuggestFromHistory):

tests/test_cli.py

@@ -2,6 +2,7 @@
 import types
 from collections.abc import Callable
 from io import StringIO
+from pathlib import Path
 from typing import Any
 
 import pytest
@@ -22,7 +23,7 @@
     from prompt_toolkit.output import DummyOutput
     from prompt_toolkit.shortcuts import PromptSession
 
-    from pydantic_ai._cli import cli, cli_agent, handle_slash_command
+    from pydantic_ai._cli import LAST_CONVERSATION_FILENAME, cli, cli_agent, handle_slash_command
     from pydantic_ai.models.openai import OpenAIChatModel
 
 pytestmark = pytest.mark.skipif(not imports_successful(), reason='install cli extras to run cli tests')
@@ -56,6 +57,15 @@ def _create_test_module(**namespace: Any) -> None:
             del sys.modules['test_module']
 
 
+@pytest.fixture
+def empty_last_conversation_path(tmp_path: Path, mocker: MockerFixture) -> Path:
+    path = tmp_path / LAST_CONVERSATION_FILENAME
+    mocker.patch('pydantic_ai._cli.PYDANTIC_AI_HOME', tmp_path)
+    path.unlink(missing_ok=True)
+
+    return path
+
+
 def test_agent_flag(
     capfd: CaptureFixture[str],
     mocker: MockerFixture,
@@ -164,6 +174,51 @@ def test_cli_prompt(capfd: CaptureFixture[str], env: TestEnv):
         assert capfd.readouterr().out.splitlines() == snapshot([IsStr(), '# result', '', 'py', 'x = 1', '/py'])
 
 
+@pytest.mark.parametrize('args', [['hello', '-c'], ['hello', '--continue']])
+def test_cli_continue_last_conversation(
+    args: list[str],
+    capfd: CaptureFixture[str],
+    env: TestEnv,
+    empty_last_conversation_path: Path,
+):
+    env.set('OPENAI_API_KEY', 'test')
+    with cli_agent.override(model=TestModel(custom_output_text='# world')):
+        assert cli(args) == 0
+        assert capfd.readouterr().out.splitlines() == snapshot([IsStr(), '# world'])
+        assert empty_last_conversation_path.exists()
+        content = empty_last_conversation_path.read_text()
+        assert content
+
+        assert cli(args) == 0
+        assert capfd.readouterr().out.splitlines() == snapshot([IsStr(), '# world'])
+        assert empty_last_conversation_path.exists()
+        # verify that new content is appended to the file
+        assert len(empty_last_conversation_path.read_text()) > len(content)
+
+
+@pytest.mark.parametrize('args', [['hello', '-c'], ['hello', '--continue']])
+def test_cli_continue_last_conversation_corrupted_file(
+    args: list[str],
+    capfd: CaptureFixture[str],
+    env: TestEnv,
+    empty_last_conversation_path: Path,
+):
+    env.set('OPENAI_API_KEY', 'test')
+    empty_last_conversation_path.write_text('not a valid json')
+    with cli_agent.override(model=TestModel(custom_output_text='# world')):
+        assert cli(args) == 0
+        assert capfd.readouterr().out.splitlines() == snapshot(
+            [
+                IsStr(),
+                'Error loading last conversation, it is corrupted or invalid.',
+                'Starting a new conversation.',
+                '# world',
+            ]
+        )
+        assert empty_last_conversation_path.exists()
+        assert empty_last_conversation_path.read_text()
+
+
 def test_chat(capfd: CaptureFixture[str], mocker: MockerFixture, env: TestEnv):
     env.set('OPENAI_API_KEY', 'test')
 
@@ -264,21 +319,42 @@ def test_code_theme_unset(mocker: MockerFixture, env: TestEnv):
     env.set('OPENAI_API_KEY', 'test')
     mock_run_chat = mocker.patch('pydantic_ai._cli.run_chat')
     cli([])
-    mock_run_chat.assert_awaited_once_with(True, IsInstance(Agent), IsInstance(Console), 'monokai', 'pai')
+    mock_run_chat.assert_awaited_once_with(
+        True,
+        IsInstance(Agent),
+        IsInstance(Console),
+        'monokai',
+        'pai',
+        message_history=None,
+    )
 
 
 def test_code_theme_light(mocker: MockerFixture, env: TestEnv):
     env.set('OPENAI_API_KEY', 'test')
     mock_run_chat = mocker.patch('pydantic_ai._cli.run_chat')
     cli(['--code-theme=light'])
-    mock_run_chat.assert_awaited_once_with(True, IsInstance(Agent), IsInstance(Console), 'default', 'pai')
+    mock_run_chat.assert_awaited_once_with(
+        True,
+        IsInstance(Agent),
+        IsInstance(Console),
+        'default',
+        'pai',
+        message_history=None,
+    )
 
 
 def test_code_theme_dark(mocker: MockerFixture, env: TestEnv):
     env.set('OPENAI_API_KEY', 'test')
     mock_run_chat = mocker.patch('pydantic_ai._cli.run_chat')
     cli(['--code-theme=dark'])
-    mock_run_chat.assert_awaited_once_with(True, IsInstance(Agent), IsInstance(Console), 'monokai', 'pai')
+    mock_run_chat.assert_awaited_once_with(
+        True,
+        IsInstance(Agent),
+        IsInstance(Console),
+        'monokai',
+        'pai',
+        message_history=None,
+    )
 
 
 def test_agent_to_cli_sync(mocker: MockerFixture, env: TestEnv):