Get default chat paramters from settings file

In the current CLI implementation, default values for the model,
temperature, and history directory were provided as defaults to the
`typer` CLI interface. This bypassed the ability to set values via
environment variables and relied on `typer` rather than `pydantic` to
validate the history directory. This prevented the directory's creation
when it doesn't exist.

This commit sets the default values in the CLI to `None` and thus relies
on the `OpenAISettings` class for default values and parameter
validation.

pyproject.toml

@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "llm-chat"
-version = "1.1.3"
+version = "1.1.4"
 description = "A general CLI interface for large language models."
 authors = ["Paul Harrison <paul@harrison.sh>"]
 readme = "README.md"

src/llm_chat/cli.py

@@ -8,13 +8,7 @@ from rich.markdown import Markdown
 
 from llm_chat.chat import ChatProtocol, get_chat, get_chat_class
 from llm_chat.models import Message, Role
-from llm_chat.settings import (
-    DEFAULT_HISTORY_DIR,
-    DEFAULT_MODEL,
-    DEFAULT_TEMPERATURE,
-    Model,
-    OpenAISettings,
-)
+from llm_chat.settings import Model, OpenAISettings
 
 app = typer.Typer()
 
@@ -106,15 +100,15 @@ def chat(
         ),
     ] = None,
     model: Annotated[
-        Model,
+        Optional[Model],
         typer.Option(..., "--model", "-m", help="Model to use.", show_choices=True),
-    ] = DEFAULT_MODEL,
+    ] = None,
     temperature: Annotated[
-        float,
+        Optional[float],
         typer.Option(
             ..., "--temperature", "-t", help="Model temperature (i.e. creativeness)."
         ),
-    ] = DEFAULT_TEMPERATURE,
+    ] = None,
     context: Annotated[
         list[Path],
         typer.Option(
@@ -132,17 +126,14 @@ def chat(
         ),
     ] = [],
     history_dir: Annotated[
-        Path,
+        Optional[Path],
         typer.Option(
             ...,
             "--history-dir",
             "-d",
             help="Path to the directory where conversation history will be saved.",
-            exists=True,
-            dir_okay=True,
-            file_okay=False,
         ),
-    ] = DEFAULT_HISTORY_DIR,
+    ] = None,
     name: Annotated[
         str,
         typer.Option(
@@ -155,17 +146,16 @@ def chat(
 ) -> None:
     """Start a chat session."""
     # TODO: Add option to provide context string as an argument.
+    args: dict[str, Any] = {}
     if api_key is not None:
-        settings = OpenAISettings(
-            api_key=api_key,
-            model=model,
-            temperature=temperature,
-            history_dir=history_dir,
-        )
-    else:
-        settings = OpenAISettings(
-            model=model, temperature=temperature, history_dir=history_dir
-        )
+        args |= {"api_key": api_key}
+    if model is not None:
+        args |= {"model": model}
+    if temperature is not None:
+        args |= {"temperature": temperature}
+    if history_dir is not None:
+        args |= {"history_dir": history_dir}
+    settings = OpenAISettings(**args)
 
     context_messages = [load_context(path) for path in context]