Fix parsing of bool-type backend options

this made it necessary to plumb 'ctx' through some additional
places, all to make it easy to call BoolParamType().convert().

src/chap/commands/tui.py

@@ -7,6 +7,7 @@ import subprocess
 import sys
 from typing import Any, Optional, cast
 
+import click
 from markdown_it import MarkdownIt
 from textual import work
 from textual.app import App, ComposeResult
@@ -66,7 +67,7 @@ class Tui(App[None]):
         self, api: Optional[Backend] = None, session: Optional[Session] = None
     ) -> None:
         super().__init__()
-        self.api = api or get_api("lorem")
+        self.api = api or get_api(click.Context(click.Command("chap tui")), "lorem")
         self.session = (
             new_session(self.api.system_message) if session is None else session
         )

src/chap/core.py

@@ -10,7 +10,7 @@ import os
 import pathlib
 import pkgutil
 import subprocess
-from dataclasses import MISSING, dataclass, fields
+from dataclasses import MISSING, Field, dataclass, fields
 from typing import Any, AsyncGenerator, Callable, Optional, Union, cast
 
 import click
@@ -69,7 +69,25 @@ def new_session_path(opt_path: Optional[pathlib.Path] = None) -> pathlib.Path:
     )
 
 
-def configure_api_from_environment(api_name: str, api: Backend) -> None:
+def convert_str_to_field(ctx: click.Context, field: Field[Any], value: str) -> Any:
+    field_type = field.type
+    if isinstance(field_type, UnionType):
+        field_type = field_type.__args__[0]
+    try:
+        if field_type is bool:
+            tv = click.types.BoolParamType().convert(value, None, ctx)
+        else:
+            tv = field_type(value)
+        return tv
+    except ValueError as e:
+        raise click.BadParameter(
+            f"Invalid value for {field.name} with value {value}: {e}"
+        ) from e
+
+
+def configure_api_from_environment(
+    ctx: click.Context, api_name: str, api: Backend
+) -> None:
     if not hasattr(api, "parameters"):
         return
 
@@ -78,21 +96,16 @@ def configure_api_from_environment(api_name: str, api: Backend) -> None:
         value = os.environ.get(envvar)
         if value is None:
             continue
-        try:
-            tv = field.type(value)
-        except ValueError as e:
-            raise click.BadParameter(
-                f"Invalid value for {field.name} with value {value}: {e}"
-            ) from e
+        tv = convert_str_to_field(ctx, field, value)
         setattr(api.parameters, field.name, tv)
 
 
-def get_api(name: str = "openai_chatgpt") -> Backend:
+def get_api(ctx: click.Context, name: str = "openai_chatgpt") -> Backend:
     name = name.replace("-", "_")
     backend = cast(
         Backend, importlib.import_module(f"{__package__}.backends.{name}").factory()
     )
-    configure_api_from_environment(name, backend)
+    configure_api_from_environment(ctx, name, backend)
     return backend
 
 
@@ -159,7 +172,7 @@ def set_backend(  # pylint: disable=unused-argument
         ctx.exit()
 
     try:
-        ctx.obj.api = get_api(value)
+        ctx.obj.api = get_api(ctx, value)
     except ModuleNotFoundError as e:
         raise click.BadParameter(str(e))
 
@@ -197,16 +210,8 @@ def set_backend_option(  # pylint: disable=unused-argument
         field = all_fields.get(name)
         if field is None:
             raise click.BadParameter(f"Invalid parameter {name}")
-        f_type = field.type
-        if isinstance(f_type, UnionType):
-            f_type = f_type.__args__[0]
-        try:
-            tv = f_type(value)
-        except ValueError as e:
-            raise click.BadParameter(
-                f"Invalid value for {name} with value {value}: {e}"
-            ) from e
-        setattr(api.parameters, name, tv)
+        tv = convert_str_to_field(ctx, field, value)
+        setattr(api.parameters, field.name, tv)
 
     for kv in opts:
         set_one_backend_option(kv)
@@ -334,7 +339,7 @@ class MyCLI(click.MultiCommand):
         self, ctx: click.Context, formatter: click.HelpFormatter
     ) -> None:
         super().format_options(ctx, formatter)
-        api = ctx.obj.api or get_api()
+        api = ctx.obj.api or get_api(ctx)
         if hasattr(api, "parameters"):
             format_backend_help(api, formatter)