Python: Replace Pydantic Settings with TypedDict + load_settings() (#3843)

* Replace Pydantic Settings with TypedDict + load_settings()

- Remove pydantic-settings dependency, add python-dotenv
- Delete _pydantic.py (AFBaseSettings, HTTPsUrl)
- Add _settings.py with generic load_settings() function, SecretString,
  type coercion, and Required field validation (SettingNotFoundError)
- Convert all 13 settings classes from AFBaseSettings subclasses to
  TypedDict definitions with load_settings() calls
- Update all consumers from attribute access to dict access
- Add 20 unit tests for load_settings() covering basic loading, dotenv,
  SecretString, type coercion, and required field validation
- Update all existing tests for new settings patterns

* Fix mypy type errors from settings conversion

- Fix str | None attribute access in responses_client (walrus operator)
- Fix SecretString | None narrowing in bedrock (type: ignore after guard)
- Convert _context_provider.py attribute access to dict access (missed file)
- Fix endpoint type narrowing in search_provider and context_provider
- Fix purview: str | None .rstrip(), int | None defaults, urlparse bytes

* Address PR review: required_fields param, type validation, fixes

- Move required field validation from TypedDict annotations (Required)
  to a required_fields parameter on load_settings(), enabling runtime
  decisions about which fields are required
- Remove Required imports and restore from __future__ import annotations
  in ollama and foundry_local
- Add _check_override_type() for deterministic ServiceInitializationError
  on invalid override types (e.g. dict passed for str field)
- Fix all multi-exception test catches back to single exception type
- Fix Ollama host=None: use .get() so None is passed through to SDK default
- Fix Purview processor: use explicit is-None checks instead of or operator
- Remove unused BaseModel import from openai/_shared.py
- Add 4 new tests (24 total): required_fields param, type validation

* Fix type validation: allow int for float fields

_check_override_type now permits int values for float-typed fields,
matching Python's standard numeric promotion behavior.

* fix: wrap urlparse arg with str() to fix mypy bytes endswith error

python/packages/ollama/agent_framework_ollama/_chat_client.py

@@ -30,9 +30,8 @@ from agent_framework import (
     UsageDetails,
     get_logger,
 )
-from agent_framework._pydantic import AFBaseSettings
+from agent_framework._settings import load_settings
 from agent_framework.exceptions import (
-    ServiceInitializationError,
     ServiceInvalidRequestError,
     ServiceResponseException,
 )
@@ -42,7 +41,7 @@ from ollama import AsyncClient
 # Rename imported types to avoid naming conflicts with Agent Framework types
 from ollama._types import ChatResponse as OllamaChatResponse
 from ollama._types import Message as OllamaMessage
-from pydantic import BaseModel, ValidationError
+from pydantic import BaseModel
 
 if sys.version_info >= (3, 13):
     from typing import TypeVar  # type: ignore # pragma: no cover
@@ -275,13 +274,11 @@ OllamaChatOptionsT = TypeVar("OllamaChatOptionsT", bound=TypedDict, default="Oll
 # endregion
 
 
-class OllamaSettings(AFBaseSettings):
+class OllamaSettings(TypedDict, total=False):
     """Ollama settings."""
 
-    env_prefix: ClassVar[str] = "OLLAMA_"
-
-    host: str | None = None
-    model_id: str | None = None
+    host: str | None
+    model_id: str | None
 
 
 logger = get_logger("agent_framework.ollama")
@@ -322,23 +319,19 @@ class OllamaChatClient(
             env_file_encoding: The encoding to use when reading the dotenv (.env) file. Defaults to 'utf-8'.
             **kwargs: Additional keyword arguments passed to BaseChatClient.
         """
-        try:
-            ollama_settings = OllamaSettings(
-                host=host,
-                model_id=model_id,
-                env_file_encoding=env_file_encoding,
-                env_file_path=env_file_path,
-            )
-        except ValidationError as ex:
-            raise ServiceInitializationError("Failed to create Ollama settings.", ex) from ex
+        ollama_settings = load_settings(
+            OllamaSettings,
+            env_prefix="OLLAMA_",
+            required_fields=["model_id"],
+            host=host,
+            model_id=model_id,
+            env_file_encoding=env_file_encoding,
+            env_file_path=env_file_path,
+        )
 
-        if ollama_settings.model_id is None:
-            raise ServiceInitializationError(
-                "Ollama chat model ID must be provided via model_id or OLLAMA_MODEL_ID environment variable."
-            )
-
-        self.model_id = ollama_settings.model_id
-        self.client = client or AsyncClient(host=ollama_settings.host)
+        self.model_id = ollama_settings["model_id"]
+        # we can just pass in None for the host, the default is set by the Ollama package.
+        self.client = client or AsyncClient(host=ollama_settings.get("host"))
         # Save Host URL for serialization with to_dict()
         self.host = str(self.client._client.base_url)  # pyright: ignore[reportUnknownMemberType,reportPrivateUsage,reportUnknownArgumentType]
 

python/packages/ollama/tests/test_ollama_chat_client.py

@@ -15,9 +15,9 @@ from agent_framework import (
     tool,
 )
 from agent_framework.exceptions import (
-    ServiceInitializationError,
     ServiceInvalidRequestError,
     ServiceResponseException,
+    SettingNotFoundError,
 )
 from ollama import AsyncClient
 from ollama._types import ChatResponse as OllamaChatResponse
@@ -182,7 +182,7 @@ def test_init_client(ollama_unit_test_env: dict[str, str]) -> None:
 
 @pytest.mark.parametrize("exclude_list", [["OLLAMA_MODEL_ID"]], indirect=True)
 def test_with_invalid_settings(ollama_unit_test_env: dict[str, str]) -> None:
-    with pytest.raises(ServiceInitializationError):
+    with pytest.raises(SettingNotFoundError, match="Required setting 'model_id'"):
         OllamaChatClient(
             host="http://localhost:12345",
             model_id=None,