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/github_copilot/agent_framework_github_copilot/_agent.py

@@ -21,9 +21,10 @@ from agent_framework import (
     ResponseStream,
     normalize_messages,
 )
+from agent_framework._settings import load_settings
 from agent_framework._tools import FunctionTool
 from agent_framework._types import normalize_tools
-from agent_framework.exceptions import ServiceException, ServiceInitializationError
+from agent_framework.exceptions import ServiceException
 from copilot import CopilotClient, CopilotSession
 from copilot.generated.session_events import SessionEvent, SessionEventType
 from copilot.types import (
@@ -38,7 +39,6 @@ from copilot.types import (
     ToolResult,
 )
 from copilot.types import Tool as CopilotTool
-from pydantic import ValidationError
 
 from ._settings import GitHubCopilotSettings
 
@@ -207,17 +207,16 @@ class GitHubCopilotAgent(BaseAgent, Generic[OptionsT]):
         on_permission_request: PermissionHandlerType | None = opts.pop("on_permission_request", None)
         mcp_servers: dict[str, MCPServerConfig] | None = opts.pop("mcp_servers", None)
 
-        try:
-            self._settings = GitHubCopilotSettings(
-                cli_path=cli_path,
-                model=model,
-                timeout=timeout,
-                log_level=log_level,
-                env_file_path=env_file_path,
-                env_file_encoding=env_file_encoding,
-            )
-        except ValidationError as ex:
-            raise ServiceInitializationError("Failed to create GitHub Copilot settings.", ex) from ex
+        self._settings = load_settings(
+            GitHubCopilotSettings,
+            env_prefix="GITHUB_COPILOT_",
+            cli_path=cli_path,
+            model=model,
+            timeout=timeout,
+            log_level=log_level,
+            env_file_path=env_file_path,
+            env_file_encoding=env_file_encoding,
+        )
 
         self._tools = normalize_tools(tools)
         self._permission_handler = on_permission_request
@@ -249,10 +248,10 @@ class GitHubCopilotAgent(BaseAgent, Generic[OptionsT]):
 
         if self._client is None:
             client_options: CopilotClientOptions = {}
-            if self._settings.cli_path:
-                client_options["cli_path"] = self._settings.cli_path
-            if self._settings.log_level:
-                client_options["log_level"] = self._settings.log_level  # type: ignore[typeddict-item]
+            if self._settings["cli_path"]:
+                client_options["cli_path"] = self._settings["cli_path"]
+            if self._settings["log_level"]:
+                client_options["log_level"] = self._settings["log_level"]  # type: ignore[typeddict-item]
 
             self._client = CopilotClient(client_options if client_options else None)
 
@@ -355,7 +354,7 @@ class GitHubCopilotAgent(BaseAgent, Generic[OptionsT]):
             thread = self.get_new_thread()
 
         opts: dict[str, Any] = dict(options) if options else {}
-        timeout = opts.pop("timeout", None) or self._settings.timeout or DEFAULT_TIMEOUT_SECONDS
+        timeout = opts.pop("timeout", None) or self._settings["timeout"] or DEFAULT_TIMEOUT_SECONDS
 
         session = await self._get_or_create_session(thread, streaming=False, runtime_options=opts)
         input_messages = normalize_messages(messages)
@@ -578,7 +577,7 @@ class GitHubCopilotAgent(BaseAgent, Generic[OptionsT]):
         opts = runtime_options or {}
         config: SessionConfig = {"streaming": streaming}
 
-        model = opts.get("model") or self._settings.model
+        model = opts.get("model") or self._settings["model"]
         if model:
             config["model"] = model  # type: ignore[typeddict-item]
 

python/packages/github_copilot/agent_framework_github_copilot/_settings.py

@@ -1,19 +1,16 @@
 # Copyright (c) Microsoft. All rights reserved.
 
-from typing import ClassVar
-
-from agent_framework._pydantic import AFBaseSettings
+from typing import TypedDict
 
 
-class GitHubCopilotSettings(AFBaseSettings):
+class GitHubCopilotSettings(TypedDict, total=False):
     """GitHub Copilot model settings.
 
     The settings are first loaded from environment variables with the prefix 'GITHUB_COPILOT_'.
     If the environment variables are not found, the settings can be loaded from a .env file
-    with the encoding 'utf-8'. If the settings are not found in the .env file, the settings
-    are ignored; however, validation will fail alerting that the settings are missing.
+    with the encoding 'utf-8'.
 
-    Keyword Args:
+    Keys:
         cli_path: Path to the Copilot CLI executable.
             Can be set via environment variable GITHUB_COPILOT_CLI_PATH.
         model: Model to use (e.g., "gpt-5", "claude-sonnet-4").
@@ -22,28 +19,9 @@ class GitHubCopilotSettings(AFBaseSettings):
             Can be set via environment variable GITHUB_COPILOT_TIMEOUT.
         log_level: CLI log level.
             Can be set via environment variable GITHUB_COPILOT_LOG_LEVEL.
-        env_file_path: If provided, the .env settings are read from this file path location.
-        env_file_encoding: The encoding of the .env file, defaults to 'utf-8'.
-
-    Examples:
-        .. code-block:: python
-
-            from agent_framework_github_copilot import GitHubCopilotSettings
-
-            # Using environment variables
-            # Set GITHUB_COPILOT_MODEL=gpt-5
-            settings = GitHubCopilotSettings()
-
-            # Or passing parameters directly
-            settings = GitHubCopilotSettings(model="claude-sonnet-4", timeout=120)
-
-            # Or loading from a .env file
-            settings = GitHubCopilotSettings(env_file_path="path/to/.env")
     """
 
-    env_prefix: ClassVar[str] = "GITHUB_COPILOT_"
-
-    cli_path: str | None = None
-    model: str | None = None
-    timeout: float | None = None
-    log_level: str | None = None
+    cli_path: str | None
+    model: str | None
+    timeout: float | None
+    log_level: str | None

python/packages/github_copilot/tests/test_github_copilot_agent.py

@@ -122,8 +122,8 @@ class TestGitHubCopilotAgentInit:
         agent: GitHubCopilotAgent[GitHubCopilotOptions] = GitHubCopilotAgent(
             default_options={"model": "claude-sonnet-4", "timeout": 120}
         )
-        assert agent._settings.model == "claude-sonnet-4"  # type: ignore
-        assert agent._settings.timeout == 120  # type: ignore
+        assert agent._settings["model"] == "claude-sonnet-4"  # type: ignore
+        assert agent._settings["timeout"] == 120  # type: ignore
 
     def test_init_with_tools(self) -> None:
         """Test initialization with function tools."""