Python: [BREAKING] Redesign Python exception hierarchy (#4082)

* [BREAKING] Redesign Python exception hierarchy

Replace the flat ServiceException family with domain-scoped branches:
- AgentException (with InvalidAuth, InvalidRequest, InvalidResponse, ContentFilter)
- ChatClientException (same consistent suberrors)
- IntegrationException (same + InitializationError)
- WorkflowException (Runner, Convergence, Checkpoint, Validation, Action, Declarative)
- ContentError (AdditionItemMismatch)
- ToolException / ToolExecutionException (unchanged)
- MiddlewareException / MiddlewareTermination (unchanged)

Key changes:
- All Service* exceptions removed (ServiceException, ServiceInitializationError, etc.)
- AgentExecutionException split into AgentInvalidRequest/ResponseException
- AgentInvocationError removed, split into AgentInvalidRequest/ResponseException
- Workflow exceptions moved from _workflows/_exceptions.py into main exceptions.py
- _workflows/__init__.py emptied; main __init__.py imports directly from submodules
- Purview exceptions re-parented under IntegrationException hierarchy
- Init validation errors use built-in ValueError/TypeError instead of custom exceptions
- CODING_STANDARD.md updated with hierarchy design and rationale

Fixes microsoft/agent-framework#3410

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Clarify ToolException vs ToolExecutionException docstrings

ToolException: base class for all tool-related exceptions (preconditions,
connection/init failures).
ToolExecutionException: runtime call failures (tool call failed, reconnect
failed, MCP errors).

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Fix remaining stale imports from agent_framework._workflows

- azurefunctions: _context.py, _app.py, _serialization.py, test_func_utils.py
  used 'from agent_framework._workflows import X' which broke after
  emptying _workflows/__init__.py; changed to direct submodule imports
- azure-ai-search: test still referenced ServiceInitializationError;
  updated to ValueError to match production code

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

---------

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

python/packages/purview/AGENTS.md

@@ -20,10 +20,10 @@ Integration with Microsoft Purview for data governance and policy enforcement.
 
 ### Exceptions
 
-- **`PurviewAuthenticationError`** - Authentication failures
-- **`PurviewRateLimitError`** - Rate limit exceeded
-- **`PurviewRequestError`** / **`PurviewServiceError`** - Request/service errors
-- **`PurviewPaymentRequiredError`** - Payment required
+- **`PurviewAuthenticationError`** - Authentication failures (inherits from `IntegrationInvalidAuthException`)
+- **`PurviewRateLimitError`** - Rate limit exceeded (inherits from `IntegrationException` via `PurviewServiceError`)
+- **`PurviewRequestError`** / **`PurviewServiceError`** - Request/service errors (inherit from `IntegrationException`)
+- **`PurviewPaymentRequiredError`** - Payment required (inherits from `IntegrationException` via `PurviewServiceError`)
 
 ## Usage
 

python/packages/purview/agent_framework_purview/_exceptions.py

@@ -1,7 +1,7 @@
 # Copyright (c) Microsoft. All rights reserved.
-"""Purview specific exceptions (minimal error shaping)."""
+"""Purview specific exceptions mapped to the Integration exception hierarchy."""
 
-from agent_framework.exceptions import ServiceResponseException
+from agent_framework.exceptions import IntegrationException, IntegrationInvalidAuthException
 
 __all__ = [
     "PurviewAuthenticationError",
@@ -12,11 +12,11 @@ __all__ = [
 ]
 
 
-class PurviewServiceError(ServiceResponseException):
+class PurviewServiceError(IntegrationException):
     """Base exception for Purview errors."""
 
 
-class PurviewAuthenticationError(PurviewServiceError):
+class PurviewAuthenticationError(IntegrationInvalidAuthException):
     """Authentication / authorization failure (401/403)."""
 
 

python/packages/purview/tests/purview/test_exceptions.py

@@ -2,6 +2,8 @@
 
 """Tests for Purview exceptions."""
 
+from agent_framework.exceptions import IntegrationException, IntegrationInvalidAuthException
+
 from agent_framework_purview import (
     PurviewAuthenticationError,
     PurviewPaymentRequiredError,
@@ -18,28 +20,28 @@ class TestPurviewExceptions:
         """Test PurviewServiceError base exception."""
         error = PurviewServiceError("Service error occurred")
         assert str(error) == "Service error occurred"
-        assert isinstance(error, Exception)
+        assert isinstance(error, IntegrationException)
 
     def test_purview_authentication_error(self) -> None:
         """Test PurviewAuthenticationError exception."""
         error = PurviewAuthenticationError("Authentication failed")
         assert str(error) == "Authentication failed"
-        assert isinstance(error, PurviewServiceError)
+        assert isinstance(error, IntegrationInvalidAuthException)
 
     def test_purview_payment_required_error(self) -> None:
         """Test PurviewPaymentRequiredError exception."""
         error = PurviewPaymentRequiredError("Payment required")
         assert str(error) == "Payment required"
-        assert isinstance(error, PurviewServiceError)
+        assert isinstance(error, IntegrationException)
 
     def test_purview_rate_limit_error(self) -> None:
         """Test PurviewRateLimitError exception."""
         error = PurviewRateLimitError("Rate limit exceeded")
         assert str(error) == "Rate limit exceeded"
-        assert isinstance(error, PurviewServiceError)
+        assert isinstance(error, IntegrationException)
 
     def test_purview_request_error(self) -> None:
         """Test PurviewRequestError exception."""
         error = PurviewRequestError("Request failed")
         assert str(error) == "Request failed"
-        assert isinstance(error, PurviewServiceError)
+        assert isinstance(error, IntegrationException)