Python: fix(claude): handle API errors in run_stream() method

[droideronline]

Summary

This PR fixes a bug where ClaudeAgent.run_stream() silently ignored API errors and AssistantMessage responses, returning empty results instead of raising exceptions.

Changes

_agent.py

• Import AssistantMessage and TextBlock from claude_agent_sdk
• Handle AssistantMessage.error by raising ServiceException with descriptive error messages mapped from error types (authentication_failed, billing_error, rate_limit, invalid_request, server_error, unknown)
• Check ResultMessage.is_error and raise ServiceException with the error details from ResultMessage.result

test_claude_agent.py

• Added test_run_stream_raises_on_assistant_message_error - verifies ServiceException is raised when AssistantMessage contains an error
• Added test_run_stream_raises_on_result_message_error - verifies ServiceException is raised when ResultMessage.is_error is True

Testing

All 46 tests pass:

pytest tests/test_claude_agent.py -v
============================== 46 passed in 0.28s ==============================

Fixes #3652

[Copilot]

Pull request overview

This PR fixes a critical bug where ClaudeAgent.run_stream() silently ignored API errors and returned empty results instead of raising exceptions. The fix adds proper error handling for both AssistantMessage and ResultMessage error conditions.

Changes:

• Added error handling for AssistantMessage.error field with descriptive error messages mapped from error types
• Added error checking for ResultMessage.is_error flag to surface API errors as exceptions
• Added comprehensive test coverage for both error scenarios

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
python/packages/claude/agent_framework_claude/_agent.py	Added imports for AssistantMessage and TextBlock; implemented error handling logic in run_stream() to raise ServiceException for API errors
python/packages/claude/tests/test_claude_agent.py	Added two new test cases verifying exception raising for AssistantMessage errors and ResultMessage errors

[markwallace-microsoft]

Python Test Coverage Report •

File	Stmts	Miss	Cover	Missing
TOTAL	16255	1918	88%

report-only-changed-files is enabled. No files were changed during this commit :)

Python Unit Test Overview

Tests	Skipped	Failures	Errors	Time
3931	221 💤	0 ❌	0 🔥	1m 5s ⏱️

[moonbox3]

I've got a fix in #3661 that allows for the failing unit test to pass.

[droideronline]

@moonbox3 - I cherry picked your changes, ready to merge.

[droideronline]

@moonbox3 - kindly have a look at this as well

[moonbox3]

This one needs a refresh on the uv.lock file: uv sync --dev then uv run poe install and commit and push please.

[droideronline]

This one needs a refresh on the uv.lock file: uv sync --dev then uv run poe install and commit and push please.

pre-commit hooks were also failing. its fixed now.

[moonbox3]

We'll get this in, but before that, we're trying to get #3379 in, which may cause some merge conflicts here. Please be aware.