fix: standardize open() calls with explicit encoding='utf-8' across codebase

[ANIRUDDHA ADAK (aniruddhaadak80)]

Related to issue #5566. Calling open() without explicitly passing encoding='utf-8' causes fatal UnicodeDecodeErrors on Windows machines operating in non-English environments (such as cp1252 or cp950).

While the root issue reported in #5566 was fixed for one file, this PR acts as a comprehensive repository-wide cleanup, adding explicit utf-8 encodings to over 60 Python files where text paths were opened without it.

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[Copilot]

Pull request overview

Repository-wide hardening against Windows locale-dependent decoding by standardizing text file I/O to use explicit UTF-8 encoding (addresses UnicodeDecodeError class of failures described in #5566).

Changes:

• Add encoding="utf-8" to open() calls across samples, packages, docs tooling, and tests.
• Add encoding="utf-8" to aiofiles.open() calls in FastAPI samples.
• Minor whitespace-only adjustments in a couple of sample files included in the diff hunks.

Reviewed changes

Copilot reviewed 51 out of 51 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
python/samples/task_centric_memory/utils.py	Use UTF-8 when reading YAML.
python/samples/gitty/src/gitty/_gitty.py	Use UTF-8 when reading global/local config files.
python/samples/gitty/src/gitty/main.py	Use UTF-8 when creating the config file.
python/samples/core_streaming_response_fastapi/app.py	Use UTF-8 when reading model config via aiofiles.
python/samples/core_streaming_handoffs_fastapi/app.py	Use UTF-8 for model config and chat history file reads via aiofiles.
python/samples/core_streaming_handoffs_fastapi/agent_user.py	Use UTF-8 when writing chat history JSON.
python/samples/core_distributed-group-chat/_utils.py	Use UTF-8 when reading YAML config.
python/samples/core_chess_game/main.py	Use UTF-8 when reading model config.
python/samples/core_chainlit/app_team.py	Use UTF-8 when reading model config (plus whitespace-only change).
python/samples/core_chainlit/app_agent.py	Use UTF-8 when reading model config (plus whitespace-only change).
python/samples/agentchat_streamlit/agent.py	Use UTF-8 when reading model config.
python/samples/agentchat_fastapi/app_team.py	Use UTF-8 for config/state/history reads and writes via aiofiles.
python/samples/agentchat_fastapi/app_agent.py	Use UTF-8 for config/state/history reads and writes via aiofiles.
python/samples/agentchat_chess_game/main.py	Use UTF-8 when reading model config.
python/samples/agentchat_chainlit/app_team_user_proxy.py	Use UTF-8 when reading model config.
python/samples/agentchat_chainlit/app_team.py	Use UTF-8 when reading model config.
python/samples/agentchat_chainlit/app_agent.py	Use UTF-8 when reading model config.
python/packages/magentic-one-cli/src/magentic_one_cli/_m1.py	Use UTF-8 when reading the default CLI config.
python/packages/autogen-studio/tests/test_team_manager.py	Use UTF-8 when writing temporary JSON/YAML configs in tests.
python/packages/autogen-studio/tests/test_lite_studio.py	Use UTF-8 when reading/writing JSON and env files in tests.
python/packages/autogen-studio/autogenstudio/web/auth/manager.py	Use UTF-8 when reading YAML auth config.
python/packages/autogen-studio/autogenstudio/lite/studio.py	Use UTF-8 when writing the generated env file.
python/packages/autogen-studio/autogenstudio/gallery/builder.py	Use UTF-8 when writing default gallery JSON.
python/packages/autogen-studio/autogenstudio/database/schema_manager.py	Use UTF-8 when writing Alembic files (plus flagged env.py template issue).
python/packages/autogen-studio/autogenstudio/cli.py	Use UTF-8 when writing the temporary env file.
python/packages/autogen-ext/tests/test_filesurfer_agent.py	Use UTF-8 when writing a temporary HTML test file via aiofiles.
python/packages/autogen-ext/tests/task_centric_memory/utils.py	Use UTF-8 when reading YAML in tests.
python/packages/autogen-ext/tests/code_executors/test_user_defined_functions.py	Ensure embedded code blocks open files with UTF-8.
python/packages/autogen-ext/tests/code_executors/test_docker_jupyter_code_executor.py	Ensure embedded code blocks open files with UTF-8.
python/packages/autogen-ext/tests/code_executors/test_docker_commandline_code_executor.py	Ensure embedded code blocks open files with UTF-8.
python/packages/autogen-ext/tests/code_executors/test_commandline_code_executor.py	Ensure embedded code blocks open files with UTF-8.
python/packages/autogen-ext/tests/code_executors/test_aca_dynamic_sessions.py	Ensure embedded code blocks open files with UTF-8.
python/packages/autogen-ext/src/autogen_ext/experimental/task_centric_memory/utils/page_logger.py	Use UTF-8 when writing HTML/log artifacts.
python/packages/autogen-ext/src/autogen_ext/experimental/task_centric_memory/utils/chat_completion_client_recorder.py	Use UTF-8 when reading/writing session recordings.
python/packages/autogen-ext/src/autogen_ext/code_executors/docker_jupyter/_docker_jupyter.py	Use UTF-8 when writing HTML output artifacts.
python/packages/autogen-ext/examples/mcp_session_host_example.py	Use UTF-8 when reading JSON/YAML model config.
python/packages/agbench/src/agbench/tabulate_cmd.py	Use UTF-8 when reading console logs.
python/packages/agbench/src/agbench/run_cmd.py	Use UTF-8 when reading scenario/env/config files and writing scripts.
python/packages/agbench/src/agbench/remove_missing_cmd.py	Use UTF-8 when reading console logs.
python/packages/agbench/src/agbench/linter/coders/oai_coder.py	Use UTF-8 for cache reads/writes.
python/packages/agbench/src/agbench/linter/cli.py	Use UTF-8 when reading log files.
python/packages/agbench/benchmarks/process_logs.py	Use UTF-8 when reading benchmark logs/prompts/messages.
python/packages/agbench/benchmarks/HumanEval/Templates/AgentChat/scenario.py	Use UTF-8 when reading config/prompt.
python/packages/agbench/benchmarks/HumanEval/Templates/AgentChat/custom_code_executor.py	Use UTF-8 when reading test code.
python/packages/agbench/benchmarks/GAIA/Templates/SelectorGroupChat/scenario.py	Use UTF-8 when reading config/prompt.
python/packages/agbench/benchmarks/GAIA/Templates/ParallelAgents/scenario.py	Use UTF-8 when reading config/prompt and writing per-team console logs.
python/packages/agbench/benchmarks/GAIA/Templates/MagenticOne/scenario.py	Use UTF-8 when reading config/prompt.
python/packages/agbench/benchmarks/GAIA/Scripts/custom_tabulate.py	Use UTF-8 when reading expected answers and console logs.
python/fixup_generated_files.py	Use UTF-8 when reading/writing files during fixup.
python/docs/src/generate_api_reference.py	Use UTF-8 when writing generated docs files.
python/docs/redirects/redirects.py	Use UTF-8 when reading redirects config and writing redirect pages (plus whitespace-only change).

[Copilot]

The _create_minimal_env_py template string appears to generate invalid Python: inside context.configure(...), compare_type=True is missing a trailing comma (both in offline and online sections). This will produce a syntax error in the generated env.py and break Alembic migrations. Add the missing commas in the template content.

[ANIRUDDHA ADAK (aniruddhaadak80)]

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