feat(agent): provider/model/connection for agent harnesses - #4815

collection failure
ImportError while importing test module '/home/runner/work/agenta/agenta/services/oss/tests/pytest/unit/agent/test_invoke_handler.py'.
Hint: make sure your test modules/packages have valid Python names.
Traceback:
/opt/hostedtoolcache/Python/3.13.14/x64/lib/python3.13/importlib/__init__.py:88: in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
oss/tests/pytest/unit/agent/test_invoke_handler.py:12: in <module>
    from agenta.sdk.agents import (
E   ImportError: cannot import name 'ConnectionNotFoundError' from 'agenta.sdk.agents' (/home/runner/work/agenta/agenta/sdks/python/agenta/sdk/agents/__init__.py)

collection failure
ImportError while importing test module '/home/runner/work/agenta/agenta/services/oss/tests/pytest/unit/agent/test_secrets_mapping.py'.
Hint: make sure your test modules/packages have valid Python names.
Traceback:
/opt/hostedtoolcache/Python/3.13.14/x64/lib/python3.13/importlib/__init__.py:88: in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
oss/tests/pytest/unit/agent/test_secrets_mapping.py:10: in <module>
    from oss.src.agent.secrets import _PROVIDER_ENV_VARS
oss/src/agent/__init__.py:11: in <module>
    from oss.src.agent.app import agent_v0_app, create_agent_app
oss/src/agent/app.py:19: in <module>
    from agenta.sdk.agents import (
E   ImportError: cannot import name 'ConnectionResolutionError' from 'agenta.sdk.agents' (/home/runner/work/agenta/agenta/sdks/python/agenta/sdk/agents/__init__.py)

collection failure
ImportError while importing test module '/home/runner/work/agenta/agenta/services/oss/tests/pytest/unit/agent/test_select_backend.py'.
Hint: make sure your test modules/packages have valid Python names.
Traceback:
/opt/hostedtoolcache/Python/3.13.14/x64/lib/python3.13/importlib/__init__.py:88: in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
oss/tests/pytest/unit/agent/test_select_backend.py:15: in <module>
    from oss.src.agent.app import select_backend
oss/src/agent/__init__.py:11: in <module>
    from oss.src.agent.app import agent_v0_app, create_agent_app
oss/src/agent/app.py:19: in <module>
    from agenta.sdk.agents import (
E   ImportError: cannot import name 'ConnectionResolutionError' from 'agenta.sdk.agents' (/home/runner/work/agenta/agenta/sdks/python/agenta/sdk/agents/__init__.py)

collection failure
ImportError while importing test module '/home/runner/work/agenta/agenta/services/oss/tests/pytest/unit/agent/tools/test_gateway_mapping.py'.
Hint: make sure your test modules/packages have valid Python names.
Traceback:
/opt/hostedtoolcache/Python/3.13.14/x64/lib/python3.13/importlib/__init__.py:88: in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
oss/tests/pytest/unit/agent/tools/test_gateway_mapping.py:3: in <module>
    from oss.src.agent.tools import _to_gateway_reference
oss/src/agent/__init__.py:11: in <module>
    from oss.src.agent.app import agent_v0_app, create_agent_app
oss/src/agent/app.py:19: in <module>
    from agenta.sdk.agents import (
E   ImportError: cannot import name 'ConnectionResolutionError' from 'agenta.sdk.agents' (/home/runner/work/agenta/agenta/sdks/python/agenta/sdk/agents/__init__.py)

collection failure
ImportError while importing test module '/home/runner/work/agenta/agenta/services/oss/tests/pytest/unit/agent/tools/test_resolution.py'.
Hint: make sure your test modules/packages have valid Python names.
Traceback:
/opt/hostedtoolcache/Python/3.13.14/x64/lib/python3.13/importlib/__init__.py:88: in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
oss/tests/pytest/unit/agent/tools/test_resolution.py:13: in <module>
    from oss.src.agent.tools import resolve_mcp_servers, resolve_tools
oss/src/agent/__init__.py:11: in <module>
    from oss.src.agent.app import agent_v0_app, create_agent_app
oss/src/agent/app.py:19: in <module>
    from agenta.sdk.agents import (
E   ImportError: cannot import name 'ConnectionResolutionError' from 'agenta.sdk.agents' (/home/runner/work/agenta/agenta/sdks/python/agenta/sdk/agents/__init__.py)