fix(harness): move Retell agent listing and browser calls off legacy endpoints before October 18

[23821]

Summary

Retell AI is deprecating legacy endpoints: GET /list-agents and GET /list-chat-agents have returned errors since July 31, 2026, and browser SDK 2.x is deprecated October 18, 2026 (11 days from now). Details: https://docs.retellai.com/deprecation-notice/overview

This repo doesn't use /list-agents, /list-chat-agents, or RetellWebClient directly, but it does POST directly to Retell's web-call creation endpoint, which is moving from v2 to v3 (same JSON body). Updated the default/fallback api_url in three places so web calls keep working after the deadline:

• src/fi/alk/harness/call_runner.py:591 — default api_url POSTed by the retell bridge to create a web call
• src/fi/simulate/agent/definition.py:238 — default api_url for RetellTargetConfig
• src/fi/simulate/simulation/bridge/retell.py:65 — fallback RETELL_API_URL env default

All three changed from https://api.retellai.com/v2/create-web-call to https://api.retellai.com/v3/create-web-call.

Verification

• uv run ruff check .
• Focused pytest target:
• Full uv run pytest -q when touching shared runtime, CLI, SDK, or release gates
• TypeScript build/test when touching typescript/
• agent-learn release-proof when touching release-candidate behavior

Tests are inconclusive: uv run pytest -q failed before this change too, with ModuleNotFoundError: No module named 'hypothesis' and ModuleNotFoundError: No module named 'livekit' during collection, unrelated to this change. Output:

Test output

… (14 earlier lines not shown)
Hint: make sure your test modules/packages have valid Python names.
Traceback:
/usr/local/lib/python3.12/importlib/__init__.py:90: in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
tests/runtime/test_caller_barge_in.py:10: in <module>
    from fi.simulate.simulation.engines.caller_barge_in import (
src/fi/simulate/simulation/engines/caller_barge_in.py:16: in <module>
    from livekit import rtc
E   ModuleNotFoundError: No module named 'livekit'
____________ ERROR collecting tests/runtime/test_livekit_engine.py _____________
ImportError while importing test module '/work/tests/runtime/test_livekit_engine.py'.
Hint: make sure your test modules/packages have valid Python names.
Traceback:
/usr/local/lib/python3.12/importlib/__init__.py:90: in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
tests/runtime/test_livekit_engine.py:12: in <module>
    from livekit.agents.llm import ChatMessage
E   ModuleNotFoundError: No module named 'livekit'
=============================== warnings summary ===============================
src/fi/simulate/agent/definition.py:350
  /work/src/fi/simulate/agent/definition.py:350: PydanticDeprecatedSince20: Support for class-based `config` is deprecated, use ConfigDict instead. Deprecated in Pydantic V2.0 to be removed in V3.0. See Pydantic V2 Migration Guide at https://errors.pydantic.dev/2.13/migration/
    class AgentDefinition(BaseModel):

src/fi/simulate/agent/definition.py:518
  /work/src/fi/simulate/agent/definition.py:518: PydanticDeprecatedSince20: Support for class-based `config` is deprecated, use ConfigDict instead. Deprecated in Pydantic V2.0 to be removed in V3.0. See Pydantic V2 Migration Guide at https://errors.pydantic.dev/2.13/migration/
    class SimulatorAgentDefinition(BaseModel):

src/fi/simulate/simulation/models.py:195
  /work/src/fi/simulate/simulation/models.py:195: PydanticDeprecatedSince20: Pydantic V1 style `@​validator` validators are deprecated. You should migrate to Pydantic V2 style `@​field_validator` validators, see the migration guide for more details. Deprecated in Pydantic V2.0 to be removed in V3.0. S …
    @validator('dataset', pre=True)

src/fi/simulate/runtime/run.py:34
  /work/src/fi/simulate/runtime/run.py:34: PytestCollectionWarning: cannot collect test class 'TestCaseStatus' because it has a __init__ constructor (from: tests/harness/test_dispatch_ack.py)
    class TestCaseStatus(str, Enum):

src/fi/evals/metrics/llm_as_judges/types.py:20
  /work/src/fi/evals/metrics/llm_as_judges/types.py:20: PydanticDeprecatedSince20: Support for class-based `config` is deprecated, use ConfigDict instead. Deprecated in Pydantic V2.0 to be removed in V3.0. See Pydantic V2 Migration Guide at https://errors.pydantic.dev/2.13/migration/
    class CustomInput(BaseLLMJudgeInput):

src/fi/simulate/simulation/bridge/audio.py:4
  /work/src/fi/simulate/simulation/bridge/audio.py:4: DeprecationWarning: 'audioop' is deprecated and slated for removal in Python 3.13
    import audioop

src/fi/simulate/simulation/models.py:224
  /work/src/fi/simulate/simulation/models.py:224: PytestCollectionWarning: cannot collect test class 'TestCaseResult' because it has a __init__ constructor (from: tests/test_phase7_persona_studio.py)
    class TestCaseResult(BaseModel):

src/fi/simulate/simulation/models.py:271
  /work/src/fi/simulate/simulation/models.py:271: PytestCollectionWarning: cannot collect test class 'TestReport' because it has a __init__ constructor (from: tests/test_phase7_persona_studio.py)
    class TestReport(BaseModel):

-- Docs: https://docs.pytest.org/en/stable/how-to/capture-warnings.html
=========================== short test summary info ============================
ERROR tests/harness/test_compiler_properties.py
ERROR tests/runtime/test_caller_barge_in.py
ERROR tests/runtime/test_livekit_engine.py
!!!!!!!!!!!!!!!!!!! Interrupted: 3 errors during collection !!!!!!!!!!!!!!!!!!!!
2 skipped, 8 warnings, 3 errors in 33.82s

Checklist

• Public API names stay under agent_learning.*, agent-learn, or @future-agi/agent-learning-kit
• This PR was generated or assisted by AI

---

Prepared with YakBarber, a tool I'm building that updates code when an API changes (the check is open source), and reviewed by me before sending. It was sent once, to this repository only; if it isn't useful, feel free to close it.