feat(US7+US8): finetune management and health check test

- app/models/finetune_models.py: FinetuneStartRequest, FinetuneStartResponse, FinetuneStatusResponse
- app/services/finetune_service.py: submit_finetune + get_finetune_status via run_in_executor; status map running→RUNNING, succeeded→SUCCESS, failed→FAILED, unknown→RUNNING; LLMCallError on SDK failure
- app/routers/finetune.py: POST /finetune/start + GET /finetune/status/{job_id} with get_llm_client dependency
- tests/test_finetune_service.py: 12 unit tests (TDD, written before implementation)
- tests/test_finetune_router.py: 6 integration tests
- tests/test_health.py: GET /health → 200 {"status":"ok"}

Full suite: 72/72 passing (was 53)

tests/test_finetune_service.py

@@ -0,0 +1,154 @@
+"""T046: Tests for finetune_service — written FIRST (TDD), must FAIL before implementation."""
+import asyncio
+import pytest
+from unittest.mock import MagicMock, AsyncMock, patch
+
+from app.core.exceptions import LLMCallError
+from app.models.finetune_models import (
+    FinetuneStartRequest,
+    FinetuneStartResponse,
+    FinetuneStatusResponse,
+)
+
+
+# ---------------------------------------------------------------------------
+# Helpers
+# ---------------------------------------------------------------------------
+
+def _make_llm(job_id: str = "glm-ft-test", status: str = "running", progress: int | None = None):
+    """Return a mock that looks like ZhipuAIClient with ._client.fine_tuning.jobs.*"""
+    create_resp = MagicMock()
+    create_resp.id = job_id
+
+    retrieve_resp = MagicMock()
+    retrieve_resp.status = status
+    retrieve_resp.progress = progress
+    retrieve_resp.error_message = None  # explicitly set to avoid MagicMock auto-attribute
+
+    llm = MagicMock()
+    llm._client.fine_tuning.jobs.create.return_value = create_resp
+    llm._client.fine_tuning.jobs.retrieve.return_value = retrieve_resp
+    return llm
+
+
+# ---------------------------------------------------------------------------
+# submit_finetune
+# ---------------------------------------------------------------------------
+
+@pytest.mark.asyncio
+async def test_submit_finetune_returns_job_id():
+    from app.services.finetune_service import submit_finetune
+
+    llm = _make_llm(job_id="glm-ft-abc123")
+    req = FinetuneStartRequest(
+        jsonl_url="s3://bucket/train.jsonl",
+        base_model="glm-4",
+        hyperparams={"n_epochs": 3},
+    )
+
+    result = await submit_finetune(req, llm)
+
+    assert isinstance(result, FinetuneStartResponse)
+    assert result.job_id == "glm-ft-abc123"
+
+
+@pytest.mark.asyncio
+async def test_submit_finetune_calls_sdk_with_correct_params():
+    from app.services.finetune_service import submit_finetune
+
+    llm = _make_llm(job_id="glm-ft-xyz")
+    req = FinetuneStartRequest(
+        jsonl_url="s3://bucket/train.jsonl",
+        base_model="glm-4",
+        hyperparams={"n_epochs": 5},
+    )
+
+    await submit_finetune(req, llm)
+
+    llm._client.fine_tuning.jobs.create.assert_called_once_with(
+        training_file="s3://bucket/train.jsonl",
+        model="glm-4",
+        hyperparameters={"n_epochs": 5},
+    )
+
+
+@pytest.mark.asyncio
+async def test_submit_finetune_none_hyperparams_passes_empty_dict():
+    """hyperparams=None should be passed as {} to the SDK."""
+    from app.services.finetune_service import submit_finetune
+
+    llm = _make_llm(job_id="glm-ft-nohp")
+    req = FinetuneStartRequest(
+        jsonl_url="s3://bucket/train.jsonl",
+        base_model="glm-4",
+    )
+
+    await submit_finetune(req, llm)
+
+    llm._client.fine_tuning.jobs.create.assert_called_once_with(
+        training_file="s3://bucket/train.jsonl",
+        model="glm-4",
+        hyperparameters={},
+    )
+
+
+@pytest.mark.asyncio
+async def test_submit_finetune_raises_llm_call_error_on_sdk_failure():
+    from app.services.finetune_service import submit_finetune
+
+    llm = MagicMock()
+    llm._client.fine_tuning.jobs.create.side_effect = RuntimeError("SDK exploded")
+
+    req = FinetuneStartRequest(
+        jsonl_url="s3://bucket/train.jsonl",
+        base_model="glm-4",
+    )
+
+    with pytest.raises(LLMCallError):
+        await submit_finetune(req, llm)
+
+
+# ---------------------------------------------------------------------------
+# get_finetune_status — status mapping
+# ---------------------------------------------------------------------------
+
+@pytest.mark.asyncio
+@pytest.mark.parametrize("sdk_status,expected", [
+    ("running", "RUNNING"),
+    ("succeeded", "SUCCESS"),
+    ("failed", "FAILED"),
+    ("pending", "RUNNING"),      # unknown → conservative RUNNING
+    ("queued", "RUNNING"),       # unknown → conservative RUNNING
+    ("cancelled", "RUNNING"),    # unknown → conservative RUNNING
+])
+async def test_get_finetune_status_maps_status(sdk_status, expected):
+    from app.services.finetune_service import get_finetune_status
+
+    llm = _make_llm(status=sdk_status)
+
+    result = await get_finetune_status("glm-ft-test", llm)
+
+    assert isinstance(result, FinetuneStatusResponse)
+    assert result.status == expected
+    assert result.job_id == "glm-ft-test"
+
+
+@pytest.mark.asyncio
+async def test_get_finetune_status_includes_progress():
+    from app.services.finetune_service import get_finetune_status
+
+    llm = _make_llm(status="running", progress=42)
+    result = await get_finetune_status("glm-ft-test", llm)
+
+    assert result.progress == 42
+
+
+@pytest.mark.asyncio
+async def test_get_finetune_status_raises_llm_call_error_on_sdk_failure():
+    from app.services.finetune_service import get_finetune_status
+
+    llm = MagicMock()
+    llm._client.fine_tuning.jobs.retrieve.side_effect = RuntimeError("SDK exploded")
+
+    with pytest.raises(LLMCallError):
+        await get_finetune_status("glm-ft-bad", llm)