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_router.py

@@ -0,0 +1,112 @@
+"""T050: Integration tests for finetune router endpoints."""
+import pytest
+from unittest.mock import MagicMock, patch
+
+from app.core.exceptions import LLMCallError
+from app.models.finetune_models import FinetuneStartResponse, FinetuneStatusResponse
+
+
+# ---------------------------------------------------------------------------
+# POST /api/v1/finetune/start
+# ---------------------------------------------------------------------------
+
+def test_finetune_start_returns_200_with_job_id(client):
+    start_resp = FinetuneStartResponse(job_id="glm-ft-router-test")
+
+    with patch("app.routers.finetune.finetune_service.submit_finetune") as mock_submit:
+        mock_submit.return_value = start_resp
+
+        resp = client.post(
+            "/api/v1/finetune/start",
+            json={
+                "jsonl_url": "s3://bucket/train.jsonl",
+                "base_model": "glm-4",
+                "hyperparams": {"n_epochs": 3},
+            },
+        )
+
+    assert resp.status_code == 200
+    data = resp.json()
+    assert data["job_id"] == "glm-ft-router-test"
+
+
+def test_finetune_start_without_hyperparams(client):
+    start_resp = FinetuneStartResponse(job_id="glm-ft-nohp")
+
+    with patch("app.routers.finetune.finetune_service.submit_finetune") as mock_submit:
+        mock_submit.return_value = start_resp
+
+        resp = client.post(
+            "/api/v1/finetune/start",
+            json={
+                "jsonl_url": "s3://bucket/train.jsonl",
+                "base_model": "glm-4",
+            },
+        )
+
+    assert resp.status_code == 200
+    assert resp.json()["job_id"] == "glm-ft-nohp"
+
+
+def test_finetune_start_llm_call_error_returns_503(client):
+    with patch("app.routers.finetune.finetune_service.submit_finetune") as mock_submit:
+        mock_submit.side_effect = LLMCallError("SDK failed")
+
+        resp = client.post(
+            "/api/v1/finetune/start",
+            json={
+                "jsonl_url": "s3://bucket/train.jsonl",
+                "base_model": "glm-4",
+            },
+        )
+
+    assert resp.status_code == 503
+    assert resp.json()["code"] == "LLM_CALL_ERROR"
+
+
+# ---------------------------------------------------------------------------
+# GET /api/v1/finetune/status/{job_id}
+# ---------------------------------------------------------------------------
+
+def test_finetune_status_returns_200_with_fields(client):
+    status_resp = FinetuneStatusResponse(
+        job_id="glm-ft-router-test",
+        status="RUNNING",
+        progress=30,
+    )
+
+    with patch("app.routers.finetune.finetune_service.get_finetune_status") as mock_status:
+        mock_status.return_value = status_resp
+
+        resp = client.get("/api/v1/finetune/status/glm-ft-router-test")
+
+    assert resp.status_code == 200
+    data = resp.json()
+    assert data["job_id"] == "glm-ft-router-test"
+    assert data["status"] == "RUNNING"
+    assert data["progress"] == 30
+
+
+def test_finetune_status_succeeded(client):
+    status_resp = FinetuneStatusResponse(
+        job_id="glm-ft-done",
+        status="SUCCESS",
+    )
+
+    with patch("app.routers.finetune.finetune_service.get_finetune_status") as mock_status:
+        mock_status.return_value = status_resp
+
+        resp = client.get("/api/v1/finetune/status/glm-ft-done")
+
+    assert resp.status_code == 200
+    assert resp.json()["status"] == "SUCCESS"
+
+
+def test_finetune_status_llm_call_error_returns_503(client):
+    with patch("app.routers.finetune.finetune_service.get_finetune_status") as mock_status:
+        mock_status.side_effect = LLMCallError("SDK failed")
+
+        resp = client.get("/api/v1/finetune/status/glm-ft-bad")
+
+    assert resp.status_code == 503
+    assert resp.json()["code"] == "LLM_CALL_ERROR"