feat(api): Ollama /api/chat client with one retry + typed ModelError

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

api/tests/test_ollama_client.py

@@ -0,0 +1,83 @@
+import json
+
+import httpx
+import pytest
+
+from app.ollama_client import ModelError, chat
+
+
+def _client(handler):
+    return httpx.Client(transport=httpx.MockTransport(handler), base_url="http://ollama")
+
+
+def test_success_returns_content_and_sends_payload():
+    seen = {}
+
+    def handler(request):
+        seen["body"] = json.loads(request.content)
+        return httpx.Response(200, json={"message": {"content": "You stand on the wharf."}})
+
+    out = chat("qwen3.5:latest", [{"role": "user", "content": "hi"}], {"seed": 7},
+               think=False, client=_client(handler))
+    assert out == "You stand on the wharf."
+    assert seen["body"]["model"] == "qwen3.5:latest"
+    assert seen["body"]["stream"] is False
+    assert seen["body"]["options"]["seed"] == 7
+    assert seen["body"]["think"] is False
+
+
+def test_think_omitted_when_none():
+    seen = {}
+
+    def handler(request):
+        seen["body"] = json.loads(request.content)
+        return httpx.Response(200, json={"message": {"content": "ok"}})
+
+    chat("m", [{"role": "user", "content": "x"}], {}, client=_client(handler))
+    assert "think" not in seen["body"]
+
+
+def test_retries_once_then_succeeds():
+    calls = {"n": 0}
+
+    def handler(request):
+        calls["n"] += 1
+        if calls["n"] == 1:
+            raise httpx.ConnectError("boom")
+        return httpx.Response(200, json={"message": {"content": "recovered"}})
+
+    out = chat("m", [{"role": "user", "content": "x"}], {}, client=_client(handler))
+    assert out == "recovered"
+    assert calls["n"] == 2
+
+
+def test_two_transport_failures_raise_modelerror():
+    def handler(request):
+        raise httpx.ConnectError("down")
+
+    with pytest.raises(ModelError):
+        chat("m", [{"role": "user", "content": "x"}], {}, client=_client(handler))
+
+
+def test_timeout_exhausted_raises_modelerror():
+    def handler(request):
+        raise httpx.TimeoutException("slow")
+
+    with pytest.raises(ModelError):
+        chat("m", [{"role": "user", "content": "x"}], {}, client=_client(handler))
+
+
+def test_non_2xx_retried_then_modelerror():
+    def handler(request):
+        return httpx.Response(500, json={"error": "nope"})
+
+    with pytest.raises(ModelError):
+        chat("m", [{"role": "user", "content": "x"}], {}, client=_client(handler))
+
+
+def test_empty_content_retried_then_modelerror():
+    def handler(request):
+        return httpx.Response(200, json={"message": {"content": "   "}})
+
+    with pytest.raises(ModelError):
+        chat("m", [{"role": "user", "content": "x"}], {}, client=_client(handler))