Add complete Ouroboros trading system with TDD test suite

Implement the full autonomous trading agent architecture:
- KIS broker with async API, token refresh, leaky bucket rate limiter, and hash key signing
- Gemini-powered decision engine with JSON parsing and confidence threshold enforcement
- Risk manager with circuit breaker (-3% P&L) and fat finger protection (30% cap)
- Evolution engine for self-improving strategy generation via failure analysis
- 35 passing tests written TDD-first covering risk, broker, and brain modules
- CI/CD pipeline, Docker multi-stage build, and AI agent context docs

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

tests/test_broker.py

@@ -0,0 +1,140 @@
+"""TDD tests for broker/kis_api.py — written BEFORE implementation."""
+
+from __future__ import annotations
+
+import asyncio
+from unittest.mock import AsyncMock, MagicMock, patch
+
+import aiohttp
+import pytest
+
+from src.broker.kis_api import KISBroker
+
+
+# ---------------------------------------------------------------------------
+# Token Management
+# ---------------------------------------------------------------------------
+
+
+class TestTokenManagement:
+    """Access token must be auto-refreshed and cached."""
+
+    @pytest.mark.asyncio
+    async def test_fetches_token_on_first_call(self, settings):
+        broker = KISBroker(settings)
+        mock_resp = AsyncMock()
+        mock_resp.status = 200
+        mock_resp.json = AsyncMock(
+            return_value={
+                "access_token": "tok_abc123",
+                "token_type": "Bearer",
+                "expires_in": 86400,
+            }
+        )
+        mock_resp.__aenter__ = AsyncMock(return_value=mock_resp)
+        mock_resp.__aexit__ = AsyncMock(return_value=False)
+
+        with patch("aiohttp.ClientSession.post", return_value=mock_resp):
+            token = await broker._ensure_token()
+            assert token == "tok_abc123"
+
+        await broker.close()
+
+    @pytest.mark.asyncio
+    async def test_reuses_cached_token(self, settings):
+        broker = KISBroker(settings)
+        broker._access_token = "cached_token"
+        broker._token_expires_at = asyncio.get_event_loop().time() + 3600
+
+        token = await broker._ensure_token()
+        assert token == "cached_token"
+
+        await broker.close()
+
+
+# ---------------------------------------------------------------------------
+# Network Error Handling
+# ---------------------------------------------------------------------------
+
+
+class TestNetworkErrorHandling:
+    """Broker must handle network timeouts and HTTP errors gracefully."""
+
+    @pytest.mark.asyncio
+    async def test_timeout_raises_connection_error(self, settings):
+        broker = KISBroker(settings)
+        broker._access_token = "tok"
+        broker._token_expires_at = asyncio.get_event_loop().time() + 3600
+
+        with patch(
+            "aiohttp.ClientSession.get",
+            side_effect=asyncio.TimeoutError(),
+        ):
+            with pytest.raises(ConnectionError):
+                await broker.get_orderbook("005930")
+
+        await broker.close()
+
+    @pytest.mark.asyncio
+    async def test_http_500_raises_connection_error(self, settings):
+        broker = KISBroker(settings)
+        broker._access_token = "tok"
+        broker._token_expires_at = asyncio.get_event_loop().time() + 3600
+
+        mock_resp = AsyncMock()
+        mock_resp.status = 500
+        mock_resp.text = AsyncMock(return_value="Internal Server Error")
+        mock_resp.__aenter__ = AsyncMock(return_value=mock_resp)
+        mock_resp.__aexit__ = AsyncMock(return_value=False)
+
+        with patch("aiohttp.ClientSession.get", return_value=mock_resp):
+            with pytest.raises(ConnectionError):
+                await broker.get_orderbook("005930")
+
+        await broker.close()
+
+
+# ---------------------------------------------------------------------------
+# Rate Limiter
+# ---------------------------------------------------------------------------
+
+
+class TestRateLimiter:
+    """The leaky bucket rate limiter must throttle requests."""
+
+    @pytest.mark.asyncio
+    async def test_rate_limiter_does_not_block_under_limit(self, settings):
+        broker = KISBroker(settings)
+        # Should complete without blocking when under limit
+        await broker._rate_limiter.acquire()
+        await broker.close()
+
+
+# ---------------------------------------------------------------------------
+# Hash Key Generation
+# ---------------------------------------------------------------------------
+
+
+class TestHashKey:
+    """POST requests to KIS require a hash key."""
+
+    @pytest.mark.asyncio
+    async def test_generates_hash_key_for_post_body(self, settings):
+        broker = KISBroker(settings)
+        broker._access_token = "tok"
+        broker._token_expires_at = asyncio.get_event_loop().time() + 3600
+
+        body = {"CANO": "12345678", "ACNT_PRDT_CD": "01"}
+
+        mock_resp = AsyncMock()
+        mock_resp.status = 200
+        mock_resp.json = AsyncMock(return_value={"HASH": "abc123hash"})
+        mock_resp.__aenter__ = AsyncMock(return_value=mock_resp)
+        mock_resp.__aexit__ = AsyncMock(return_value=False)
+
+        with patch("aiohttp.ClientSession.post", return_value=mock_resp):
+            hash_key = await broker._get_hash_key(body)
+            assert isinstance(hash_key, str)
+            assert len(hash_key) > 0
+
+        await broker.close()