feat: add pricing table and cost calculation in telemetry emitter

tests/unit/test_pricing.py

@@ -0,0 +1,159 @@
+"""pricing.py 价格表与 TelemetryEmitter 成本换算(M2 设计 §6)。
+
+零内置单价(实验室走中转网关,内置表必然过时掩盖真实成本,P5);
+价格由使用方经 JSON 文件或 dict 注入;查不到 → cost=None + 每 model
+仅首次 warning,不阻塞调用;计算点收敛在 Emitter(单一 helper 铁律)。
+"""
+
+import json
+
+import pytest
+
+from polygateway.middleware.telemetry import TelemetryEmitter
+from polygateway.pricing import ModelPrice, PricingTable
+from polygateway.types import ChatRequest, LLMResponse, SourceConfig
+
+_TABLE = PricingTable(
+    {
+        "qwen-max": ModelPrice(input_per_1m=2.4, output_per_1m=9.6),
+        "free-model": ModelPrice(input_per_1m=0.0, output_per_1m=0.0),
+    }
+)
+
+
+class TestPricingTable:
+    def test_cost_formula_per_million(self):
+        # 1M prompt + 0.5M completion: 2.4 + 4.8
+        assert _TABLE.cost("qwen-max", 1_000_000, 500_000) == pytest.approx(7.2)
+        assert _TABLE.cost("qwen-max", 1000, 2000) == pytest.approx(0.0216)
+        assert _TABLE.cost("free-model", 999, 999) == 0.0
+
+    def test_unknown_model_returns_none(self):
+        assert _TABLE.cost("mystery", 100, 100) is None
+
+    def test_from_file_roundtrip(self, tmp_path):
+        path = tmp_path / "prices.json"
+        path.write_text(
+            json.dumps({"m1": {"input_per_1m": 1.0, "output_per_1m": 2.0}}), encoding="utf-8"
+        )
+        table = PricingTable.from_file(path)
+        assert table.cost("m1", 1_000_000, 1_000_000) == pytest.approx(3.0)
+
+    def test_from_file_missing_or_bad_fails_loudly(self, tmp_path):
+        with pytest.raises(ValueError, match="价格表"):
+            PricingTable.from_file(tmp_path / "nope.json")
+        bad = tmp_path / "bad.json"
+        bad.write_text("not json", encoding="utf-8")
+        with pytest.raises(ValueError, match="价格表"):
+            PricingTable.from_file(bad)
+        malformed = tmp_path / "malformed.json"
+        malformed.write_text(json.dumps({"m": {"input_per_1m": 1.0}}), encoding="utf-8")
+        with pytest.raises(ValueError, match="output_per_1m"):
+            PricingTable.from_file(malformed)
+
+    def test_negative_price_rejected(self):
+        with pytest.raises(ValueError):
+            ModelPrice(input_per_1m=-1.0, output_per_1m=0.0)
+
+
+class _MemoryRecorder:
+    def __init__(self):
+        self.rows = []
+
+    async def record_llm_call(self, **fields):
+        self.rows.append(fields)
+
+
+_REQ = ChatRequest(messages=[{"role": "user", "content": "hi"}])
+
+
+def _resp(**overrides):
+    base = {
+        "content": "ok",
+        "thinking": "",
+        "model": "qwen-max",
+        "provider": "qwen",
+        "prompt_tokens": 1_000_000,
+        "completion_tokens": 500_000,
+        "latency_ms": 30,
+        "ttft_ms": None,
+        "max_inter_token_ms": None,
+        "cache_hit": False,
+        "call_id": "cid-1",
+        "source_name": "s1",
+        "usage_source": "measured",
+    }
+    base.update(overrides)
+    return LLMResponse(**base)
+
+
+def _source(model="qwen-max"):
+    return SourceConfig(
+        name="s1",
+        provider="qwen",
+        base_url="https://gw.example/v1",
+        api_key="sk",
+        model=model,
+        timeout_s=10.0,
+    )
+
+
+class TestEmitterCost:
+    async def test_success_row_costed(self):
+        rec = _MemoryRecorder()
+        emitter = TelemetryEmitter(rec, pricing=_TABLE)
+        await emitter.emit_attempt(
+            request=_REQ,
+            source=_source(),
+            call_id="c",
+            latency_ms=1,
+            response=_resp(),
+            error=None,
+        )
+        assert rec.rows[0]["cost"] == pytest.approx(7.2)
+
+    async def test_cache_hit_row_costs_zero(self):
+        rec = _MemoryRecorder()
+        emitter = TelemetryEmitter(rec, pricing=_TABLE)
+        await emitter.emit_cache_hit(request=_REQ, response=_resp(cache_hit=True))
+        assert rec.rows[0]["cost"] == 0.0
+
+    async def test_failure_row_cost_none(self):
+        rec = _MemoryRecorder()
+        emitter = TelemetryEmitter(rec, pricing=_TABLE)
+        await emitter.emit_attempt(
+            request=_REQ,
+            source=_source(),
+            call_id="c",
+            latency_ms=1,
+            response=None,
+            error="TransientError: boom",
+        )
+        assert rec.rows[0]["cost"] is None
+
+    async def test_unknown_model_none_without_blocking(self):
+        rec = _MemoryRecorder()
+        emitter = TelemetryEmitter(rec, pricing=_TABLE)
+        await emitter.emit_attempt(
+            request=_REQ,
+            source=_source(model="mystery"),
+            call_id="c",
+            latency_ms=1,
+            response=_resp(model="mystery"),
+            error=None,
+        )
+        assert rec.rows[0]["cost"] is None
+
+    async def test_no_pricing_keeps_none(self):
+        """未注入价格表 = M1 现状: cost 恒 None(回归)。"""
+        rec = _MemoryRecorder()
+        emitter = TelemetryEmitter(rec)
+        await emitter.emit_attempt(
+            request=_REQ,
+            source=_source(),
+            call_id="c",
+            latency_ms=1,
+            response=_resp(),
+            error=None,
+        )
+        assert rec.rows[0]["cost"] is None