feat: 性能监控基础设施、解密缓存及计费简化

- 新增 PerfRecorder 性能记录工具，支持采样率与慢请求日志
- 在请求管道中埋点：auth、body_read、json_parse、context_build、authorize、handle
- 流处理器增加 parse/conversion 耗时追踪与 perf_metrics 落库
- 解密服务添加 LRU 缓存，降低高频解密 CPU 开销
- 格式转换分层开关设计：全局 OFF 时回退到端点配置，而非一刀切拒绝
- 移除 shadow billing 模块，统一使用新计费引擎
- 新增 Codex 网关请求适配器（store=false、role 映射、include 补齐）
- endpoint 创建接口支持 body_rules 参数

src/core/api_format/conversion/compatibility.py

@@ -78,10 +78,18 @@ def is_format_compatible(
     if provider_key == client_key:
         return True, False, None
 
-    # 2. 格式不同 -> 需要检查格式转换开关
-    # 如果总开关为 False，直接拒绝（禁用任何跨格式转换）
-    if not effective_conversion_enabled:
-        return False, False, "格式转换已禁用（enable_format_conversion=false）"
+    # 2. 格式不同 -> 需要检查格式转换开关（分层开关）
+    #
+    # 设计语义（与模块顶部注释一致）：
+    # - 全局开关 ON  -> 强制允许跨格式（通常 caller 会传 skip_endpoint_check=True）
+    # - 全局开关 OFF -> 不再“一刀切”拒绝，而是回退到 provider/endpoint 开关：
+    #   - provider 开关 ON  -> 强制允许（skip_endpoint_check=True，跳过端点检查）
+    #   - provider 开关 OFF -> 由端点 format_acceptance_config 决定（skip_endpoint_check=False）
+    #
+    # 说明：
+    # - effective_conversion_enabled 表示“全局默认允许”，不是“全局总闸/kill switch”
+    # - 当它为 False 时，我们仍然会继续执行后续检查（provider/endpoint），
+    #   兼容“按 Provider/Endpoint 精细化开启转换”的场景。
 
     # 3. 如果全局或提供商开关为 ON，跳过端点配置检查
     if not skip_endpoint_check:

src/core/crypto.py

@@ -12,12 +12,16 @@ from __future__ import annotations
 
 import base64
 import hashlib
+import threading
+import time
+from collections import OrderedDict
 
 from cryptography.fernet import Fernet
 from cryptography.hazmat.primitives import hashes
 from cryptography.hazmat.primitives.kdf.pbkdf2 import PBKDF2HMAC
 
 from src.core.logger import logger
+from src.utils.perf import PerfRecorder
 
 from ..config import config
 from ..core.exceptions import DecryptionException
@@ -31,8 +35,8 @@ class CryptoService:
     使用 Fernet（AES-128-CBC + HMAC-SHA256）确保数据机密性和完整性。
     """
 
-    _instance = None
-    _cipher = None
+    _instance: CryptoService | None = None
+    _cipher: Fernet | None = None
     _key_source: str = "unknown"  # 记录密钥来源，用于调试
 
     # 应用级 salt（基于应用名称生成，比硬编码更安全）
@@ -70,6 +74,21 @@ class CryptoService:
         self._cipher = Fernet(key)
         logger.info(f"加密服务初始化成功 (key_source={self._key_source})")
 
+        # 解密缓存配置（使用实例变量，避免测试场景下缓存跨实例持久化）
+        self._decrypt_cache: OrderedDict[str, tuple[str, float]] = OrderedDict()
+        self._decrypt_cache_lock = threading.Lock()
+        self._decrypt_cache_enabled = bool(getattr(config, "crypto_decrypt_cache_enabled", False))
+        self._decrypt_cache_size = int(getattr(config, "crypto_decrypt_cache_size", 0) or 0)
+        self._decrypt_cache_ttl_seconds = float(
+            getattr(config, "crypto_decrypt_cache_ttl_seconds", 0.0) or 0.0
+        )
+        if self._decrypt_cache_enabled and self._decrypt_cache_size > 0:
+            logger.info(
+                "解密缓存已启用 (size={}, ttl={}s)",
+                self._decrypt_cache_size,
+                self._decrypt_cache_ttl_seconds,
+            )
+
     def _derive_fernet_key(self, encryption_key: str) -> bytes:
         """
         从密码/密钥派生 Fernet 兼容的密钥
@@ -138,11 +157,22 @@ class CryptoService:
         if not ciphertext:
             return ciphertext
 
+        cached = self._get_cached_decrypt(ciphertext)
+        if cached is not None:
+            PerfRecorder.record_counter("crypto_decrypt_cache_hits_total", 1)
+            return cached
+
+        PerfRecorder.record_counter("crypto_decrypt_cache_misses_total", 1)
+        start = PerfRecorder.start()
         try:
             encrypted = base64.urlsafe_b64decode(ciphertext.encode())
             decrypted = self._cipher.decrypt(encrypted)
-            return decrypted.decode()
+            plaintext = decrypted.decode()
+            self._set_cached_decrypt(ciphertext, plaintext)
+            PerfRecorder.stop(start, "crypto_decrypt")
+            return plaintext
         except Exception as e:
+            PerfRecorder.stop(start, "crypto_decrypt")
             if not silent:
                 logger.error(f"Decryption failed: {e}")
             # 抛出自定义异常，方便在上层通过类型判断是否需要打印堆栈
@@ -163,6 +193,47 @@ class CryptoService:
         """
         return hashlib.sha256(api_key.encode()).hexdigest()
 
+    def _cache_key(self, ciphertext: str) -> str:
+        """生成缓存 key（使用密文 hash，避免内存中保留完整密文）"""
+        return hashlib.sha256(ciphertext.encode()).hexdigest()[:32]
+
+    def _get_cached_decrypt(self, ciphertext: str) -> str | None:
+        if not self._decrypt_cache_enabled:
+            return None
+        if not ciphertext:
+            return None
+        if self._decrypt_cache_size <= 0:
+            return None
+        cache_key = self._cache_key(ciphertext)
+        with self._decrypt_cache_lock:
+            entry = self._decrypt_cache.get(cache_key)
+            if not entry:
+                return None
+            value, expires_at = entry
+            if expires_at <= time.time():
+                self._decrypt_cache.pop(cache_key, None)
+                return None
+            # 维护 LRU 顺序
+            self._decrypt_cache.move_to_end(cache_key)
+            return value
+
+    def _set_cached_decrypt(self, ciphertext: str, plaintext: str) -> None:
+        if not self._decrypt_cache_enabled:
+            return
+        if not ciphertext:
+            return
+        if self._decrypt_cache_size <= 0:
+            return
+        if self._decrypt_cache_ttl_seconds <= 0:
+            return
+        cache_key = self._cache_key(ciphertext)
+        expires_at = time.time() + self._decrypt_cache_ttl_seconds
+        with self._decrypt_cache_lock:
+            self._decrypt_cache[cache_key] = (plaintext, expires_at)
+            self._decrypt_cache.move_to_end(cache_key)
+            while len(self._decrypt_cache) > self._decrypt_cache_size:
+                self._decrypt_cache.popitem(last=False)
+
 
 # 创建全局加密服务实例
 crypto_service = CryptoService()

src/core/metrics.py

@@ -80,28 +80,3 @@ format_conversion_duration_seconds = Histogram(
     ["direction", "source_format", "target_format"],
     buckets=[0.0005, 0.001, 0.0025, 0.005, 0.01, 0.025, 0.05, 0.1, 0.25, 0.5, 1.0],
 )
-
-# ==================== Billing migration / shadow billing ====================
-
-billing_requests_total = Counter(
-    "billing_requests_total",
-    "Total number of billing calculations",
-    ["engine_mode", "truth_engine"],  # low-cardinality labels
-)
-
-billing_fallback_total = Counter(
-    "billing_fallback_total",
-    "Total number of billing fallbacks to legacy engine",
-)
-
-billing_diff_exceeds_threshold_total = Counter(
-    "billing_diff_exceeds_threshold_total",
-    "Total number of shadow billing diffs exceeding threshold",
-    ["engine_mode"],
-)
-
-billing_invariant_violation_total = Counter(
-    "billing_invariant_violation_total",
-    "Total number of billing invariant violations (sum(breakdown)!=total)",
-    ["engine_mode", "truth_engine"],
-)