feat(api): Phase 15.3 Deep Linking 三系統互連

實現 Sentry ↔ SignOz ↔ Langfuse 零斷鏈觀測:

新增 deep_linking.py:
- SignOz Trace URL 生成器
- Langfuse Trace URL 生成器
- Sentry Issue URL 生成器
- get_all_links() 統一取得所有連結

整合點:
- main.py: Sentry before_send 注入 otel_trace_id + signoz_trace_url
- langfuse_client.py: 自動注入 OTEL trace_id 到 metadata
- openclaw.py: SignOz span 記錄 langfuse.trace_id 反向連結

架構圖:
┌─────────┐ trace_id ┌─────────┐ trace_id ┌──────────┐
│ Sentry  │◄────────►│ SignOz  │◄────────►│ Langfuse │
│ Errors  │          │ Traces  │          │ LLMOps   │
└─────────┘          └─────────┘          └──────────┘

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

apps/api/src/services/langfuse_client.py

@@ -1,21 +1,23 @@
 """
-Langfuse LLMOps Client - Phase 15.1
-===================================
+Langfuse LLMOps Client - Phase 15.1 + 15.3
+==========================================
 LLM 呼叫追蹤、成本監控、Prompt 版本管理
 
-Phase 15.1 (2026-03-26)
+Phase 15.1 (2026-03-26): 基礎整合
+Phase 15.3 (2026-03-26): Deep Linking (Langfuse ↔ SignOz)
+
 端點: http://192.168.0.110:3100 (DevOps 金庫)
 
 Features:
 - 自動追蹤所有 LLM 呼叫 (Ollama/Gemini/Claude)
 - 成本估算與監控
 - Prompt 版本管理
-- 與 OTEL Trace 整合
+- **Phase 15.3**: OTEL Trace 整合 (SignOz Deep Link)
 
 Usage:
     from src.services.langfuse_client import get_langfuse, langfuse_trace
 
-    # 方法 1: Context Manager
+    # 方法 1: Context Manager (自動整合 OTEL trace_id)
     async with langfuse_trace("openclaw_decision") as trace:
         result = await call_llm(prompt)
         trace.generation(
@@ -24,6 +26,7 @@ Usage:
             input=prompt,
             output=result,
         )
+        # trace.metadata 自動包含 signoz_trace_url
 
     # 方法 2: 裝飾器
     @langfuse_observe(name="analyze_incident")
@@ -88,21 +91,53 @@ def get_langfuse():
 
 
 class LangfuseTraceContext:
-    """Langfuse Trace Context for tracking LLM calls"""
+    """
+    Langfuse Trace Context for tracking LLM calls
+
+    Phase 15.3: 自動整合 OTEL trace_id，實現 Langfuse ↔ SignOz Deep Linking
+    """
 
     def __init__(self, name: str, metadata: dict[str, Any] | None = None):
         self.name = name
         self.metadata = metadata or {}
         self.trace = None
         self._client = get_langfuse()
+        self._otel_trace_id: str | None = None
+        self._langfuse_trace_id: str | None = None
 
     def __enter__(self):
         if self._client:
             try:
+                # Phase 15.3: 取得當前 OTEL trace_id 並注入 metadata
+                from src.core.deep_linking import DeepLinking
+                from src.core.telemetry import get_current_trace_id
+
+                self._otel_trace_id = get_current_trace_id()
+
+                # 建立含 SignOz Deep Link 的 metadata
+                enriched_metadata = {**self.metadata}
+                if self._otel_trace_id:
+                    enriched_metadata["otel_trace_id"] = self._otel_trace_id
+                    enriched_metadata["signoz_trace_url"] = DeepLinking.signoz_trace_url(
+                        self._otel_trace_id
+                    )
+
                 self.trace = self._client.trace(
                     name=self.name,
-                    metadata=self.metadata,
+                    metadata=enriched_metadata,
                 )
+
+                # 記錄 Langfuse trace_id 供反向連結
+                if self.trace:
+                    self._langfuse_trace_id = self.trace.id
+
+                logger.debug(
+                    "langfuse_trace_started",
+                    name=self.name,
+                    otel_trace_id=self._otel_trace_id,
+                    langfuse_trace_id=self._langfuse_trace_id,
+                )
+
             except Exception as e:
                 logger.warning("langfuse_trace_start_failed", error=str(e))
         return self
@@ -111,6 +146,16 @@ class LangfuseTraceContext:
         # Langfuse auto-flushes, no explicit close needed
         pass
 
+    @property
+    def otel_trace_id(self) -> str | None:
+        """取得關聯的 OTEL trace_id"""
+        return self._otel_trace_id
+
+    @property
+    def langfuse_trace_id(self) -> str | None:
+        """取得 Langfuse trace_id"""
+        return self._langfuse_trace_id
+
     def generation(
         self,
         name: str,

apps/api/src/services/openclaw.py

@@ -832,7 +832,7 @@ class OpenClawService:
             logger.info("mock_mode_enabled", using="mock_llm")
             return self._generate_mock_response(alert_context or {}, signoz_metrics), "mock", True
 
-        # Phase 15.1: Langfuse 追蹤整合
+        # Phase 15.1 + 15.3: Langfuse 追蹤整合 + SignOz Deep Linking
         with langfuse_trace(
             "openclaw_fallback_chain",
             metadata={
@@ -841,6 +841,21 @@ class OpenClawService:
                 "alert_fingerprint": (alert_context or {}).get("fingerprint", "unknown"),
             },
         ) as trace:
+            # Phase 15.3: SignOz → Langfuse 反向連結
+            # 在當前 OTEL span 中記錄 Langfuse trace_id
+            if trace.langfuse_trace_id:
+                from opentelemetry import trace as otel_trace
+
+                from src.core.deep_linking import DeepLinking
+
+                current_span = otel_trace.get_current_span()
+                if current_span:
+                    current_span.set_attribute("langfuse.trace_id", trace.langfuse_trace_id)
+                    current_span.set_attribute(
+                        "langfuse.trace_url",
+                        DeepLinking.langfuse_trace_url(trace.langfuse_trace_id),
+                    )
+
             for provider in settings.AI_FALLBACK_ORDER:
                 logger.info("ai_provider_attempt", provider=provider)