diff --git a/apps/api/src/services/ai_providers/ollama.py b/apps/api/src/services/ai_providers/ollama.py
index 66a8442e..6fe8317e 100644
--- a/apps/api/src/services/ai_providers/ollama.py
+++ b/apps/api/src/services/ai_providers/ollama.py
@@ -389,3 +389,38 @@ class Ollama188Provider(OllamaProvider):
             return resp.status_code == 200
         except Exception:
             return False
+
+
+class OllamaGcpBProvider(OllamaProvider):
+    """
+    GCP-B Secondary Ollama Provider
+
+    繼承 OllamaProvider，使用 OLLAMA_SECONDARY_URL（34.21.145.224:11434）。
+    ADR-110 三層容災：GCP-A → GCP-B → Local(111)。
+    OllamaFailoverManager 回傳 provider_name="ollama_gcp_b" 時由此 Provider 執行。
+
+    2026-05-04 ogt + Claude Sonnet 4.6: ADR-110 GCP-B 容災補全
+    根因：AIProviderRegistry 缺少 "ollama_gcp_b" → not_registered → 跳 Gemini
+    """
+
+    @property
+    def name(self) -> str:
+        return "ollama_gcp_b"
+
+    @property
+    def is_enabled(self) -> bool:
+        return bool(getattr(settings, "OLLAMA_SECONDARY_URL", ""))
+
+    def _endpoint_url(self) -> str:
+        return getattr(settings, "OLLAMA_SECONDARY_URL", "")
+
+    async def health_check(self) -> bool:
+        url = getattr(settings, "OLLAMA_SECONDARY_URL", "")
+        if not url:
+            return False
+        try:
+            client = await self._get_client()
+            resp = await client.get(f"{url}/api/tags", timeout=5.0)
+            return resp.status_code == 200
+        except Exception:
+            return False
diff --git a/apps/api/src/services/ai_router.py b/apps/api/src/services/ai_router.py
index 52473668..8e05b911 100644
--- a/apps/api/src/services/ai_router.py
+++ b/apps/api/src/services/ai_router.py
@@ -77,6 +77,12 @@ class AIProviderEnum(str, Enum):
     # P1.1b OllamaFailoverManager 使用 provider_name="ollama_188"，
     # 但 AIProviderEnum 沒有此值 → P1.2 整合時 lookup 失敗
     OLLAMA_188 = "ollama_188"  # 188 CPU-only 備援節點（P1.1b）
+    # 2026-05-04 ogt + Claude Sonnet 4.6: ADR-110 GCP 三層容災
+    # OllamaFailoverManager 回傳 provider_name="ollama_gcp_a"/"ollama_gcp_b"/"ollama_local"
+    # 缺少 enum 值 → AIProviderEnum(primary_str) 拋 ValueError → fallback chain 清空 → 直跳 Gemini
+    OLLAMA_GCP_A = "ollama_gcp_a"   # GCP-A 34.143.170.20 Primary
+    OLLAMA_GCP_B = "ollama_gcp_b"   # GCP-B 34.21.145.224 Secondary
+    OLLAMA_LOCAL = "ollama_local"    # 192.168.0.111 Local Fallback
     GEMINI = "gemini"
     CLAUDE = "claude"
     # 2026-04-02 ogt: C1 修復 — 對齊 Registry 實際名稱
@@ -92,6 +98,10 @@ PROVIDER_LATENCY_BUDGET: dict[AIProviderEnum, int] = {
     AIProviderEnum.OLLAMA: 60000,  # 本地，允許較長處理時間
     # 2026-04-25 critic-fix Part2 B2 by Claude Engineer-C2 — 188 CPU-only 推理較慢
     AIProviderEnum.OLLAMA_188: 120000,  # 120s budget for CPU inference
+    # 2026-05-04 ogt: ADR-110 GCP 三層容災 — GCP NVMe SSD 推理快，60s 足夠
+    AIProviderEnum.OLLAMA_GCP_A: 60000,
+    AIProviderEnum.OLLAMA_GCP_B: 60000,
+    AIProviderEnum.OLLAMA_LOCAL: 90000,  # 111 本地 HDD 稍慢
     AIProviderEnum.GEMINI: 30000,  # 雲端，較低延遲
     AIProviderEnum.CLAUDE: 30000,  # 雲端，較低延遲
     # 2026-04-02 ogt: C1 修復 — 對齊 Registry 名稱
@@ -1294,13 +1304,21 @@ _executor: AIRouterExecutor | None = None
 
 def _init_registry() -> AIProviderRegistry:
     """初始化 Provider Registry (首次呼叫時自動註冊所有 Provider)"""
-    from src.services.ai_providers.ollama import OllamaProvider, Ollama188Provider  # 2026-04-26 Wave5 B1-fix by Claude Engineer-A4
+    from src.services.ai_providers.ollama import (
+        OllamaProvider,
+        Ollama188Provider,
+        OllamaGcpBProvider,  # 2026-05-04 ADR-110 GCP-B
+    )
     from src.services.ai_providers.gemini import GeminiProvider
     from src.services.ai_providers.claude import ClaudeProvider
     from src.services.ai_providers.openclaw_nemo import OpenClawNemoProvider
 
     registry = AIProviderRegistry()
-    registry.register(OllamaProvider())
+
+    # GCP-A Primary（name="ollama"，OLLAMA_URL）
+    ollama_gcp_a = OllamaProvider()
+    registry.register(ollama_gcp_a)
+
     registry.register(GeminiProvider())
     registry.register(ClaudeProvider())
     registry.register(OpenClawNemoProvider())
@@ -1310,9 +1328,19 @@ def _init_registry() -> AIProviderRegistry:
     registry.register(NemotronProvider())
 
     # 2026-04-26 Wave5 B1-fix by Claude Engineer-A4 — 補登 OLLAMA_188 備援 provider
-    # 修復：原本 failover_manager 決策返回 "ollama_188"，但 executor 查不到 → not_registered
-    # → 188 從未被打到。必須明確 register 才能讓 executor.execute() 路由到 188。
-    registry.register(Ollama188Provider())
+    ollama_local = Ollama188Provider()
+    registry.register(ollama_local)
+
+    # 2026-05-04 ogt + Claude Sonnet 4.6: ADR-110 GCP 三層容災修復
+    # 根因：OllamaFailoverManager 回傳 "ollama_gcp_a"/"ollama_gcp_b"/"ollama_local"
+    # 但 registry 無這些名稱 → not_registered → 整條 Ollama 鏈跳過 → 直接跳 Gemini
+    # 修復：
+    #   "ollama_gcp_a" alias → 同 OllamaProvider（OLLAMA_URL = GCP-A）
+    #   "ollama_gcp_b" → 新 OllamaGcpBProvider（OLLAMA_SECONDARY_URL = GCP-B）
+    #   "ollama_local" alias → 同 Ollama188Provider（OLLAMA_FALLBACK_URL = 111）
+    registry._providers["ollama_gcp_a"] = ollama_gcp_a
+    registry.register(OllamaGcpBProvider())
+    registry._providers["ollama_local"] = ollama_local
 
     return registry