fix(solver): 相容 openclaw_nemo 回傳格式 → candidates 格式轉換

與 diagnostician 同步：openclaw_nemo 回傳 action_title/risk_level/confidence，
solver 的 _extract_candidates() 找不到 candidates key → 空方案 → no_candidates

修復: 檢測 action_title 存在時轉換為 candidates 格式
risk_level → blast_radius 映射: critical=60, high=40, medium=25, low=10

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

apps/api/src/agents/solver_agent.py

@@ -200,7 +200,31 @@ blast_radius 參考：
 # ─────────────────────────────────────────────────────────────────────────────
 
 def _extract_candidates(parsed: dict[str, Any]) -> list[CandidateAction]:
-    """從 LLM 解析結果提取候選方案（按信心降序）。"""
+    """從 LLM 解析結果提取候選方案（按信心降序）。
+
+    支援兩種格式：
+    1. 標準格式：{"candidates": [{action, blast_radius, rollback_cost, confidence, rationale}]}
+    2. OpenClaw Nemo 格式：{"action_title": "...", "risk_level": "...", "confidence": 0.85}
+
+    2026-04-16 ogt + Claude Sonnet 4.6: 與 diagnostician 同步，修復 openclaw_nemo 格式不相容
+    """
+    # OpenClaw Nemo 格式轉換
+    if "action_title" in parsed and "candidates" not in parsed:
+        action_title = str(parsed.get("action_title", ""))
+        confidence = float(parsed.get("confidence", 0.5))
+        risk_level = str(parsed.get("risk_level", "medium"))
+        risk_to_blast = {"critical": 60, "high": 40, "medium": 25, "low": 10}
+        blast = risk_to_blast.get(risk_level.lower(), 30)
+        if action_title and confidence > 0:
+            return [CandidateAction(
+                action=action_title[:200],
+                blast_radius=blast,
+                rollback_cost=20,
+                confidence=confidence,
+                rationale=f"OpenClaw Nemo 建議: {action_title}",
+            )]
+        return []
+
     raw = parsed.get("candidates", [])
     candidates = []
     for item in raw: