fix: toFloat handles json.Number, CORS credentials+wildcard bug, strategy config error handling

- agent/agent.go: toFloat() now handles json.Number and int32 types to prevent silent data loss
- api/server.go: CORS fix — echo specific origin instead of '*' when credentials are enabled (browsers reject Allow-Credentials with wildcard)
- api/strategy.go: all 4 json.Unmarshal calls now check errors and return 'config_error' field instead of silently serving zero-value configs
- store/decision.go: explicitly mark best-effort unmarshal with _ = assignment for clarity

agent/agent.go

@@ -7,6 +7,7 @@ package agent
 
 import (
 	"context"
+	"encoding/json"
 	"fmt"
 	"log/slog"
 	"net/http"
@@ -548,7 +549,9 @@ func toFloat(v interface{}) float64 {
 	case float32: return float64(x)
 	case int: return float64(x)
 	case int64: return float64(x)
+	case int32: return float64(x)
 	case string: f, _ := strconv.ParseFloat(x, 64); return f
+	case json.Number: f, _ := x.Float64(); return f
 	}
 	return 0
 }

api/server.go

@@ -98,7 +98,14 @@ func corsMiddleware() gin.HandlerFunc {
 	return func(c *gin.Context) {
 		origin := c.Request.Header.Get("Origin")
 		if allowAll {
-			c.Writer.Header().Set("Access-Control-Allow-Origin", "*")
+			if origin != "" {
+				// When credentials are needed, we must echo the specific origin
+				// instead of "*" (browsers reject Allow-Credentials with wildcard).
+				c.Writer.Header().Set("Access-Control-Allow-Origin", origin)
+				c.Writer.Header().Set("Vary", "Origin")
+			} else {
+				c.Writer.Header().Set("Access-Control-Allow-Origin", "*")
+			}
 		} else if origin != "" && allowed[origin] {
 			c.Writer.Header().Set("Access-Control-Allow-Origin", origin)
 			c.Writer.Header().Set("Vary", "Origin")

api/strategy.go

@@ -56,8 +56,11 @@ func (s *Server) handlePublicStrategies(c *gin.Context) {
 		// Only include config if config_visible is true
 		if st.ConfigVisible {
 			var config store.StrategyConfig
-			json.Unmarshal([]byte(st.Config), &config)
-			item["config"] = config
+			if err := json.Unmarshal([]byte(st.Config), &config); err != nil {
+				item["config_error"] = "invalid config format"
+			} else {
+				item["config"] = config
+			}
 		}
 
 		result = append(result, item)
@@ -86,9 +89,9 @@ func (s *Server) handleGetStrategies(c *gin.Context) {
 	result := make([]gin.H, 0, len(strategies))
 	for _, st := range strategies {
 		var config store.StrategyConfig
-		json.Unmarshal([]byte(st.Config), &config)
+		configErr := json.Unmarshal([]byte(st.Config), &config)
 
-		result = append(result, gin.H{
+		item := gin.H{
 			"id":             st.ID,
 			"name":           st.Name,
 			"description":    st.Description,
@@ -96,10 +99,15 @@ func (s *Server) handleGetStrategies(c *gin.Context) {
 			"is_default":     st.IsDefault,
 			"is_public":      st.IsPublic,
 			"config_visible": st.ConfigVisible,
-			"config":         config,
 			"created_at":     st.CreatedAt,
 			"updated_at":     st.UpdatedAt,
-		})
+		}
+		if configErr != nil {
+			item["config_error"] = "invalid config format"
+		} else {
+			item["config"] = config
+		}
+		result = append(result, item)
 	}
 
 	c.JSON(http.StatusOK, gin.H{
@@ -124,18 +132,23 @@ func (s *Server) handleGetStrategy(c *gin.Context) {
 	}
 
 	var config store.StrategyConfig
-	json.Unmarshal([]byte(strategy.Config), &config)
+	configErr := json.Unmarshal([]byte(strategy.Config), &config)
 
-	c.JSON(http.StatusOK, gin.H{
+	result := gin.H{
 		"id":          strategy.ID,
 		"name":        strategy.Name,
 		"description": strategy.Description,
 		"is_active":   strategy.IsActive,
 		"is_default":  strategy.IsDefault,
-		"config":      config,
 		"created_at":  strategy.CreatedAt,
 		"updated_at":  strategy.UpdatedAt,
-	})
+	}
+	if configErr != nil {
+		result["config_error"] = "invalid config format"
+	} else {
+		result["config"] = config
+	}
+	c.JSON(http.StatusOK, result)
 }
 
 // handleCreateStrategy Create strategy.
@@ -383,18 +396,23 @@ func (s *Server) handleGetActiveStrategy(c *gin.Context) {
 	}
 
 	var config store.StrategyConfig
-	json.Unmarshal([]byte(strategy.Config), &config)
+	configErr := json.Unmarshal([]byte(strategy.Config), &config)
 
-	c.JSON(http.StatusOK, gin.H{
+	result := gin.H{
 		"id":          strategy.ID,
 		"name":        strategy.Name,
 		"description": strategy.Description,
 		"is_active":   strategy.IsActive,
 		"is_default":  strategy.IsDefault,
-		"config":      config,
 		"created_at":  strategy.CreatedAt,
 		"updated_at":  strategy.UpdatedAt,
-	})
+	}
+	if configErr != nil {
+		result["config_error"] = "invalid config format"
+	} else {
+		result["config"] = config
+	}
+	c.JSON(http.StatusOK, result)
 }
 
 // handleGetDefaultStrategyConfig Get default strategy configuration template

store/decision.go

@@ -138,9 +138,10 @@ func (db *DecisionRecordDB) toRecord() *DecisionRecord {
 		ErrorMessage:        db.ErrorMessage,
 		AIRequestDurationMs: db.AIRequestDurationMs,
 	}
-	json.Unmarshal([]byte(db.CandidateCoins), &record.CandidateCoins)
-	json.Unmarshal([]byte(db.ExecutionLog), &record.ExecutionLog)
-	json.Unmarshal([]byte(db.Decisions), &record.Decisions)
+	// Best-effort unmarshal — empty/malformed JSON fields are left as zero values.
+	_ = json.Unmarshal([]byte(db.CandidateCoins), &record.CandidateCoins)
+	_ = json.Unmarshal([]byte(db.ExecutionLog), &record.ExecutionLog)
+	_ = json.Unmarshal([]byte(db.Decisions), &record.Decisions)
 	return record
 }