feat(harness): improve trace fallback and reasoning audit

src/main/java/com/superbiz/agent/domain/entity/AgentReasoningAudit.java

@@ -0,0 +1,61 @@
+package com.superbiz.agent.domain.entity;
+
+import jakarta.persistence.Column;
+import jakarta.persistence.Entity;
+import jakarta.persistence.GeneratedValue;
+import jakarta.persistence.GenerationType;
+import jakarta.persistence.Id;
+import jakarta.persistence.Index;
+import jakarta.persistence.PrePersist;
+import jakarta.persistence.Table;
+import lombok.AllArgsConstructor;
+import lombok.Builder;
+import lombok.Data;
+import lombok.NoArgsConstructor;
+
+import java.time.LocalDateTime;
+
+@Entity
+@Table(name = "agent_reasoning_audit", indexes = {
+        @Index(name = "idx_reasoning_run_step", columnList = "run_id, step_index"),
+        @Index(name = "idx_reasoning_session_created", columnList = "session_id, created_at")
+})
+@Data
+@Builder
+@NoArgsConstructor
+@AllArgsConstructor
+public class AgentReasoningAudit {
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
+    private Long id;
+
+    @Column(name = "session_id", nullable = false, length = 64)
+    private String sessionId;
+
+    @Column(name = "run_id", nullable = false, length = 64)
+    private String runId;
+
+    @Column(name = "step_index", nullable = false)
+    private Integer stepIndex;
+
+    @Column(name = "agent_name", nullable = false, length = 64)
+    private String agentName;
+
+    @Column(name = "reasoning_available", nullable = false)
+    private Boolean reasoningAvailable;
+
+    @Column(name = "reasoning_content", columnDefinition = "LONGTEXT")
+    private String reasoningContent;
+
+    @Column(name = "content_bytes", nullable = false)
+    private Integer contentBytes;
+
+    @Column(name = "created_at", nullable = false, updatable = false)
+    private LocalDateTime createdAt;
+
+    @PrePersist
+    protected void onCreate() {
+        createdAt = LocalDateTime.now();
+    }
+}

src/main/java/com/superbiz/agent/domain/entity/DiagnosisTraceEvent.java

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+package com.superbiz.agent.domain.entity;
+
+import jakarta.persistence.Column;
+import jakarta.persistence.Entity;
+import jakarta.persistence.GeneratedValue;
+import jakarta.persistence.GenerationType;
+import jakarta.persistence.Id;
+import jakarta.persistence.Index;
+import jakarta.persistence.PrePersist;
+import jakarta.persistence.Table;
+import lombok.AllArgsConstructor;
+import lombok.Builder;
+import lombok.Data;
+import lombok.NoArgsConstructor;
+import org.hibernate.annotations.JdbcTypeCode;
+import org.hibernate.type.SqlTypes;
+
+import java.time.LocalDateTime;
+
+@Entity
+@Table(name = "diagnosis_trace_event", indexes = {
+    @Index(name = "idx_trace_event_run_sequence", columnList = "run_id, sequence_no, id"),
+    @Index(name = "idx_trace_event_session_created", columnList = "session_id, created_at, id"),
+    @Index(name = "idx_trace_event_phase", columnList = "phase, event_type")
+})
+@Data
+@Builder
+@NoArgsConstructor
+@AllArgsConstructor
+public class DiagnosisTraceEvent {
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
+    private Long id;
+
+    @Column(name = "session_id", nullable = false, length = 64)
+    private String sessionId;
+
+    @Column(name = "run_id", nullable = false, length = 64)
+    private String runId;
+
+    @Column(name = "sequence_no", nullable = false)
+    private Integer sequenceNo;
+
+    @Column(name = "phase", nullable = false, length = 32)
+    private String phase;
+
+    @Column(name = "event_type", nullable = false, length = 48)
+    private String eventType;
+
+    @Column(name = "status", nullable = false, length = 32)
+    private String status;
+
+    @Column(name = "attempt_no")
+    private Integer attemptNo;
+
+    @Column(name = "duration_ms")
+    private Integer durationMs;
+
+    @JdbcTypeCode(SqlTypes.JSON)
+    @Column(name = "details", nullable = false, columnDefinition = "JSON")
+    private String details;
+
+    @Column(name = "created_at", nullable = false, updatable = false)
+    private LocalDateTime createdAt;
+
+    @PrePersist
+    protected void onCreate() {
+        if (createdAt == null) {
+            createdAt = LocalDateTime.now();
+        }
+    }
+}