优化: sanitize 告警降级

- 修复告警 warn 降 debug,同份畸形历史每请求重复触发成洪水
- 涉 sanitize.rs 四处与 openai_compat 两处,含逐 orphan 单条刷屏点
- view-only 修复语义不变,存量配对清洗已完成

crates/df-ai/src/context/sanitize.rs

@@ -142,7 +142,8 @@ pub fn sanitize_messages(messages: Vec<ChatMessage>) -> Vec<ChatMessage> {
             })
             .collect();
 
-        tracing::warn!(
+        // debug 级:同份畸形历史每请求重复触发,降级防告警洪水;根治=ai_messages 配对清洗(DB 原始保留不动)
+        tracing::debug!(
             full_drop_heads,
             partial_rewrite_heads = partial_heads,
             orphaned_tool_results = orphaned_ids.len(),
@@ -252,7 +253,7 @@ pub fn drop_reverse_orphans(messages: Vec<ChatMessage>) -> Vec<ChatMessage> {
     }
 
     if healed > 0 || unidentifiable_kept > 0 {
-        tracing::warn!(
+        tracing::debug!(
             healed_orphan_tool_results = healed,
             unidentifiable_tool_results_kept = unidentifiable_kept,
             "history sanitized: healed orphan tool_results by inserting placeholder heads (view-only, persisted history untouched)"
@@ -331,7 +332,7 @@ pub fn assert_placeholder_pairing(
         out.push(m);
     }
     if healed > 0 {
-        tracing::warn!(
+        tracing::debug!(
             healed_orphan_tool_results = healed,
             "send-view exit: healed orphan tool_results by inserting TOOL_MISSING_PREFIX heads (view-only, persisted history untouched)"
         );
@@ -425,7 +426,7 @@ pub fn ensure_sequence_legal(messages: Vec<ChatMessage>) -> Vec<ChatMessage> {
         fixed.push(m);
     }
     if skipped > 0 || merged > 0 {
-        tracing::warn!(
+        tracing::debug!(
             skipped,
             merged,
             "序列修复:skip 开头非 user(含连带丢 orphan result)+ 合并连续同 role(view-only,避免 Anthropic/GLM 1214)"

crates/df-ai/src/openai_compat.rs

@@ -424,7 +424,7 @@ fn sanitize_openai_triplets(messages: &mut Vec<OpenAiMessage>) {
         // 无配对头(id 不在任何保留 assistant 头内)→ orphan tool_result,丢弃。
         // 含两类:(a) assistant 头被 step2 剥后残留的 tool;(b) 全程无配对头的直构造/DB 残留。
         dropped_orphan_tools += 1;
-        tracing::warn!(
+        tracing::debug!(
             tool_call_id = %id,
             "[openai] orphan tool result(无配对 assistant tool_calls),已丢弃(防 'tool must be response to preceding tool_calls' 400)",
         );
@@ -432,7 +432,7 @@ fn sanitize_openai_triplets(messages: &mut Vec<OpenAiMessage>) {
     });
 
     if stripped_heads > 0 || dropped_orphan_tools > 0 {
-        tracing::warn!(
+        tracing::debug!(
             stripped_heads,
             total_stripped,
             dropped_orphan_tools,