新增: 消息级溯源 P1 + 修复流式失败重试(UX-260619-06)

消息级溯源 P1(溯源字段升级):
- ContextManager 加 last_assistant/last_user_message_id 取消息 id
- audit 6 处 message_id 接真值(替换 P0 None 占位)
- 知识提炼 source_ref 升级 conv_msg:{id}(知识生命线 extracted/referenced 双事件)
- 4 处 build_knowledge_context 调用方传 user message id
- 老数据 id=None 降级 conv:{id} 兼容

流式失败重试修复(UX-260619-06):
- 症状1(回答一半消失):AiError 收尾前 flushCurrentText 保留部分回复到占位气泡
  (原仅 AiAgentRound/AiCompleted 回填,AiError 清 currentText 致部分回复丢失)
- 症状2(重试报"没有可重新生成的回复"):ai_regenerate pop_last_assistant_round 返 false 时
  末尾是 user(流式中途失败这轮 assistant 未持久化)直接从该 user 重跑(等价重发)
  1214 连续 user 已由 merge_consecutive_users(7c98134)修,本批补失败重试链路

自验: workspace EXIT 0 + cargo test 全绿 + vue-tsc EXIT 0

src-tauri/src/commands/ai/audit/mod.rs

@@ -216,6 +216,16 @@ pub(crate) async fn process_tool_calls(
     let mut pending_count = 0usize;
     let audit_repo = AiToolExecutionRepo::new(db);
 
+    // F-260619-04 P1 消息级溯源:取当前 assistant 消息 id。
+    // 调用前 agentic.rs 已把本轮 assistant_with_tools 消息(LLM 返回带 tool_calls 的那条)
+    // push 到 per_conv.messages(audit/mod.rs:882),此处取末条 assistant id 作为本轮工具
+    // 调用所属的溯源 message_id,贯穿所有 audit_tool_call 写入。None 表示无 assistant 消息
+    // (异常路径/老数据无 id),audit 落 message_id=None,展示侧兼容。
+    let current_message_id: Option<String> = session
+        .conv_read(conv_id)
+        .and_then(|c| c.messages.last_assistant_message_id());
+    let current_message_id = current_message_id.as_deref();
+
     // 解析 args + 批量发 Started（前端骨架按原始 index 顺序展示）
     let drafts: Vec<(u32, ToolCallDraft, serde_json::Value)> = tc_list.into_iter()
         .map(|(idx, draft)| {
@@ -273,6 +283,7 @@ pub(crate) async fn process_tool_calls(
         audit_tool_call(
             &audit_repo, conv_id, &draft.id, &draft.name, &draft.args,
             "rejected", risk_level, Some(err_msg), Some("auto_blacklist"),
+            current_message_id,
         ).await;
     }
 
@@ -308,6 +319,7 @@ pub(crate) async fn process_tool_calls(
         audit_tool_call(
             &audit_repo, conv_id, &draft.id, &draft.name, &draft.args,
             "pending", risk_level, None, None,
+            current_message_id,
         ).await;
     }
 
@@ -381,7 +393,7 @@ pub(crate) async fn process_tool_calls(
                             conversation_id: Some(conv_id.to_string()),
                         });
                         // 审计:去重命中记一条(status 透传缓存来源 completed/rejected/failed,SW-260618-16;decided_by=auto_dedup),不进 pending
-                        audit_tool_call(&audit_repo, conv_id, &draft.id, &draft.name, &draft.args, &status, risk_level, Some(cached), Some("auto_dedup")).await;
+                        audit_tool_call(&audit_repo, conv_id, &draft.id, &draft.name, &draft.args, &status, risk_level, Some(cached), Some("auto_dedup"), current_message_id).await;
                         continue;
                     }
                 }
@@ -414,7 +426,7 @@ pub(crate) async fn process_tool_calls(
                     diff: approval_diff,
                     conversation_id: Some(conv_id.to_string()),
                 });
-                audit_tool_call(&audit_repo, conv_id, &draft.id, &draft.name, &draft.args, "pending", risk_level, None, None).await;
+                audit_tool_call(&audit_repo, conv_id, &draft.id, &draft.name, &draft.args, "pending", risk_level, None, None, current_message_id).await;
             }
         }
     }
@@ -468,7 +480,7 @@ pub(crate) async fn process_tool_calls(
             // F-260616-09 B 批2:写 per_conv.messages。
             session.conv(conv_id).messages.push(ChatMessage::tool_result(&draft.id, content.clone()));
             // 审计:trust 放行仍记一条(decided_by=auto_trust),留痕可追溯
-            audit_tool_call(&audit_repo, conv_id, &draft.id, &draft.name, &draft.args, status, risk_level, Some(content), Some("auto_trust")).await;
+            audit_tool_call(&audit_repo, conv_id, &draft.id, &draft.name, &draft.args, status, risk_level, Some(content), Some("auto_trust"), current_message_id).await;
         }
     }
 
@@ -521,7 +533,7 @@ pub(crate) async fn process_tool_calls(
             };
             // F-260616-09 B 批2:写 per_conv.messages。
             session.conv(conv_id).messages.push(ChatMessage::tool_result(&draft.id, content.clone()));
-            audit_tool_call(&audit_repo, conv_id, &draft.id, &draft.name, &draft.args, status, RiskLevel::Low, Some(content), Some("auto")).await;
+            audit_tool_call(&audit_repo, conv_id, &draft.id, &draft.name, &draft.args, status, RiskLevel::Low, Some(content), Some("auto"), current_message_id).await;
         }
     }