feat: 实现消息长度分布图

electron/main/worker/query/basic.ts

@@ -302,6 +302,84 @@ export function getMessageTypeDistribution(sessionId: string, filter?: TimeFilte
   }))
 }
 
+/**
+ * 获取消息长度分布（仅统计文字消息）
+ * 返回两组数据：
+ * - detail: 1-25 字逐字分布
+ * - grouped: 5-100+ 每5字一组
+ */
+export function getMessageLengthDistribution(sessionId: string, filter?: TimeFilter): {
+  detail: Array<{ len: number; count: number }>
+  grouped: Array<{ range: string; count: number }>
+} {
+  const db = openDatabase(sessionId)
+  if (!db) return { detail: [], grouped: [] }
+
+  const { clause, params } = buildTimeFilter(filter)
+  const clauseWithSystem = buildSystemMessageFilter(clause)
+
+  // 只统计文字消息 (type = 0)，并且 content 不为空
+  const typeCondition = clauseWithSystem
+    ? clauseWithSystem + ' AND msg.type = 0 AND msg.content IS NOT NULL AND LENGTH(msg.content) > 0'
+    : 'WHERE msg.type = 0 AND msg.content IS NOT NULL AND LENGTH(msg.content) > 0'
+
+  // 直接获取每条消息的长度
+  const rows = db
+    .prepare(
+      `
+      SELECT LENGTH(msg.content) as len, COUNT(*) as count
+      FROM message msg
+      JOIN member m ON msg.sender_id = m.id
+      ${typeCondition}
+      GROUP BY len
+      ORDER BY len
+    `
+    )
+    .all(...params) as Array<{ len: number; count: number }>
+
+  // 构建 detail：1-25 逐字
+  const detail: Array<{ len: number; count: number }> = []
+  for (let i = 1; i <= 25; i++) {
+    const found = rows.find((r) => r.len === i)
+    detail.push({
+      len: i,
+      count: found ? found.count : 0,
+    })
+  }
+
+  // 构建 grouped：每5字一段
+  const ranges5 = [
+    { min: 1, max: 5, label: '1-5' },
+    { min: 6, max: 10, label: '6-10' },
+    { min: 11, max: 15, label: '11-15' },
+    { min: 16, max: 20, label: '16-20' },
+    { min: 21, max: 25, label: '21-25' },
+    { min: 26, max: 30, label: '26-30' },
+    { min: 31, max: 35, label: '31-35' },
+    { min: 36, max: 40, label: '36-40' },
+    { min: 41, max: 45, label: '41-45' },
+    { min: 46, max: 50, label: '46-50' },
+    { min: 51, max: 60, label: '51-60' },
+    { min: 61, max: 70, label: '61-70' },
+    { min: 71, max: 80, label: '71-80' },
+    { min: 81, max: 100, label: '81-100' },
+    { min: 101, max: Infinity, label: '100+' },
+  ]
+
+  const grouped: Array<{ range: string; count: number }> = []
+  for (const r of ranges5) {
+    const count = rows
+      .filter((row) => row.len >= r.min && row.len <= r.max)
+      .reduce((sum, row) => sum + row.count, 0)
+    grouped.push({
+      range: r.label,
+      count,
+    })
+  }
+
+  return { detail, grouped }
+}
+
 /**
  * 获取时间范围
  */

electron/main/worker/query/index.ts

@@ -12,6 +12,7 @@ export {
   getWeekdayActivity,
   getMonthlyActivity,
   getYearlyActivity,
+  getMessageLengthDistribution,
   getMessageTypeDistribution,
   getTimeRange,
   getMemberNameHistory,