AskaEth
d102f75469
- history/session_preview.go: SessionMeta.LastMessage + 单条SQL(LEFT JOIN取每会话ORDER BY created_at DESC,rowid DESC LIMIT 1,走覆盖索引)
- ListSessions 迁出重写(签名不变), content折叠空白截前60rune
- gateway: historySessionSummary 增 lastMessage{role,content,createdAt}(omitempty), /sessions与/admin/sessions共用
- 新增测试(session_preview_test, history_lastmessage_test)
- Docs/api-client.md v0.22 同步
104 lines
3.8 KiB
Go
104 lines
3.8 KiB
Go
package history
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import (
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"context"
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"database/sql"
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"fmt"
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"strings"
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)
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// This file owns the last-message preview carried in the session list
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// (GET /api/v1/sessions): a display-only summary of each session's newest message so a
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// client can render a conversation row without one request per session. The preview is
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// truncated for display and never feeds identity or permission decisions — identity
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// comes from channel actor metadata / JWT (project red line).
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// lastMessagePreviewRunes bounds the preview content so a long message cannot bloat the
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// session-list response. A longer message is whitespace-collapsed and truncated to this
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// many runes with an ellipsis.
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const lastMessagePreviewRunes = 60
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// MessageSummary is a display-only preview of a session's most recent message.
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type MessageSummary struct {
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Role string // "user" | "assistant"
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Content string // whitespace-collapsed, truncated preview
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CreatedAt int64 // Unix milliseconds
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}
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// listSessionsQuery reads every session plus its newest message in one statement. The
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// LEFT JOIN's correlated subquery resolves each session's newest row via the
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// (session_id, created_at DESC) index (rowid DESC breaks a same-millisecond tie by
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// insertion order), so a session with no messages still appears with NULL preview
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// columns. Ordering keeps the main session first, then subs oldest-first.
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const listSessionsQuery = `SELECT s.id, s.type, s.title, s.created_at,
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m.role, m.content, m.created_at
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FROM chat_sessions s
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LEFT JOIN chat_messages m ON m.rowid = (
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SELECT rowid FROM chat_messages
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WHERE session_id = s.id
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ORDER BY created_at DESC, rowid DESC
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LIMIT 1
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)
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ORDER BY (s.type = ?) DESC, s.created_at ASC`
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// ListSessions returns the main session first, then every sub session, oldest first,
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// each carrying a LastMessage preview of its newest message (nil when the session has
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// none). Sessions and previews are read in a single query, so the query count does not
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// grow with the number of sessions. The returned slice is non-nil.
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func (s *Store) ListSessions(ctx context.Context) ([]SessionMeta, error) {
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rows, err := s.db.QueryContext(ctx, listSessionsQuery, SessionMain)
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if err != nil {
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return nil, fmt.Errorf("history: list sessions: %w", err)
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}
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defer func() { _ = rows.Close() }()
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sessions := make([]SessionMeta, 0)
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for rows.Next() {
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meta, err := scanSessionMeta(rows)
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if err != nil {
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return nil, fmt.Errorf("history: scan session: %w", err)
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}
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sessions = append(sessions, meta)
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}
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if err := rows.Err(); err != nil {
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return nil, fmt.Errorf("history: iterate sessions: %w", err)
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}
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return sessions, nil
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}
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// scanSessionMeta reads one joined chat_sessions + last-message row. The three message
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// columns are NULL for a session that has never received a message, so they scan into
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// nullable holders and only produce a LastMessage when a row is present.
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func scanSessionMeta(sc rowScanner) (SessionMeta, error) {
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var (
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meta SessionMeta
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typeStr string
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role sql.NullString
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content sql.NullString
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lastAt sql.NullInt64
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)
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if err := sc.Scan(&meta.ID, &typeStr, &meta.Title, &meta.CreatedAt, &role, &content, &lastAt); err != nil {
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return SessionMeta{}, err
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}
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meta.Type = typeStr
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if role.Valid && lastAt.Valid {
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meta.LastMessage = &MessageSummary{
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Role: role.String,
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Content: previewContent(content.String),
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CreatedAt: lastAt.Int64,
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}
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}
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return meta, nil
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}
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// previewContent collapses whitespace runs (newlines included) to single spaces and
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// truncates to lastMessagePreviewRunes runes with an ellipsis. It is display-only.
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func previewContent(content string) string {
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joined := strings.Join(strings.Fields(content), " ")
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runes := []rune(joined)
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if len(runes) <= lastMessagePreviewRunes {
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return joined
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}
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return string(runes[:lastMessagePreviewRunes]) + "…"
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}
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