feat: implement Redis Streams support with stream checkpoints and update history

- Added Redis Streams operations to the message bus interface and implementation.
- Introduced StreamCheckpoint model to track last processed stream entry per document.
- Implemented UpsertStreamCheckpoint and GetStreamCheckpoint methods in the Postgres store.
- Created document_update_history table for storing update payloads for recovery and replay.
- Developed update persist worker to handle Redis Stream updates and persist them to Postgres.
- Enhanced Docker Compose configuration for Redis with persistence.
- Updated frontend API to support fetching document state with optional share token.
- Added connection stability monitoring in the Yjs document hook.

backend/internal/store/update_history.go

@@ -0,0 +1,115 @@
+package store
+
+import (
+	"context"
+	"fmt"
+	"strings"
+	"time"
+	"unicode/utf8"
+
+	"github.com/google/uuid"
+)
+
+// UpdateHistoryEntry represents a persisted update from Redis Streams
+// used for recovery and replay.
+type UpdateHistoryEntry struct {
+	DocumentID uuid.UUID
+	StreamID   string
+	Seq        int64
+	Payload    []byte
+	MsgType    string
+	ServerID   string
+	CreatedAt  time.Time
+}
+
+// InsertUpdateHistoryBatch inserts update history entries in a single batch.
+// Uses ON CONFLICT DO NOTHING to make inserts idempotent.
+func (s *PostgresStore) InsertUpdateHistoryBatch(ctx context.Context, entries []UpdateHistoryEntry) error {
+	if len(entries) == 0 {
+		return nil
+	}
+
+	var sb strings.Builder
+	sb.WriteString("INSERT INTO document_update_history (document_id, stream_id, seq, payload, msg_type, server_id, created_at) VALUES ")
+
+	args := make([]interface{}, 0, len(entries)*7)
+	for i, e := range entries {
+		if i > 0 {
+			sb.WriteString(",")
+		}
+		base := i*7 + 1
+		sb.WriteString(fmt.Sprintf("($%d,$%d,$%d,$%d,$%d,$%d,$%d)", base, base+1, base+2, base+3, base+4, base+5, base+6))
+		msgType := sanitizeTextForDB(e.MsgType)
+		serverID := sanitizeTextForDB(e.ServerID)
+		args = append(args, e.DocumentID, e.StreamID, e.Seq, e.Payload, nullIfEmpty(msgType), nullIfEmpty(serverID), e.CreatedAt)
+	}
+	// Idempotent insert
+	sb.WriteString(" ON CONFLICT (document_id, stream_id) DO NOTHING")
+
+	if _, err := s.db.ExecContext(ctx, sb.String(), args...); err != nil {
+		return fmt.Errorf("failed to insert update history batch: %w", err)
+	}
+	return nil
+}
+
+// ListUpdateHistoryAfterSeq returns updates with seq greater than afterSeq, ordered by seq.
+func (s *PostgresStore) ListUpdateHistoryAfterSeq(ctx context.Context, documentID uuid.UUID, afterSeq int64, limit int) ([]UpdateHistoryEntry, error) {
+	if limit <= 0 {
+		limit = 1000
+	}
+	query := `
+		SELECT document_id, stream_id, seq, payload, COALESCE(msg_type, ''), COALESCE(server_id, ''), created_at
+		FROM document_update_history
+		WHERE document_id = $1 AND seq > $2
+		ORDER BY seq ASC
+		LIMIT $3
+	`
+
+	rows, err := s.db.QueryContext(ctx, query, documentID, afterSeq, limit)
+	if err != nil {
+		return nil, fmt.Errorf("failed to list update history: %w", err)
+	}
+	defer rows.Close()
+
+	var results []UpdateHistoryEntry
+	for rows.Next() {
+		var e UpdateHistoryEntry
+		if err := rows.Scan(&e.DocumentID, &e.StreamID, &e.Seq, &e.Payload, &e.MsgType, &e.ServerID, &e.CreatedAt); err != nil {
+			return nil, fmt.Errorf("failed to scan update history: %w", err)
+		}
+		results = append(results, e)
+	}
+	return results, nil
+}
+
+// DeleteUpdateHistoryUpToSeq deletes updates with seq <= maxSeq for a document.
+func (s *PostgresStore) DeleteUpdateHistoryUpToSeq(ctx context.Context, documentID uuid.UUID, maxSeq int64) error {
+	query := `
+		DELETE FROM document_update_history
+		WHERE document_id = $1 AND seq <= $2
+	`
+	if _, err := s.db.ExecContext(ctx, query, documentID, maxSeq); err != nil {
+		return fmt.Errorf("failed to delete update history: %w", err)
+	}
+	return nil
+}
+
+func nullIfEmpty(s string) interface{} {
+	if s == "" {
+		return nil
+	}
+	return s
+}
+
+func sanitizeTextForDB(s string) string {
+	if s == "" {
+		return ""
+	}
+	if strings.IndexByte(s, 0) >= 0 {
+		return ""
+	}
+	if !utf8.ValidString(s) {
+		return ""
+	}
+	return s
+}