try implement sync.GetRecord

go.mod

@@ -12,6 +12,7 @@ require (
 	github.com/gorilla/mux v1.8.1
 	github.com/gorilla/websocket v1.5.3
 	github.com/ipfs/go-cid v0.4.1
+	github.com/ipld/go-car v0.6.1-0.20230509095817-92d28eb23ba4
 	github.com/klauspost/compress v1.18.0
 	github.com/mattn/go-sqlite3 v1.14.32
 	github.com/opencontainers/go-digest v1.0.0
@@ -68,7 +69,6 @@ require (
 	github.com/ipfs/go-merkledag v0.11.0 // indirect
 	github.com/ipfs/go-metrics-interface v0.0.1 // indirect
 	github.com/ipfs/go-verifcid v0.0.3 // indirect
-	github.com/ipld/go-car v0.6.1-0.20230509095817-92d28eb23ba4 // indirect
 	github.com/ipld/go-codec-dagpb v1.6.0 // indirect
 	github.com/ipld/go-ipld-prime v0.21.0 // indirect
 	github.com/jackc/pgpassfile v1.0.0 // indirect

pkg/hold/pds/xrpc.go

@@ -1,10 +1,15 @@
 package pds
 
 import (
+	"bytes"
 	"encoding/json"
 	"fmt"
 	"net/http"
 	"strings"
+
+	"github.com/ipfs/go-cid"
+	"github.com/ipld/go-car"
+	carutil "github.com/ipld/go-car/util"
 )
 
 // XRPC handler for ATProto endpoints
@@ -63,6 +68,7 @@ func (h *XRPCHandler) RegisterHandlers(mux *http.ServeMux) {
 
 	// Sync endpoints
 	mux.HandleFunc("/xrpc/com.atproto.sync.listRepos", corsMiddleware(h.HandleListRepos))
+	mux.HandleFunc("/xrpc/com.atproto.sync.getRecord", corsMiddleware(h.HandleSyncGetRecord))
 
 	// Blob endpoints (wrap existing presigned URL logic)
 	mux.HandleFunc("/xrpc/com.atproto.repo.uploadBlob", corsMiddleware(h.HandleUploadBlob))
@@ -240,6 +246,75 @@ func (h *XRPCHandler) HandleListRecords(w http.ResponseWriter, r *http.Request)
 	json.NewEncoder(w).Encode(response)
 }
 
+// HandleSyncGetRecord returns a single record as a CAR file for sync
+func (h *XRPCHandler) HandleSyncGetRecord(w http.ResponseWriter, r *http.Request) {
+	if r.Method != http.MethodGet {
+		http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
+		return
+	}
+
+	did := r.URL.Query().Get("did")
+	collection := r.URL.Query().Get("collection")
+	rkey := r.URL.Query().Get("rkey")
+
+	if did == "" || collection == "" || rkey == "" {
+		http.Error(w, "missing required parameters", http.StatusBadRequest)
+		return
+	}
+
+	if did != h.pds.DID() {
+		http.Error(w, "invalid did", http.StatusBadRequest)
+		return
+	}
+
+	// Only support crew collection for now
+	if collection != CrewCollection {
+		http.Error(w, "collection not found", http.StatusNotFound)
+		return
+	}
+
+	// Get the record CID and raw bytes
+	recordCID, _, err := h.pds.GetCrewMember(r.Context(), rkey)
+	if err != nil {
+		http.Error(w, fmt.Sprintf("failed to get record: %v", err), http.StatusNotFound)
+		return
+	}
+
+	// Get the raw block from the blockstore
+	blk, err := h.pds.repo.Blockstore().Get(r.Context(), recordCID)
+	if err != nil {
+		http.Error(w, fmt.Sprintf("failed to get record block: %v", err), http.StatusInternalServerError)
+		return
+	}
+
+	// Write CAR file with the single record
+	w.Header().Set("Content-Type", "application/vnd.ipld.car")
+
+	// Create a buffer to write the CAR data
+	var buf bytes.Buffer
+
+	// Create CAR header with the record CID as root
+	header := &car.CarHeader{
+		Roots:   []cid.Cid{recordCID},
+		Version: 1,
+	}
+
+	// Write the CAR header
+	if err := car.WriteHeader(header, &buf); err != nil {
+		http.Error(w, fmt.Sprintf("failed to write CAR header: %v", err), http.StatusInternalServerError)
+		return
+	}
+
+	// Write the block using LdWrite
+	if err := carutil.LdWrite(&buf, recordCID.Bytes(), blk.RawData()); err != nil {
+		http.Error(w, fmt.Sprintf("failed to write block to CAR: %v", err), http.StatusInternalServerError)
+		return
+	}
+
+	// Write the CAR data to the response
+	w.Write(buf.Bytes())
+}
+
 // HandleUploadBlob wraps existing presigned upload URL logic
 func (h *XRPCHandler) HandleUploadBlob(w http.ResponseWriter, r *http.Request) {
 	if r.Method != http.MethodPost {