implement HandleGetLatestCommit

pkg/atproto/endpoints.go

@@ -135,6 +135,12 @@ const (
 	// Response: {"did": "...", "active": true, "rev": "..."}
 	SyncGetRepoStatus = "/xrpc/com.atproto.sync.getRepoStatus"
 
+	// SyncGetLatestCommit gets the current commit CID and revision for a repository.
+	// Method: GET
+	// Query: did={did}
+	// Response: {"cid": "...", "rev": "..."}
+	SyncGetLatestCommit = "/xrpc/com.atproto.sync.getLatestCommit"
+
 	// SyncGetHostStatus gets the hosting/crawl status for a hostname on a relay.
 	// Method: GET
 	// Query: hostname={hostname}

pkg/hold/pds/xrpc.go

@@ -169,6 +169,7 @@ func (h *XRPCHandler) RegisterHandlers(r chi.Router) {
 		r.Get(atproto.SyncGetRecord, h.HandleSyncGetRecord)
 		r.Get(atproto.SyncGetRepo, h.HandleGetRepo)
 		r.Get(atproto.SyncGetRepoStatus, h.HandleGetRepoStatus)
+		r.Get(atproto.SyncGetLatestCommit, h.HandleGetLatestCommit)
 		r.Get(atproto.SyncSubscribeRepos, h.HandleSubscribeRepos)
 
 		// DID document and handle resolution
@@ -1294,6 +1295,38 @@ func (h *XRPCHandler) HandleGetRepoStatus(w http.ResponseWriter, r *http.Request
 	})
 }
 
+// HandleGetLatestCommit returns the current commit CID and revision for a repository.
+// Spec: https://docs.bsky.app/docs/api/com-atproto-sync-get-latest-commit
+func (h *XRPCHandler) HandleGetLatestCommit(w http.ResponseWriter, r *http.Request) {
+	did := r.URL.Query().Get("did")
+	if did == "" {
+		http.Error(w, "missing required parameter: did", http.StatusBadRequest)
+		return
+	}
+
+	if did != h.pds.DID() {
+		http.Error(w, "RepoNotFound", http.StatusNotFound)
+		return
+	}
+
+	head, err := h.pds.repomgr.GetRepoRoot(r.Context(), h.pds.uid)
+	if err != nil {
+		http.Error(w, "RepoNotFound", http.StatusNotFound)
+		return
+	}
+
+	rev, err := h.pds.repomgr.GetRepoRev(r.Context(), h.pds.uid)
+	if err != nil || rev == "" {
+		http.Error(w, "RepoNotFound", http.StatusNotFound)
+		return
+	}
+
+	render.JSON(w, r, map[string]any{
+		"cid": head.String(),
+		"rev": rev,
+	})
+}
+
 // HandleDIDDocument returns the DID document
 func (h *XRPCHandler) HandleDIDDocument(w http.ResponseWriter, r *http.Request) {
 	doc, err := h.pds.GenerateDIDDocument(h.pds.PublicURL)