diff --git a/ais/backend/common.go b/ais/backend/common.go
index cd7bb718763..4149e53cb00 100644
--- a/ais/backend/common.go
+++ b/ais/backend/common.go
@@ -10,6 +10,7 @@ import (
 
 	"github.com/NVIDIA/aistore/api/apc"
 	"github.com/NVIDIA/aistore/cmn"
+	"github.com/NVIDIA/aistore/cmn/cos"
 	"github.com/NVIDIA/aistore/cmn/debug"
 	"github.com/NVIDIA/aistore/core"
 	"github.com/NVIDIA/aistore/core/meta"
@@ -19,41 +20,91 @@ import (
 
 type base struct {
 	provider string
-	metrics  map[string]string // this backend's metric names (below)
+	metrics  cos.StrKVs // this backend's metric names (below)
 }
 
 // NOTE: `stats.LatencyToCounter()` - a public helper that relies on the naming convention below
-func (b *base) init(snode *meta.Snode, tstats stats.Tracker) {
+func (b *base) init(snode *meta.Snode, tr stats.Tracker) {
 	prefix := b.provider
 	if prefix == apc.AIS {
 		prefix = apc.RemAIS
 	}
+
+	labels := cos.StrKVs{"backend": prefix}
 	b.metrics = make(map[string]string, 12)
+
+	// GET
 	b.metrics[stats.GetCount] = prefix + "." + stats.GetCount
 	b.metrics[stats.GetLatencyTotal] = prefix + "." + stats.GetLatencyTotal
 	b.metrics[stats.GetE2ELatencyTotal] = prefix + "." + stats.GetE2ELatencyTotal
 	b.metrics[stats.GetSize] = prefix + "." + stats.GetSize
 
-	tstats.RegExtMetric(snode, b.metrics[stats.GetCount], stats.KindCounter)
-	tstats.RegExtMetric(snode, b.metrics[stats.GetLatencyTotal], stats.KindTotal)
-	tstats.RegExtMetric(snode, b.metrics[stats.GetE2ELatencyTotal], stats.KindTotal)
-	tstats.RegExtMetric(snode, b.metrics[stats.GetSize], stats.KindSize)
-
+	tr.RegExtMetric(snode,
+		b.metrics[stats.GetCount],
+		stats.KindCounter,
+		&stats.Extra{Help: "Total number of cold-GET requests", StrName: "remote_get_n", Labels: labels},
+	)
+	tr.RegExtMetric(snode,
+		b.metrics[stats.GetLatencyTotal],
+		stats.KindTotal,
+		&stats.Extra{Help: "Total nanoseconds cold-GET object into AIStore", StrName: "remote_get_ns_total", Labels: labels},
+	)
+	tr.RegExtMetric(snode,
+		b.metrics[stats.GetE2ELatencyTotal],
+		stats.KindTotal,
+		&stats.Extra{
+			Help:    "Total nanoseconds spent by AIStore to service cold-GET request",
+			StrName: "remote_e2e_get_ns_total",
+			Labels:  labels,
+		},
+	)
+	tr.RegExtMetric(snode,
+		b.metrics[stats.GetSize],
+		stats.KindSize,
+		&stats.Extra{Help: "Total bytes received through cold-GET", StrName: "remote_get_bytes_total", Labels: labels},
+	)
+
+	// PUT
 	b.metrics[stats.PutCount] = prefix + "." + stats.PutCount
 	b.metrics[stats.PutLatencyTotal] = prefix + "." + stats.PutLatencyTotal
 	b.metrics[stats.PutE2ELatencyTotal] = prefix + "." + stats.PutE2ELatencyTotal
 	b.metrics[stats.PutSize] = prefix + "." + stats.PutSize
 
-	tstats.RegExtMetric(snode, b.metrics[stats.PutCount], stats.KindCounter)
-	tstats.RegExtMetric(snode, b.metrics[stats.PutLatencyTotal], stats.KindTotal)
-	tstats.RegExtMetric(snode, b.metrics[stats.PutE2ELatencyTotal], stats.KindTotal)
-	tstats.RegExtMetric(snode, b.metrics[stats.PutSize], stats.KindSize)
-
+	tr.RegExtMetric(snode,
+		b.metrics[stats.PutCount],
+		stats.KindCounter,
+		&stats.Extra{Help: "Total number of remote PUT requests", StrName: "remote_put_n", Labels: labels},
+	)
+	tr.RegExtMetric(snode,
+		b.metrics[stats.PutLatencyTotal],
+		stats.KindTotal,
+		&stats.Extra{Help: "Total nanoseconds PUT object from AIStore to remote", StrName: "remote_put_ns_total", Labels: labels},
+	)
+	tr.RegExtMetric(snode,
+		b.metrics[stats.PutE2ELatencyTotal],
+		stats.KindTotal,
+		&stats.Extra{StrName: "remote_e2e_put_ns_total", Labels: labels},
+	)
+	tr.RegExtMetric(snode,
+		b.metrics[stats.PutSize],
+		stats.KindSize,
+		&stats.Extra{StrName: "remote_e2e_put_bytes_total", Labels: labels},
+	)
+
+	// version changed out-of-band
 	b.metrics[stats.VerChangeCount] = prefix + "." + stats.VerChangeCount
 	b.metrics[stats.VerChangeSize] = prefix + "." + stats.VerChangeSize
 
-	tstats.RegExtMetric(snode, b.metrics[stats.VerChangeCount], stats.KindCounter)
-	tstats.RegExtMetric(snode, b.metrics[stats.VerChangeSize], stats.KindSize)
+	tr.RegExtMetric(snode,
+		b.metrics[stats.VerChangeCount],
+		stats.KindCounter,
+		&stats.Extra{StrName: "remote_ver_change_n", Labels: labels},
+	)
+	tr.RegExtMetric(snode,
+		b.metrics[stats.VerChangeSize],
+		stats.KindSize,
+		&stats.Extra{StrName: "remote_ver_change_bytes_total", Labels: labels},
+	)
 }
 
 func (b *base) Provider() string              { return b.provider }
diff --git a/cmd/cli/cli/auth_hdlr.go b/cmd/cli/cli/auth_hdlr.go
index b969dd12b87..30541729497 100644
--- a/cmd/cli/cli/auth_hdlr.go
+++ b/cmd/cli/cli/auth_hdlr.go
@@ -242,7 +242,7 @@ func readMasked(c *cli.Context, prompt string) string {
 }
 
 func cliAuthnURL(cfg *config.Config) string {
-	return cos.Rather(cfg.Auth.URL, os.Getenv(env.AuthN.URL))
+	return cos.Right(cfg.Auth.URL, os.Getenv(env.AuthN.URL))
 }
 
 func lookupClusterID(cluID string) (string, error) {
diff --git a/cmd/cli/cli/completions.go b/cmd/cli/cli/completions.go
index e24c67fae82..aed245c0a99 100644
--- a/cmd/cli/cli/completions.go
+++ b/cmd/cli/cli/completions.go
@@ -798,7 +798,7 @@ func oneClusterCompletions(c *cli.Context) {
 		return
 	}
 	for _, clu := range cluList {
-		fmt.Println(cos.Either(clu.Alias, clu.ID))
+		fmt.Println(cos.Left(clu.Alias, clu.ID))
 	}
 }
 
diff --git a/cmd/cli/cli/show_hdlr.go b/cmd/cli/cli/show_hdlr.go
index 1269e0d5f0a..7ebafcc0428 100644
--- a/cmd/cli/cli/show_hdlr.go
+++ b/cmd/cli/cli/show_hdlr.go
@@ -407,7 +407,7 @@ func showClusterHandler(c *cli.Context) error {
 		return V(err)
 	}
 
-	return cluDaeStatus(c, smap, tstatusMap, pstatusMap, cluConfig, cos.Either(sid, what))
+	return cluDaeStatus(c, smap, tstatusMap, pstatusMap, cluConfig, cos.Left(sid, what))
 }
 
 func xactList(c *cli.Context, xargs *xact.ArgsMsg, caption bool) (int, error) {
diff --git a/cmd/cli/go.mod b/cmd/cli/go.mod
index d3b31780853..5929c07df41 100644
--- a/cmd/cli/go.mod
+++ b/cmd/cli/go.mod
@@ -3,7 +3,7 @@ module github.com/NVIDIA/aistore/cmd/cli
 go 1.22.3
 
 require (
-	github.com/NVIDIA/aistore v1.3.24-0.20240727161516-d5b75b650095
+	github.com/NVIDIA/aistore v1.3.24-0.20240727222627-5dd9704f790f
 	github.com/fatih/color v1.17.0
 	github.com/json-iterator/go v1.1.12
 	github.com/onsi/ginkgo/v2 v2.19.0
diff --git a/cmd/cli/go.sum b/cmd/cli/go.sum
index 44093d8e74d..020bc260577 100644
--- a/cmd/cli/go.sum
+++ b/cmd/cli/go.sum
@@ -1,7 +1,7 @@
 code.cloudfoundry.org/bytefmt v0.0.0-20190710193110-1eb035ffe2b6/go.mod h1:wN/zk7mhREp/oviagqUXY3EwuHhWyOvAdsn5Y4CzOrc=
 github.com/BurntSushi/toml v1.3.2/go.mod h1:CxXYINrC8qIiEnFrOxCa7Jy5BFHlXnUU2pbicEuybxQ=
-github.com/NVIDIA/aistore v1.3.24-0.20240727161516-d5b75b650095 h1:80TQClOFgyTrwdaC8LD+4Y2uNkwTss6mFFinjHt3ZV0=
-github.com/NVIDIA/aistore v1.3.24-0.20240727161516-d5b75b650095/go.mod h1:A4wCIW7GooZSzDxTxh4pS092Ve9gCiXh1EvtjlVB8ew=
+github.com/NVIDIA/aistore v1.3.24-0.20240727222627-5dd9704f790f h1:l9yJlM7QkeMSd9u2AZMy8e8gckQkPFk1FBvzjhK7buc=
+github.com/NVIDIA/aistore v1.3.24-0.20240727222627-5dd9704f790f/go.mod h1:A4wCIW7GooZSzDxTxh4pS092Ve9gCiXh1EvtjlVB8ew=
 github.com/OneOfOne/xxhash v1.2.8 h1:31czK/TI9sNkxIKfaUfGlU47BAxQ0ztGgd9vPyqimf8=
 github.com/OneOfOne/xxhash v1.2.8/go.mod h1:eZbhyaAYD41SGSSsnmcpxVoRiQ/MPUTjUdIIOT9Um7Q=
 github.com/VividCortex/ewma v1.1.1/go.mod h1:2Tkkvm3sRDVXaiyucHiACn4cqf7DpdyLvmxzcbUokwA=
diff --git a/core/mock/stats_mock.go b/core/mock/stats_mock.go
index d49494e3f61..1a09513b77a 100644
--- a/core/mock/stats_mock.go
+++ b/core/mock/stats_mock.go
@@ -30,7 +30,7 @@ func (*StatsTracker) SetFlag(string, cos.NodeStateFlags)
 func (*StatsTracker) SetClrFlag(string, cos.NodeStateFlags, cos.NodeStateFlags) {}
 func (*StatsTracker) AddMany(...cos.NamedVal64)                                 {}
 func (*StatsTracker) InitPrometheus(*meta.Snode)                                {}
-func (*StatsTracker) RegExtMetric(*meta.Snode, string, string)                  {}
+func (*StatsTracker) RegExtMetric(*meta.Snode, string, string, *stats.Extra)    {}
 func (*StatsTracker) GetMetricNames() cos.StrKVs                                { return nil }
 func (*StatsTracker) GetStats() *stats.Node                                     { return nil }
 func (*StatsTracker) GetStatsV322() *stats.NodeV322                             { return nil }
diff --git a/stats/api.go b/stats/api.go
index 47320e1c6df..16c647f42ec 100644
--- a/stats/api.go
+++ b/stats/api.go
@@ -46,8 +46,12 @@ type (
 		ResetStats(errorsOnly bool)
 		GetMetricNames() cos.StrKVs // (name, kind) pairs
 
-		RegExtMetric(node *meta.Snode, name, kind string)
+		// for aistore modules, to add their respective metrics
+		RegExtMetric(node *meta.Snode, name, kind string, extra *Extra)
 	}
+)
+
+type (
 
 	// REST API
 	Node struct {
@@ -105,6 +109,14 @@ type (
 	}
 )
 
+type (
+	Extra struct {
+		StrName string
+		Help    string
+		Labels  cos.StrKVs
+	}
+)
+
 func IsErrMetric(name string) bool {
 	return strings.HasPrefix(name, errPrefix) // e.g., "err.get.n"
 }
diff --git a/stats/common.go b/stats/common.go
index 9a3270ba3be..9ddab55257a 100644
--- a/stats/common.go
+++ b/stats/common.go
@@ -77,18 +77,18 @@ const (
 
 	// error counters
 	// see also: `IncErr`, `regCommon`, `ioErrNames`
-	ErrGetCount    = "err.get.n"
-	ErrPutCount    = "err.put.n"
-	ErrAppendCount = "err.append.n"
-	ErrDeleteCount = "err.del.n"
-	ErrRenameCount = "err.ren.n"
-	ErrListCount   = "err.lst.n"
+	ErrGetCount    = errPrefix + GetCount
+	ErrPutCount    = errPrefix + PutCount
+	ErrAppendCount = errPrefix + AppendCount
+	ErrDeleteCount = errPrefix + DeleteCount
+	ErrRenameCount = errPrefix + RenameCount
+	ErrListCount   = errPrefix + ListCount
 
 	// more errors
 	// (for even more errors, see target_stats)
-	ErrHTTPWriteCount = "err.http.write.n" //nolint:gosec // false positive G101
-	ErrDownloadCount  = "err.dl.n"
-	ErrPutMirrorCount = "err.put.mirror.n"
+	ErrHTTPWriteCount = errPrefix + "http.write.n"
+	ErrDownloadCount  = errPrefix + "dl.n"
+	ErrPutMirrorCount = errPrefix + "put.mirror.n"
 
 	// KindLatency
 	GetLatency         = "get.ns"
@@ -165,7 +165,9 @@ func (r *runner) InitPrometheus(snode *meta.Snode) {
 	r.core.initProm(snode)
 }
 
-func (r *runner) RegExtMetric(snode *meta.Snode, name, kind string) { r.reg(snode, name, kind) }
+func (r *runner) RegExtMetric(snode *meta.Snode, name, kind string, extra *Extra) {
+	r.reg(snode, name, kind, extra)
+}
 
 // common (target, proxy) metrics
 func (r *runner) regCommon(snode *meta.Snode) {
diff --git a/stats/common_prom.go b/stats/common_prom.go
index 091dc85f04c..ac4cc0055ac 100644
--- a/stats/common_prom.go
+++ b/stats/common_prom.go
@@ -263,7 +263,9 @@ var (
 
 // NOTE naming convention: ".n" for the count and ".ns" for duration (nanoseconds)
 // compare with coreStats.initProm()
-func (r *runner) reg(_ *meta.Snode, name, kind string) {
+func (r *runner) reg(_ *meta.Snode, name, kind string, extra ...*Extra) {
+	_ = extra // TODO -- FIXME: in progress
+
 	v := &statsValue{kind: kind}
 	// in StatsD metrics ":" delineates the name and the value - replace with underscore
 	switch kind {
diff --git a/stats/common_statsd.go b/stats/common_statsd.go
index f91e35ac55c..0f7b95b84fb 100644
--- a/stats/common_statsd.go
+++ b/stats/common_statsd.go
@@ -281,7 +281,9 @@ func (s *coreStats) reset(errorsOnly bool) {
 
 // NOTE naming convention: ".n" for the count and ".ns" for duration (nanoseconds)
 // compare with coreStats.initProm()
-func (r *runner) reg(snode *meta.Snode, name, kind string) {
+func (r *runner) reg(snode *meta.Snode, name, kind string, extra ...*Extra) {
+	_ = extra // TODO -- FIXME: in progress
+
 	v := &statsValue{kind: kind}
 	// in StatsD metrics ":" delineates the name and the value - replace with underscore
 	switch kind {
diff --git a/stats/proxy_stats.go b/stats/proxy_stats.go
index b2b2d3a996d..66952df6a22 100644
--- a/stats/proxy_stats.go
+++ b/stats/proxy_stats.go
@@ -11,6 +11,7 @@ import (
 	"github.com/NVIDIA/aistore/cmn"
 	"github.com/NVIDIA/aistore/cmn/atomic"
 	"github.com/NVIDIA/aistore/cmn/cos"
+	"github.com/NVIDIA/aistore/cmn/debug"
 	"github.com/NVIDIA/aistore/cmn/nlog"
 	"github.com/NVIDIA/aistore/core"
 	"github.com/NVIDIA/aistore/core/meta"
@@ -77,8 +78,9 @@ func (r *Prunner) log(now int64, uptime time.Duration, _ *cmn.Config) {
 	if now >= r.next || !idle {
 		s.sgl.Reset() // sharing w/ CoreStats.copyT
 		r.ctracker.write(s.sgl, r.sorted, false /*target*/, idle)
-		if s.sgl.Len() > 3 { // skip '{}'
+		if l := s.sgl.Len(); l > 3 { // skip '{}'
 			line := string(s.sgl.Bytes())
+			debug.Assert(l < s.sgl.Slab().Size(), l, " vs slab ", s.sgl.Slab().Size())
 			if line != r.prev {
 				nlog.Infoln(line)
 				r.prev = line
diff --git a/stats/target_stats.go b/stats/target_stats.go
index a0976dd0bf1..eb7971372ea 100644
--- a/stats/target_stats.go
+++ b/stats/target_stats.go
@@ -47,15 +47,15 @@ const (
 	VerChangeSize  = "ver.change.size"
 
 	// errors
-	ErrCksumCount = "err.cksum.n"
-	ErrCksumSize  = "err.cksum.size"
+	ErrCksumCount = errPrefix + "cksum.n"
+	ErrCksumSize  = errPrefix + "cksum.size"
 
-	ErrFSHCCount = "err.fshc.n"
+	ErrFSHCCount = errPrefix + "fshc.n"
 
 	// IO errors (must have ioErrPrefix)
-	IOErrGetCount    = "err.io.get.n"
-	IOErrPutCount    = "err.io.put.n"
-	IOErrDeleteCount = "err.io.del.n"
+	IOErrGetCount    = ioErrPrefix + "get.n"
+	IOErrPutCount    = ioErrPrefix + "put.n"
+	IOErrDeleteCount = ioErrPrefix + "del.n"
 
 	// KindLatency
 	PutLatency         = "put.ns"
@@ -409,8 +409,9 @@ func (r *Trunner) log(now int64, uptime time.Duration, config *cmn.Config) {
 	if now >= r.next || !idle {
 		s.sgl.Reset() // sharing w/ CoreStats.copyT
 		r.ctracker.write(s.sgl, r.sorted, true /*target*/, idle)
-		if s.sgl.Len() > 3 { // skip '{}'
+		if l := s.sgl.Len(); l > 3 { // skip '{}'
 			line := string(s.sgl.Bytes())
+			debug.Assert(l < s.sgl.Slab().Size(), l, " vs slab ", s.sgl.Slab().Size())
 			if line != r.prev {
 				r.lines = append(r.lines, line)
 				r.prev = line