diff --git a/pkg/logs/sender/grpc/batch_strategy.go b/pkg/logs/sender/grpc/batch_strategy.go
index 5ef9b22a2168..80798d6b2893 100644
--- a/pkg/logs/sender/grpc/batch_strategy.go
+++ b/pkg/logs/sender/grpc/batch_strategy.go
@@ -29,6 +29,8 @@ var (
 // When false: patternId, tags, and timestamp are sent as absolute values on every Log datum.
 const enableDeltaEncoding = true
 
+const datumBytesTelemetrySampleRate = 16
+
 // StatefulExtra holds state changes (non-Log datums) from a batch
 // Used by inflight tracker to maintain snapshot state for stream rotation
 type StatefulExtra struct {
@@ -59,6 +61,8 @@ type batchStrategy struct {
 
 	// marshalBuf is reused across flushes for proto.Marshal output to reduce per-flush allocations.
 	marshalBuf []byte
+	// datumBytesTelemetryCount keeps sampling unbiased across batch boundaries.
+	datumBytesTelemetryCount uint64
 
 	// Delta encoding state - tracks previous values within current batch
 	lastTimestamp      int64  // milliseconds since epoch
@@ -179,21 +183,92 @@ func deltaEncodeDatumsForWire(datums []*statefulpb.Datum) []*statefulpb.Datum {
 	encoded := make([]*statefulpb.Datum, 0, len(datums))
 	state := batchStrategy{}
 	for _, datum := range datums {
-		cloned := proto.Clone(datum).(*statefulpb.Datum)
-		if patternDefine := cloned.GetPatternDefine(); patternDefine != nil {
-			state.lastPatternID = patternDefine.PatternId
-		}
-		if logDatum := cloned.GetLogs(); logDatum != nil {
-			state.applyDeltaEncoding(logDatum)
-		}
-		if flatLogDatum := cloned.GetFlatLog(); flatLogDatum != nil {
-			state.applyFlatLogDeltaEncoding(flatLogDatum)
+		switch data := datum.GetData().(type) {
+		case *statefulpb.Datum_PatternDefine:
+			if data.PatternDefine != nil {
+				state.lastPatternID = data.PatternDefine.PatternId
+			}
+			encoded = append(encoded, datum)
+		case *statefulpb.Datum_Logs:
+			if data.Logs == nil {
+				encoded = append(encoded, datum)
+				continue
+			}
+			cloned := cloneLogForDeltaEncoding(data.Logs)
+			state.applyDeltaEncoding(cloned)
+			encoded = append(encoded, &statefulpb.Datum{
+				Data: &statefulpb.Datum_Logs{Logs: cloned},
+			})
+		case *statefulpb.Datum_FlatLog:
+			if data.FlatLog == nil {
+				encoded = append(encoded, datum)
+				continue
+			}
+			cloned := cloneFlatLogForDeltaEncoding(data.FlatLog)
+			state.applyFlatLogDeltaEncoding(cloned)
+			encoded = append(encoded, &statefulpb.Datum{
+				Data: &statefulpb.Datum_FlatLog{FlatLog: cloned},
+			})
+		default:
+			encoded = append(encoded, datum)
 		}
-		encoded = append(encoded, cloned)
 	}
 	return encoded
 }
 
+func cloneLogForDeltaEncoding(logDatum *statefulpb.Log) *statefulpb.Log {
+	cloned := &statefulpb.Log{
+		Timestamp: logDatum.Timestamp,
+		Tags:      logDatum.Tags,
+		Uuid:      logDatum.Uuid,
+		Status:    logDatum.Status,
+		Service:   logDatum.Service,
+	}
+	switch content := logDatum.Content.(type) {
+	case *statefulpb.Log_Structured:
+		clonedStructured := cloneStructuredLogForDeltaEncoding(content.Structured)
+		cloned.Content = &statefulpb.Log_Structured{Structured: clonedStructured}
+	case *statefulpb.Log_Raw:
+		cloned.Content = &statefulpb.Log_Raw{Raw: content.Raw}
+	}
+	return cloned
+}
+
+func cloneStructuredLogForDeltaEncoding(logDatum *statefulpb.StructuredLog) *statefulpb.StructuredLog {
+	if logDatum == nil {
+		return nil
+	}
+	return &statefulpb.StructuredLog{
+		PatternId:           logDatum.PatternId,
+		DynamicValues:       logDatum.DynamicValues,
+		JsonMessageKey:      logDatum.JsonMessageKey,
+		JsonContextSchemaId: logDatum.JsonContextSchemaId,
+		JsonContextValues:   logDatum.JsonContextValues,
+		JsonContext:         logDatum.JsonContext,
+	}
+}
+
+func cloneFlatLogForDeltaEncoding(logDatum *statefulpb.FlatLog) *statefulpb.FlatLog {
+	return &statefulpb.FlatLog{
+		Timestamp:               logDatum.Timestamp,
+		Status:                  logDatum.Status,
+		Service:                 logDatum.Service,
+		Tags:                    logDatum.Tags,
+		PatternId:               logDatum.PatternId,
+		DynamicValues:           logDatum.DynamicValues,
+		RawLog:                  logDatum.RawLog,
+		JsonSchemaId:            logDatum.JsonSchemaId,
+		JsonContextValues:       logDatum.JsonContextValues,
+		JsonContextValueKinds:   logDatum.JsonContextValueKinds,
+		JsonContextIntValues:    logDatum.JsonContextIntValues,
+		JsonContextFloatValues:  logDatum.JsonContextFloatValues,
+		JsonContextDictValues:   logDatum.JsonContextDictValues,
+		JsonContextRawValues:    logDatum.JsonContextRawValues,
+		JsonContextStringValues: logDatum.JsonContextStringValues,
+		Uuid:                    logDatum.Uuid,
+	}
+}
+
 func (s *batchStrategy) applyTimestampDeltaEncoding(timestamp *int64) {
 	currentTimestamp := *timestamp
 	if s.lastTimestamp == 0 {
@@ -340,33 +415,13 @@ func (s *batchStrategy) sendMessagesWithDatums(messagesMetadata []*message.Messa
 
 	stateChanges, wireDatums := splitStateAndWireDatums(grpcDatums)
 
-	// Track per-datum-type counts and sizes
 	for _, datum := range grpcDatums {
-		var datumType string
-		switch datum.Data.(type) {
-		case *statefulpb.Datum_PatternDefine:
-			datumType = "pattern_define"
-		case *statefulpb.Datum_PatternDelete:
-			datumType = "pattern_delete"
-		case *statefulpb.Datum_Logs:
-			datumType = "logs"
-		case *statefulpb.Datum_FlatLog:
-			datumType = "logs"
-		case *statefulpb.Datum_DictEntryDefine:
-			datumType = "dict_entry_define"
-		case *statefulpb.Datum_DictEntryDelete:
-			datumType = "dict_entry_delete"
-		case *statefulpb.Datum_DeltaEncodingSync:
-			datumType = "delta_encoding_sync"
-		case *statefulpb.Datum_JsonSchemaDefine:
-			datumType = "json_schema_define"
-		case *statefulpb.Datum_JsonSchemaDelete:
-			datumType = "json_schema_delete"
-		default:
-			datumType = "unknown"
-		}
+		datumType := datumTelemetryType(datum)
 		metrics.TlmDatumCount.Add(1, datumType)
-		metrics.TlmDatumBytes.Add(float64(proto.Size(datum)), datumType)
+		if s.datumBytesTelemetryCount%datumBytesTelemetrySampleRate == 0 {
+			metrics.TlmDatumBytes.Add(float64(proto.Size(datum)*datumBytesTelemetrySampleRate), datumType)
+		}
+		s.datumBytesTelemetryCount++
 	}
 
 	encodedDatums := deltaEncodeDatumsForWire(wireDatums)
@@ -416,3 +471,26 @@ func (s *batchStrategy) sendMessagesWithDatums(messagesMetadata []*message.Messa
 	s.pipelineMonitor.ReportComponentEgress(p, metrics.StrategyTlmName, s.instanceID)
 	s.pipelineMonitor.ReportComponentIngress(p, metrics.SenderTlmName, metrics.SenderTlmInstanceID)
 }
+
+func datumTelemetryType(datum *statefulpb.Datum) string {
+	switch datum.Data.(type) {
+	case *statefulpb.Datum_PatternDefine:
+		return "pattern_define"
+	case *statefulpb.Datum_PatternDelete:
+		return "pattern_delete"
+	case *statefulpb.Datum_Logs, *statefulpb.Datum_FlatLog:
+		return "logs"
+	case *statefulpb.Datum_DictEntryDefine:
+		return "dict_entry_define"
+	case *statefulpb.Datum_DictEntryDelete:
+		return "dict_entry_delete"
+	case *statefulpb.Datum_DeltaEncodingSync:
+		return "delta_encoding_sync"
+	case *statefulpb.Datum_JsonSchemaDefine:
+		return "json_schema_define"
+	case *statefulpb.Datum_JsonSchemaDelete:
+		return "json_schema_delete"
+	default:
+		return "unknown"
+	}
+}
diff --git a/pkg/logs/sender/grpc/inflight.go b/pkg/logs/sender/grpc/inflight.go
index eb551b0dcfcf..5a0dc82cc7ea 100644
--- a/pkg/logs/sender/grpc/inflight.go
+++ b/pkg/logs/sender/grpc/inflight.go
@@ -86,7 +86,12 @@ func (t *inflightTracker) pop() *message.Payload {
 	// Apply state changes from this payload to snapshot
 	if payload.StatefulExtra != nil {
 		if extra, ok := payload.StatefulExtra.(*StatefulExtra); ok {
-			if refs, ok := t.inflightReferences(); ok {
+			if t.ackNeedsProtectedRefs(extra) {
+				refs, ok := t.inflightReferences()
+				if !ok {
+					t.planner.applyAcked(extra, nil)
+					return payload
+				}
 				t.planner.applyAcked(extra, &refs)
 			} else {
 				t.planner.applyAcked(extra, nil)
@@ -218,6 +223,10 @@ func (t *inflightTracker) resetStreamSent() {
 	t.planner.resetStream()
 }
 
+func (t *inflightTracker) ackNeedsProtectedRefs(extra *StatefulExtra) bool {
+	return t.planner.hasDeferredDeletes() || stateChangesContainDeletes(extra.StateChanges)
+}
+
 func (t *inflightTracker) inflightReferences() (stateReferences, bool) {
 	refs := newStateReferences()
 	for count, index := 0, t.head; count < t.totalCount(); count++ {
diff --git a/pkg/logs/sender/grpc/mock_state.go b/pkg/logs/sender/grpc/mock_state.go
index 7c48cdbf2013..1b6539595a86 100644
--- a/pkg/logs/sender/grpc/mock_state.go
+++ b/pkg/logs/sender/grpc/mock_state.go
@@ -547,7 +547,8 @@ func (mt *MessageTranslator) buildTagSet(msg *message.Message) (*statefulpb.TagS
 	currentOrigin := msg.Origin
 	currentHostname := msg.MessageMetadata.Hostname
 	currentSource := msg.Origin.Source()
-	currentTagsString := msg.MessageMetadata.TagsToString()
+	baseTags := msg.MessageMetadata.Tags()
+	currentTagsString := strings.Join(baseTags, ",")
 	currentProcessingTags := strings.Join(msg.MessageMetadata.ProcessingTags, ",")
 
 	// Cache hit: all inputs identical and cached dict index still live (not evicted).
@@ -563,8 +564,6 @@ func (mt *MessageTranslator) buildTagSet(msg *message.Message) (*statefulpb.TagS
 
 	// Cache miss: build tag string normally.
 
-	// Start with metadata tags (container tags, source config tags, processing tags)
-	baseTags := msg.MessageMetadata.Tags()
 	tagStrings := make([]string, len(baseTags), len(baseTags)+4)
 	copy(tagStrings, baseTags)
 
@@ -1037,6 +1036,9 @@ func buildJsonSchemaDelete(schemaID uint64) *statefulpb.Datum {
 // like "00123" are kept as strings so they can round-trip without losing lexeme
 // fidelity when reconstructed downstream.
 func parseLosslessIntString(value string) (int64, bool) {
+	if !couldBeInteger(value) {
+		return 0, false
+	}
 	intVal, err := strconv.ParseInt(value, 10, 64)
 	if err != nil {
 		return 0, false
@@ -1050,6 +1052,9 @@ func parseLosslessIntString(value string) (int64, bool) {
 // parseLosslessFloatString returns a float64 only when the original string is already
 // the canonical representation produced by strconv.FormatFloat(..., 'g', -1, 64).
 func parseLosslessFloatString(value string) (float64, bool) {
+	if !couldBeFloat(value) {
+		return 0, false
+	}
 	floatVal, err := strconv.ParseFloat(value, 64)
 	if err != nil {
 		return 0, false
@@ -1060,6 +1065,47 @@ func parseLosslessFloatString(value string) (float64, bool) {
 	return floatVal, true
 }
 
+func couldBeInteger(value string) bool {
+	if value == "" {
+		return false
+	}
+	start := 0
+	if value[0] == '-' {
+		start = 1
+		if len(value) == 1 {
+			return false
+		}
+	}
+	for index := start; index < len(value); index++ {
+		if value[index] < '0' || value[index] > '9' {
+			return false
+		}
+	}
+	return true
+}
+
+func couldBeFloat(value string) bool {
+	if value == "" {
+		return false
+	}
+	hasFloatMarker := false
+	for index := 0; index < len(value); index++ {
+		switch value[index] {
+		case '.', 'e', 'E':
+			hasFloatMarker = true
+		case '+', '-':
+			if index != 0 && value[index-1] != 'e' && value[index-1] != 'E' {
+				return false
+			}
+		default:
+			if value[index] < '0' || value[index] > '9' {
+				return false
+			}
+		}
+	}
+	return hasFloatMarker
+}
+
 func parseLosslessBoolString(value string) (bool, bool) {
 	switch value {
 	case "true":
diff --git a/pkg/logs/sender/grpc/state_planner.go b/pkg/logs/sender/grpc/state_planner.go
index 05ddc14dca4c..eba2140c4708 100644
--- a/pkg/logs/sender/grpc/state_planner.go
+++ b/pkg/logs/sender/grpc/state_planner.go
@@ -37,6 +37,10 @@ func (p *statePlanner) applyAcked(extra *StatefulExtra, protectedRefs *stateRefe
 	p.snapshot.applyWithProtectedRefs(extra, &expanded)
 }
 
+func (p *statePlanner) hasDeferredDeletes() bool {
+	return p.snapshot.hasDeferredDeletes()
+}
+
 func (p *statePlanner) snapshotBytes(refs *stateReferences) ([]byte, stateReferences) {
 	var snapshotRefs *stateReferences
 	if refs != nil {
@@ -345,6 +349,12 @@ func (s *snapshotState) pruneDeferredDeletes(protectedRefs *stateReferences) {
 	}
 }
 
+func (s *snapshotState) hasDeferredDeletes() bool {
+	return len(s.deferredDeletes.patternIDs) > 0 ||
+		len(s.deferredDeletes.dictEntryIDs) > 0 ||
+		len(s.deferredDeletes.jsonSchemaIDs) > 0
+}
+
 func (s *snapshotState) serialize(refs *stateReferences) ([]byte, stateReferences) {
 	sent := newStateReferences()
 	datums := make([]*statefulpb.Datum, 0, len(s.patternMap)+len(s.dictMap)+len(s.jsonSchemaMap))
@@ -493,6 +503,18 @@ func splitStateAndWireDatums(datums []*statefulpb.Datum) (stateChanges []*statef
 	return stateChanges, wireDatums
 }
 
+func stateChangesContainDeletes(datums []*statefulpb.Datum) bool {
+	for _, datum := range datums {
+		switch datum.Data.(type) {
+		case *statefulpb.Datum_PatternDelete,
+			*statefulpb.Datum_DictEntryDelete,
+			*statefulpb.Datum_JsonSchemaDelete:
+			return true
+		}
+	}
+	return false
+}
+
 func isStateDatum(datum *statefulpb.Datum) bool {
 	switch datum.Data.(type) {
 	case *statefulpb.Datum_PatternDefine, *statefulpb.Datum_PatternDelete,