Improvements:

offchainreporting/internal/protocol/observation/observation.go

@@ -58,7 +58,6 @@ func (o Observation) GoEthereumValue() *big.Int { return o.v }
 
 func (o Observation) Deviates(old Observation, thresholdPPB uint64) bool {
 	if old.v.Cmp(i(0)) == 0 {
-		//nolint:gosimple
 		if o.v.Cmp(i(0)) == 0 {
 			return false // Both values are zero; no deviation
 		}

offchainreporting/internal/serialization/serialization.go

@@ -389,7 +389,7 @@ func finalToProtoMessage(v protocol.MessageFinal) *protobuf.MessageFinal {
 			Signatures:             make([][]byte, len(v.Report.Signatures)),
 		},
 	}
-	for i, sig := range v.Report.Signatures { //nolint:gosimple
+	for i, sig := range v.Report.Signatures { //nolint:staticcheck
 		pm.Report.Signatures[i] = sig
 	}
 	return pm

offchainreporting2/reportingplugin/median/median.go

@@ -337,7 +337,7 @@ func (fac NumericalMedianFactory) NewReportingPlugin(ctx context.Context, config
 
 func DefaultDeviationFunc(_ context.Context, thresholdPPB uint64, old *big.Int, new *big.Int) (bool, error) {
 	if old.Cmp(i(0)) == 0 {
-		if new.Cmp(i(0)) == 0 { //nolint:gosimple
+		if new.Cmp(i(0)) == 0 {
 			return false, nil // Both values are zero; no deviation
 		}
 		return true, nil // Any deviation from 0 is significant

offchainreporting2plus/internal/config/ocr2config/public_config.go

@@ -12,8 +12,10 @@ import (
 	"github.com/smartcontractkit/libocr/offchainreporting2plus/types"
 )
 
-// PublicConfig is the configuration disseminated through the smart contract
-// It's public, because anybody can read it from the blockchain
+// PublicConfig is the configuration disseminated through the smart contract.
+// It's public, because anybody can read it from the blockchain.
+// The various parameters (e.g. Delta*, MaxDuration*) have some dependencies
+// on each other, so be sure to consider the holistic impact of changes to them.
 type PublicConfig struct {
 	// If an epoch (driven by a leader) fails to achieve progress (generate a
 	// report) after DeltaProgress, we enter a new epoch. This parameter must be

offchainreporting2plus/internal/config/ocr3config/public_config.go

@@ -13,8 +13,10 @@ import (
 	"github.com/smartcontractkit/libocr/offchainreporting2plus/types"
 )
 
-// PublicConfig is the configuration disseminated through the smart contract
-// It's public, because anybody can read it from the blockchain
+// PublicConfig is the configuration disseminated through the smart contract.
+// It's public, because anybody can read it from the blockchain.
+// The various parameters (e.g. Delta*, MaxDuration*) have some dependencies
+// on each other, so be sure to consider the holistic impact of changes to them.
 type PublicConfig struct {
 	// If an epoch (driven by a leader) fails to achieve progress (generate a
 	// report) after DeltaProgress, we enter a new epoch. This parameter must be

offchainreporting2plus/internal/managed/limits/ocr3_limits.go

@@ -61,9 +61,9 @@ func ocr3limits(cfg ocr3config.PublicConfig, pluginLimits ocr3types.ReportingPlu
 	maxLenMsgNewEpoch := overhead
 	maxLenMsgEpochStartRequest := add(maxLenCertifiedPrepareOrCommit, overhead)
 	maxLenMsgEpochStart := add(maxLenCertifiedPrepareOrCommit, mul(2*(ed25519.SignatureSize+sigOverhead), cfg.ByzQuorumSize()), overhead)
-	maxLenMsgRoundStart := add(pluginLimits.MaxQueryLength, overhead)
+	maxLenMsgRoundStart := add(pluginLimits.MaxQueryLength, ed25519.SignatureSize+sigOverhead, overhead)
 	maxLenMsgObservation := add(pluginLimits.MaxObservationLength, overhead)
-	maxLenMsgProposal := add(mul(add(pluginLimits.MaxObservationLength, ed25519.SignatureSize+sigOverhead), cfg.N()), overhead)
+	maxLenMsgProposal := add(mul(add(pluginLimits.MaxObservationLength, ed25519.SignatureSize+sigOverhead), cfg.N()), ed25519.SignatureSize+sigOverhead, overhead)
 	maxLenMsgPrepare := overhead
 	maxLenMsgCommit := overhead
 	maxLenMsgReportSignatures := add(mul(add(maxSigLen, sigOverhead), pluginLimits.MaxReportCount), overhead)

offchainreporting2plus/internal/managed/managed_mercury_oracle.go

@@ -229,7 +229,7 @@ func RunManagedMercuryOracle(
 				offchainKeyring,
 				ocr3OnchainKeyring,
 				shim.LimitCheckOCR3ReportingPlugin[mercuryshim.MercuryReportInfo]{reportingPlugin, reportingPluginLimits},
-				shim.NewOCR3TelemetrySender(chTelemetrySend, childLogger),
+				shim.NewOCR3TelemetrySender(chTelemetrySend, childLogger, localConfig.EnableTransmissionTelemetry),
 			)
 
 			return nil, false

offchainreporting2plus/internal/managed/managed_ocr2_oracle.go

@@ -237,7 +237,7 @@ func RunManagedOCR2Oracle(
 				onchainKeyring,
 				shim.LimitCheckReportingPlugin{reportingPlugin, reportingPluginInfo.Limits},
 				reportQuorum,
-				shim.NewOCR2TelemetrySender(chTelemetrySend, childLogger),
+				shim.NewOCR2TelemetrySender(chTelemetrySend, childLogger, localConfig.EnableTransmissionTelemetry),
 			)
 
 			return nil, false

offchainreporting2plus/internal/managed/managed_ocr3_oracle.go

@@ -208,7 +208,7 @@ func RunManagedOCR3Oracle[RI any](
 				offchainKeyring,
 				onchainKeyring,
 				shim.LimitCheckOCR3ReportingPlugin[RI]{reportingPlugin, reportingPluginInfo.Limits},
-				shim.NewOCR3TelemetrySender(chTelemetrySend, childLogger),
+				shim.NewOCR3TelemetrySender(chTelemetrySend, childLogger, localConfig.EnableTransmissionTelemetry),
 			)
 
 			return nil, false

offchainreporting2plus/internal/ocr2/protocol/oracle.go

@@ -202,6 +202,7 @@ func (o *oracleState) run() {
 			o.localConfig,
 			o.logger,
 			o.reportingPlugin,
+			o.telemetrySender,
 			o.contractTransmitter,
 		)
 	})

offchainreporting2plus/internal/ocr2/protocol/pacemaker.go

@@ -456,6 +456,8 @@ func (pace *pacemakerState) messageNewepoch(msg MessageNewEpoch, sender commonty
 			pace.metrics.leader.Set(float64(pace.l))
 			pace.persist()
 
+			pace.telemetrySender.EpochStarted(pace.config.ConfigDigest, pace.e, pace.l)
+
 			// abort instance [...], initialize instance (e,l) of report generation
 			pace.spawnReportGeneration()
 

offchainreporting2plus/internal/ocr2/protocol/report_generation_follower.go

@@ -116,12 +116,7 @@ func (repgen *reportGenerationState) messageObserveReq(msg MessageObserveReq, se
 	repgen.followerState.sentReport = false
 	repgen.followerState.completedRound = false
 
-	repgen.telemetrySender.RoundStarted(
-		repgen.config.ConfigDigest,
-		repgen.e,
-		repgen.followerState.r,
-		repgen.l,
-	)
+	repgen.telemetrySender.RoundStarted(repgen.followerReportTimestamp(), repgen.l)
 
 	var o types.Observation
 	{

offchainreporting2plus/internal/ocr2/protocol/telemetry.go

@@ -1,15 +1,39 @@
 package protocol
 
 import (
+	"time"
+
 	"github.com/smartcontractkit/libocr/commontypes"
 	"github.com/smartcontractkit/libocr/offchainreporting2plus/types"
 )
 
 type TelemetrySender interface {
-	RoundStarted(
+	EpochStarted(
 		configDigest types.ConfigDigest,
 		epoch uint32,
-		round uint8,
 		leader commontypes.OracleID,
 	)
+
+	RoundStarted(
+		reportTimestamp types.ReportTimestamp,
+		leader commontypes.OracleID,
+	)
+
+	TransmissionScheduleComputed(
+		reportTimestamp types.ReportTimestamp,
+		now time.Time,
+		schedule map[commontypes.OracleID]time.Duration,
+	)
+
+	TransmissionShouldAcceptFinalizedReportComputed(
+		reportTimestamp types.ReportTimestamp,
+		result bool,
+		ok bool,
+	)
+
+	TransmissionShouldTransmitAcceptedReportComputed(
+		reportTimestamp types.ReportTimestamp,
+		result bool,
+		ok bool,
+	)
 }

offchainreporting2plus/internal/ocr2/protocol/transmission.go

@@ -37,6 +37,7 @@ func RunTransmission(
 	localConfig types.LocalConfig,
 	logger loghelper.LoggerWithContext,
 	reportingPlugin types.ReportingPlugin,
+	telemetrySender TelemetrySender,
 	transmitter types.ContractTransmitter,
 ) {
 	t := transmissionState{
@@ -50,6 +51,7 @@ func RunTransmission(
 		localConfig:                        localConfig,
 		logger:                             logger,
 		reportingPlugin:                    reportingPlugin,
+		telemetrySender:                    telemetrySender,
 		transmitter:                        transmitter,
 	}
 	t.run()
@@ -66,6 +68,7 @@ type transmissionState struct {
 	localConfig                        types.LocalConfig
 	logger                             loghelper.LoggerWithContext
 	reportingPlugin                    types.ReportingPlugin
+	telemetrySender                    TelemetrySender
 	transmitter                        types.ContractTransmitter
 
 	chPersist chan<- persist.TransmissionDBUpdate
@@ -173,6 +176,7 @@ func (t *transmissionState) eventTransmit(ev EventTransmit) {
 				"epoch": ev.Epoch,
 				"round": ev.Round,
 			})
+			t.telemetrySender.TransmissionShouldAcceptFinalizedReportComputed(ts, false, false)
 			return
 		}
 
@@ -181,16 +185,20 @@ func (t *transmissionState) eventTransmit(ev EventTransmit) {
 				"epoch": ev.Epoch,
 				"round": ev.Round,
 			})
+			t.telemetrySender.TransmissionShouldAcceptFinalizedReportComputed(ts, false, true)
 			return
 		}
 	}
 
+	t.telemetrySender.TransmissionShouldAcceptFinalizedReportComputed(ts, true, true)
+
 	now := time.Now()
-	delayMaybe := t.transmitDelay(ev.Epoch, ev.Round)
-	if delayMaybe == nil {
+	delays := t.transmitDelays(ev.Epoch, ev.Round)
+	t.telemetrySender.TransmissionScheduleComputed(ts, now, delays)
+	delay, ok := delays[t.id]
+	if !ok {
 		return
 	}
-	delay := *delayMaybe
 
 	transmission := types.PendingTransmission{
 		now.Add(delay),
@@ -266,11 +274,13 @@ func (t *transmissionState) eventTTransmitTimeout() {
 
 		if err != nil {
 			t.logger.Error("eventTTransmitTimeout: ReportingPlugin.ShouldTransmitAcceptedReport error", commontypes.LogFields{"error": err})
+			t.telemetrySender.TransmissionShouldTransmitAcceptedReportComputed(item.ReportTimestamp, false, false)
 			return
 		}
 
 		if !shouldTransmit {
 			t.logger.Info("eventTTransmitTimeout: ReportingPlugin.ShouldTransmitAcceptedReport returned false", nil)
+			t.telemetrySender.TransmissionShouldTransmitAcceptedReportComputed(item.ReportTimestamp, false, true)
 			return
 		}
 	}
@@ -279,6 +289,7 @@ func (t *transmissionState) eventTTransmitTimeout() {
 		"epoch": item.Epoch,
 		"round": item.Round,
 	})
+	t.telemetrySender.TransmissionShouldTransmitAcceptedReportComputed(item.ReportTimestamp, true, true)
 
 	{
 		ctx, cancel := context.WithTimeout(
@@ -321,7 +332,10 @@ func (t *transmissionState) eventTTransmitTimeout() {
 	})
 }
 
-func (t *transmissionState) transmitDelay(epoch uint32, round uint8) *time.Duration {
+// Computes a map from oracle ids to to transmission delays. This is
+// deterministic across all oracles. The result is derived pseudorandomly
+// uniformly and independently per epoch and round.
+func (t *transmissionState) transmitDelays(epoch uint32, round uint8) map[commontypes.OracleID]time.Duration {
 	// No need for HMAC. Since we use Keccak256, prepending
 	// with key gives us a PRF already.
 	hash := sha3.NewLegacyKeccak256()
@@ -336,15 +350,36 @@ func (t *transmissionState) transmitDelay(epoch uint32, round uint8) *time.Durat
 
 	var key [16]byte
 	copy(key[:], hash.Sum(nil))
-	pi := permutation.Permutation(t.config.N(), key)
-
-	sum := 0
-	for i, s := range t.config.S {
-		sum += s
-		if pi[t.id] < sum {
-			result := time.Duration(i) * t.config.DeltaStage
-			return &result
+
+	// Permutation from transmission order index to oracle id
+	piInv := make([]int, t.config.N())
+	{
+		// Permutation from oracle id to transmission order index. The
+		// permutations are structured in this "inverted" way for historical
+		// compatibility
+		pi := permutation.Permutation(t.config.N(), key)
+		for i := range pi {
+			piInv[pi[i]] = i
+		}
+	}
+
+	result := make(map[commontypes.OracleID]time.Duration, t.config.N())
+
+	accumulatedStageSize := 0
+	for stageIdx, stageSize := range t.config.S {
+		// i is the index of the oracle sorted by transmission order
+		for i := accumulatedStageSize; i < accumulatedStageSize+stageSize; i++ {
+			if i >= len(piInv) {
+				// Index is larger than index of the last oracle. This happens
+				// when sum(S) > N.
+				break
+			}
+			oracleId := commontypes.OracleID(piInv[i])
+			result[oracleId] = time.Duration(stageIdx) * t.config.DeltaStage
 		}
+
+		accumulatedStageSize += stageSize
 	}
-	return nil
+
+	return result
 }