chain/chain.go

@@ -8,10 +8,11 @@
 package chain
 
 import (
+	"errors"
 	"fmt"
 
-	store "forge.lthn.ai/core/go-store"
 	"forge.lthn.ai/core/go-blockchain/types"
+	store "forge.lthn.ai/core/go-store"
 )
 
 // Chain manages blockchain storage and indexing.
@@ -41,7 +42,7 @@ func (c *Chain) TopBlock() (*types.Block, *BlockMeta, error) {
 		return nil, nil, err
 	}
 	if h == 0 {
-		return nil, nil, fmt.Errorf("chain: no blocks stored")
+		return nil, nil, errors.New("chain: no blocks stored")
 	}
 	return c.GetBlockByHeight(h - 1)
 }

chain/difficulty.go

@@ -28,10 +28,7 @@ func (c *Chain) NextDifficulty(height uint64, forks []config.HardFork) (uint64,
 	// LWMA needs N+1 entries (N solve-time intervals).
 	// Start from height 1 — genesis is excluded from the difficulty window.
 	maxLookback := difficulty.LWMAWindow + 1
-	lookback := height // height excludes genesis since we start from 1
-	if lookback > maxLookback {
-		lookback = maxLookback
-	}
+	lookback := min(height, maxLookback) // height excludes genesis since we start from 1
 
 	// Start from max(1, height - lookback) to exclude genesis.
 	startHeight := height - lookback
@@ -48,7 +45,7 @@ func (c *Chain) NextDifficulty(height uint64, forks []config.HardFork) (uint64,
 	timestamps := make([]uint64, count)
 	cumulDiffs := make([]*big.Int, count)
 
-	for i := 0; i < count; i++ {
+	for i := range count {
 		meta, err := c.getBlockMeta(startHeight + uint64(i))
 		if err != nil {
 			// Fewer blocks than expected — use what we have.

chain/sync.go

@@ -10,6 +10,7 @@ import (
 	"context"
 	"encoding/hex"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"log"
 	"regexp"
@@ -66,10 +67,7 @@ func (c *Chain) Sync(ctx context.Context, client *rpc.Client, opts SyncOptions)
 		}
 
 		remaining := remoteHeight - localHeight
-		batch := uint64(syncBatchSize)
-		if remaining < batch {
-			batch = remaining
-		}
+		batch := min(remaining, uint64(syncBatchSize))
 
 		blocks, err := client.GetBlocksDetails(localHeight, batch)
 		if err != nil {
@@ -413,7 +411,7 @@ var aggregatedRE = regexp.MustCompile(`"AGGREGATED"\s*:\s*\{([^}]+)\}`)
 func parseBlockHeader(objectInJSON string) (*types.BlockHeader, error) {
 	m := aggregatedRE.FindStringSubmatch(objectInJSON)
 	if m == nil {
-		return nil, fmt.Errorf("AGGREGATED section not found in object_in_json")
+		return nil, errors.New("AGGREGATED section not found in object_in_json")
 	}
 
 	var hj blockHeaderJSON

chain/validate.go

@@ -7,6 +7,7 @@ package chain
 
 import (
 	"bytes"
+	"errors"
 	"fmt"
 
 	"forge.lthn.ai/core/go-blockchain/config"
@@ -31,7 +32,7 @@ func (c *Chain) ValidateHeader(b *types.Block, expectedHeight uint64) error {
 	// Genesis block: prev_id must be zero.
 	if expectedHeight == 0 {
 		if !b.PrevID.IsZero() {
-			return fmt.Errorf("validate: genesis block has non-zero prev_id")
+			return errors.New("validate: genesis block has non-zero prev_id")
 		}
 		return nil
 	}

consensus/block.go

@@ -7,7 +7,7 @@ package consensus
 
 import (
 	"fmt"
-	"sort"
+	"slices"
 
 	"forge.lthn.ai/core/go-blockchain/config"
 	"forge.lthn.ai/core/go-blockchain/types"
@@ -50,7 +50,7 @@ func CheckTimestamp(blockTimestamp uint64, flags uint8, adjustedTime uint64, rec
 func medianTimestamp(timestamps []uint64) uint64 {
 	sorted := make([]uint64, len(timestamps))
 	copy(sorted, timestamps)
-	sort.Slice(sorted, func(i, j int) bool { return sorted[i] < sorted[j] })
+	slices.Sort(sorted)
 
 	n := len(sorted)
 	if n == 0 {

consensus/pow.go

@@ -27,7 +27,7 @@ func CheckDifficulty(hash types.Hash, difficulty uint64) bool {
 	// Convert hash to big.Int (little-endian as per CryptoNote convention).
 	// Reverse to big-endian for big.Int.
 	var be [32]byte
-	for i := 0; i < 32; i++ {
+	for i := range 32 {
 		be[i] = hash[31-i]
 	}
 	hashInt := new(big.Int).SetBytes(be[:])

consensus/reward.go

@@ -6,6 +6,7 @@
 package consensus
 
 import (
+	"errors"
 	"fmt"
 	"math/bits"
 
@@ -55,7 +56,7 @@ func BlockReward(baseReward, blockSize, medianSize uint64) (uint64, error) {
 
 	// Since hi1 should be 0 for reasonable block sizes, simplify:
 	if hi1 > 0 {
-		return 0, fmt.Errorf("consensus: reward overflow")
+		return 0, errors.New("consensus: reward overflow")
 	}
 	hi2, lo2 := bits.Mul64(baseReward, lo1)
 

consensus/verify.go

@@ -6,6 +6,7 @@
 package consensus
 
 import (
+	"errors"
 	"fmt"
 
 	"forge.lthn.ai/core/go-blockchain/config"
@@ -222,7 +223,7 @@ func verifyV2Signatures(tx *types.Transaction, getZCRingOutputs ZCRingOutputsFn)
 	// Verify BPP range proof if present.
 	if len(proofs.bppProofBytes) > 0 && len(proofs.bppCommitments) > 0 {
 		if !crypto.VerifyBPP(proofs.bppProofBytes, proofs.bppCommitments) {
-			return fmt.Errorf("consensus: BPP range proof verification failed")
+			return errors.New("consensus: BPP range proof verification failed")
 		}
 	}
 

crypto/clsag.go

@@ -8,7 +8,7 @@ package crypto
 import "C"
 
 import (
-	"fmt"
+	"errors"
 	"unsafe"
 )
 
@@ -20,7 +20,7 @@ func PointMul8(pk [32]byte) ([32]byte, error) {
 		(*C.uint8_t)(unsafe.Pointer(&result[0])),
 	)
 	if rc != 0 {
-		return result, fmt.Errorf("crypto: point_mul8 failed")
+		return result, errors.New("crypto: point_mul8 failed")
 	}
 	return result, nil
 }
@@ -34,7 +34,7 @@ func PointDiv8(pk [32]byte) ([32]byte, error) {
 		(*C.uint8_t)(unsafe.Pointer(&result[0])),
 	)
 	if rc != 0 {
-		return result, fmt.Errorf("crypto: point_div8 failed")
+		return result, errors.New("crypto: point_div8 failed")
 	}
 	return result, nil
 }
@@ -48,7 +48,7 @@ func PointSub(a, b [32]byte) ([32]byte, error) {
 		(*C.uint8_t)(unsafe.Pointer(&result[0])),
 	)
 	if rc != 0 {
-		return result, fmt.Errorf("crypto: point_sub failed")
+		return result, errors.New("crypto: point_sub failed")
 	}
 	return result, nil
 }
@@ -81,7 +81,7 @@ func GenerateCLSAGGG(hash [32]byte, ring []byte, ringSize int,
 		(*C.uint8_t)(unsafe.Pointer(&sig[0])),
 	)
 	if rc != 0 {
-		return nil, fmt.Errorf("crypto: generate_CLSAG_GG failed")
+		return nil, errors.New("crypto: generate_CLSAG_GG failed")
 	}
 	return sig, nil
 }

crypto/keygen.go

@@ -8,6 +8,7 @@ package crypto
 import "C"
 
 import (
+	"errors"
 	"fmt"
 	"unsafe"
 )
@@ -51,7 +52,7 @@ func GenerateKeyDerivation(pub [32]byte, sec [32]byte) ([32]byte, error) {
 		(*C.uint8_t)(unsafe.Pointer(&d[0])),
 	)
 	if rc != 0 {
-		return d, fmt.Errorf("crypto: generate_key_derivation failed")
+		return d, errors.New("crypto: generate_key_derivation failed")
 	}
 	return d, nil
 }
@@ -66,7 +67,7 @@ func DerivePublicKey(derivation [32]byte, index uint64, base [32]byte) ([32]byte
 		(*C.uint8_t)(unsafe.Pointer(&derived[0])),
 	)
 	if rc != 0 {
-		return derived, fmt.Errorf("crypto: derive_public_key failed")
+		return derived, errors.New("crypto: derive_public_key failed")
 	}
 	return derived, nil
 }
@@ -81,7 +82,7 @@ func DeriveSecretKey(derivation [32]byte, index uint64, base [32]byte) ([32]byte
 		(*C.uint8_t)(unsafe.Pointer(&derived[0])),
 	)
 	if rc != 0 {
-		return derived, fmt.Errorf("crypto: derive_secret_key failed")
+		return derived, errors.New("crypto: derive_secret_key failed")
 	}
 	return derived, nil
 }

crypto/keyimage.go

@@ -8,7 +8,7 @@ package crypto
 import "C"
 
 import (
-	"fmt"
+	"errors"
 	"unsafe"
 )
 
@@ -22,7 +22,7 @@ func GenerateKeyImage(pub [32]byte, sec [32]byte) ([32]byte, error) {
 		(*C.uint8_t)(unsafe.Pointer(&ki[0])),
 	)
 	if rc != 0 {
-		return ki, fmt.Errorf("crypto: generate_key_image failed")
+		return ki, errors.New("crypto: generate_key_image failed")
 	}
 	return ki, nil
 }

crypto/signature.go

@@ -8,7 +8,7 @@ package crypto
 import "C"
 
 import (
-	"fmt"
+	"errors"
 	"unsafe"
 )
 
@@ -22,7 +22,7 @@ func GenerateSignature(hash [32]byte, pub [32]byte, sec [32]byte) ([64]byte, err
 		(*C.uint8_t)(unsafe.Pointer(&sig[0])),
 	)
 	if rc != 0 {
-		return sig, fmt.Errorf("crypto: generate_signature failed")
+		return sig, errors.New("crypto: generate_signature failed")
 	}
 	return sig, nil
 }
@@ -60,7 +60,7 @@ func GenerateRingSignature(hash [32]byte, image [32]byte, pubs [][32]byte,
 		(*C.uint8_t)(unsafe.Pointer(&flatSigs[0])),
 	)
 	if rc != 0 {
-		return nil, fmt.Errorf("crypto: generate_ring_signature failed")
+		return nil, errors.New("crypto: generate_ring_signature failed")
 	}
 
 	sigs := make([][64]byte, n)

p2p/handshake.go

@@ -79,7 +79,7 @@ type PeerlistEntry struct {
 func DecodePeerlist(blob []byte) []PeerlistEntry {
 	n := len(blob) / PeerlistEntrySize
 	entries := make([]PeerlistEntry, n)
-	for i := 0; i < n; i++ {
+	for i := range n {
 		off := i * PeerlistEntrySize
 		entries[i] = PeerlistEntry{
 			IP:       binary.LittleEndian.Uint32(blob[off : off+4]),

p2p/relay.go

@@ -252,7 +252,7 @@ func (r *ResponseChainEntry) Decode(data []byte) error {
 func splitHashes(blob []byte, size int) [][]byte {
 	n := len(blob) / size
 	out := make([][]byte, n)
-	for i := 0; i < n; i++ {
+	for i := range n {
 		out[i] = blob[i*size : (i+1)*size]
 	}
 	return out

tui/explorer_model.go

@@ -224,22 +224,13 @@ func (m *ExplorerModel) viewBlockList() string {
 	b.WriteByte('\n')
 
 	// Visible window centred on cursor.
-	visibleRows := m.height - 2 // header + bottom margin
-	if visibleRows < 1 {
-		visibleRows = 1
-	}
+	visibleRows := max(m.height-2, 1) // header + bottom margin
 
-	start := m.cursor - visibleRows/2
-	if start < 0 {
-		start = 0
-	}
+	start := max(m.cursor-visibleRows/2, 0)
 	end := start + visibleRows
 	if end > len(m.rows) {
 		end = len(m.rows)
-		start = end - visibleRows
-		if start < 0 {
-			start = 0
-		}
+		start = max(end-visibleRows, 0)
 	}
 
 	for i := start; i < end; i++ {
@@ -356,13 +347,10 @@ func (m *ExplorerModel) loadBlocks() {
 	}
 
 	// Show up to 1000 most recent blocks.
-	count := int(height)
-	if count > 1000 {
-		count = 1000
-	}
+	count := min(int(height), 1000)
 
 	rows := make([]blockRow, count)
-	for i := 0; i < count; i++ {
+	for i := range count {
 		h := height - 1 - uint64(i)
 		blk, meta, err := m.chain.GetBlockByHeight(h)
 		if err != nil {
@@ -381,9 +369,5 @@ func (m *ExplorerModel) loadBlocks() {
 
 // pageSize returns the number of rows to jump for page up/down.
 func pageSize(height int) int {
-	n := height - 3
-	if n < 1 {
-		n = 1
-	}
-	return n
+	return max(height-3, 1)
 }

types/address.go

@@ -170,7 +170,7 @@ func base58Encode(data []byte) string {
 	fullBlocks := len(data) / 8
 	lastBlockSize := len(data) % 8
 
-	for i := 0; i < fullBlocks; i++ {
+	for i := range fullBlocks {
 		block := data[i*8 : (i+1)*8]
 		encoded := encodeBlock(block, 11)
 		result = append(result, encoded...)
@@ -227,7 +227,7 @@ func base58Decode(s string) ([]byte, error) {
 
 	var result []byte
 
-	for i := 0; i < fullBlocks; i++ {
+	for i := range fullBlocks {
 		blockStr := s[i*11 : (i+1)*11]
 		decoded, err := decodeBlock(blockStr, 8)
 		if err != nil {

wallet/account.go

@@ -15,6 +15,7 @@ import (
 	"crypto/rand"
 	"encoding/hex"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"io"
 
@@ -54,8 +55,8 @@ type Account struct {
 	SpendSecretKey types.SecretKey `json:"spend_secret_key"`
 	ViewPublicKey  types.PublicKey `json:"view_public_key"`
 	ViewSecretKey  types.SecretKey `json:"view_secret_key"`
-	CreatedAt      uint64         `json:"created_at"`
-	Flags          uint8          `json:"flags"`
+	CreatedAt      uint64          `json:"created_at"`
+	Flags          uint8           `json:"flags"`
 }
 
 // GenerateAccount creates a new account with random spend keys and a
@@ -162,7 +163,7 @@ func LoadAccount(s *store.Store, password string) (*Account, error) {
 	}
 
 	if len(blob) < saltLen+nonceLen+1 {
-		return nil, fmt.Errorf("wallet: account data too short")
+		return nil, errors.New("wallet: account data too short")
 	}
 
 	salt := blob[:saltLen]

wallet/builder.go

@@ -11,8 +11,10 @@ package wallet
 
 import (
 	"bytes"
+	"cmp"
+	"errors"
 	"fmt"
-	"sort"
+	"slices"
 
 	"forge.lthn.ai/core/go-blockchain/config"
 	"forge.lthn.ai/core/go-blockchain/crypto"
@@ -157,20 +159,16 @@ func (b *V1Builder) buildInput(src *Transfer) (types.TxInputToKey, inputMeta, er
 	})
 
 	// Sort by global index (consensus rule).
-	sort.Slice(ring, func(a, b int) bool {
-		return ring[a].GlobalIndex < ring[b].GlobalIndex
+	slices.SortFunc(ring, func(a, b RingMember) int {
+		return cmp.Compare(a.GlobalIndex, b.GlobalIndex)
 	})
 
 	// Find real index after sorting.
-	realIdx := -1
-	for j, m := range ring {
-		if m.GlobalIndex == src.GlobalIndex {
-			realIdx = j
-			break
-		}
-	}
+	realIdx := slices.IndexFunc(ring, func(m RingMember) bool {
+		return m.GlobalIndex == src.GlobalIndex
+	})
 	if realIdx < 0 {
-		return types.TxInputToKey{}, inputMeta{}, fmt.Errorf("real output not found in ring")
+		return types.TxInputToKey{}, inputMeta{}, errors.New("real output not found in ring")
 	}
 
 	// Build key offsets and public key list.

wallet/mnemonic.go

@@ -2,6 +2,7 @@ package wallet
 
 import (
 	"encoding/binary"
+	"errors"
 	"fmt"
 	"hash/crc32"
 	"strings"
@@ -43,12 +44,12 @@ func MnemonicDecode(phrase string) ([32]byte, error) {
 
 	expected := checksumIndex(words[:24])
 	if words[24] != words[expected] {
-		return key, fmt.Errorf("wallet: mnemonic checksum failed")
+		return key, errors.New("wallet: mnemonic checksum failed")
 	}
 
 	n := uint32(numWords)
 
-	for i := 0; i < 8; i++ {
+	for i := range 8 {
 		w1, ok1 := wordIndex[words[i*3]]
 		w2, ok2 := wordIndex[words[i*3+1]]
 		w3, ok3 := wordIndex[words[i*3+2]]

wallet/wallet.go

@@ -10,15 +10,17 @@
 package wallet
 
 import (
+	"cmp"
+	"errors"
 	"fmt"
-	"sort"
+	"slices"
 	"strconv"
 
-	store "forge.lthn.ai/core/go-store"
 	"forge.lthn.ai/core/go-blockchain/chain"
 	"forge.lthn.ai/core/go-blockchain/rpc"
 	"forge.lthn.ai/core/go-blockchain/types"
 	"forge.lthn.ai/core/go-blockchain/wire"
+	store "forge.lthn.ai/core/go-store"
 )
 
 const (
@@ -165,7 +167,7 @@ func (w *Wallet) Balance() (confirmed, locked uint64, err error) {
 // Send constructs and submits a transaction.
 func (w *Wallet) Send(destinations []Destination, fee uint64) (*types.Transaction, error) {
 	if w.builder == nil || w.client == nil {
-		return nil, fmt.Errorf("wallet: no RPC client configured")
+		return nil, errors.New("wallet: no RPC client configured")
 	}
 
 	chainHeight, err := w.chain.Height()
@@ -192,8 +194,8 @@ func (w *Wallet) Send(destinations []Destination, fee uint64) (*types.Transactio
 			spendable = append(spendable, tr)
 		}
 	}
-	sort.Slice(spendable, func(i, j int) bool {
-		return spendable[i].Amount > spendable[j].Amount
+	slices.SortFunc(spendable, func(a, b Transfer) int {
+		return cmp.Compare(b.Amount, a.Amount) // descending
 	})
 
 	var selected []Transfer

wire/decoder.go

@@ -55,7 +55,7 @@ func (d *Decoder) ReadVarint() uint64 {
 	}
 	var val uint64
 	var shift uint
-	for i := 0; i < MaxVarintLen; i++ {
+	for range MaxVarintLen {
 		_, d.err = io.ReadFull(d.r, d.buf[:1])
 		if d.err != nil {
 			return 0