diff --git a/go.mod b/go.mod
index 2d4541f..295ce63 100644
--- a/go.mod
+++ b/go.mod
@@ -16,9 +16,11 @@ require (
 
 require (
 	github.com/btcsuite/btcd/btcutil v1.1.6 // indirect
+	github.com/cenkalti/backoff v2.2.1+incompatible // indirect
 	github.com/cloudflare/circl v1.6.3 // indirect
 	github.com/decred/dcrd/dcrec/secp256k1/v4 v4.4.1 // indirect
 	github.com/gorilla/rpc v1.2.1 // indirect
+	github.com/grandcat/zeroconf v1.0.0 // indirect
 	github.com/holiman/uint256 v1.3.2 // indirect
 	github.com/luxfi/accel v1.2.4 // indirect
 	github.com/luxfi/cache v1.3.1 // indirect
@@ -27,14 +29,18 @@ require (
 	github.com/luxfi/geth v1.20.1 // indirect
 	github.com/luxfi/math v1.5.1 // indirect
 	github.com/luxfi/math/big v0.1.0 // indirect
+	github.com/luxfi/mdns v0.1.1 // indirect
 	github.com/luxfi/metric v1.8.1 // indirect
 	github.com/luxfi/mock v0.1.1 // indirect
 	github.com/luxfi/sampler v1.1.0 // indirect
 	github.com/luxfi/vm v1.3.1 // indirect
-	github.com/mr-tron/base58 v1.2.0 // indirect
+	github.com/luxfi/zap v1.2.6 // indirect
+	github.com/miekg/dns v1.1.72 // indirect
+	github.com/mr-tron/base58 v1.3.0 // indirect
 	github.com/supranational/blst v0.3.16 // indirect
 	go.uber.org/mock v0.6.0 // indirect
-	golang.org/x/exp v0.0.0-20260312153236-7ab1446f8b90 // indirect
+	golang.org/x/exp v0.0.0-20260529124908-c761662dc8c9 // indirect
+	golang.org/x/net v0.55.0 // indirect
 	golang.org/x/sys v0.45.0 // indirect
 	gonum.org/v1/gonum v0.17.0 // indirect
 	google.golang.org/protobuf v1.36.11 // indirect
diff --git a/pq_validator.go b/pq_validator.go
new file mode 100644
index 0000000..64f1a53
--- /dev/null
+++ b/pq_validator.go
@@ -0,0 +1,219 @@
+// Copyright (C) 2024-2026, Lux Industries Inc. All rights reserved.
+// See the file LICENSE for licensing terms.
+
+// pq_validator.go — deterministic strict-PQ validator identity derivation.
+//
+// A strict-PQ validator's identity is two FIPS-standard keys:
+//
+//	ML-DSA-65 (FIPS 204)  the staking-signature key that ANCHORS the NodeID
+//	                      (ids.NodeIDSchemeMLDSA65.DeriveMLDSA over its pubkey)
+//	ML-KEM-768 (FIPS 203) the handshake KEM key peers encapsulate to
+//
+// Both are derived DETERMINISTICALLY from the one BIP-39 deploy mnemonic and
+// a validator index, exactly like the classical TLS+BLS keys that
+// DeriveValidatorFromMnemonic produces. Determinism is the whole point: a
+// restarted or replacement pod re-derives the SAME NodeID with nothing
+// custodied on disk. Without it, staking/pq.go's mldsa.GenerateKey(rand.Reader,
+// …) mints a fresh key — hence a DIFFERENT validator — on every boot.
+//
+// Derivation tree (coin type 60, the same tree DeriveValidatorFromMnemonic
+// funds — accounts 0=EC, 1=TLS, 2=BLS are taken; the strict-PQ keys take the
+// next free accounts):
+//
+//	ML-DSA-65 : m/44'/60'/3'/0/<index>
+//	ML-KEM-768: m/44'/60'/4'/0/<index>
+//
+// The 32-byte BIP-32 leaf key is domain-separated and HKDF-expanded into the
+// deterministic keygen stream — the identical idiom service_identity.go uses
+// (cryptographer-reviewed: same HKDF-Expand output drives keygen to the same
+// keypair byte-for-byte). The domain strings below are DISTINCT from every
+// other derivation string in this package so a validator staking key is never
+// the same byte-string as a service-auth key, even at a colliding BIP-32 leaf.
+//
+// ENTROPY CEILING (I1). These are FIPS 204/203 keys at NIST Level 3, but when
+// derived here their effective root entropy is bounded by the BIP-39 mnemonic
+// that seeds the whole tree. A 12-word (128-bit) deploy mnemonic caps the
+// unpredictability of every derived ML-DSA-65 / ML-KEM-768 key at 128 bits: an
+// adversary who can brute-force the 2^128 mnemonic space recovers ALL derived
+// validator keys, regardless of the primitives' nominal ~192-bit strength. The
+// 128-bit floor is acceptable for the classical-adversary threat model, but a
+// deployment that wants the PQ keys' full nominal strength as its root-secret
+// floor must seed the tree from a 24-word (256-bit) mnemonic. GenerateValidatorPQ
+// (CSPRNG) has no such ceiling — its keys carry the primitives' full entropy.
+
+package keys
+
+import (
+	"crypto/rand"
+	"errors"
+	"fmt"
+
+	mldsa "github.com/luxfi/crypto/mldsa"
+	mlkem "github.com/luxfi/crypto/mlkem"
+	"github.com/luxfi/ids"
+	"golang.org/x/crypto/hkdf"
+	"golang.org/x/crypto/sha3"
+)
+
+// BIP-44 account indices for the strict-PQ validator keys. Chosen to sit
+// immediately after the classical accounts (0=EC, 1=TLS, 2=BLS) in the same
+// coin-type-60 tree so one mnemonic covers a validator's whole identity.
+const (
+	pqMLDSAAccount uint32 = 3
+	pqMLKEMAccount uint32 = 4
+)
+
+// Domain-separation strings for the deterministic keygen seeds. Pinned at v1;
+// bumping either invalidates every strict-PQ NodeID derived under it (a
+// hardfork of the derivation encoding — the correct behaviour for a change).
+// DISTINCT from serviceIdentityDomain / HybridPQDomain so a validator key and
+// a service-auth key derived from the same mnemonic never coincide.
+const (
+	validatorMLDSADomain = "lux-validator-mldsa65-v1"
+	validatorMLKEMDomain = "lux-validator-mlkem768-v1"
+)
+
+// ErrInvalidAccountIndex is returned when the validator index is out of the
+// supported range. The cap mirrors DeriveValidatorsFromMnemonic's 1..100
+// convention: a validator index far above the plausible fleet size is almost
+// always a misconfiguration, and refusing it early beats silently deriving an
+// unexpected NodeID.
+var ErrInvalidAccountIndex = errors.New("keys: validator account index out of range (0..9999)")
+
+// maxValidatorIndex bounds the non-hardened BIP-32 leaf index. Generous
+// (10k validators) but finite — a uint32 typo (e.g. reading an address as an
+// index) is caught rather than pointing the node at a silent, wrong NodeID.
+const maxValidatorIndex uint32 = 9999
+
+// PQValidatorKey is the strict-PQ staking identity material for one validator,
+// derived deterministically from a BIP-39 mnemonic. The private fields hold
+// live key material — call Wipe() when the derived node.StakingConfig no longer
+// needs them.
+type PQValidatorKey struct {
+	// MLDSAPriv / MLDSAPub — FIPS 204 ML-DSA-65. MLDSAPub is the NodeID anchor
+	// under ids.NodeIDSchemeMLDSA65; MLDSAPriv signs blocks/handshakes.
+	MLDSAPriv []byte
+	MLDSAPub  []byte
+
+	// MLKEMPriv / MLKEMPub — FIPS 203 ML-KEM-768. MLKEMPub is published in the
+	// validator-set entry so peers encapsulate to it; MLKEMPriv stays local.
+	MLKEMPriv []byte
+	MLKEMPub  []byte
+}
+
+// DeriveValidatorPQ derives the strict-PQ staking identity (ML-DSA-65 +
+// ML-KEM-768) for a validator at accountIndex from a BIP-39 mnemonic.
+//
+// Pure function: given the same (mnemonic, accountIndex) it returns the same
+// keys, byte-for-byte, on every call and every machine. No randomness, no I/O,
+// no clock reads. This is what makes a strict-PQ NodeID stable across restarts
+// without custody.
+func DeriveValidatorPQ(mnemonic string, accountIndex uint32) (*PQValidatorKey, error) {
+	if accountIndex > maxValidatorIndex {
+		return nil, ErrInvalidAccountIndex
+	}
+	// deriveMnemonicKeyForPath validates the mnemonic (BIP-39) internally and
+	// walks m/44'/60'/<account>'/0/<index>.
+	mldsaLeaf, err := deriveMnemonicKeyForPath(mnemonic, pqMLDSAAccount, accountIndex)
+	if err != nil {
+		return nil, fmt.Errorf("keys: derive ML-DSA leaf: %w", err)
+	}
+	defer zero(mldsaLeaf)
+	mlkemLeaf, err := deriveMnemonicKeyForPath(mnemonic, pqMLKEMAccount, accountIndex)
+	if err != nil {
+		return nil, fmt.Errorf("keys: derive ML-KEM leaf: %w", err)
+	}
+	defer zero(mlkemLeaf)
+
+	// ML-DSA-65: HKDF-expand the domain-separated leaf into the FIPS 204 keygen
+	// stream. Deterministic — same seed → same keypair.
+	mldsaReader := hkdf.New(sha3.New256, pqSeed(mldsaLeaf, validatorMLDSADomain), nil, []byte(validatorMLDSADomain))
+	mldsaPriv, err := mldsa.GenerateKey(mldsaReader, mldsa.MLDSA65)
+	if err != nil {
+		return nil, fmt.Errorf("keys: ML-DSA-65 keygen: %w", err)
+	}
+
+	// ML-KEM-768: same deterministic construction, distinct domain.
+	mlkemReader := hkdf.New(sha3.New256, pqSeed(mlkemLeaf, validatorMLKEMDomain), nil, []byte(validatorMLKEMDomain))
+	mlkemPub, mlkemPriv, err := mlkem.GenerateKeyPair(mlkemReader, mlkem.MLKEM768)
+	if err != nil {
+		return nil, fmt.Errorf("keys: ML-KEM-768 keygen: %w", err)
+	}
+
+	return &PQValidatorKey{
+		MLDSAPriv: append([]byte(nil), mldsaPriv.Bytes()...),
+		MLDSAPub:  append([]byte(nil), mldsaPriv.PublicKey.Bytes()...),
+		MLKEMPriv: append([]byte(nil), mlkemPriv.Bytes()...),
+		MLKEMPub:  append([]byte(nil), mlkemPub.Bytes()...),
+	}, nil
+}
+
+// GenerateValidatorPQ mints a FRESH strict-PQ validator identity from the system
+// CSPRNG (crypto/rand). It is the orthogonal sibling of DeriveValidatorPQ — use
+// it for the custody model, where a node holds a UNIQUE, non-derived identity
+// that is then persisted to KMS (StakingIdentity.Marshal → SaveAt). A fresh key
+// has NO stable NodeID across restarts on its own; custody in KMS is what makes
+// it stable. Prefer DeriveValidatorPQ (one seed, N paths) unless a per-node
+// unique key is specifically required.
+func GenerateValidatorPQ() (*PQValidatorKey, error) {
+	mldsaPriv, err := mldsa.GenerateKey(rand.Reader, mldsa.MLDSA65)
+	if err != nil {
+		return nil, fmt.Errorf("keys: ML-DSA-65 keygen: %w", err)
+	}
+	mlkemPub, mlkemPriv, err := mlkem.GenerateKeyPair(rand.Reader, mlkem.MLKEM768)
+	if err != nil {
+		return nil, fmt.Errorf("keys: ML-KEM-768 keygen: %w", err)
+	}
+	return &PQValidatorKey{
+		MLDSAPriv: append([]byte(nil), mldsaPriv.Bytes()...),
+		MLDSAPub:  append([]byte(nil), mldsaPriv.PublicKey.Bytes()...),
+		MLKEMPriv: append([]byte(nil), mlkemPriv.Bytes()...),
+		MLKEMPub:  append([]byte(nil), mlkemPub.Bytes()...),
+	}, nil
+}
+
+// StrictPQNodeID returns the NodeID this key anchors, under the SAME derivation
+// the node applies at boot (node.StakingConfig.DeriveNodeID):
+// ids.NodeIDSchemeMLDSA65.DeriveMLDSA(chainID, MLDSAPub). Pass ids.Empty for
+// the primary-network validator identity (the node uses ids.Empty).
+func (k *PQValidatorKey) StrictPQNodeID(chainID ids.ID) (ids.NodeID, error) {
+	if k == nil || len(k.MLDSAPub) == 0 {
+		return ids.EmptyNodeID, errors.New("keys: PQ validator key has no ML-DSA public key")
+	}
+	id, _, err := ids.NodeIDSchemeMLDSA65.DeriveMLDSA(chainID, k.MLDSAPub)
+	return id, err
+}
+
+// Wipe zeroes the private key material in place. Idempotent; safe on nil.
+func (k *PQValidatorKey) Wipe() {
+	if k == nil {
+		return
+	}
+	zero(k.MLDSAPriv)
+	zero(k.MLKEMPriv)
+	k.MLDSAPriv = nil
+	k.MLKEMPriv = nil
+}
+
+// pqSeed compresses a BIP-32 leaf key into a 32-byte deterministic seed under
+// a domain string. SHAKE256 with SP 800-185 left_encode framing on each field
+// so the (domain, leaf) concatenation is unambiguous.
+func pqSeed(leafKey []byte, domain string) []byte {
+	h := sha3.NewShake256()
+	_, _ = h.Write(leftEncode(uint64(len(domain)) * 8))
+	_, _ = h.Write([]byte(domain))
+	_, _ = h.Write(leftEncode(uint64(len(leafKey)) * 8))
+	_, _ = h.Write(leafKey)
+	out := make([]byte, 32)
+	_, _ = h.Read(out)
+	return out
+}
+
+// zero overwrites a byte slice in place. Best-effort — Go's GC offers no
+// harder guarantee, but it shortens the window a private key sits readable in
+// process memory.
+func zero(b []byte) {
+	for i := range b {
+		b[i] = 0
+	}
+}
diff --git a/pq_validator_test.go b/pq_validator_test.go
new file mode 100644
index 0000000..0ac30f1
--- /dev/null
+++ b/pq_validator_test.go
@@ -0,0 +1,177 @@
+// Copyright (C) 2024-2026, Lux Industries Inc. All rights reserved.
+// See the file LICENSE for licensing terms.
+
+package keys
+
+import (
+	"bytes"
+	"testing"
+
+	mldsa "github.com/luxfi/crypto/mldsa"
+	mlkem "github.com/luxfi/crypto/mlkem"
+	"github.com/luxfi/ids"
+)
+
+// validMnemonic is the canonical BIP-39 all-zero-entropy English test vector.
+const validMnemonic = "abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon about"
+
+// Deterministic: same (mnemonic, index) → identical strict-PQ keys, every call.
+// This is the invariant that makes a strict-PQ NodeID stable across restarts
+// with nothing custodied on disk.
+func TestDeriveValidatorPQ_Deterministic(t *testing.T) {
+	a, err := DeriveValidatorPQ(validMnemonic, 0)
+	if err != nil {
+		t.Fatalf("derive a: %v", err)
+	}
+	b, err := DeriveValidatorPQ(validMnemonic, 0)
+	if err != nil {
+		t.Fatalf("derive b: %v", err)
+	}
+	if !bytes.Equal(a.MLDSAPriv, b.MLDSAPriv) || !bytes.Equal(a.MLDSAPub, b.MLDSAPub) {
+		t.Fatal("ML-DSA-65 derivation is not deterministic")
+	}
+	if !bytes.Equal(a.MLKEMPriv, b.MLKEMPriv) || !bytes.Equal(a.MLKEMPub, b.MLKEMPub) {
+		t.Fatal("ML-KEM-768 derivation is not deterministic")
+	}
+}
+
+// The derived key material must be the real FIPS 204 / FIPS 203 keypairs: the
+// public key parses and matches the one derivable from the private key.
+func TestDeriveValidatorPQ_WellFormedKeys(t *testing.T) {
+	k, err := DeriveValidatorPQ(validMnemonic, 7)
+	if err != nil {
+		t.Fatalf("derive: %v", err)
+	}
+	// ML-DSA-65: pub derivable from priv must equal the stored pub.
+	priv, err := mldsa.PrivateKeyFromBytes(mldsa.MLDSA65, k.MLDSAPriv)
+	if err != nil {
+		t.Fatalf("parse ML-DSA priv: %v", err)
+	}
+	if !bytes.Equal(priv.PublicKey.Bytes(), k.MLDSAPub) {
+		t.Fatal("ML-DSA-65 stored pub != pub derived from priv")
+	}
+	// ML-DSA-65 sign/verify round-trip over the derived key.
+	msg := []byte("strict-pq staking identity")
+	sig, err := priv.Sign(nil, msg, nil)
+	if err != nil {
+		t.Fatalf("sign: %v", err)
+	}
+	pub, err := mldsa.PublicKeyFromBytes(k.MLDSAPub, mldsa.MLDSA65)
+	if err != nil {
+		t.Fatalf("parse ML-DSA pub: %v", err)
+	}
+	if !pub.VerifySignature(msg, sig) {
+		t.Fatal("ML-DSA-65 signature over derived key failed to verify")
+	}
+	// ML-KEM-768: both halves parse at the FIPS 203 sizes.
+	if len(k.MLKEMPub) != mlkem.MLKEM768PublicKeySize {
+		t.Fatalf("ML-KEM pub size = %d, want %d", len(k.MLKEMPub), mlkem.MLKEM768PublicKeySize)
+	}
+	if len(k.MLKEMPriv) != mlkem.MLKEM768PrivateKeySize {
+		t.Fatalf("ML-KEM priv size = %d, want %d", len(k.MLKEMPriv), mlkem.MLKEM768PrivateKeySize)
+	}
+	if _, err := mlkem.PrivateKeyFromBytes(k.MLKEMPriv, mlkem.MLKEM768); err != nil {
+		t.Fatalf("parse ML-KEM priv: %v", err)
+	}
+}
+
+// The NodeID the derived key anchors matches the node's boot derivation exactly
+// (ids.NodeIDSchemeMLDSA65.DeriveMLDSA(ids.Empty, MLDSAPub)) — a re-derived key
+// yields the same NodeID, which is the whole point of custody-free stability.
+func TestDeriveValidatorPQ_NodeIDRoundTrip(t *testing.T) {
+	k, err := DeriveValidatorPQ(validMnemonic, 3)
+	if err != nil {
+		t.Fatalf("derive: %v", err)
+	}
+	got, err := k.StrictPQNodeID(ids.Empty)
+	if err != nil {
+		t.Fatalf("NodeID: %v", err)
+	}
+	// Independently compute what node.StakingConfig.DeriveNodeID(ids.Empty)
+	// would produce for a strict-PQ node holding this pub.
+	want, _, err := ids.NodeIDSchemeMLDSA65.DeriveMLDSA(ids.Empty, k.MLDSAPub)
+	if err != nil {
+		t.Fatalf("reference DeriveMLDSA: %v", err)
+	}
+	if got != want {
+		t.Fatalf("NodeID mismatch: helper=%s reference=%s", got, want)
+	}
+	// A freshly re-derived key from the same mnemonic+index yields the SAME
+	// NodeID — the restart-stability guarantee.
+	k2, err := DeriveValidatorPQ(validMnemonic, 3)
+	if err != nil {
+		t.Fatalf("re-derive: %v", err)
+	}
+	got2, _ := k2.StrictPQNodeID(ids.Empty)
+	if got != got2 {
+		t.Fatal("re-derived key produced a different NodeID (custody-free stability broken)")
+	}
+}
+
+// Distinct validator indices produce distinct keys and distinct NodeIDs — a
+// fleet derived from one mnemonic must not collapse onto one identity.
+func TestDeriveValidatorPQ_IndexSeparation(t *testing.T) {
+	k0, _ := DeriveValidatorPQ(validMnemonic, 0)
+	k1, _ := DeriveValidatorPQ(validMnemonic, 1)
+	if bytes.Equal(k0.MLDSAPub, k1.MLDSAPub) {
+		t.Fatal("different indices produced the same ML-DSA public key")
+	}
+	if bytes.Equal(k0.MLKEMPub, k1.MLKEMPub) {
+		t.Fatal("different indices produced the same ML-KEM public key")
+	}
+	n0, _ := k0.StrictPQNodeID(ids.Empty)
+	n1, _ := k1.StrictPQNodeID(ids.Empty)
+	if n0 == n1 {
+		t.Fatal("different indices produced the same NodeID")
+	}
+}
+
+// Domain separation: the validator ML-DSA key must NEVER equal the service-auth
+// ML-DSA key derived from the same mnemonic (distinct derivation strings + tree
+// positions). A collision would let a KMS-auth credential masquerade as a
+// staking key, or vice versa.
+func TestDeriveValidatorPQ_DomainSeparatedFromServiceIdentity(t *testing.T) {
+	vk, err := DeriveValidatorPQ(validMnemonic, 0)
+	if err != nil {
+		t.Fatalf("derive validator pq: %v", err)
+	}
+	svc, err := NewServiceIdentity(validMnemonic, "luxd/staking-bootstrap")
+	if err != nil {
+		t.Fatalf("derive service identity: %v", err)
+	}
+	if bytes.Equal(vk.MLDSAPub, svc.PublicKey) {
+		t.Fatal("validator ML-DSA key collides with service-auth ML-DSA key")
+	}
+}
+
+// An invalid BIP-39 phrase is rejected before any derivation.
+func TestDeriveValidatorPQ_InvalidMnemonic(t *testing.T) {
+	if _, err := DeriveValidatorPQ("not a valid bip39 phrase at all", 0); err == nil {
+		t.Fatal("expected error for invalid mnemonic")
+	}
+}
+
+// An out-of-range index is rejected (misconfiguration guard).
+func TestDeriveValidatorPQ_IndexBounds(t *testing.T) {
+	if _, err := DeriveValidatorPQ(validMnemonic, maxValidatorIndex+1); err == nil {
+		t.Fatal("expected ErrInvalidAccountIndex for out-of-range index")
+	}
+}
+
+// Wipe zeroes the private material.
+func TestPQValidatorKey_Wipe(t *testing.T) {
+	k, err := DeriveValidatorPQ(validMnemonic, 0)
+	if err != nil {
+		t.Fatalf("derive: %v", err)
+	}
+	// Snapshot pub before wipe (pub must survive).
+	pub := append([]byte(nil), k.MLDSAPub...)
+	k.Wipe()
+	if k.MLDSAPriv != nil || k.MLKEMPriv != nil {
+		t.Fatal("Wipe did not nil the private slices")
+	}
+	if !bytes.Equal(k.MLDSAPub, pub) {
+		t.Fatal("Wipe destroyed the public key (should be preserved)")
+	}
+	k.Wipe() // idempotent
+}
diff --git a/service_identity.go b/service_identity.go
index 85d014e..d15d99c 100644
--- a/service_identity.go
+++ b/service_identity.go
@@ -161,8 +161,22 @@ type ServiceIdentity struct {
 	PublicKey []byte
 
 	// privateKey is the ML-DSA-65 private key bytes. Never exposed via
-	// a getter; the only legal use is internal Sign().
+	// a getter; the only legal use is internal Sign() and the wiped-state
+	// sentinel.
 	privateKey []byte
+
+	// signer is the parsed ML-DSA-65 private key, cached ONCE at
+	// construction. Sign() reuses it instead of re-parsing s.privateKey
+	// on every call. This is deliberate and load-bearing: mldsa.
+	// PrivateKeyFromBytes stores its input slice by reference
+	// (secretKey: data) and arms a GC finalizer that Zeroize()s it. A
+	// per-call transient parse therefore ALIASES a byte slice whose
+	// finalizer, once the transient goes unreachable, zeroes the shared
+	// key mid-run — corrupting the next Sign (bites the CUSTODY+Save path
+	// that signs two envelopes per boot). Holding the parsed key on the
+	// struct keeps it reachable for the identity's whole lifetime, so the
+	// finalizer only fires at Wipe/teardown. Never exposed via a getter.
+	signer *mldsa.PrivateKey
 }
 
 // NewServiceIdentity is the canonical constructor. mnemonic must be a
@@ -236,6 +250,10 @@ func NewServiceIdentity(mnemonic, servicePath string) (*ServiceIdentity, error)
 		FullDigest:  full,
 		PublicKey:   pubBytes,
 		privateKey:  privBytes,
+		// Cache the freshly-generated key as the signer. Its secretKey is
+		// independent of privBytes (privBytes is a copy), and holding it on
+		// the struct keeps its Zeroize finalizer dormant until Wipe.
+		signer: priv,
 	}, nil
 }
 
@@ -254,19 +272,19 @@ func NewServiceIdentity(mnemonic, servicePath string) (*ServiceIdentity, error)
 // rejects an envelope signed by a different identity — even a key with
 // the same NodeID prefix.
 func (s *ServiceIdentity) Sign(envelope []byte) ([]byte, error) {
-	if s == nil || len(s.privateKey) == 0 {
+	if s == nil || s.signer == nil {
 		return nil, errors.New("keys: service identity is empty (wiped?)")
 	}
 	digest := envelopeDigest(s.FullDigest, envelope)
-	priv, err := mldsa.PrivateKeyFromBytes(mldsa.MLDSA65, s.privateKey)
-	if err != nil {
-		return nil, fmt.Errorf("keys: parse private key: %w", err)
-	}
-	// FIPS 204 §5.2 hedged sign — circl reads its own randomness
-	// internally. The EnvelopeDomain context byte string is bound
-	// into the signature so a cross-protocol replay of the same key
-	// against a different envelope shape rejects.
-	sig, err := priv.SignCtx(nil, digest, []byte(EnvelopeDomain))
+	// Reuse the cached signer — do NOT re-parse s.privateKey here. A
+	// per-call PrivateKeyFromBytes builds a transient that aliases
+	// s.privateKey and arms a Zeroize finalizer; once the transient goes
+	// unreachable the finalizer zeroes the shared key mid-run. See the
+	// signer field doc. circl reads its own randomness for the FIPS 204
+	// §5.2 hedged sign; the EnvelopeDomain context binds the signature to
+	// this envelope shape so a cross-protocol replay of the same key
+	// against a different shape rejects.
+	sig, err := s.signer.SignCtx(nil, digest, []byte(EnvelopeDomain))
 	if err != nil {
 		return nil, fmt.Errorf("keys: sign: %w", err)
 	}
@@ -307,6 +325,13 @@ func (s *ServiceIdentity) Wipe() {
 		s.privateKey[i] = 0
 	}
 	s.privateKey = nil
+	// Zeroize the cached signer's own key material (a distinct allocation
+	// from privateKey) and drop the reference so a subsequent Sign fails
+	// closed rather than signing with a zeroed key.
+	if s.signer != nil {
+		s.signer.Zeroize()
+		s.signer = nil
+	}
 }
 
 // envelopeDigest computes the canonical SHAKE256 digest a signature
diff --git a/service_identity_test.go b/service_identity_test.go
new file mode 100644
index 0000000..d964813
--- /dev/null
+++ b/service_identity_test.go
@@ -0,0 +1,118 @@
+// Copyright (C) 2019-2026, Lux Industries Inc. All rights reserved.
+// See the file LICENSE for licensing terms.
+
+package keys
+
+import (
+	"runtime"
+	"testing"
+	"time"
+)
+
+// svcMnemonic is the canonical BIP-39 all-zero-entropy English test vector.
+const svcMnemonic = "abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon about"
+
+// NewServiceIdentity is a pure function: same (mnemonic, path) → same NodeID.
+func TestServiceIdentity_Deterministic(t *testing.T) {
+	a, err := NewServiceIdentity(svcMnemonic, "luxd/staking-bootstrap")
+	if err != nil {
+		t.Fatalf("a: %v", err)
+	}
+	defer a.Wipe()
+	b, err := NewServiceIdentity(svcMnemonic, "luxd/staking-bootstrap")
+	if err != nil {
+		t.Fatalf("b: %v", err)
+	}
+	defer b.Wipe()
+	if a.NodeID != b.NodeID {
+		t.Fatal("service identity NodeID is not deterministic")
+	}
+}
+
+// L1 regression: Sign must NOT re-parse s.privateKey into a transient
+// mldsa.PrivateKey on every call. That transient aliases s.privateKey and arms
+// a Zeroize GC finalizer; when it goes unreachable the finalizer zeroes the
+// SHARED key mid-run, so the NEXT Sign signs with (or over) a corrupted key.
+// This is exactly the CUSTODY+Save boot path, which signs two envelopes (GetAt
+// then PutAt) from one identity.
+//
+// The test signs, then aggressively drives GC + finalizers between signs, then
+// signs again. With the cached-signer fix BOTH signatures are produced over the
+// intact key and verify. With the aliasing regression, the second Sign operates
+// on a zeroed key and the check fails.
+func TestServiceIdentity_SignSurvivesGCBetweenCalls(t *testing.T) {
+	id, err := NewServiceIdentity(svcMnemonic, "hanzo/kms-operator")
+	if err != nil {
+		t.Fatalf("new: %v", err)
+	}
+	defer id.Wipe()
+
+	env1 := []byte("envelope-one: OpSecretGet")
+	sig1, err := id.Sign(env1)
+	if err != nil {
+		t.Fatalf("first sign: %v", err)
+	}
+
+	// Force any finalizer-bearing transient created during the first Sign to be
+	// collected and its finalizer to run. Under the regression this zeroes the
+	// shared key; under the fix there is no such transient.
+	forceFinalizers()
+
+	env2 := []byte("envelope-two: OpSecretPut")
+	sig2, err := id.Sign(env2)
+	if err != nil {
+		t.Fatalf("second sign after GC failed (key zeroed by aliased transient finalizer?): %v", err)
+	}
+
+	if err := VerifyServiceEnvelope(id.PublicKey, id.FullDigest, env1, sig1); err != nil {
+		t.Fatalf("first signature did not verify (key corrupted mid-run): %v", err)
+	}
+	if err := VerifyServiceEnvelope(id.PublicKey, id.FullDigest, env2, sig2); err != nil {
+		t.Fatalf("second signature did not verify (key corrupted mid-run): %v", err)
+	}
+
+	// Signing many more times across GC pressure must all verify — the cached
+	// signer is stable for the identity's whole lifetime.
+	for i := 0; i < 8; i++ {
+		forceFinalizers()
+		msg := []byte{byte(i), 'x'}
+		sig, serr := id.Sign(msg)
+		if serr != nil {
+			t.Fatalf("sign %d: %v", i, serr)
+		}
+		if verr := VerifyServiceEnvelope(id.PublicKey, id.FullDigest, msg, sig); verr != nil {
+			t.Fatalf("sign %d did not verify: %v", i, verr)
+		}
+	}
+}
+
+// After Wipe the identity fails closed: Sign returns an error rather than
+// signing with a zeroed key, and the cached signer is dropped.
+func TestServiceIdentity_WipeFailsClosed(t *testing.T) {
+	id, err := NewServiceIdentity(svcMnemonic, "luxd/staking-bootstrap")
+	if err != nil {
+		t.Fatalf("new: %v", err)
+	}
+	if _, err := id.Sign([]byte("pre-wipe")); err != nil {
+		t.Fatalf("pre-wipe sign: %v", err)
+	}
+	id.Wipe()
+	if id.signer != nil {
+		t.Fatal("Wipe did not drop the cached signer")
+	}
+	if _, err := id.Sign([]byte("post-wipe")); err == nil {
+		t.Fatal("Sign after Wipe must fail closed")
+	}
+	id.Wipe() // idempotent
+}
+
+// forceFinalizers drives the GC and gives the finalizer goroutine a window to
+// run. runtime.GC identifies unreachable objects; finalizers run asynchronously
+// on a dedicated goroutine, so we loop with a brief yield to make their
+// execution overwhelmingly likely within the test.
+func forceFinalizers() {
+	for i := 0; i < 4; i++ {
+		runtime.GC()
+		time.Sleep(time.Millisecond)
+	}
+}
diff --git a/staking_identity.go b/staking_identity.go
new file mode 100644
index 0000000..88a22f7
--- /dev/null
+++ b/staking_identity.go
@@ -0,0 +1,256 @@
+// Copyright (C) 2024-2026, Lux Industries Inc. All rights reserved.
+// See the file LICENSE for licensing terms.
+
+// staking_identity.go — the portable, complete staking identity of one node,
+// plus its deterministic wire codec.
+//
+// A StakingIdentity bundles BOTH ChainSecurityProfiles' materials:
+//
+//	classical : TLS cert/key (NodeID anchor + transport) + BLS signer (consensus)
+//	strict-PQ : ML-DSA-65 (NodeID anchor + sign) + ML-KEM-768 (handshake KEM)
+//
+// It is the unit a node CUSTODIES in KMS so a restart or replacement pod
+// recovers the SAME NodeID under whichever profile the chain runs. Two ways to
+// obtain the same stable identity:
+//
+//	1. derive it   — StakingIdentityFromValidatorKey(DeriveValidatorFromMnemonic,
+//	                 DeriveValidatorPQ). Nothing to persist; re-derivable from the
+//	                 mnemonic. This is the canonical Lux "one seed, N paths" model.
+//	2. custody it  — generate once, Marshal, store the blob in KMS, Unmarshal on
+//	                 the next boot. For nodes that hold a unique, non-derived key.
+//
+// SEPARATION OF CONCERNS: this type owns ONLY (de)serialization — pure
+// functions, no I/O, no KMS, no network. The KMS transport that carries a
+// marshalled blob lives in the consumer (luxd staking-init), so luxfi/keys
+// keeps NO edge to luxfi/kms. The module graph stays acyclic: kms → keys, never
+// keys → kms. (kms/pkg/mnemonic already composes keys with the ZAP client on
+// the far side of that edge.)
+//
+// INTEGRITY: Marshal appends a SHA-256 checksum over the framed body. This is a
+// framing/corruption guard (truncation, bit-rot, wrong-blob) — NOT a keyed MAC
+// and NOT confidentiality. The authenticated-encryption boundary is KMS itself
+// (AES-256-GCM payload + ML-KEM-wrapped DEK, AAD-bound to path/name/env). The
+// checksum is defense-in-depth on top of that, so a mangled blob is rejected
+// rather than mis-parsed into a wrong (and unusable) NodeID.
+
+package keys
+
+import (
+	"crypto/sha256"
+	"crypto/subtle"
+	"encoding/binary"
+	"errors"
+	"fmt"
+)
+
+// stakingIdentityMagic tags the wire format so a blob from another producer (or
+// a raw mnemonic accidentally routed here) is rejected at byte 0.
+var stakingIdentityMagic = []byte("LUXSTAKEID")
+
+// stakingIdentityVersion is the only supported codec version. Bump on any wire
+// change; Unmarshal refuses unknown versions rather than guessing. v2 adds the
+// NodeLabel field (index 7) — an operator-supplied label bound INTO the
+// integrity-checksummed blob so a stored custody identity is tied to one node
+// and a second node pointed at the same KMS path detects the mismatch on load
+// (equivocation tripwire; the primary control is server-side path-scoped write
+// authz). Forward-only: there is no v1 fallback.
+const stakingIdentityVersion byte = 2
+
+// stakingIdentityFieldCount is the fixed number of length-prefixed fields.
+const stakingIdentityFieldCount = 8
+
+// maxStakingField caps any single field at 64 KiB. ML-DSA-65 private keys are
+// ~4 KB and TLS PEM a few KB, so 64 KiB is generous; the cap turns a hostile or
+// corrupt length prefix into a bounded rejection instead of a huge allocation.
+const maxStakingField = 64 * 1024
+
+// ErrStakingIdentityCodec is the base error for every malformed-blob rejection.
+// Wrapped with a specific cause; match with errors.Is.
+var ErrStakingIdentityCodec = errors.New("keys: staking identity codec")
+
+// StakingIdentity is the complete staking identity of one node. Any field may
+// be empty (a classical-only or strict-PQ-only custody); Marshal preserves
+// exactly what is set and Unmarshal restores it byte-for-byte.
+type StakingIdentity struct {
+	// Classical.
+	TLSCertPEM []byte // PEM-encoded staking certificate (public — NodeID anchor)
+	TLSKeyPEM  []byte // PEM-encoded staking private key (SECRET)
+	BLSSigner  []byte // raw BLS secret key bytes (SECRET)
+
+	// Strict-PQ.
+	MLDSAPriv []byte // ML-DSA-65 private key (SECRET)
+	MLDSAPub  []byte // ML-DSA-65 public key (public — strict-PQ NodeID anchor)
+	MLKEMPriv []byte // ML-KEM-768 private key (SECRET)
+	MLKEMPub  []byte // ML-KEM-768 public key (public — handshake)
+
+	// Custody binding. NodeLabel is an operator-supplied label (e.g. the
+	// node's hostname or fleet index) bound into the blob so a CUSTODY load
+	// can reject an identity minted for a DIFFERENT node — the equivocation
+	// tripwire for two nodes accidentally sharing one KMS identity path.
+	// Public, not secret; empty for DERIVE identities (which are re-derivable,
+	// never stored, and so carry no shared-path risk). Preserved verbatim by
+	// the codec.
+	NodeLabel []byte
+}
+
+// fields returns the seven field slices in canonical, fixed order. The order is
+// the wire order and MUST never be reordered without a version bump.
+func (s *StakingIdentity) fields() [][]byte {
+	return [][]byte{
+		s.TLSCertPEM,
+		s.TLSKeyPEM,
+		s.BLSSigner,
+		s.MLDSAPriv,
+		s.MLDSAPub,
+		s.MLKEMPriv,
+		s.MLKEMPub,
+		s.NodeLabel,
+	}
+}
+
+// HasClassical reports whether the classical materials needed to run a
+// classical-compat validator are present (TLS cert + key + BLS signer).
+func (s *StakingIdentity) HasClassical() bool {
+	return len(s.TLSCertPEM) > 0 && len(s.TLSKeyPEM) > 0 && len(s.BLSSigner) > 0
+}
+
+// HasStrictPQ reports whether the strict-PQ materials needed to run a strict-PQ
+// validator are present (ML-DSA-65 pair + ML-KEM-768 pair).
+func (s *StakingIdentity) HasStrictPQ() bool {
+	return len(s.MLDSAPriv) > 0 && len(s.MLDSAPub) > 0 &&
+		len(s.MLKEMPriv) > 0 && len(s.MLKEMPub) > 0
+}
+
+// Marshal serializes the identity into the canonical wire blob:
+//
+//	magic("LUXSTAKEID") || version(1) || fieldCount(1) ||
+//	  { u32 len || bytes } × 8 (canonical order, NodeLabel last) ||
+//	  sha256(everything above)          // 32-byte integrity tail
+//
+// Deterministic: the same StakingIdentity always marshals to identical bytes,
+// so a save→load round-trip and a hash-compare are stable.
+func (s *StakingIdentity) Marshal() ([]byte, error) {
+	fields := s.fields()
+	if len(fields) != stakingIdentityFieldCount {
+		return nil, fmt.Errorf("%w: field count %d != %d",
+			ErrStakingIdentityCodec, len(fields), stakingIdentityFieldCount)
+	}
+	body := make([]byte, 0, 64)
+	body = append(body, stakingIdentityMagic...)
+	body = append(body, stakingIdentityVersion, byte(stakingIdentityFieldCount))
+	var lenBuf [4]byte
+	for _, f := range fields {
+		if len(f) > maxStakingField {
+			return nil, fmt.Errorf("%w: field length %d exceeds cap %d",
+				ErrStakingIdentityCodec, len(f), maxStakingField)
+		}
+		binary.BigEndian.PutUint32(lenBuf[:], uint32(len(f)))
+		body = append(body, lenBuf[:]...)
+		body = append(body, f...)
+	}
+	sum := sha256.Sum256(body)
+	return append(body, sum[:]...), nil
+}
+
+// UnmarshalStakingIdentity parses a blob produced by Marshal, verifying the
+// magic, version, field count, per-field length caps, and the trailing SHA-256
+// checksum (constant-time compare) before returning any field. A checksum
+// mismatch, truncation, trailing garbage, or oversize field is a hard error —
+// the node fails closed rather than boot with a half-parsed identity.
+func UnmarshalStakingIdentity(blob []byte) (*StakingIdentity, error) {
+	if len(blob) < len(stakingIdentityMagic)+2+sha256.Size {
+		return nil, fmt.Errorf("%w: blob too short (%d bytes)", ErrStakingIdentityCodec, len(blob))
+	}
+	// Split body || checksum and verify integrity FIRST (constant-time).
+	body := blob[:len(blob)-sha256.Size]
+	got := blob[len(blob)-sha256.Size:]
+	want := sha256.Sum256(body)
+	if subtle.ConstantTimeCompare(got, want[:]) != 1 {
+		return nil, fmt.Errorf("%w: integrity checksum mismatch", ErrStakingIdentityCodec)
+	}
+
+	off := 0
+	if subtle.ConstantTimeCompare(body[:len(stakingIdentityMagic)], stakingIdentityMagic) != 1 {
+		return nil, fmt.Errorf("%w: bad magic", ErrStakingIdentityCodec)
+	}
+	off += len(stakingIdentityMagic)
+	if body[off] != stakingIdentityVersion {
+		return nil, fmt.Errorf("%w: unsupported version %d", ErrStakingIdentityCodec, body[off])
+	}
+	off++
+	if body[off] != byte(stakingIdentityFieldCount) {
+		return nil, fmt.Errorf("%w: field count %d != %d", ErrStakingIdentityCodec, body[off], stakingIdentityFieldCount)
+	}
+	off++
+
+	out := make([][]byte, stakingIdentityFieldCount)
+	for i := 0; i < stakingIdentityFieldCount; i++ {
+		if off+4 > len(body) {
+			return nil, fmt.Errorf("%w: truncated length prefix (field %d)", ErrStakingIdentityCodec, i)
+		}
+		n := binary.BigEndian.Uint32(body[off : off+4])
+		off += 4
+		if n > maxStakingField {
+			return nil, fmt.Errorf("%w: field %d length %d exceeds cap %d", ErrStakingIdentityCodec, i, n, maxStakingField)
+		}
+		if off+int(n) > len(body) {
+			return nil, fmt.Errorf("%w: truncated field %d (need %d bytes)", ErrStakingIdentityCodec, i, n)
+		}
+		// Copy out of the caller's buffer so the returned identity owns its
+		// memory (and the caller can wipe/reuse the input blob).
+		out[i] = append([]byte(nil), body[off:off+int(n)]...)
+		off += int(n)
+	}
+	if off != len(body) {
+		return nil, fmt.Errorf("%w: %d trailing bytes after last field", ErrStakingIdentityCodec, len(body)-off)
+	}
+
+	return &StakingIdentity{
+		TLSCertPEM: out[0],
+		TLSKeyPEM:  out[1],
+		BLSSigner:  out[2],
+		MLDSAPriv:  out[3],
+		MLDSAPub:   out[4],
+		MLKEMPriv:  out[5],
+		MLKEMPub:   out[6],
+		NodeLabel:  out[7],
+	}, nil
+}
+
+// Wipe zeroes every SECRET field in place (TLS key, BLS signer, ML-DSA private,
+// ML-KEM private). Public materials are left intact — they are not sensitive
+// and the caller may still need the NodeID anchors for logging. Idempotent;
+// safe on nil.
+func (s *StakingIdentity) Wipe() {
+	if s == nil {
+		return
+	}
+	zero(s.TLSKeyPEM)
+	zero(s.BLSSigner)
+	zero(s.MLDSAPriv)
+	zero(s.MLKEMPriv)
+	s.TLSKeyPEM = nil
+	s.BLSSigner = nil
+	s.MLDSAPriv = nil
+	s.MLKEMPriv = nil
+}
+
+// StakingIdentityFromValidatorKey assembles a StakingIdentity from the classical
+// ValidatorKey (DeriveValidatorFromMnemonic / GenerateValidatorKey) and, when
+// non-nil, the strict-PQ PQValidatorKey (DeriveValidatorPQ). Pure — it copies
+// the referenced key bytes; the sources may be wiped afterward.
+func StakingIdentityFromValidatorKey(vk *ValidatorKey, pq *PQValidatorKey) *StakingIdentity {
+	s := &StakingIdentity{}
+	if vk != nil {
+		s.TLSCertPEM = append([]byte(nil), vk.StakerCert...)
+		s.TLSKeyPEM = append([]byte(nil), vk.StakerKey...)
+		s.BLSSigner = append([]byte(nil), vk.BLSSecretKey...)
+	}
+	if pq != nil {
+		s.MLDSAPriv = append([]byte(nil), pq.MLDSAPriv...)
+		s.MLDSAPub = append([]byte(nil), pq.MLDSAPub...)
+		s.MLKEMPriv = append([]byte(nil), pq.MLKEMPriv...)
+		s.MLKEMPub = append([]byte(nil), pq.MLKEMPub...)
+	}
+	return s
+}
diff --git a/staking_identity_test.go b/staking_identity_test.go
new file mode 100644
index 0000000..53834c0
--- /dev/null
+++ b/staking_identity_test.go
@@ -0,0 +1,240 @@
+// Copyright (C) 2024-2026, Lux Industries Inc. All rights reserved.
+// See the file LICENSE for licensing terms.
+
+package keys
+
+import (
+	"bytes"
+	"crypto/sha256"
+	"errors"
+	"testing"
+)
+
+// sample returns a fully-populated StakingIdentity with recognisable field
+// bytes so a round-trip can assert exact preservation.
+func sample() *StakingIdentity {
+	return &StakingIdentity{
+		TLSCertPEM: []byte("-----BEGIN CERTIFICATE-----\ncert\n-----END CERTIFICATE-----"),
+		TLSKeyPEM:  []byte("-----BEGIN PRIVATE KEY-----\ntlskey\n-----END PRIVATE KEY-----"),
+		BLSSigner:  bytes.Repeat([]byte{0xB1}, 32),
+		MLDSAPriv:  bytes.Repeat([]byte{0xD5}, 4032),
+		MLDSAPub:   bytes.Repeat([]byte{0xD6}, 1952),
+		MLKEMPriv:  bytes.Repeat([]byte{0xE7}, 2400),
+		MLKEMPub:   bytes.Repeat([]byte{0xE8}, 1184),
+		NodeLabel:  []byte("luxd-validator-2"),
+	}
+}
+
+func equalIdentity(a, b *StakingIdentity) bool {
+	return bytes.Equal(a.TLSCertPEM, b.TLSCertPEM) &&
+		bytes.Equal(a.TLSKeyPEM, b.TLSKeyPEM) &&
+		bytes.Equal(a.BLSSigner, b.BLSSigner) &&
+		bytes.Equal(a.MLDSAPriv, b.MLDSAPriv) &&
+		bytes.Equal(a.MLDSAPub, b.MLDSAPub) &&
+		bytes.Equal(a.MLKEMPriv, b.MLKEMPriv) &&
+		bytes.Equal(a.MLKEMPub, b.MLKEMPub) &&
+		bytes.Equal(a.NodeLabel, b.NodeLabel)
+}
+
+// Marshal → Unmarshal preserves every field byte-for-byte, and Marshal is
+// deterministic (same identity → identical blob).
+func TestStakingIdentity_RoundTrip(t *testing.T) {
+	in := sample()
+	blob, err := in.Marshal()
+	if err != nil {
+		t.Fatalf("marshal: %v", err)
+	}
+	blob2, err := in.Marshal()
+	if err != nil {
+		t.Fatalf("marshal 2: %v", err)
+	}
+	if !bytes.Equal(blob, blob2) {
+		t.Fatal("Marshal is not deterministic")
+	}
+	out, err := UnmarshalStakingIdentity(blob)
+	if err != nil {
+		t.Fatalf("unmarshal: %v", err)
+	}
+	if !equalIdentity(in, out) {
+		t.Fatal("round-trip did not preserve all fields")
+	}
+	if !out.HasClassical() || !out.HasStrictPQ() {
+		t.Fatal("expected both profiles present")
+	}
+}
+
+// The v2 NodeLabel field round-trips verbatim, is covered by the integrity
+// checksum, and an empty label (the DERIVE case) round-trips too.
+func TestStakingIdentity_NodeLabel(t *testing.T) {
+	in := sample()
+	in.NodeLabel = []byte("luxd-mainnet-node-07")
+	blob, err := in.Marshal()
+	if err != nil {
+		t.Fatalf("marshal: %v", err)
+	}
+	out, err := UnmarshalStakingIdentity(blob)
+	if err != nil {
+		t.Fatalf("unmarshal: %v", err)
+	}
+	if string(out.NodeLabel) != "luxd-mainnet-node-07" {
+		t.Fatalf("NodeLabel not preserved: %q", out.NodeLabel)
+	}
+
+	// Tampering with the label bytes is rejected by the checksum — the label
+	// cannot be swapped to point one node's blob at another node's label
+	// without failing integrity. The label lives just before the 32-byte tail.
+	bad := append([]byte(nil), blob...)
+	bad[len(bad)-sha256.Size-1] ^= 0xFF
+	if _, err := UnmarshalStakingIdentity(bad); err == nil {
+		t.Fatal("tampered NodeLabel was not rejected")
+	}
+
+	// Empty label (DERIVE identities carry none) round-trips.
+	noLabel := sample()
+	noLabel.NodeLabel = nil
+	nb, err := noLabel.Marshal()
+	if err != nil {
+		t.Fatalf("marshal no-label: %v", err)
+	}
+	back, err := UnmarshalStakingIdentity(nb)
+	if err != nil {
+		t.Fatalf("unmarshal no-label: %v", err)
+	}
+	if len(back.NodeLabel) != 0 {
+		t.Fatalf("expected empty NodeLabel, got %q", back.NodeLabel)
+	}
+}
+
+// Empty fields (classical-only, strict-PQ-only) round-trip exactly.
+func TestStakingIdentity_PartialProfiles(t *testing.T) {
+	classicalOnly := &StakingIdentity{
+		TLSCertPEM: []byte("cert"), TLSKeyPEM: []byte("key"), BLSSigner: []byte("bls"),
+	}
+	pqOnly := &StakingIdentity{
+		MLDSAPriv: []byte("dp"), MLDSAPub: []byte("dP"),
+		MLKEMPriv: []byte("kp"), MLKEMPub: []byte("kP"),
+	}
+	for name, in := range map[string]*StakingIdentity{"classical": classicalOnly, "pq": pqOnly} {
+		blob, err := in.Marshal()
+		if err != nil {
+			t.Fatalf("%s marshal: %v", name, err)
+		}
+		out, err := UnmarshalStakingIdentity(blob)
+		if err != nil {
+			t.Fatalf("%s unmarshal: %v", name, err)
+		}
+		if !equalIdentity(in, out) {
+			t.Fatalf("%s round-trip mismatch", name)
+		}
+	}
+	if !classicalOnly.HasClassical() || classicalOnly.HasStrictPQ() {
+		t.Fatal("classicalOnly profile flags wrong")
+	}
+	if pqOnly.HasClassical() || !pqOnly.HasStrictPQ() {
+		t.Fatal("pqOnly profile flags wrong")
+	}
+}
+
+// A single flipped byte anywhere in the blob is rejected by the integrity
+// checksum — the node fails closed rather than boot a half-parsed identity.
+func TestStakingIdentity_TamperRejected(t *testing.T) {
+	blob, err := sample().Marshal()
+	if err != nil {
+		t.Fatalf("marshal: %v", err)
+	}
+	for _, pos := range []int{0, 11, 20, len(blob) / 2, len(blob) - 1} {
+		bad := append([]byte(nil), blob...)
+		bad[pos] ^= 0xFF
+		if _, err := UnmarshalStakingIdentity(bad); err == nil {
+			t.Fatalf("flip at %d was not rejected", pos)
+		} else if !errors.Is(err, ErrStakingIdentityCodec) {
+			t.Fatalf("flip at %d: wrong error type: %v", pos, err)
+		}
+	}
+}
+
+// Truncation is rejected (short blob and body cut before the checksum).
+func TestStakingIdentity_TruncationRejected(t *testing.T) {
+	blob, _ := sample().Marshal()
+	for _, cut := range []int{0, 5, len(blob) - 40, len(blob) - 1} {
+		if cut < 0 {
+			continue
+		}
+		if _, err := UnmarshalStakingIdentity(blob[:cut]); err == nil {
+			t.Fatalf("truncation to %d bytes was not rejected", cut)
+		}
+	}
+}
+
+// Trailing garbage after a valid blob is rejected (checksum covers exact body).
+func TestStakingIdentity_TrailingGarbageRejected(t *testing.T) {
+	blob, _ := sample().Marshal()
+	if _, err := UnmarshalStakingIdentity(append(blob, 0x00)); err == nil {
+		t.Fatal("trailing byte was not rejected")
+	}
+}
+
+// A hostile oversize length prefix is rejected before allocation.
+func TestStakingIdentity_OversizeFieldRejected(t *testing.T) {
+	big := &StakingIdentity{TLSCertPEM: bytes.Repeat([]byte{1}, maxStakingField+1)}
+	if _, err := big.Marshal(); err == nil {
+		t.Fatal("Marshal accepted an oversize field")
+	}
+}
+
+// A blob with the wrong magic is rejected even if its checksum is valid.
+func TestStakingIdentity_BadMagicRejected(t *testing.T) {
+	blob, _ := sample().Marshal()
+	// Corrupt magic, then re-checksum so only the magic check can catch it.
+	bad := append([]byte(nil), blob...)
+	bad[0] = 'X'
+	// Recompute checksum over the tampered body so integrity passes.
+	body := bad[:len(bad)-32]
+	if _, err := UnmarshalStakingIdentity(reChecksum(body)); err == nil {
+		t.Fatal("bad magic with valid checksum was not rejected")
+	}
+}
+
+// Wipe zeroes secrets, preserves public materials.
+func TestStakingIdentity_Wipe(t *testing.T) {
+	in := sample()
+	pub := append([]byte(nil), in.MLDSAPub...)
+	in.Wipe()
+	if in.TLSKeyPEM != nil || in.BLSSigner != nil || in.MLDSAPriv != nil || in.MLKEMPriv != nil {
+		t.Fatal("Wipe left a secret slice non-nil")
+	}
+	if !bytes.Equal(in.MLDSAPub, pub) || len(in.TLSCertPEM) == 0 || len(in.MLKEMPub) == 0 {
+		t.Fatal("Wipe destroyed public material")
+	}
+	in.Wipe() // idempotent
+}
+
+// StakingIdentityFromValidatorKey copies source bytes (wiping the source after
+// does not corrupt the bundle).
+func TestStakingIdentityFromValidatorKey_Copies(t *testing.T) {
+	pq, err := DeriveValidatorPQ(validMnemonic, 0)
+	if err != nil {
+		t.Fatalf("derive pq: %v", err)
+	}
+	vk := &ValidatorKey{
+		StakerCert:   []byte("cert"),
+		StakerKey:    []byte("key"),
+		BLSSecretKey: []byte("bls"),
+	}
+	bundle := StakingIdentityFromValidatorKey(vk, pq)
+	pqPub := append([]byte(nil), pq.MLDSAPub...)
+	pq.Wipe()
+	if !bytes.Equal(bundle.MLDSAPub, pqPub) {
+		t.Fatal("bundle shares memory with source (source wipe leaked)")
+	}
+	if !bundle.HasClassical() || !bundle.HasStrictPQ() {
+		t.Fatal("bundle missing a profile")
+	}
+}
+
+// reChecksum recomputes the SHA-256 tail for a hand-tampered body so a test can
+// isolate a non-integrity check (e.g. magic/version) from the checksum guard.
+func reChecksum(body []byte) []byte {
+	sum := sha256.Sum256(body)
+	return append(append([]byte(nil), body...), sum[:]...)
+}