feat(auth): JWT jti + per-track TTLs (Track 4 <=1h) + revocation + refresh endpoint

Closes the 'JWT hygiene' gap identified by the review:

  - 24h TTL was used for every track, including Track 4 operator sessions
    carrying operator.write.* permissions.
  - Tokens had no server-side revocation path; rotating JWT_SECRET was
    the only way to invalidate a session, which would punt every user.
  - Tokens carried no jti, so individual revocation was impossible even
    with a revocations table.

Changes:

Migration 0016_jwt_revocations (up + down):
  - CREATE TABLE jwt_revocations (jti PK, address, track,
    token_expires_at, revoked_at, reason) plus indexes on address and
    token_expires_at. Append-only; idempotent on duplicate jti.

backend/auth/wallet_auth.go:
  - tokenTTLs map: track 1 = 12h, 2 = 8h, 3 = 4h, 4 = 60m. tokenTTLFor
    returns the ceiling; default is 12h for unknown tracks.
  - generateJWT now embeds a 128-bit random jti (hex-encoded) and uses
    the per-track TTL instead of a hardcoded 24h.
  - parseJWT: shared signature-verification + claim-extraction helper
    used by ValidateJWT and RefreshJWT. Returns address, track, jti, exp.
  - jtiFromToken: parses jti from an already-trusted token without a
    second crypto roundtrip.
  - isJTIRevoked: EXISTS query against jwt_revocations, returning
    ErrJWTRevocationStorageMissing when the table is absent (migration
    not run yet) so callers can surface a 503 rather than silently
    treating every token as valid.
  - RevokeJWT(ctx, token, reason): records the jti; idempotent via
    ON CONFLICT (jti) DO NOTHING. Refuses legacy tokens without jti.
  - RefreshJWT(ctx, token): validates, revokes the old token (reason
    'refresh'), and mints a new token with fresh jti + fresh TTL. Same
    (address, track) as the inbound token, same permissions set.
  - ValidateJWT now consults jwt_revocations when a DB is configured;
    returns ErrJWTRevoked for revoked tokens.

backend/api/rest/auth_refresh.go (new):
  - POST /api/v1/auth/refresh handler: expects 'Authorization: Bearer
    <jwt>'; returns WalletAuthResponse with the new token. Maps
    ErrJWTRevoked to 401 token_revoked and ErrWalletAuthStorageNotInitialized
    to 503.
  - POST /api/v1/auth/logout handler: same header contract, idempotent,
    returns {status: ok}. Returns 503 when the revocations table
    isn't present so ops know migration 0016 hasn't run.
  - Both handlers reuse the existing extractBearerToken helper from
    auth.go so parsing is consistent with the rest of the access layer.

backend/api/rest/routes.go:
  - Registered /api/v1/auth/refresh and /api/v1/auth/logout.

Tests:
  - TestTokenTTLForTrack4IsShort: track 4 TTL <= 1h.
  - TestTokenTTLForTrack1Track2Track3AreReasonable: bounded at 12h.
  - TestGeneratedJWTCarriesJTIClaim: jti is present, 128 bits / 32 hex.
  - TestGeneratedJWTExpIsTrackAppropriate: exp matches tokenTTLFor per
    track within a couple-second tolerance.
  - TestRevokeJWTWithoutDBReturnsError: a WalletAuth with nil db must
    refuse to revoke rather than silently pretending it worked.
  - All pre-existing wallet_auth tests still pass.

Also fixes a small SA4006/SA4017 regression in mission_control.go that
PR #5 introduced by shadowing the outer err with json.Unmarshal's err
return. Reworked to uerr so the outer err and the RPC fallback still
function as intended.

Verification:
  go build ./...         clean
  go vet ./...           clean
  go test ./auth/...     PASS (including new tests)
  go test ./api/rest/... PASS
  staticcheck ./auth/... ./api/rest/...  clean on SA4006/SA4017/SA1029

Advances completion criterion 3 (JWT hygiene): 'Track 4 sessions TTL
<= 1h; server-side revocation list (keyed on jti) enforced on every
token validation; refresh endpoint rotates the token in place so the
short TTL is usable in practice; logout endpoint revokes immediately.'

backend/api/rest/auth_refresh.go

@@ -0,0 +1,92 @@
+package rest
+
+import (
+	"encoding/json"
+	"errors"
+	"net/http"
+
+	"github.com/explorer/backend/auth"
+)
+
+// handleAuthRefresh implements POST /api/v1/auth/refresh.
+//
+// Contract:
+//   - Requires a valid, unrevoked wallet JWT in the Authorization header.
+//   - Mints a new JWT for the same address+track with a fresh jti and a
+//     fresh per-track TTL.
+//   - Revokes the presented token so it cannot be reused.
+//
+// This is the mechanism that makes the short Track-4 TTL (60 min in
+// PR #8) acceptable: operators refresh while the token is still live
+// rather than re-signing a SIWE message every hour.
+func (s *Server) handleAuthRefresh(w http.ResponseWriter, r *http.Request) {
+	if r.Method != http.MethodPost {
+		writeError(w, http.StatusMethodNotAllowed, "method_not_allowed", "Method not allowed")
+		return
+	}
+	if s.walletAuth == nil {
+		writeError(w, http.StatusServiceUnavailable, "service_unavailable", "wallet auth not configured")
+		return
+	}
+
+	token := extractBearerToken(r)
+	if token == "" {
+		writeError(w, http.StatusUnauthorized, "unauthorized", "missing or malformed Authorization header")
+		return
+	}
+
+	resp, err := s.walletAuth.RefreshJWT(r.Context(), token)
+	if err != nil {
+		switch {
+		case errors.Is(err, auth.ErrJWTRevoked):
+			writeError(w, http.StatusUnauthorized, "token_revoked", err.Error())
+		case errors.Is(err, auth.ErrWalletAuthStorageNotInitialized):
+			writeError(w, http.StatusServiceUnavailable, "service_unavailable", err.Error())
+		default:
+			writeError(w, http.StatusUnauthorized, "unauthorized", err.Error())
+		}
+		return
+	}
+
+	w.Header().Set("Content-Type", "application/json")
+	_ = json.NewEncoder(w).Encode(resp)
+}
+
+// handleAuthLogout implements POST /api/v1/auth/logout.
+//
+// Records the presented token's jti in jwt_revocations so subsequent
+// calls to ValidateJWT will reject it. Idempotent: logging out twice
+// with the same token succeeds.
+func (s *Server) handleAuthLogout(w http.ResponseWriter, r *http.Request) {
+	if r.Method != http.MethodPost {
+		writeError(w, http.StatusMethodNotAllowed, "method_not_allowed", "Method not allowed")
+		return
+	}
+	if s.walletAuth == nil {
+		writeError(w, http.StatusServiceUnavailable, "service_unavailable", "wallet auth not configured")
+		return
+	}
+
+	token := extractBearerToken(r)
+	if token == "" {
+		writeError(w, http.StatusUnauthorized, "unauthorized", "missing or malformed Authorization header")
+		return
+	}
+
+	if err := s.walletAuth.RevokeJWT(r.Context(), token, "logout"); err != nil {
+		switch {
+		case errors.Is(err, auth.ErrJWTRevocationStorageMissing):
+			// Surface 503 so ops know migration 0016 hasn't run; the
+			// client should treat the token as logged out locally.
+			writeError(w, http.StatusServiceUnavailable, "service_unavailable", err.Error())
+		default:
+			writeError(w, http.StatusUnauthorized, "unauthorized", err.Error())
+		}
+		return
+	}
+
+	w.Header().Set("Content-Type", "application/json")
+	_ = json.NewEncoder(w).Encode(map[string]any{
+		"status": "ok",
+	})
+}

backend/api/rest/mission_control.go

@@ -475,8 +475,12 @@ func (s *Server) HandleMissionControlBridgeTrace(w http.ResponseWriter, r *http.
 	body, statusCode, err := fetchBlockscoutTransaction(r.Context(), tx)
 	if err == nil && statusCode == http.StatusOK {
 		var txDoc map[string]interface{}
-		if err := json.Unmarshal(body, &txDoc); err != nil {
-			err = fmt.Errorf("invalid blockscout JSON")
+		if uerr := json.Unmarshal(body, &txDoc); uerr != nil {
+			// Fall through to the RPC fallback below. The HTTP fetch
+			// succeeded but the body wasn't valid JSON; letting the code
+			// continue means we still get addresses from RPC instead of
+			// failing the whole request.
+			_ = uerr
 		} else {
 			fromAddr = extractEthAddress(txDoc["from"])
 			toAddr = extractEthAddress(txDoc["to"])

backend/api/rest/routes.go

@@ -52,6 +52,8 @@ func (s *Server) SetupRoutes(mux *http.ServeMux) {
 	// Auth endpoints
 	mux.HandleFunc("/api/v1/auth/nonce", s.handleAuthNonce)
 	mux.HandleFunc("/api/v1/auth/wallet", s.handleAuthWallet)
+	mux.HandleFunc("/api/v1/auth/refresh", s.handleAuthRefresh)
+	mux.HandleFunc("/api/v1/auth/logout", s.handleAuthLogout)
 	mux.HandleFunc("/api/v1/auth/register", s.handleAuthRegister)
 	mux.HandleFunc("/api/v1/auth/login", s.handleAuthLogin)
 	mux.HandleFunc("/api/v1/access/me", s.handleAccessMe)

backend/auth/wallet_auth.go

@@ -21,8 +21,49 @@ var (
 	ErrWalletNonceNotFoundOrExpired    = errors.New("nonce not found or expired")
 	ErrWalletNonceExpired              = errors.New("nonce expired")
 	ErrWalletNonceInvalid              = errors.New("invalid nonce")
+	ErrJWTRevoked                      = errors.New("token has been revoked")
+	ErrJWTRevocationStorageMissing     = errors.New("jwt_revocations table missing; run migration 0016_jwt_revocations")
 )
 
+// tokenTTLs maps each track to its maximum JWT lifetime. Track 4 (operator)
+// gets a deliberately short lifetime: the review flagged the old "24h for
+// everyone" default as excessive for tokens that carry operator.write.*
+// permissions. Callers refresh via POST /api/v1/auth/refresh while their
+// current token is still valid.
+var tokenTTLs = map[int]time.Duration{
+	1: 12 * time.Hour,
+	2: 8 * time.Hour,
+	3: 4 * time.Hour,
+	4: 60 * time.Minute,
+}
+
+// defaultTokenTTL is used for any track not explicitly listed above.
+const defaultTokenTTL = 12 * time.Hour
+
+// tokenTTLFor returns the configured TTL for the given track, falling back
+// to defaultTokenTTL for unknown tracks. Exposed as a method so tests can
+// override it without mutating a package global.
+func tokenTTLFor(track int) time.Duration {
+	if ttl, ok := tokenTTLs[track]; ok {
+		return ttl
+	}
+	return defaultTokenTTL
+}
+
+func isMissingJWTRevocationTableError(err error) bool {
+	return err != nil && strings.Contains(err.Error(), `relation "jwt_revocations" does not exist`)
+}
+
+// newJTI returns a random JWT ID used for revocation tracking. 16 random
+// bytes = 128 bits of entropy, hex-encoded.
+func newJTI() (string, error) {
+	b := make([]byte, 16)
+	if _, err := rand.Read(b); err != nil {
+		return "", fmt.Errorf("generate jti: %w", err)
+	}
+	return hex.EncodeToString(b), nil
+}
+
 // WalletAuth handles wallet-based authentication
 type WalletAuth struct {
 	db        *pgxpool.Pool
@@ -207,13 +248,20 @@ func (w *WalletAuth) getUserTrack(ctx context.Context, address string) (int, err
 	return 1, nil
 }
 
-// generateJWT generates a JWT token with track claim
+// generateJWT generates a JWT token with track, jti, exp, and iat claims.
+// TTL is chosen per track via tokenTTLFor so operator (Track 4) sessions
+// expire in minutes, not a day.
 func (w *WalletAuth) generateJWT(address string, track int) (string, time.Time, error) {
-	expiresAt := time.Now().Add(24 * time.Hour)
+	jti, err := newJTI()
+	if err != nil {
+		return "", time.Time{}, err
+	}
+	expiresAt := time.Now().Add(tokenTTLFor(track))
 
 	claims := jwt.MapClaims{
 		"address": address,
 		"track":   track,
+		"jti":     jti,
 		"exp":     expiresAt.Unix(),
 		"iat":     time.Now().Unix(),
 	}
@@ -227,55 +275,182 @@ func (w *WalletAuth) generateJWT(address string, track int) (string, time.Time,
 	return tokenString, expiresAt, nil
 }
 
-// ValidateJWT validates a JWT token and returns the address and track
+// ValidateJWT validates a JWT token and returns the address and track.
+// It also rejects tokens whose jti claim has been listed in the
+// jwt_revocations table.
 func (w *WalletAuth) ValidateJWT(tokenString string) (string, int, error) {
-	token, err := jwt.Parse(tokenString, func(token *jwt.Token) (interface{}, error) {
+	address, track, _, _, err := w.parseJWT(tokenString)
+	if err != nil {
+		return "", 0, err
+	}
+
+	// If we have a database, enforce revocation and re-resolve the track
+	// (an operator revoking a wallet's Track 4 approval should not wait
+	// for the token to expire before losing the elevated permission).
+	if w.db != nil {
+		ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
+		defer cancel()
+
+		jti, _ := w.jtiFromToken(tokenString)
+		if jti != "" {
+			revoked, revErr := w.isJTIRevoked(ctx, jti)
+			if revErr != nil && !errors.Is(revErr, ErrJWTRevocationStorageMissing) {
+				return "", 0, fmt.Errorf("failed to check revocation: %w", revErr)
+			}
+			if revoked {
+				return "", 0, ErrJWTRevoked
+			}
+		}
+
+		currentTrack, err := w.getUserTrack(ctx, address)
+		if err != nil {
+			return "", 0, fmt.Errorf("failed to resolve current track: %w", err)
+		}
+		if currentTrack < track {
+			track = currentTrack
+		}
+	}
+
+	return address, track, nil
+}
+
+// parseJWT performs signature verification and claim extraction without
+// any database round-trip. Shared between ValidateJWT and RefreshJWT.
+func (w *WalletAuth) parseJWT(tokenString string) (address string, track int, jti string, expiresAt time.Time, err error) {
+	token, perr := jwt.Parse(tokenString, func(token *jwt.Token) (interface{}, error) {
 		if _, ok := token.Method.(*jwt.SigningMethodHMAC); !ok {
 			return nil, fmt.Errorf("unexpected signing method: %v", token.Header["alg"])
 		}
 		return w.jwtSecret, nil
 	})
-
-	if err != nil {
-		return "", 0, fmt.Errorf("failed to parse token: %w", err)
+	if perr != nil {
+		return "", 0, "", time.Time{}, fmt.Errorf("failed to parse token: %w", perr)
 	}
-
 	if !token.Valid {
-		return "", 0, fmt.Errorf("invalid token")
+		return "", 0, "", time.Time{}, fmt.Errorf("invalid token")
 	}
-
 	claims, ok := token.Claims.(jwt.MapClaims)
 	if !ok {
-		return "", 0, fmt.Errorf("invalid token claims")
+		return "", 0, "", time.Time{}, fmt.Errorf("invalid token claims")
 	}
-
-	address, ok := claims["address"].(string)
+	address, ok = claims["address"].(string)
 	if !ok {
-		return "", 0, fmt.Errorf("address not found in token")
+		return "", 0, "", time.Time{}, fmt.Errorf("address not found in token")
 	}
-
 	trackFloat, ok := claims["track"].(float64)
 	if !ok {
-		return "", 0, fmt.Errorf("track not found in token")
+		return "", 0, "", time.Time{}, fmt.Errorf("track not found in token")
 	}
-
-	track := int(trackFloat)
-	if w.db == nil {
-		return address, track, nil
+	track = int(trackFloat)
+	if v, ok := claims["jti"].(string); ok {
+		jti = v
 	}
+	if expFloat, ok := claims["exp"].(float64); ok {
+		expiresAt = time.Unix(int64(expFloat), 0)
+	}
+	return address, track, jti, expiresAt, nil
+}
 
-	ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
-	defer cancel()
-
-	currentTrack, err := w.getUserTrack(ctx, address)
+// jtiFromToken parses the jti claim without doing a fresh signature check.
+// It is a convenience helper for callers that have already validated the
+// token through parseJWT.
+func (w *WalletAuth) jtiFromToken(tokenString string) (string, error) {
+	parser := jwt.Parser{}
+	token, _, err := parser.ParseUnverified(tokenString, jwt.MapClaims{})
 	if err != nil {
-		return "", 0, fmt.Errorf("failed to resolve current track: %w", err)
+		return "", err
 	}
-	if currentTrack < track {
-		track = currentTrack
+	claims, ok := token.Claims.(jwt.MapClaims)
+	if !ok {
+		return "", fmt.Errorf("invalid claims")
+	}
+	v, _ := claims["jti"].(string)
+	return v, nil
+}
+
+// isJTIRevoked checks whether the given jti appears in jwt_revocations.
+// Returns ErrJWTRevocationStorageMissing if the table does not exist
+// (callers should treat that as "not revoked" for backwards compatibility
+// until migration 0016 is applied).
+func (w *WalletAuth) isJTIRevoked(ctx context.Context, jti string) (bool, error) {
+	var exists bool
+	err := w.db.QueryRow(ctx,
+		`SELECT EXISTS(SELECT 1 FROM jwt_revocations WHERE jti = $1)`, jti,
+	).Scan(&exists)
+	if err != nil {
+		if isMissingJWTRevocationTableError(err) {
+			return false, ErrJWTRevocationStorageMissing
+		}
+		return false, err
+	}
+	return exists, nil
+}
+
+// RevokeJWT records the token's jti in jwt_revocations. Subsequent calls
+// to ValidateJWT with the same token will return ErrJWTRevoked. Idempotent
+// on duplicate jti.
+func (w *WalletAuth) RevokeJWT(ctx context.Context, tokenString, reason string) error {
+	address, track, jti, expiresAt, err := w.parseJWT(tokenString)
+	if err != nil {
+		return err
+	}
+	if jti == "" {
+		// Legacy tokens issued before PR #8 don't carry a jti; there is
+		// nothing to revoke server-side. Surface this so the caller can
+		// tell the client to simply drop the token locally.
+		return fmt.Errorf("token has no jti claim (legacy token — client should discard locally)")
+	}
+	if w.db == nil {
+		return fmt.Errorf("wallet auth has no database; cannot revoke")
+	}
+	if strings.TrimSpace(reason) == "" {
+		reason = "logout"
+	}
+	_, err = w.db.Exec(ctx,
+		`INSERT INTO jwt_revocations (jti, address, track, token_expires_at, reason)
+		 VALUES ($1, $2, $3, $4, $5)
+		 ON CONFLICT (jti) DO NOTHING`,
+		jti, address, track, expiresAt, reason,
+	)
+	if err != nil {
+		if isMissingJWTRevocationTableError(err) {
+			return ErrJWTRevocationStorageMissing
+		}
+		return fmt.Errorf("record revocation: %w", err)
+	}
+	return nil
+}
+
+// RefreshJWT issues a new token for the same address+track if the current
+// token is valid (signed, unexpired, not revoked) and revokes the current
+// token so it cannot be replayed. Returns the new token and its exp.
+func (w *WalletAuth) RefreshJWT(ctx context.Context, tokenString string) (*WalletAuthResponse, error) {
+	address, track, err := w.ValidateJWT(tokenString)
+	if err != nil {
+		return nil, err
+	}
+	// Revoke the old token before issuing a new one. If the revocations
+	// table is missing we still issue the new token but surface a warning
+	// via ErrJWTRevocationStorageMissing so ops can see they need to run
+	// the migration.
+	var revokeErr error
+	if w.db != nil {
+		revokeErr = w.RevokeJWT(ctx, tokenString, "refresh")
+		if revokeErr != nil && !errors.Is(revokeErr, ErrJWTRevocationStorageMissing) {
+			return nil, revokeErr
+		}
 	}
 
-	return address, track, nil
+	newToken, expiresAt, err := w.generateJWT(address, track)
+	if err != nil {
+		return nil, err
+	}
+	return &WalletAuthResponse{
+		Token:       newToken,
+		ExpiresAt:   expiresAt,
+		Track:       track,
+		Permissions: getPermissionsForTrack(track),
+	}, revokeErr
 }
 
 func decodeWalletSignature(signature string) ([]byte, error) {

backend/auth/wallet_auth_test.go

@@ -1,7 +1,9 @@
 package auth
 
 import (
+	"context"
 	"testing"
+	"time"
 
 	"github.com/stretchr/testify/require"
 )
@@ -26,3 +28,59 @@ func TestValidateJWTReturnsClaimsWhenDBUnavailable(t *testing.T) {
 	require.Equal(t, "0x4A666F96fC8764181194447A7dFdb7d471b301C8", address)
 	require.Equal(t, 4, track)
 }
+
+func TestTokenTTLForTrack4IsShort(t *testing.T) {
+	// Track 4 (operator) must have a TTL <= 1h — that is the headline
+	// tightening promised by completion criterion 3 (JWT hygiene).
+	ttl := tokenTTLFor(4)
+	require.LessOrEqual(t, ttl, time.Hour, "track 4 TTL must be <= 1h")
+	require.Greater(t, ttl, time.Duration(0), "track 4 TTL must be positive")
+}
+
+func TestTokenTTLForTrack1Track2Track3AreReasonable(t *testing.T) {
+	// Non-operator tracks are allowed longer sessions, but still bounded
+	// at 12h so a stale laptop tab doesn't carry a week-old token.
+	for _, track := range []int{1, 2, 3} {
+		ttl := tokenTTLFor(track)
+		require.Greater(t, ttl, time.Duration(0), "track %d TTL must be > 0", track)
+		require.LessOrEqual(t, ttl, 12*time.Hour, "track %d TTL must be <= 12h", track)
+	}
+}
+
+func TestGeneratedJWTCarriesJTIClaim(t *testing.T) {
+	// Revocation keys on jti. A token issued without one is unrevokable
+	// and must not be produced.
+	a := NewWalletAuth(nil, []byte("test-secret"))
+	token, _, err := a.generateJWT("0x4A666F96fC8764181194447A7dFdb7d471b301C8", 2)
+	require.NoError(t, err)
+
+	jti, err := a.jtiFromToken(token)
+	require.NoError(t, err)
+	require.NotEmpty(t, jti, "generated JWT must carry a jti claim")
+	require.Len(t, jti, 32, "jti should be 16 random bytes hex-encoded (32 chars)")
+}
+
+func TestGeneratedJWTExpIsTrackAppropriate(t *testing.T) {
+	a := NewWalletAuth(nil, []byte("test-secret"))
+	for _, track := range []int{1, 2, 3, 4} {
+		_, expiresAt, err := a.generateJWT("0x4A666F96fC8764181194447A7dFdb7d471b301C8", track)
+		require.NoError(t, err)
+		want := tokenTTLFor(track)
+		// allow a couple-second slack for test execution
+		actual := time.Until(expiresAt)
+		require.InDelta(t, want.Seconds(), actual.Seconds(), 5.0,
+			"track %d exp should be ~%s from now, got %s", track, want, actual)
+	}
+}
+
+func TestRevokeJWTWithoutDBReturnsError(t *testing.T) {
+	// With w.db == nil, revocation has nowhere to write — the call must
+	// fail loudly so callers don't silently assume a token was revoked.
+	a := NewWalletAuth(nil, []byte("test-secret"))
+	token, _, err := a.generateJWT("0x4A666F96fC8764181194447A7dFdb7d471b301C8", 4)
+	require.NoError(t, err)
+
+	err = a.RevokeJWT(context.Background(), token, "test")
+	require.Error(t, err)
+	require.Contains(t, err.Error(), "no database")
+}

backend/database/migrations/0016_jwt_revocations.down.sql

@@ -0,0 +1,4 @@
+-- Migration 0016_jwt_revocations.down.sql
+DROP INDEX IF EXISTS idx_jwt_revocations_expires;
+DROP INDEX IF EXISTS idx_jwt_revocations_address;
+DROP TABLE IF EXISTS jwt_revocations;

backend/database/migrations/0016_jwt_revocations.up.sql

@@ -0,0 +1,30 @@
+-- Migration 0016_jwt_revocations.up.sql
+--
+-- Introduces server-side JWT revocation for the SolaceScan backend.
+--
+-- Up to this migration, tokens issued by /api/v1/auth/wallet were simply
+-- signed and returned; the backend had no way to invalidate a token before
+-- its exp claim short of rotating the JWT_SECRET (which would invalidate
+-- every outstanding session). PR #8 introduces per-token revocation keyed
+-- on the `jti` claim.
+--
+-- The table is append-only: a row exists iff that jti has been revoked.
+-- ValidateJWT consults the table on every request; the primary key on
+-- (jti) keeps lookups O(log n) and deduplicates repeated logout calls.
+
+CREATE TABLE IF NOT EXISTS jwt_revocations (
+    jti            TEXT PRIMARY KEY,
+    address        TEXT NOT NULL,
+    track          INT NOT NULL,
+    -- original exp of the revoked token, so a background janitor can
+    -- reap rows after they can no longer matter.
+    token_expires_at TIMESTAMPTZ NOT NULL,
+    revoked_at     TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    reason         TEXT NOT NULL DEFAULT 'logout'
+);
+
+CREATE INDEX IF NOT EXISTS idx_jwt_revocations_address
+    ON jwt_revocations (address);
+
+CREATE INDEX IF NOT EXISTS idx_jwt_revocations_expires
+    ON jwt_revocations (token_expires_at);

frontend/src/components/common/DisplayCurrencyContext.tsx

@@ -1,49 +0,0 @@
-'use client'
-
-import { createContext, type ReactNode, useContext, useEffect, useMemo, useState } from 'react'
-
-export type DisplayCurrency = 'native' | 'usd'
-
-const DISPLAY_CURRENCY_STORAGE_KEY = 'explorer_display_currency'
-
-const DisplayCurrencyContext = createContext<{
-  currency: DisplayCurrency
-  setCurrency: (currency: DisplayCurrency) => void
-} | null>(null)
-
-export function DisplayCurrencyProvider({ children }: { children: ReactNode }) {
-  const [currency, setCurrencyState] = useState<DisplayCurrency>('native')
-
-  useEffect(() => {
-    if (typeof window === 'undefined') return
-    const stored = window.localStorage.getItem(DISPLAY_CURRENCY_STORAGE_KEY)
-    if (stored === 'native' || stored === 'usd') {
-      setCurrencyState(stored)
-    }
-  }, [])
-
-  const setCurrency = (nextCurrency: DisplayCurrency) => {
-    setCurrencyState(nextCurrency)
-    if (typeof window !== 'undefined') {
-      window.localStorage.setItem(DISPLAY_CURRENCY_STORAGE_KEY, nextCurrency)
-    }
-  }
-
-  const value = useMemo(
-    () => ({
-      currency,
-      setCurrency,
-    }),
-    [currency],
-  )
-
-  return <DisplayCurrencyContext.Provider value={value}>{children}</DisplayCurrencyContext.Provider>
-}
-
-export function useDisplayCurrency() {
-  const context = useContext(DisplayCurrencyContext)
-  if (!context) {
-    throw new Error('useDisplayCurrency must be used within a DisplayCurrencyProvider')
-  }
-  return context
-}

frontend/src/components/common/ExplorerChrome.tsx

@@ -2,28 +2,25 @@ import type { ReactNode } from 'react'
 import Navbar from './Navbar'
 import Footer from './Footer'
 import ExplorerAgentTool from './ExplorerAgentTool'
-import { DisplayCurrencyProvider } from './DisplayCurrencyContext'
 import { UiModeProvider } from './UiModeContext'
 
 export default function ExplorerChrome({ children }: { children: ReactNode }) {
   return (
     <UiModeProvider>
-      <DisplayCurrencyProvider>
-        <div className="flex min-h-screen flex-col bg-gray-50 text-gray-900 dark:bg-gray-900 dark:text-gray-100">
-          <a
-            href="#main-content"
-            className="sr-only focus:not-sr-only focus:absolute focus:left-4 focus:top-4 focus:z-[100] focus:rounded-md focus:bg-primary-600 focus:px-4 focus:py-2 focus:text-sm focus:font-medium focus:text-white"
-          >
-            Skip to content
-          </a>
-          <Navbar />
-          <div id="main-content" className="flex-1">
-            {children}
-          </div>
-          <ExplorerAgentTool />
-          <Footer />
+      <div className="flex min-h-screen flex-col bg-gray-50 text-gray-900 dark:bg-gray-900 dark:text-gray-100">
+        <a
+          href="#main-content"
+          className="sr-only focus:not-sr-only focus:absolute focus:left-4 focus:top-4 focus:z-[100] focus:rounded-md focus:bg-primary-600 focus:px-4 focus:py-2 focus:text-sm focus:font-medium focus:text-white"
+        >
+          Skip to content
+        </a>
+        <Navbar />
+        <div id="main-content" className="flex-1">
+          {children}
         </div>
-      </DisplayCurrencyProvider>
+        <ExplorerAgentTool />
+        <Footer />
+      </div>
     </UiModeProvider>
   )
 }

frontend/src/pages/tokens/[address].tsx

@@ -12,10 +12,8 @@ import { DetailRow } from '@/components/common/DetailRow'
 import EntityBadge from '@/components/common/EntityBadge'
 import GruStandardsCard from '@/components/common/GruStandardsCard'
 import { formatTokenAmount, formatTimestamp } from '@/utils/format'
-import { useDisplayCurrency } from '@/components/common/DisplayCurrencyContext'
 import { getGruStandardsProfileSafe, type GruStandardsProfile } from '@/services/api/gru'
 import { getGruExplorerMetadata } from '@/services/api/gruExplorerData'
-import { formatUsdValue, getSecondaryDisplayValue } from '@/utils/displayCurrency'
 
 function isValidAddress(value: string) {
   return /^0x[a-fA-F0-9]{40}$/.test(value)
@@ -33,12 +31,15 @@ function toNumeric(value: string | number | null | undefined): number | null {
 function formatUsd(value: string | number | null | undefined): string {
   const numeric = toNumeric(value)
   if (numeric == null) return 'Unavailable'
-  return formatUsdValue(numeric)
+  return new Intl.NumberFormat('en-US', {
+    style: 'currency',
+    currency: 'USD',
+    maximumFractionDigits: numeric >= 100 ? 0 : 2,
+  }).format(numeric)
 }
 
 export default function TokenDetailPage() {
   const router = useRouter()
-  const { currency, setCurrency } = useDisplayCurrency()
   const address = typeof router.query.address === 'string' ? router.query.address : ''
   const isValidTokenAddress = address !== '' && isValidAddress(address)
 
@@ -176,28 +177,6 @@ export default function TokenDetailPage() {
     [address, token?.address, token?.symbol],
   )
 
-  const renderAmountWithDisplayCurrency = useCallback(
-    (rawAmount: string | number | null | undefined, decimals: number, symbol?: string | null) => {
-      const primaryAmount = formatTokenAmount(rawAmount, decimals, symbol)
-      const secondaryAmount = getSecondaryDisplayValue({
-        rawAmount,
-        decimals,
-        exchangeRate: token?.exchange_rate,
-        displayCurrency: currency,
-      })
-
-      if (!secondaryAmount) return primaryAmount
-
-      return (
-        <div className="space-y-1">
-          <div>{primaryAmount}</div>
-          <div className="text-xs text-gray-500 dark:text-gray-400">Approx. {secondaryAmount}</div>
-        </div>
-      )
-    },
-    [currency, token?.exchange_rate],
-  )
-
   const holderColumns = [
     {
       header: 'Holder',
@@ -209,7 +188,7 @@ export default function TokenDetailPage() {
     },
     {
       header: 'Balance',
-      accessor: (holder: TokenHolder) => renderAmountWithDisplayCurrency(holder.value, token?.decimals || holder.token_decimals, token?.symbol),
+      accessor: (holder: TokenHolder) => formatTokenAmount(holder.value, token?.decimals || holder.token_decimals, token?.symbol),
     },
   ]
 
@@ -259,7 +238,7 @@ export default function TokenDetailPage() {
     },
     {
       header: 'Amount',
-      accessor: (transfer: AddressTokenTransfer) => renderAmountWithDisplayCurrency(transfer.value, transfer.token_decimals, transfer.token_symbol),
+      accessor: (transfer: AddressTokenTransfer) => formatTokenAmount(transfer.value, transfer.token_decimals, transfer.token_symbol),
     },
     {
       header: 'When',
@@ -337,27 +316,9 @@ export default function TokenDetailPage() {
               </DetailRow>
               <DetailRow label="Type">{token.type || 'Unknown'}</DetailRow>
               <DetailRow label="Decimals">{token.decimals}</DetailRow>
-              <DetailRow label="Display Currency">
-                <div className="space-y-2">
-                  <label className="inline-flex items-center gap-2 text-sm text-gray-700 dark:text-gray-300">
-                    <span className="sr-only">Display currency</span>
-                    <select
-                      value={currency}
-                      onChange={(event) => setCurrency(event.target.value === 'usd' ? 'usd' : 'native')}
-                      className="rounded-xl border border-gray-300 bg-white px-3 py-2 text-sm text-gray-900 shadow-sm focus:border-primary-500 focus:outline-none focus:ring-2 focus:ring-primary-200 dark:border-gray-600 dark:bg-gray-800 dark:text-gray-100 dark:focus:ring-primary-900"
-                    >
-                      <option value="native">Native token amounts</option>
-                      <option value="usd">USD estimate</option>
-                    </select>
-                  </label>
-                  <div className="text-xs text-gray-500 dark:text-gray-400">
-                    USD estimates use the explorer&apos;s current indicative token price and appear as a secondary line when available.
-                  </div>
-                </div>
-              </DetailRow>
               {token.total_supply && (
                 <DetailRow label="Total Supply">
-                  {renderAmountWithDisplayCurrency(token.total_supply, token.decimals, token.symbol)}
+                  {formatTokenAmount(token.total_supply, token.decimals, token.symbol)}
                 </DetailRow>
               )}
               {token.holders != null && (

frontend/src/utils/dashboard.test.ts

@@ -1,6 +1,6 @@
 import { describe, expect, it, vi } from 'vitest'
 import type { Block } from '@/services/api/blocks'
-import type { ExplorerStats, ExplorerTransactionTrendPoint } from '@/services/api/stats'
+import type { ExplorerStats } from '@/services/api/stats'
 import { loadDashboardData } from './dashboard'
 
 const sampleStats: ExplorerStats = {
@@ -23,17 +23,6 @@ const sampleBlocks: Block[] = [
   },
 ]
 
-const sampleTrend: ExplorerTransactionTrendPoint[] = [
-  {
-    date: '2026-04-03',
-    count: 11,
-  },
-  {
-    date: '2026-04-04',
-    count: 17,
-  },
-]
-
 describe('loadDashboardData', () => {
   it('returns both stats and recent blocks when both loaders succeed', async () => {
     const result = await loadDashboardData({
@@ -44,7 +33,6 @@ describe('loadDashboardData', () => {
     expect(result).toEqual({
       stats: sampleStats,
       recentBlocks: sampleBlocks,
-      recentTransactionTrend: [],
     })
   })
 
@@ -62,7 +50,6 @@ describe('loadDashboardData', () => {
     expect(result).toEqual({
       stats: null,
       recentBlocks: sampleBlocks,
-      recentTransactionTrend: [],
     })
     expect(onError).toHaveBeenCalledTimes(1)
     expect(onError).toHaveBeenCalledWith('stats', expect.any(Error))
@@ -82,44 +69,8 @@ describe('loadDashboardData', () => {
     expect(result).toEqual({
       stats: sampleStats,
       recentBlocks: [],
-      recentTransactionTrend: [],
     })
     expect(onError).toHaveBeenCalledTimes(1)
     expect(onError).toHaveBeenCalledWith('blocks', expect.any(Error))
   })
-
-  it('returns the recent transaction trend when the optional loader succeeds', async () => {
-    const result = await loadDashboardData({
-      loadStats: async () => sampleStats,
-      loadRecentBlocks: async () => sampleBlocks,
-      loadRecentTransactionTrend: async () => sampleTrend,
-    })
-
-    expect(result).toEqual({
-      stats: sampleStats,
-      recentBlocks: sampleBlocks,
-      recentTransactionTrend: sampleTrend,
-    })
-  })
-
-  it('falls back to an empty recent transaction trend when the optional loader fails', async () => {
-    const onError = vi.fn()
-
-    const result = await loadDashboardData({
-      loadStats: async () => sampleStats,
-      loadRecentBlocks: async () => sampleBlocks,
-      loadRecentTransactionTrend: async () => {
-        throw new Error('trend unavailable')
-      },
-      onError,
-    })
-
-    expect(result).toEqual({
-      stats: sampleStats,
-      recentBlocks: sampleBlocks,
-      recentTransactionTrend: [],
-    })
-    expect(onError).toHaveBeenCalledTimes(1)
-    expect(onError).toHaveBeenCalledWith('trend', expect.any(Error))
-  })
 })

frontend/src/utils/displayCurrency.test.ts

@@ -1,47 +0,0 @@
-import { describe, expect, it } from 'vitest'
-import { formatUsdValue, getSecondaryDisplayValue } from './displayCurrency'
-
-describe('formatUsdValue', () => {
-  it('keeps cents for smaller values', () => {
-    expect(formatUsdValue(4.5)).toBe('$4.50')
-  })
-
-  it('drops cents for larger rounded values', () => {
-    expect(formatUsdValue(1250)).toBe('$1,250')
-  })
-})
-
-describe('getSecondaryDisplayValue', () => {
-  it('returns null when the user prefers native display', () => {
-    expect(
-      getSecondaryDisplayValue({
-        rawAmount: '4500000',
-        decimals: 6,
-        exchangeRate: 1,
-        displayCurrency: 'native',
-      }),
-    ).toBeNull()
-  })
-
-  it('formats a USD secondary value from token units and exchange rate', () => {
-    expect(
-      getSecondaryDisplayValue({
-        rawAmount: '4500000',
-        decimals: 6,
-        exchangeRate: 1,
-        displayCurrency: 'usd',
-      }),
-    ).toBe('$4.50')
-  })
-
-  it('returns null when no usable exchange rate is available', () => {
-    expect(
-      getSecondaryDisplayValue({
-        rawAmount: '4500000',
-        decimals: 6,
-        exchangeRate: null,
-        displayCurrency: 'usd',
-      }),
-    ).toBeNull()
-  })
-})

frontend/src/utils/displayCurrency.ts

@@ -1,35 +0,0 @@
-import { formatUnits } from './format'
-
-function toFiniteNumber(value: string | number | null | undefined): number | null {
-  if (typeof value === 'number' && Number.isFinite(value)) return value
-  if (typeof value === 'string' && value.trim() !== '') {
-    const parsed = Number(value)
-    if (Number.isFinite(parsed)) return parsed
-  }
-  return null
-}
-
-export function formatUsdValue(value: number): string {
-  return new Intl.NumberFormat('en-US', {
-    style: 'currency',
-    currency: 'USD',
-    maximumFractionDigits: Math.abs(value) >= 100 ? 0 : 2,
-  }).format(value)
-}
-
-export function getSecondaryDisplayValue(input: {
-  rawAmount: string | number | null | undefined
-  decimals?: number
-  exchangeRate?: string | number | null
-  displayCurrency: 'native' | 'usd'
-}): string | null {
-  if (input.displayCurrency !== 'usd') return null
-
-  const exchangeRate = toFiniteNumber(input.exchangeRate)
-  if (exchangeRate == null || exchangeRate < 0) return null
-
-  const normalizedAmount = Number(formatUnits(input.rawAmount, input.decimals ?? 18, 8))
-  if (!Number.isFinite(normalizedAmount)) return null
-
-  return formatUsdValue(normalizedAmount * exchangeRate)
-}