diff --git a/tools/dwh-auth/internal/command/command.go b/tools/dwh-auth/internal/command/command.go
index 8ead69a1..df70c959 100644
--- a/tools/dwh-auth/internal/command/command.go
+++ b/tools/dwh-auth/internal/command/command.go
@@ -18,6 +18,8 @@ import (
 	"path/filepath"
 	"strings"
 	"time"
+	"unicode"
+	"unicode/utf8"
 
 	"github.com/aritmolab/thothii/tools/dwh-auth/internal/credential"
 	"github.com/aritmolab/thothii/tools/dwh-auth/internal/record"
@@ -34,6 +36,13 @@ const (
 	commandServeMsg = "serve is not available in this release"
 )
 
+var (
+	nowUTC             = func() time.Time { return time.Now().UTC() }
+	generateCredential = func() (credential.Material, error) { return credential.Generate(rand.Reader) }
+	addRecord          = func(store *registry.Store, value record.Record) error { return store.Add(value) }
+	closeStore         = func(store *registry.Store) error { return store.Close() }
+)
+
 // Run executes one dwh-auth invocation and returns its stable process exit
 // status. It writes only redacted, deterministic diagnostics to stderr.
 func Run(ctx context.Context, args []string, _ io.Reader, stdout, stderr io.Writer) int {
@@ -43,6 +52,9 @@ func Run(ctx context.Context, args []string, _ io.Reader, stdout, stderr io.Writ
 	if stdout == nil || stderr == nil {
 		return exitIntegrity
 	}
+	if len(args) > 0 && args[0] == "serve" {
+		return runServe(args[1:], stderr)
+	}
 	root, rest, err := parseRoot(args)
 	if err != nil {
 		writeLine(stderr, "unsafe invocation")
@@ -58,8 +70,6 @@ func Run(ctx context.Context, args []string, _ io.Reader, stdout, stderr io.Writ
 		return runKey(ctx, root, rest[1:], stdout, stderr)
 	case "check":
 		return runCheck(ctx, root, rest[1:], stdout, stderr)
-	case "serve":
-		return runServe(root, rest[1:], stderr)
 	default:
 		writeLine(stderr, "unsafe invocation")
 		return exitUsage
@@ -105,6 +115,7 @@ type parsed struct {
 	reason         string
 	json           bool
 	legacyRaw      bool
+	socket         string
 }
 
 func parseFlags(args []string, allowed map[string]bool) (parsed, error) {
@@ -147,6 +158,8 @@ func parseFlags(args []string, allowed map[string]bool) (parsed, error) {
 			value.keyID = args[i]
 		case "--reason":
 			value.reason = args[i]
+		case "--socket":
+			value.socket = args[i]
 		}
 	}
 	return value, nil
@@ -159,11 +172,12 @@ func runCreate(ctx context.Context, root string, args []string, stdout, stderr i
 		"--expires-at":      true,
 		"--output":          true,
 	})
-	if err != nil || options.installationID == "" || options.output == "" || !filepath.IsAbs(options.output) || !validInstallationID(options.installationID) || !validMetadata(options.description) {
+	if err != nil || options.installationID == "" || options.output == "" || !filepath.IsAbs(options.output) || !validInstallationID(options.installationID) || !validMetadata(options.description) || containsCanonicalCredential(options.description) {
 		writeLine(stderr, "unsafe invocation")
 		return exitUsage
 	}
-	expiresAt, err := parseExpiry(options.expiresAt)
+	createdAt := nowUTC()
+	expiresAt, err := parseExpiry(options.expiresAt, createdAt)
 	if err != nil {
 		writeLine(stderr, "unsafe invocation")
 		return exitUsage
@@ -173,7 +187,7 @@ func runCreate(ctx context.Context, root string, args []string, stdout, stderr i
 		return exitIntegrity
 	}
 
-	material, err := credential.Generate(rand.Reader)
+	material, err := generateCredential()
 	if err != nil {
 		writeLine(stderr, "integrity failure")
 		return exitIntegrity
@@ -210,7 +224,6 @@ func runCreate(ctx context.Context, root string, args []string, stdout, stderr i
 		writeLine(stderr, "integrity failure")
 		return exitIntegrity
 	}
-	now := time.Now().UTC()
 	value := record.Record{
 		SchemaVersion:  record.SchemaVersion,
 		Kind:           record.KindV1,
@@ -218,14 +231,20 @@ func runCreate(ctx context.Context, root string, args []string, stdout, stderr i
 		InstallationID: options.installationID,
 		Description:    options.description,
 		SecretSHA256:   base64.RawURLEncoding.EncodeToString(material.Digest[:]),
-		CreatedAt:      now,
+		CreatedAt:      createdAt,
 		ExpiresAt:      expiresAt,
 	}
-	addErr := store.Add(value)
-	closeErr := store.Close()
-	if addErr != nil || closeErr != nil {
-		if cleanupOutput(options.output) != nil {
-			writeCleanupFailure(stderr, options.output)
+	addErr := addRecord(store, value)
+	if addErr != nil {
+		lookupErr := lookupCreatedRecord(store, material.KeyID)
+		closeErr := closeStore(store)
+		if errors.Is(lookupErr, registry.ErrNotFound) && closeErr == nil {
+			if cleanupOutput(options.output) != nil {
+				writeCleanupFailure(stderr, options.output)
+				return exitIntegrity
+			}
+		} else {
+			writeRecoveryFailure(stderr, options.output)
 			return exitIntegrity
 		}
 		if errors.Is(addErr, registry.ErrConflict) || errors.Is(addErr, registry.ErrRevoked) {
@@ -235,6 +254,10 @@ func runCreate(ctx context.Context, root string, args []string, stdout, stderr i
 		writeLine(stderr, "integrity failure")
 		return exitIntegrity
 	}
+	if err := closeStore(store); err != nil {
+		writeRecoveryFailure(stderr, options.output)
+		return exitIntegrity
+	}
 	_, _ = fmt.Fprintf(stdout, "created key_id=%s installation_id=%s output=%s\n", material.KeyID, options.installationID, filepath.Clean(options.output))
 	return exitOK
 }
@@ -358,7 +381,7 @@ func runStatus(ctx context.Context, root string, args []string, stdout, stderr i
 
 func runRevoke(ctx context.Context, root string, args []string, stdout, stderr io.Writer) int {
 	options, err := parseFlags(args, map[string]bool{"--key-id": true, "--reason": true})
-	if err != nil || options.keyID == "" || !validKeyID(options.keyID) || options.reason == "" || !validMetadata(options.reason) {
+	if err != nil || options.keyID == "" || !validKeyID(options.keyID) || options.reason == "" || !validMetadata(options.reason) || containsCanonicalCredential(options.reason) {
 		writeLine(stderr, "unsafe invocation")
 		return exitUsage
 	}
@@ -371,7 +394,7 @@ func runRevoke(ctx context.Context, root string, args []string, stdout, stderr i
 		writeLine(stderr, "integrity failure")
 		return exitIntegrity
 	}
-	err = store.Revoke(options.keyID, options.reason, time.Now().UTC())
+	err = store.Revoke(options.keyID, options.reason, nowUTC())
 	closeErr := store.Close()
 	if errors.Is(err, registry.ErrNotFound) {
 		writeLine(stderr, "not found")
@@ -414,27 +437,22 @@ func runCheck(ctx context.Context, root string, args []string, stdout, stderr io
 	return exitOK
 }
 
-func runServe(root string, args []string, stderr io.Writer) int {
-	options, err := parseFlags(args, map[string]bool{"--socket": true})
-	if err != nil || options.output != "" {
+func runServe(args []string, stderr io.Writer) int {
+	if len(args) != 4 || args[0] != "--registry-root" || args[2] != "--socket" || !filepath.IsAbs(args[1]) || !filepath.IsAbs(args[3]) {
 		writeLine(stderr, "unsafe invocation")
 		return exitUsage
 	}
 	// The Unix-socket service is intentionally introduced by Task 4. Keeping
-	// this grammar reserved prevents accidental plaintext or network fallback.
-	for i := range args {
-		if args[i] == "--socket" {
-			if i+1 >= len(args) || !filepath.IsAbs(args[i+1]) {
-				writeLine(stderr, "unsafe invocation")
-				return exitUsage
-			}
-		}
-	}
-	_ = root
+	// this exact grammar reserved prevents accidental plaintext or network fallback.
 	writeLine(stderr, commandServeMsg)
 	return exitIntegrity
 }
 
+func lookupCreatedRecord(store *registry.Store, keyID string) error {
+	_, err := store.Find(keyID)
+	return err
+}
+
 func openCheckedStore(ctx context.Context, root string) (*registry.Store, error) {
 	if err := ctx.Err(); err != nil {
 		return nil, err
@@ -509,12 +527,16 @@ func writeCleanupFailure(stderr io.Writer, path string) {
 	_, _ = fmt.Fprintf(stderr, "cleanup failed path=%s\n", filepath.Clean(path))
 }
 
-func parseExpiry(value string) (*time.Time, error) {
+func writeRecoveryFailure(stderr io.Writer, path string) {
+	_, _ = fmt.Fprintf(stderr, "publication uncertain path=%s\n", filepath.Clean(path))
+}
+
+func parseExpiry(value string, createdAt time.Time) (*time.Time, error) {
 	if value == "" {
 		return nil, nil
 	}
 	parsed, err := time.Parse(time.RFC3339, value)
-	if err != nil || parsed.Location() != time.UTC {
+	if err != nil || parsed.Location() != time.UTC || !parsed.After(createdAt) {
 		return nil, errors.New("expiry must be UTC RFC3339")
 	}
 	return &parsed, nil
@@ -535,17 +557,38 @@ func validInstallationID(value string) bool {
 }
 
 func validMetadata(value string) bool {
-	if len([]rune(value)) > maxReasonBytes {
+	if !utf8.ValidString(value) || len([]rune(value)) > maxReasonBytes {
 		return false
 	}
 	for _, r := range value {
-		if r < 0x20 || r == 0x7f {
+		if unicode.IsControl(r) {
 			return false
 		}
 	}
 	return true
 }
 
+func containsCanonicalCredential(value string) bool {
+	const credentialLength = len(credential.Prefix) + 1 + credential.KeyIDEncodedLength + 1 + credential.SecretEncodedLength
+	needle := credential.Prefix + "."
+	for offset := 0; offset < len(value); {
+		index := strings.Index(value[offset:], needle)
+		if index < 0 {
+			return false
+		}
+		index += offset
+		if index+credentialLength <= len(value) {
+			candidate := []byte(value[index : index+credentialLength])
+			sum := sha256.Sum256(candidate)
+			if _, ok := credential.VerifyV1(candidate, record.Digest(sum)); ok {
+				return true
+			}
+		}
+		offset = index + len(needle)
+	}
+	return false
+}
+
 func validKeyID(value string) bool {
 	if value == record.LegacyKeyID {
 		return true
diff --git a/tools/dwh-auth/internal/command/command_test.go b/tools/dwh-auth/internal/command/command_test.go
index d2d0ce24..a9c5eaf3 100644
--- a/tools/dwh-auth/internal/command/command_test.go
+++ b/tools/dwh-auth/internal/command/command_test.go
@@ -214,6 +214,151 @@ func TestCreateRejectsInvalidExpiryWithoutWritingOutput(t *testing.T) {
 	}
 }
 
+func TestMetadataRejectsEmbeddedCanonicalCredentialBeforePersistence(t *testing.T) {
+	material, err := credential.Generate(bytes.NewReader(bytes.Repeat([]byte{0x33}, 44)))
+	if err != nil {
+		t.Fatalf("Generate() error = %v", err)
+	}
+	sentinel := string(material.Value)
+	root := t.TempDir()
+	output := filepath.Join(t.TempDir(), "key")
+	stdout, stderr, code := run(t, "--registry-root", root, "key", "create", "--installation-id", "embedded", "--description", "prefix-"+sentinel+"-suffix", "--output", output)
+	if code != 2 || stdout != "" || stderr != "unsafe invocation\n" {
+		t.Fatalf("embedded description result = (%d, %q, %q)", code, stdout, stderr)
+	}
+	if strings.Contains(stdout+stderr, sentinel) {
+		t.Fatal("embedded credential appeared in create diagnostics")
+	}
+	if _, err := os.Stat(output); !errors.Is(err, os.ErrNotExist) {
+		t.Fatalf("embedded description output stat error = %v, want absent", err)
+	}
+
+	cleanOutput := filepath.Join(t.TempDir(), "clean-key")
+	if code := runOnly(t, "--registry-root", root, "key", "create", "--installation-id", "embedded", "--output", cleanOutput); code != 0 {
+		t.Fatalf("clean create exit = %d", code)
+	}
+	listOut, _, listCode := run(t, "--registry-root", root, "key", "list", "--json")
+	if listCode != 0 || strings.Contains(listOut, sentinel) {
+		t.Fatalf("list after rejected metadata = (%d, %q)", listCode, listOut)
+	}
+	var listed []registry.PublicRecord
+	if err := json.Unmarshal([]byte(listOut), &listed); err != nil || len(listed) != 1 {
+		t.Fatalf("list = %q, err=%v", listOut, err)
+	}
+	keyID := listed[0].KeyID
+	stdout, stderr, code = run(t, "--registry-root", root, "key", "revoke", "--key-id", keyID, "--reason", "prefix-"+sentinel+"-suffix")
+	if code != 2 || stdout != "" || stderr != "unsafe invocation\n" || strings.Contains(stdout+stderr, sentinel) {
+		t.Fatalf("embedded reason result = (%d, %q, %q)", code, stdout, stderr)
+	}
+	statusOut, _, statusCode := run(t, "--registry-root", root, "key", "status", "--key-id", keyID, "--json")
+	if statusCode != 0 || strings.Contains(statusOut, sentinel) {
+		t.Fatalf("status after rejected reason = (%d, %q)", statusCode, statusOut)
+	}
+}
+
+func TestMetadataAndExpiryAreValidatedBeforeKeyGeneration(t *testing.T) {
+	oldNow := nowUTC
+	nowUTC = func() time.Time { return time.Date(2026, 1, 1, 0, 0, 0, 0, time.UTC) }
+	t.Cleanup(func() { nowUTC = oldNow })
+	cases := []struct {
+		name  string
+		value string
+	}{
+		{name: "invalid utf8", value: string([]byte{0xc3, 0x28})},
+		{name: "unicode control", value: "before\u0085after"},
+	}
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			output := filepath.Join(t.TempDir(), "key")
+			if code := runOnly(t, "--registry-root", t.TempDir(), "key", "create", "--installation-id", "client", "--description", tc.value, "--output", output); code != 2 {
+				t.Fatalf("invalid metadata exit = %d, want 2", code)
+			}
+			if _, err := os.Stat(output); !errors.Is(err, os.ErrNotExist) {
+				t.Fatalf("invalid metadata output stat error = %v, want absent", err)
+			}
+		})
+	}
+	for _, expiry := range []string{"2025-12-31T23:59:59Z", "2026-01-01T00:00:00Z"} {
+		t.Run("expiry "+expiry, func(t *testing.T) {
+			output := filepath.Join(t.TempDir(), "key")
+			if code := runOnly(t, "--registry-root", t.TempDir(), "key", "create", "--installation-id", "client", "--expires-at", expiry, "--output", output); code != 2 {
+				t.Fatalf("invalid expiry exit = %d, want 2", code)
+			}
+			if _, err := os.Stat(output); !errors.Is(err, os.ErrNotExist) {
+				t.Fatalf("invalid expiry output stat error = %v, want absent", err)
+			}
+		})
+	}
+	output := filepath.Join(t.TempDir(), "future-key")
+	if code := runOnly(t, "--registry-root", t.TempDir(), "key", "create", "--installation-id", "client", "--expires-at", "2026-01-01T00:00:01Z", "--output", output); code != 0 {
+		t.Fatalf("future expiry exit = %d, want 0", code)
+	}
+}
+
+func TestServeAcceptsOnlyExactTaskFourReservation(t *testing.T) {
+	root := t.TempDir()
+	socket := filepath.Join(t.TempDir(), "verify.sock")
+	stdout, stderr, code := run(t, "serve", "--registry-root", root, "--socket", socket)
+	if code != 4 || stdout != "" || stderr != "serve is not available in this release\n" {
+		t.Fatalf("valid serve reservation = (%d, %q, %q)", code, stdout, stderr)
+	}
+	invalid := [][]string{
+		{"serve", "--registry-root", "relative", "--socket", socket},
+		{"serve", "--registry-root", root},
+		{"serve", "--registry-root", root, "--socket", "relative"},
+		{"serve", "--registry-root", root, "--socket", socket, "--socket", socket},
+		{"serve", "--socket", socket, "--registry-root", root},
+		{"serve", "--registry-root", root, "--socket", socket, "--unknown", "x"},
+		{"--registry-root", root, "serve", "--socket", socket},
+	}
+	for _, args := range invalid {
+		stdout, stderr, code = run(t, args...)
+		if code != 2 || stdout != "" || stderr != "unsafe invocation\n" {
+			t.Errorf("invalid serve %q = (%d, %q, %q)", args, code, stdout, stderr)
+		}
+	}
+}
+
+func TestCreateCleansOnlyWhenFailedPublicationProvesKeyAbsent(t *testing.T) {
+	oldAdd, oldClose := addRecord, closeStore
+	t.Cleanup(func() { addRecord, closeStore = oldAdd, oldClose })
+	root := t.TempDir()
+	output := filepath.Join(t.TempDir(), "pre-publication")
+	addRecord = func(*registry.Store, record.Record) error { return errors.New("synthetic add failure") }
+	if code := runOnly(t, "--registry-root", root, "key", "create", "--installation-id", "client", "--output", output); code != 4 {
+		t.Fatalf("pre-publication failure exit = %d, want 4", code)
+	}
+	if _, err := os.Stat(output); !errors.Is(err, os.ErrNotExist) {
+		t.Fatalf("pre-publication output stat error = %v, want absent", err)
+	}
+
+	output = filepath.Join(t.TempDir(), "post-publication")
+	addRecord = func(store *registry.Store, value record.Record) error {
+		if err := store.Add(value); err != nil {
+			return err
+		}
+		return errors.New("synthetic ambiguous post-publication failure")
+	}
+	if code := runOnly(t, "--registry-root", root, "key", "create", "--installation-id", "client", "--output", output); code != 4 {
+		t.Fatalf("post-publication failure exit = %d, want 4", code)
+	}
+	if _, err := os.Stat(output); err != nil {
+		t.Fatalf("post-publication output stat error = %v, want retained: %v", err, err)
+	}
+	closeStore = func(store *registry.Store) error {
+		_ = store.Close()
+		return errors.New("synthetic close failure")
+	}
+	output = filepath.Join(t.TempDir(), "close-failure")
+	addRecord = oldAdd
+	if code := runOnly(t, "--registry-root", root, "key", "create", "--installation-id", "client-two", "--output", output); code != 4 {
+		t.Fatalf("close failure exit = %d, want 4", code)
+	}
+	if _, err := os.Stat(output); err != nil {
+		t.Fatalf("close-failure output stat error = %v, want retained: %v", err, err)
+	}
+}
+
 func run(t *testing.T, args ...string) (string, string, int) {
 	t.Helper()
 	var stdout, stderr bytes.Buffer