fix(go): protect CLI install credentials

AGENTS.md

@@ -59,6 +59,7 @@ This repository publishes the open-source server, console, integration catalog,
 - Keep private keys and API tokens out of process arguments and generated setup commands. Accept them through hidden terminal input or owner-only credential files.
 - Keep Console instruction generation limited to agent identity and public configuration. Adapter commands use hidden CLI prompts; direct SDK examples read named runtime environment variables. Expose credentials through explicit copy controls only.
 - Persist credential-bearing files through owner-only same-directory temporary files and atomic rename.
+- Go CLI install credentials come from terminal-echo-disabled input or physical owner-only files containing one UTF-8 line of at most 64 KiB. Runtime config, private key, and audit script form one rollback-capable transaction, and generated runtimes validate file identity, size, and Unix permissions before reads.
 - Resolve every agent runtime directory as one physical child of `~/.elydora`; reject separators, traversal segments, cross-platform reserved names, symbolic-link directories, and linked identity configs before writes or recursive removal. Validate stored directory identity before changing host CLI configuration, and require an explicit agent ID when discovery is ambiguous.
 
 ## Verification

sdks/go/README.md

@@ -69,10 +69,13 @@ elydora install \
   --agent claudecode \
   --org-id org-123 \
   --agent-id agent-456 \
-  --private-key <key> \
+  --private-key-file /secure/path/private.key \
+  --token-file /secure/path/api.token \
   --kid agent-456-key-v1
 ```
 
+Credential options may be omitted in an interactive terminal; the CLI then reads the private key and optional API token without terminal echo. Credential files must contain one UTF-8 line of at most 64 KiB. Unix credential files require owner-only permissions such as `chmod 600`. Installation commits `config.json`, `private.key`, and `hook.js` as one rollback-capable runtime transaction, and the generated scripts validate those protected files at execution time.
+
 Codex performs a one-time trust review for user hooks. Run `/hooks` in Codex after installation and trust the Elydora `PreToolUse` and `PostToolUse` definitions.
 
 Cline installation writes `PreToolUse.mjs` and `PostToolUse.mjs` to `$CLINE_DIR/hooks` (default `~/.cline/hooks`). Elydora leaves the Documents and workspace hook roots unchanged. The wrappers preserve Cline's official payload and translate a frozen guard into JSON stdout cancellation control.

sdks/go/cmd/elydora/cli_secrets.go

@@ -0,0 +1,232 @@
+package main
+
+import (
+	"crypto/ed25519"
+	"encoding/base64"
+	"errors"
+	"fmt"
+	"io"
+	"os"
+	"runtime"
+	"strings"
+	"unicode/utf8"
+)
+
+const maxSecretFileBytes = 64 * 1024
+
+type installSecretSources struct {
+	privateKeyFile string
+	tokenFile      string
+}
+
+type installSecrets struct {
+	privateKey string
+	token      string
+}
+
+type secretTerminal interface {
+	Interactive() bool
+	ReadHidden(prompt string) (string, error)
+}
+
+type standardSecretTerminal struct {
+	input  *os.File
+	output *os.File
+}
+
+func newStandardSecretTerminal() standardSecretTerminal {
+	return standardSecretTerminal{input: os.Stdin, output: os.Stderr}
+}
+
+func (terminal standardSecretTerminal) Interactive() bool {
+	return isInteractiveTerminal(terminal.input) &&
+		isInteractiveTerminal(terminal.output)
+}
+
+func (terminal standardSecretTerminal) ReadHidden(prompt string) (string, error) {
+	if !terminal.Interactive() {
+		return "", errors.New("hidden input requires an interactive terminal")
+	}
+	if _, err := fmt.Fprint(terminal.output, prompt); err != nil {
+		return "", fmt.Errorf("write secret prompt: %w", err)
+	}
+	raw, readErr := readHiddenLine(terminal.input)
+	_, newlineErr := fmt.Fprintln(terminal.output)
+	if readErr != nil {
+		clear(raw)
+		return "", errors.Join(
+			fmt.Errorf("read hidden input: %w", readErr),
+			newlineErr,
+		)
+	}
+	if newlineErr != nil {
+		clear(raw)
+		return "", fmt.Errorf("finish secret prompt: %w", newlineErr)
+	}
+	value := string(raw)
+	clear(raw)
+	return value, nil
+}
+
+func parseSingleLineSecret(raw, label string, allowEmpty bool) (string, error) {
+	if len(raw) > maxSecretFileBytes {
+		return "", fmt.Errorf("%s exceeds %d bytes", label, maxSecretFileBytes)
+	}
+	if !utf8.ValidString(raw) {
+		return "", fmt.Errorf("%s must contain UTF-8 text", label)
+	}
+	value := raw
+	if strings.HasSuffix(value, "\r\n") {
+		value = strings.TrimSuffix(value, "\r\n")
+	} else if strings.HasSuffix(value, "\n") {
+		value = strings.TrimSuffix(value, "\n")
+	}
+	if !allowEmpty && value == "" {
+		return "", fmt.Errorf("%s is empty", label)
+	}
+	if strings.ContainsAny(value, "\r\n\x00") {
+		return "", fmt.Errorf("%s must contain exactly one line", label)
+	}
+	return value, nil
+}
+
+func validateSecretFile(info os.FileInfo, path, label string) error {
+	if !info.Mode().IsRegular() {
+		return fmt.Errorf("%s file is not a regular file: %s", label, path)
+	}
+	if info.Size() > maxSecretFileBytes {
+		return fmt.Errorf("%s file exceeds %d bytes: %s", label, maxSecretFileBytes, path)
+	}
+	if runtime.GOOS != "windows" && info.Mode().Perm()&0077 != 0 {
+		return fmt.Errorf("%s file must be accessible only by its owner: %s", label, path)
+	}
+	return nil
+}
+
+func readSecretFile(path, label string) (string, error) {
+	return readSecretFileWithOpen(path, label, os.Open)
+}
+
+func readSecretFileWithOpen(
+	path string,
+	label string,
+	openFile func(string) (*os.File, error),
+) (value string, returnErr error) {
+	before, err := os.Lstat(path)
+	if err != nil {
+		return "", fmt.Errorf("inspect %s file at %s: %w", label, path, err)
+	}
+	if err := validateSecretFile(before, path, label); err != nil {
+		return "", err
+	}
+	if !os.SameFile(before, before) {
+		return "", fmt.Errorf("establish %s file identity at %s", label, path)
+	}
+
+	file, err := openFile(path)
+	if err != nil {
+		return "", fmt.Errorf("open %s file at %s: %w", label, path, err)
+	}
+	defer func() {
+		if closeErr := file.Close(); closeErr != nil {
+			returnErr = errors.Join(
+				returnErr,
+				fmt.Errorf("close %s file at %s: %w", label, path, closeErr),
+			)
+		}
+	}()
+
+	after, err := file.Stat()
+	if err != nil {
+		return "", fmt.Errorf("inspect open %s file at %s: %w", label, path, err)
+	}
+	if err := validateSecretFile(after, path, label); err != nil {
+		return "", err
+	}
+	if !os.SameFile(before, after) {
+		return "", fmt.Errorf("%s file changed while opening: %s", label, path)
+	}
+
+	raw, err := io.ReadAll(io.LimitReader(file, maxSecretFileBytes+1))
+	if err != nil {
+		return "", fmt.Errorf("read %s file at %s: %w", label, path, err)
+	}
+	defer clear(raw)
+	if len(raw) > maxSecretFileBytes {
+		return "", fmt.Errorf("%s file exceeds %d bytes: %s", label, maxSecretFileBytes, path)
+	}
+	return parseSingleLineSecret(string(raw), label, false)
+}
+
+func resolveInstallSecrets(
+	sources installSecretSources,
+	terminal secretTerminal,
+) (installSecrets, error) {
+	var privateKey string
+	var err error
+	if sources.privateKeyFile != "" {
+		privateKey, err = readSecretFile(sources.privateKeyFile, "private key")
+	} else if terminal.Interactive() {
+		privateKey, err = terminal.ReadHidden("Private key: ")
+		if err == nil {
+			privateKey, err = parseSingleLineSecret(privateKey, "private key", false)
+		}
+	} else {
+		return installSecrets{}, errors.New(
+			"private key input requires an interactive terminal or --private-key-file <path>",
+		)
+	}
+	if err != nil {
+		return installSecrets{}, err
+	}
+
+	var token string
+	if sources.tokenFile != "" {
+		token, err = readSecretFile(sources.tokenFile, "API token")
+	} else if terminal.Interactive() {
+		token, err = terminal.ReadHidden("API token (optional): ")
+		if err == nil {
+			token, err = parseSingleLineSecret(token, "API token", true)
+		}
+	}
+	if err != nil {
+		return installSecrets{}, err
+	}
+	return installSecrets{privateKey: privateKey, token: token}, nil
+}
+
+func validatePrivateKey(privateKey string) error {
+	seed, err := base64.RawURLEncoding.DecodeString(privateKey)
+	if err != nil {
+		return fmt.Errorf("decode private key: %w", err)
+	}
+	defer clear(seed)
+	if len(seed) != ed25519.SeedSize {
+		return fmt.Errorf(
+			"private key seed must be %d bytes, got %d",
+			ed25519.SeedSize,
+			len(seed),
+		)
+	}
+	return nil
+}
+
+func rejectLegacySecretArguments(arguments []string) error {
+	legacyOptions := map[string]string{
+		"--private-key": "--private-key-file",
+		"-private-key":  "--private-key-file",
+		"--token":       "--token-file",
+		"-token":        "--token-file",
+	}
+	for _, argument := range arguments {
+		option := strings.SplitN(argument, "=", 2)[0]
+		if replacement, exists := legacyOptions[option]; exists {
+			return fmt.Errorf(
+				"%s exposes credentials in process arguments; use %s or hidden terminal input",
+				option,
+				replacement,
+			)
+		}
+	}
+	return nil
+}

sdks/go/cmd/elydora/cli_secrets_test.go

@@ -0,0 +1,212 @@
+package main
+
+import (
+	"bytes"
+	"encoding/base64"
+	"os"
+	"path/filepath"
+	"runtime"
+	"strings"
+	"testing"
+)
+
+const testAPIToken = "ely_test_token"
+
+type fakeSecretTerminal struct {
+	interactive bool
+	answers     []string
+	prompts     []string
+}
+
+func (terminal *fakeSecretTerminal) Interactive() bool {
+	return terminal.interactive
+}
+
+func (terminal *fakeSecretTerminal) ReadHidden(prompt string) (string, error) {
+	terminal.prompts = append(terminal.prompts, prompt)
+	if len(terminal.answers) == 0 {
+		return "", os.ErrInvalid
+	}
+	answer := terminal.answers[0]
+	terminal.answers = terminal.answers[1:]
+	return answer, nil
+}
+
+func testPrivateKey() string {
+	return base64.RawURLEncoding.EncodeToString(bytes.Repeat([]byte{7}, 32))
+}
+
+func writeSecretFile(t *testing.T, path, value string) {
+	t.Helper()
+	if err := os.WriteFile(path, []byte(value), 0600); err != nil {
+		t.Fatalf("write secret file: %v", err)
+	}
+	if runtime.GOOS != "windows" {
+		if err := os.Chmod(path, 0600); err != nil {
+			t.Fatalf("restrict secret file: %v", err)
+		}
+	}
+}
+
+func TestResolveInstallSecretsUsesHiddenPrompts(t *testing.T) {
+	terminal := &fakeSecretTerminal{
+		interactive: true,
+		answers:     []string{testPrivateKey(), testAPIToken},
+	}
+	secrets, err := resolveInstallSecrets(installSecretSources{}, terminal)
+	if err != nil {
+		t.Fatalf("resolve install secrets: %v", err)
+	}
+	if secrets.privateKey != testPrivateKey() || secrets.token != testAPIToken {
+		t.Fatalf("resolved secrets have unexpected values")
+	}
+	wantPrompts := []string{"Private key: ", "API token (optional): "}
+	if strings.Join(terminal.prompts, "|") != strings.Join(wantPrompts, "|") {
+		t.Fatalf("prompts = %q, want %q", terminal.prompts, wantPrompts)
+	}
+}
+
+func TestResolveInstallSecretsRequiresFileWhenNoninteractive(t *testing.T) {
+	terminal := &fakeSecretTerminal{interactive: false}
+	_, err := resolveInstallSecrets(installSecretSources{}, terminal)
+	if err == nil || !strings.Contains(err.Error(), "--private-key-file <path>") {
+		t.Fatalf("resolve install secrets error = %v", err)
+	}
+	if len(terminal.prompts) != 0 {
+		t.Fatalf("unexpected prompts: %q", terminal.prompts)
+	}
+}
+
+func TestResolveInstallSecretsReadsCredentialFiles(t *testing.T) {
+	directory := t.TempDir()
+	privateKeyPath := filepath.Join(directory, "private.key")
+	tokenPath := filepath.Join(directory, "token")
+	writeSecretFile(t, privateKeyPath, testPrivateKey()+"\r\n")
+	writeSecretFile(t, tokenPath, testAPIToken+"\n")
+
+	secrets, err := resolveInstallSecrets(installSecretSources{
+		privateKeyFile: privateKeyPath,
+		tokenFile:      tokenPath,
+	}, &fakeSecretTerminal{})
+	if err != nil {
+		t.Fatalf("resolve install secrets: %v", err)
+	}
+	if secrets.privateKey != testPrivateKey() || secrets.token != testAPIToken {
+		t.Fatalf("resolved secrets have unexpected values")
+	}
+}
+
+func TestReadSecretFileRejectsInvalidContent(t *testing.T) {
+	tests := []struct {
+		name    string
+		content string
+		pattern string
+	}{
+		{name: "empty", content: "", pattern: "is empty"},
+		{name: "multiple lines", content: testPrivateKey() + "\nsecond\n", pattern: "one line"},
+		{name: "nul", content: "key\x00value", pattern: "one line"},
+		{name: "invalid UTF-8", content: string([]byte{0xff}), pattern: "UTF-8"},
+	}
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			path := filepath.Join(t.TempDir(), "private.key")
+			writeSecretFile(t, path, test.content)
+			_, err := readSecretFile(path, "private key")
+			if err == nil || !strings.Contains(err.Error(), test.pattern) {
+				t.Fatalf("read secret file error = %v", err)
+			}
+		})
+	}
+}
+
+func TestReadSecretFileRejectsOversizedContent(t *testing.T) {
+	path := filepath.Join(t.TempDir(), "private.key")
+	writeSecretFile(t, path, strings.Repeat("a", maxSecretFileBytes+1))
+	_, err := readSecretFile(path, "private key")
+	if err == nil || !strings.Contains(err.Error(), "exceeds") {
+		t.Fatalf("read secret file error = %v", err)
+	}
+}
+
+func TestReadSecretFileRejectsSymbolicLink(t *testing.T) {
+	directory := t.TempDir()
+	target := filepath.Join(directory, "target.key")
+	link := filepath.Join(directory, "linked.key")
+	writeSecretFile(t, target, testPrivateKey())
+	if err := os.Symlink(target, link); err != nil {
+		t.Skipf("file symbolic links unavailable: %v", err)
+	}
+	_, err := readSecretFile(link, "private key")
+	if err == nil || !strings.Contains(err.Error(), "regular file") {
+		t.Fatalf("read secret file error = %v", err)
+	}
+}
+
+func TestReadSecretFileRequiresOwnerOnlyPermissions(t *testing.T) {
+	if runtime.GOOS == "windows" {
+		t.Skip("POSIX permission contract")
+	}
+	path := filepath.Join(t.TempDir(), "private.key")
+	writeSecretFile(t, path, testPrivateKey())
+	if err := os.Chmod(path, 0640); err != nil {
+		t.Fatalf("widen secret file permissions: %v", err)
+	}
+	_, err := readSecretFile(path, "private key")
+	if err == nil || !strings.Contains(err.Error(), "only by its owner") {
+		t.Fatalf("read secret file error = %v", err)
+	}
+}
+
+func TestReadSecretFileDetectsReplacementWhileOpening(t *testing.T) {
+	directory := t.TempDir()
+	path := filepath.Join(directory, "private.key")
+	replacement := filepath.Join(directory, "replacement.key")
+	writeSecretFile(t, path, testPrivateKey())
+	writeSecretFile(t, replacement, testPrivateKey())
+
+	_, err := readSecretFileWithOpen(path, "private key", func(name string) (*os.File, error) {
+		if removeErr := os.Remove(path); removeErr != nil {
+			return nil, removeErr
+		}
+		if renameErr := os.Rename(replacement, path); renameErr != nil {
+			return nil, renameErr
+		}
+		return os.Open(name)
+	})
+	if err == nil || !strings.Contains(err.Error(), "changed while opening") {
+		t.Fatalf("read secret file error = %v", err)
+	}
+}
+
+func TestValidatePrivateKeyRejectsInvalidSeeds(t *testing.T) {
+	tests := []string{"invalid!", base64.RawURLEncoding.EncodeToString([]byte("short"))}
+	for _, privateKey := range tests {
+		if err := validatePrivateKey(privateKey); err == nil {
+			t.Fatalf("validatePrivateKey(%q) succeeded", privateKey)
+		}
+	}
+	if err := validatePrivateKey(testPrivateKey()); err != nil {
+		t.Fatalf("validate private key: %v", err)
+	}
+}
+
+func TestRejectLegacySecretArgumentsRedactsValues(t *testing.T) {
+	tests := [][]string{
+		{"--private-key", "must-not-appear"},
+		{"--private-key=must-not-appear"},
+		{"--token", "must-not-appear"},
+		{"--token=must-not-appear"},
+	}
+	for _, arguments := range tests {
+		err := rejectLegacySecretArguments(arguments)
+		if err == nil {
+			t.Fatalf("rejectLegacySecretArguments(%q) succeeded", arguments)
+		}
+		if strings.Contains(err.Error(), "must-not-appear") {
+			t.Fatalf("legacy secret value leaked in error: %v", err)
+		}
+		if !strings.Contains(err.Error(), "-file") {
+			t.Fatalf("replacement option missing from error: %v", err)
+		}
+	}
+}

sdks/go/cmd/elydora/main.go

@@ -62,19 +62,24 @@ Run "elydora <command> -h" for details on each command.
 // ---------------------------------------------------------------------------
 
 func cmdInstall(args []string) {
+	if err := rejectLegacySecretArguments(args); err != nil {
+		fmt.Fprintf(os.Stderr, "Error: %v\n", err)
+		os.Exit(1)
+	}
+
 	fs := flag.NewFlagSet("install", flag.ExitOnError)
 	agent := fs.String("agent", "", "Agent name (required). Use 'elydora agents' to list.")
 	orgID := fs.String("org-id", "", "Organization ID (required)")
 	agentID := fs.String("agent-id", "", "Agent ID (required)")
-	privateKey := fs.String("private-key", "", "Base64url-encoded Ed25519 private key seed (required)")
+	privateKeyFile := fs.String("private-key-file", "", "Owner-only file containing the Ed25519 private key seed")
 	kid := fs.String("kid", "", "Key ID (defaults to <agent-id>-key-1)")
-	token := fs.String("token", "", "API token for authenticated requests (optional)")
+	tokenFile := fs.String("token-file", "", "Owner-only file containing the optional API token")
 	baseURL := fs.String("base-url", "https://api.elydora.com", "Elydora API base URL")
 
 	fs.Parse(args)
 
-	if *agent == "" || *orgID == "" || *agentID == "" || *privateKey == "" {
+	if *agent == "" || *orgID == "" || *agentID == "" {
-		fmt.Fprintln(os.Stderr, "Error: --agent, --org-id, --agent-id, and --private-key are required.")
+		fmt.Fprintln(os.Stderr, "Error: --agent, --org-id, and --agent-id are required.")
 		fmt.Fprintln(os.Stderr)
 		fs.Usage()
 		os.Exit(1)
@@ -89,6 +94,26 @@ func cmdInstall(args []string) {
 		fmt.Fprintf(os.Stderr, "Error: unsupported agent %q. Run 'elydora agents' to see supported agents.\n", *agent)
 		os.Exit(1)
 	}
+	if _, err := plugins.ResolveAgentRuntimeDirectory(*agentID); err != nil {
+		fmt.Fprintf(os.Stderr, "Error: %v\n", err)
+		os.Exit(1)
+	}
+
+	secrets, err := resolveInstallSecrets(
+		installSecretSources{
+			privateKeyFile: *privateKeyFile,
+			tokenFile:      *tokenFile,
+		},
+		newStandardSecretTerminal(),
+	)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Error: %v\n", err)
+		os.Exit(1)
+	}
+	if err := validatePrivateKey(secrets.privateKey); err != nil {
+		fmt.Fprintf(os.Stderr, "Error: invalid private key: %v\n", err)
+		os.Exit(1)
+	}
 
 	// Generate guard script (PreToolUse — freeze enforcement)
 	agentDirectory, err := plugins.PrepareAgentRuntimeDirectory(*agentID)
@@ -98,7 +123,12 @@ func cmdInstall(args []string) {
 	}
 	guardScriptPath := filepath.Join(agentDirectory, "guard.js")
 	guardScript := plugins.GenerateGuardScript(*agent, *agentID)
-	if err := os.WriteFile(guardScriptPath, []byte(guardScript), 0755); err != nil {
+	if err := plugins.WriteRuntimeFileAtomic(
+		guardScriptPath,
+		"Elydora guard runtime",
+		[]byte(guardScript),
+		0700,
+	); err != nil {
 		fmt.Fprintf(os.Stderr, "Error writing guard script: %v\n", err)
 		os.Exit(1)
 	}
@@ -108,9 +138,9 @@ func cmdInstall(args []string) {
 		AgentName:       *agent,
 		OrgID:           *orgID,
 		AgentID:         *agentID,
-		PrivateKey:      *privateKey,
+		PrivateKey:      secrets.privateKey,
 		KID:             *kid,
-		Token:           *token,
+		Token:           secrets.token,
 		BaseURL:         *baseURL,
 		GuardScriptPath: guardScriptPath,
 	}

sdks/go/cmd/elydora/plugins/droid.go

@@ -194,7 +194,7 @@ func prepareDroidInstallationChanges(
 		mode        os.FileMode
 	}{
 		{filepath.Join(agentDirectory, "config.json"), "Elydora runtime config", runtimeConfig, 0600},
-		{filepath.Join(agentDirectory, "private.key"), "Elydora private key", []byte(config.PrivateKey + "\n"), 0600},
+		{filepath.Join(agentDirectory, "private.key"), "Elydora private key", []byte(config.PrivateKey), 0600},
 		{auditPath, "Elydora audit runtime", []byte(buildHookScript(droidAgentKey, config.AgentID)), 0700},
 	}
 	changes := make([]*fileChange, 0, len(runtimeChanges)+len(rendered))

sdks/go/cmd/elydora/plugins/hooktemplate.go

@@ -2,71 +2,8 @@ package plugins
 
 import (
 	"fmt"
-	"os"
-	"path/filepath"
 )
 
-// GenerateHookScript writes a self-contained Node.js hook script to disk.
-// The script reads config/key from ~/.elydora/<agentId>/ at runtime, persists
-// chain state, and performs fire-and-forget EOR submission with inline Ed25519 crypto.
-// It always exits 0 so it never blocks the host agent.
-func GenerateHookScript(destPath string, config InstallConfig) error {
-	dir := filepath.Dir(destPath)
-	if err := EnsurePrivateDirectory(dir); err != nil {
-		return fmt.Errorf("create hook script directory: %w", err)
-	}
-
-	// Write the agent config and key files for runtime reading
-	if err := writeAgentConfig(config); err != nil {
-		return fmt.Errorf("write agent config: %w", err)
-	}
-
-	script := buildHookScript(config.AgentName, config.AgentID)
-	if err := os.WriteFile(destPath, []byte(script), 0755); err != nil {
-		return fmt.Errorf("write hook script: %w", err)
-	}
-	return nil
-}
-
-// writeAgentConfig persists the agent configuration and private key to
-// ~/.elydora/<agentId>/config.json and ~/.elydora/<agentId>/private.key so that
-// the generated hook script can read them at runtime without embedding secrets.
-func writeAgentConfig(config InstallConfig) error {
-	agentDir, err := PrepareAgentRuntimeDirectory(config.AgentID)
-	if err != nil {
-		return err
-	}
-
-	baseURL := config.BaseURL
-	if baseURL == "" {
-		baseURL = "https://api.elydora.com"
-	}
-
-	configJSON := fmt.Sprintf(`{
-  "org_id": %q,
-  "agent_id": %q,
-  "kid": %q,
-  "base_url": %q,
-  "token": %q,
-  "agent_name": %q
-}
-`, config.OrgID, config.AgentID, config.KID, baseURL, config.Token, config.AgentName)
-
-	configPath := filepath.Join(agentDir, "config.json")
-	// Note: 0600 permissions are a no-op on Windows; Go's os.Chmod only handles the read-only bit on Windows.
-	if err := os.WriteFile(configPath, []byte(configJSON), 0600); err != nil {
-		return fmt.Errorf("write agent config: %w", err)
-	}
-
-	keyPath := filepath.Join(agentDir, "private.key")
-	// Note: 0600 permissions are a no-op on Windows; Go's os.Chmod only handles the read-only bit on Windows.
-	if err := os.WriteFile(keyPath, []byte(config.PrivateKey+"\n"), 0600); err != nil {
-		return fmt.Errorf("write agent key: %w", err)
-	}
-
-	return nil
-}
-
 // GenerateGuardScript returns a self-contained Node.js guard script that checks
 // whether the agent is frozen and blocks tool execution if so.
 // It caches the agent status locally (60s TTL) to avoid hitting the API on every
@@ -91,6 +28,8 @@ const CONFIG_PATH = path.join(ELYDORA_DIR, AGENT_ID, 'config.json');
 const STATUS_CACHE_PATH = path.join(ELYDORA_DIR, AGENT_ID, 'status-cache.json');
 const CACHE_TTL_MS = 60000; // 60 seconds
 
+%s
+
 // Consume stdin so the parent process doesn't block on a full pipe
 process.stdin.resume();
 process.stdin.on('data', () => {});
@@ -99,7 +38,11 @@ async function main() {
   // Read agent config
   let config;
   try {
-    config = JSON.parse(fs.readFileSync(CONFIG_PATH, 'utf-8'));
+    config = JSON.parse(readProtectedFile(
+      CONFIG_PATH,
+      'Agent config',
+      MAX_PROTECTED_CONFIG_BYTES,
+    ).toString('utf-8'));
   } catch {
     return; // Can't read config — fail-open (allow)
   }
@@ -166,7 +109,7 @@ async function main() {
 }
 
 main();
-`, agentName, agentName, agentId)
+`, agentName, agentName, agentId, protectedRuntimeFileReader)
 }
 
 func buildHookScript(agentName string, agentId string) string {
@@ -191,6 +134,21 @@ const KEY_PATH = path.join(ELYDORA_DIR, AGENT_ID, 'private.key');
 const CHAIN_STATE_PATH = path.join(ELYDORA_DIR, AGENT_ID, 'chain-state.json');
 const ERROR_LOG_PATH = path.join(ELYDORA_DIR, AGENT_ID, 'error.log');
 
+%s
+
+function parsePrivateKey(raw) {
+  let value = raw.toString('utf-8');
+  if (value.endsWith('\r\n')) {
+    value = value.slice(0, -2);
+  } else if (value.endsWith('\n')) {
+    value = value.slice(0, -1);
+  }
+  if (!value || value.includes('\r') || value.includes('\n') || value.includes('\0')) {
+    throw new Error('Private key file must contain exactly one line');
+  }
+  return value;
+}
+
 // ---------------------------------------------------------------------------
 // Embedded crypto (from @elydora/sdk src/crypto.ts + src/utils.ts)
 // ---------------------------------------------------------------------------
@@ -369,8 +327,12 @@ async function main() {
     let config;
     let privateKey;
     try {
-      config = JSON.parse(fs.readFileSync(CONFIG_PATH, 'utf-8'));
+      config = JSON.parse(readProtectedFile(
-      privateKey = fs.readFileSync(KEY_PATH, 'utf-8').trim();
+        CONFIG_PATH,
+        'Agent config',
+        MAX_PROTECTED_CONFIG_BYTES,
+      ).toString('utf-8'));
+      privateKey = parsePrivateKey(readProtectedFile(KEY_PATH, 'Private key'));
     } catch (err) {
       logError(new Error('Failed to read agent config/key: ' + err.message));
       return;
@@ -471,5 +433,5 @@ async function main() {
 }
 
 main();
-`, agentName, agentName, agentId)
+`, agentName, agentName, agentId, protectedRuntimeFileReader)
 }

sdks/go/cmd/elydora/plugins/qwen.go

@@ -153,7 +153,7 @@ func prepareQwenInstallationChanges(
 		mode        os.FileMode
 	}{
 		{filepath.Join(agentDirectory, "config.json"), "Elydora runtime config", runtimeConfig, 0600},
-		{filepath.Join(agentDirectory, "private.key"), "Elydora private key", []byte(config.PrivateKey + "\n"), 0600},
+		{filepath.Join(agentDirectory, "private.key"), "Elydora private key", []byte(config.PrivateKey), 0600},
 		{auditPath, "Elydora audit runtime", []byte(buildHookScript(qwenAgentKey, config.AgentID)), 0700},
 	}
 	changes := make([]*fileChange, 0, len(items)+1)

sdks/go/cmd/elydora/plugins/runtime_files.go

@@ -0,0 +1,145 @@
+package plugins
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"os"
+	"path/filepath"
+)
+
+const (
+	maxProtectedSecretBytes = 64 * 1024
+	maxRuntimeConfigBytes   = 512 * 1024
+)
+
+type agentRuntimeConfig struct {
+	OrgID     string `json:"org_id"`
+	AgentID   string `json:"agent_id"`
+	KID       string `json:"kid"`
+	BaseURL   string `json:"base_url"`
+	Token     string `json:"token"`
+	AgentName string `json:"agent_name"`
+}
+
+// WriteRuntimeFileAtomic replaces one managed runtime file through a flushed,
+// same-directory temporary file.
+func WriteRuntimeFileAtomic(
+	path string,
+	label string,
+	content []byte,
+	mode os.FileMode,
+) error {
+	if err := validateRuntimeFileTarget(path, label); err != nil {
+		return err
+	}
+	change, err := prepareFileChange(path, label, content, mode)
+	if err != nil {
+		return err
+	}
+	return writeChanges([]*fileChange{change}, "write "+label, os.Rename)
+}
+
+// GenerateHookScript atomically commits the agent config, private key, and
+// self-contained Node.js audit runtime.
+func GenerateHookScript(destPath string, config InstallConfig) error {
+	return generateHookScriptWithRename(destPath, config, os.Rename)
+}
+
+func generateHookScriptWithRename(
+	destPath string,
+	config InstallConfig,
+	rename renameFunc,
+) error {
+	agentDirectory, err := ResolveAgentRuntimeDirectory(config.AgentID)
+	if err != nil {
+		return err
+	}
+
+	baseURL := config.BaseURL
+	if baseURL == "" {
+		baseURL = "https://api.elydora.com"
+	}
+	encodedConfig, err := json.MarshalIndent(agentRuntimeConfig{
+		OrgID:     config.OrgID,
+		AgentID:   config.AgentID,
+		KID:       config.KID,
+		BaseURL:   baseURL,
+		Token:     config.Token,
+		AgentName: config.AgentName,
+	}, "", "  ")
+	if err != nil {
+		return fmt.Errorf("encode Elydora runtime config: %w", err)
+	}
+	encodedConfig = append(encodedConfig, '\n')
+	if len(encodedConfig) > maxRuntimeConfigBytes {
+		return fmt.Errorf(
+			"Elydora runtime config exceeds %d bytes after JSON encoding",
+			maxRuntimeConfigBytes,
+		)
+	}
+
+	items := []struct {
+		path    string
+		label   string
+		content []byte
+		mode    os.FileMode
+	}{
+		{
+			path: filepath.Join(agentDirectory, "config.json"), label: "Elydora runtime config",
+			content: encodedConfig, mode: 0600,
+		},
+		{
+			path: filepath.Join(agentDirectory, "private.key"), label: "Elydora private key",
+			content: []byte(config.PrivateKey), mode: 0600,
+		},
+		{
+			path: destPath, label: "Elydora audit runtime",
+			content: []byte(buildHookScript(config.AgentName, config.AgentID)), mode: 0700,
+		},
+	}
+
+	for _, item := range items {
+		if err := validateRuntimeFileTarget(item.path, item.label); err != nil {
+			return err
+		}
+	}
+	if _, err := PrepareAgentRuntimeDirectory(config.AgentID); err != nil {
+		return err
+	}
+	if err := EnsurePrivateDirectory(filepath.Dir(destPath)); err != nil {
+		return fmt.Errorf("create hook script directory: %w", err)
+	}
+
+	changes := make([]*fileChange, 0, len(items))
+	for _, item := range items {
+		change, prepareErr := prepareFileChange(
+			item.path,
+			item.label,
+			item.content,
+			item.mode,
+		)
+		if prepareErr != nil {
+			return prepareErr
+		}
+		changes = append(changes, change)
+	}
+	if err := writeChanges(changes, "write Elydora agent runtime", rename); err != nil {
+		return fmt.Errorf("commit Elydora agent runtime: %w", err)
+	}
+	return nil
+}
+
+func validateRuntimeFileTarget(path, label string) error {
+	info, err := os.Lstat(path)
+	if errors.Is(err, os.ErrNotExist) {
+		return nil
+	}
+	if err != nil {
+		return fmt.Errorf("inspect %s at %s: %w", label, path, err)
+	}
+	if info.Mode()&os.ModeSymlink != 0 || !info.Mode().IsRegular() {
+		return fmt.Errorf("%s path is not a physical file: %s", label, path)
+	}
+	return nil
+}

sdks/go/cmd/elydora/plugins/runtime_files_test.go

@@ -0,0 +1,202 @@
+package plugins
+
+import (
+	"errors"
+	"os"
+	"path/filepath"
+	"runtime"
+	"strings"
+	"testing"
+)
+
+func setRuntimeFilesTestHome(t *testing.T) string {
+	t.Helper()
+	home := t.TempDir()
+	t.Setenv("HOME", home)
+	t.Setenv("USERPROFILE", home)
+	return home
+}
+
+func runtimeFilesTestConfig() InstallConfig {
+	return InstallConfig{
+		AgentName:  "opencode",
+		OrgID:      "org-1",
+		AgentID:    "agent-1",
+		PrivateKey: "BwcHBwcHBwcHBwcHBwcHBwcHBwcHBwcHBwcHBwcHBwc",
+		KID:        "key-1",
+		Token:      "ely_test_token",
+		BaseURL:    "https://api.elydora.test",
+	}
+}
+
+func TestGenerateHookScriptCommitsProtectedRuntimeFiles(t *testing.T) {
+	home := setRuntimeFilesTestHome(t)
+	config := runtimeFilesTestConfig()
+	agentDirectory := filepath.Join(home, ".elydora", config.AgentID)
+	hookPath := filepath.Join(agentDirectory, "hook.js")
+
+	if err := GenerateHookScript(hookPath, config); err != nil {
+		t.Fatalf("generate hook script: %v", err)
+	}
+
+	keyPath := filepath.Join(agentDirectory, "private.key")
+	key, err := os.ReadFile(keyPath)
+	if err != nil {
+		t.Fatalf("read private key: %v", err)
+	}
+	if string(key) != config.PrivateKey {
+		t.Fatalf("private key content changed")
+	}
+	hook, err := os.ReadFile(hookPath)
+	if err != nil {
+		t.Fatalf("read hook runtime: %v", err)
+	}
+	if strings.Contains(string(hook), config.PrivateKey) {
+		t.Fatalf("hook runtime embeds the private key")
+	}
+	if !strings.Contains(string(hook), "readProtectedFile") {
+		t.Fatalf("hook runtime is missing protected file validation")
+	}
+	if runtime.GOOS != "windows" {
+		assertRuntimeFileMode(t, filepath.Join(agentDirectory, "config.json"), 0600)
+		assertRuntimeFileMode(t, keyPath, 0600)
+		assertRuntimeFileMode(t, hookPath, 0700)
+	}
+	assertNoRuntimeStagingFiles(t, agentDirectory)
+}
+
+func TestGenerateHookScriptSupportsMaxEscapedCredentialInput(t *testing.T) {
+	home := setRuntimeFilesTestHome(t)
+	config := runtimeFilesTestConfig()
+	config.Token = strings.Repeat("\x01", 64*1024)
+	agentDirectory := filepath.Join(home, ".elydora", config.AgentID)
+	hookPath := filepath.Join(agentDirectory, "hook.js")
+
+	if err := GenerateHookScript(hookPath, config); err != nil {
+		t.Fatalf("generate hook script with maximum escaped token: %v", err)
+	}
+	info, err := os.Stat(filepath.Join(agentDirectory, "config.json"))
+	if err != nil {
+		t.Fatalf("stat runtime config: %v", err)
+	}
+	if info.Size() <= 64*1024 || info.Size() > maxRuntimeConfigBytes {
+		t.Fatalf("encoded runtime config size = %d", info.Size())
+	}
+	hook, err := os.ReadFile(hookPath)
+	if err != nil {
+		t.Fatalf("read hook runtime: %v", err)
+	}
+	if !strings.Contains(string(hook), "MAX_PROTECTED_CONFIG_BYTES") {
+		t.Fatalf("hook runtime is missing the config size contract")
+	}
+}
+
+func TestGenerateHookScriptRejectsOversizedRuntimeConfig(t *testing.T) {
+	home := setRuntimeFilesTestHome(t)
+	config := runtimeFilesTestConfig()
+	config.Token = strings.Repeat("\x01", maxRuntimeConfigBytes)
+	agentDirectory := filepath.Join(home, ".elydora", config.AgentID)
+
+	err := GenerateHookScript(filepath.Join(agentDirectory, "hook.js"), config)
+	if err == nil || !strings.Contains(err.Error(), "exceeds") {
+		t.Fatalf("generate oversized runtime config error = %v", err)
+	}
+	if _, statErr := os.Lstat(agentDirectory); !errors.Is(statErr, os.ErrNotExist) {
+		t.Fatalf("oversized config created runtime state: %v", statErr)
+	}
+}
+
+func TestGenerateHookScriptRollsBackRuntimeTransaction(t *testing.T) {
+	home := setRuntimeFilesTestHome(t)
+	config := runtimeFilesTestConfig()
+	agentDirectory := filepath.Join(home, ".elydora", config.AgentID)
+	if err := os.MkdirAll(agentDirectory, 0700); err != nil {
+		t.Fatalf("create runtime directory: %v", err)
+	}
+	paths := []string{
+		filepath.Join(agentDirectory, "config.json"),
+		filepath.Join(agentDirectory, "private.key"),
+		filepath.Join(agentDirectory, "hook.js"),
+	}
+	for _, path := range paths {
+		if err := os.WriteFile(path, []byte("original:"+filepath.Base(path)), 0600); err != nil {
+			t.Fatalf("write original runtime file: %v", err)
+		}
+	}
+
+	commits := 0
+	rename := func(source, destination string) error {
+		if strings.HasSuffix(source, ".tmp") {
+			commits++
+			if commits == 2 {
+				return errors.New("injected runtime commit failure")
+			}
+		}
+		return os.Rename(source, destination)
+	}
+	err := generateHookScriptWithRename(paths[2], config, rename)
+	if err == nil || !strings.Contains(err.Error(), "injected runtime commit failure") {
+		t.Fatalf("generate hook script error = %v", err)
+	}
+	for _, path := range paths {
+		raw, readErr := os.ReadFile(path)
+		if readErr != nil {
+			t.Fatalf("read restored runtime file: %v", readErr)
+		}
+		want := "original:" + filepath.Base(path)
+		if string(raw) != want {
+			t.Fatalf("restored %s = %q, want %q", path, raw, want)
+		}
+	}
+	assertNoRuntimeStagingFiles(t, agentDirectory)
+}
+
+func TestGenerateHookScriptRejectsLinkedSecretTarget(t *testing.T) {
+	home := setRuntimeFilesTestHome(t)
+	config := runtimeFilesTestConfig()
+	agentDirectory := filepath.Join(home, ".elydora", config.AgentID)
+	if err := os.MkdirAll(agentDirectory, 0700); err != nil {
+		t.Fatalf("create runtime directory: %v", err)
+	}
+	target := filepath.Join(t.TempDir(), "private.key")
+	if err := os.WriteFile(target, []byte("external"), 0600); err != nil {
+		t.Fatalf("write linked target: %v", err)
+	}
+	if err := os.Symlink(target, filepath.Join(agentDirectory, "private.key")); err != nil {
+		t.Skipf("file symbolic links unavailable: %v", err)
+	}
+
+	err := GenerateHookScript(filepath.Join(agentDirectory, "hook.js"), config)
+	if err == nil || !strings.Contains(err.Error(), "physical file") {
+		t.Fatalf("generate hook script error = %v", err)
+	}
+	raw, readErr := os.ReadFile(target)
+	if readErr != nil || string(raw) != "external" {
+		t.Fatalf("linked target changed: %q, %v", raw, readErr)
+	}
+}
+
+func assertRuntimeFileMode(t *testing.T, path string, want os.FileMode) {
+	t.Helper()
+	info, err := os.Stat(path)
+	if err != nil {
+		t.Fatalf("stat runtime file: %v", err)
+	}
+	if got := info.Mode().Perm(); got != want {
+		t.Fatalf("mode for %s = %04o, want %04o", path, got, want)
+	}
+}
+
+func assertNoRuntimeStagingFiles(t *testing.T, directory string) {
+	t.Helper()
+	entries, err := os.ReadDir(directory)
+	if err != nil {
+		t.Fatalf("read runtime directory: %v", err)
+	}
+	for _, entry := range entries {
+		if strings.HasPrefix(entry.Name(), ".") &&
+			(strings.HasSuffix(entry.Name(), ".tmp") || strings.HasSuffix(entry.Name(), ".rollback")) {
+			t.Fatalf("staging file remains: %s", entry.Name())
+		}
+	}
+}

sdks/go/cmd/elydora/plugins/runtime_reader_template.go

@@ -0,0 +1,48 @@
+package plugins
+
+import "fmt"
+
+var protectedRuntimeFileReader = fmt.Sprintf(`const MAX_PROTECTED_SECRET_BYTES = %d;
+const MAX_PROTECTED_CONFIG_BYTES = %d;
+
+function readProtectedFile(filePath, label, maxBytes = MAX_PROTECTED_SECRET_BYTES) {
+  const before = fs.lstatSync(filePath);
+  if (!before.isFile() || before.isSymbolicLink()) {
+    throw new Error(label + ' path is not a physical file: ' + filePath);
+  }
+  if (before.size > maxBytes) {
+    throw new Error(label + ' exceeds the size limit: ' + filePath);
+  }
+  if (process.platform !== 'win32' && (before.mode & 0o077) !== 0) {
+    throw new Error(label + ' permissions are too broad: ' + filePath);
+  }
+
+  let flags = fs.constants.O_RDONLY;
+  if (process.platform !== 'win32' && typeof fs.constants.O_NOFOLLOW === 'number') {
+    flags |= fs.constants.O_NOFOLLOW;
+  }
+  const descriptor = fs.openSync(filePath, flags);
+  try {
+    const after = fs.fstatSync(descriptor);
+    if (!after.isFile()) {
+      throw new Error(label + ' path is not a physical file: ' + filePath);
+    }
+    if (after.size > maxBytes) {
+      throw new Error(label + ' exceeds the size limit: ' + filePath);
+    }
+    if (process.platform !== 'win32' && (after.mode & 0o077) !== 0) {
+      throw new Error(label + ' permissions are too broad: ' + filePath);
+    }
+    if (before.dev !== after.dev || before.ino !== after.ino) {
+      throw new Error(label + ' changed while opening: ' + filePath);
+    }
+    const raw = fs.readFileSync(descriptor);
+    if (raw.length > maxBytes) {
+      throw new Error(label + ' exceeds the size limit: ' + filePath);
+    }
+    return raw;
+  } finally {
+    fs.closeSync(descriptor);
+  }
+}
+`, maxProtectedSecretBytes, maxRuntimeConfigBytes)

sdks/go/cmd/elydora/terminal_unix.go

@@ -0,0 +1,17 @@
+//go:build !windows
+
+package main
+
+import (
+	"os"
+
+	"golang.org/x/term"
+)
+
+func isInteractiveTerminal(file *os.File) bool {
+	return term.IsTerminal(int(file.Fd()))
+}
+
+func readHiddenLine(file *os.File) ([]byte, error) {
+	return term.ReadPassword(int(file.Fd()))
+}

sdks/go/cmd/elydora/terminal_windows.go

@@ -0,0 +1,116 @@
+//go:build windows
+
+package main
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"os"
+	"syscall"
+)
+
+const (
+	windowsEnableProcessedInput  = 0x0001
+	windowsEnableLineInput       = 0x0002
+	windowsEnableEchoInput       = 0x0004
+	windowsEnableProcessedOutput = 0x0001
+)
+
+var setConsoleMode = syscall.NewLazyDLL("kernel32.dll").NewProc("SetConsoleMode")
+
+func isInteractiveTerminal(file *os.File) bool {
+	var mode uint32
+	return syscall.GetConsoleMode(syscall.Handle(file.Fd()), &mode) == nil
+}
+
+func readHiddenLine(file *os.File) (raw []byte, returnErr error) {
+	handle := syscall.Handle(file.Fd())
+	var originalMode uint32
+	if err := syscall.GetConsoleMode(handle, &originalMode); err != nil {
+		return nil, fmt.Errorf("read console mode: %w", err)
+	}
+	hiddenMode := originalMode &^ (windowsEnableEchoInput | windowsEnableLineInput)
+	hiddenMode |= windowsEnableProcessedInput | windowsEnableProcessedOutput
+	if err := updateConsoleMode(handle, hiddenMode); err != nil {
+		return nil, fmt.Errorf("disable terminal echo: %w", err)
+	}
+	defer func() {
+		if err := updateConsoleMode(handle, originalMode); err != nil {
+			returnErr = errors.Join(returnErr, fmt.Errorf("restore console mode: %w", err))
+		}
+	}()
+
+	process, err := syscall.GetCurrentProcess()
+	if err != nil {
+		return nil, fmt.Errorf("get current process: %w", err)
+	}
+	var duplicate syscall.Handle
+	if err := syscall.DuplicateHandle(
+		process,
+		handle,
+		process,
+		&duplicate,
+		0,
+		false,
+		syscall.DUPLICATE_SAME_ACCESS,
+	); err != nil {
+		return nil, fmt.Errorf("duplicate terminal handle: %w", err)
+	}
+	input := os.NewFile(uintptr(duplicate), file.Name())
+	if input == nil {
+		_ = syscall.CloseHandle(duplicate)
+		return nil, errors.New("create terminal reader from duplicate handle")
+	}
+	defer func() {
+		if err := input.Close(); err != nil {
+			returnErr = errors.Join(returnErr, fmt.Errorf("close terminal reader: %w", err))
+		}
+	}()
+
+	return readWindowsPasswordLine(input)
+}
+
+func updateConsoleMode(handle syscall.Handle, mode uint32) error {
+	result, _, callErr := setConsoleMode.Call(uintptr(handle), uintptr(mode))
+	if result != 0 {
+		return nil
+	}
+	if callErr != syscall.Errno(0) {
+		return callErr
+	}
+	return syscall.EINVAL
+}
+
+func readWindowsPasswordLine(reader io.Reader) ([]byte, error) {
+	var value []byte
+	var buffer [1]byte
+	for {
+		read, err := reader.Read(buffer[:])
+		if read > 0 {
+			switch buffer[0] {
+			case '\b':
+				if len(value) > 0 {
+					value = value[:len(value)-1]
+				}
+			case '\r':
+				return value, nil
+			case '\n':
+			default:
+				value = append(value, buffer[0])
+				if len(value) > maxSecretFileBytes {
+					clear(value)
+					return nil, fmt.Errorf("hidden input exceeds %d bytes", maxSecretFileBytes)
+				}
+			}
+			continue
+		}
+		if err != nil {
+			if errors.Is(err, io.EOF) && len(value) > 0 {
+				return value, nil
+			}
+			clear(value)
+			return nil, err
+		}
+	}
+}

sdks/go/cmd/elydora/terminal_windows_test.go

@@ -0,0 +1,70 @@
+//go:build windows
+
+package main
+
+import (
+	"bytes"
+	"errors"
+	"io"
+	"strings"
+	"testing"
+)
+
+func TestReadWindowsPasswordLineHandlesConsoleInput(t *testing.T) {
+	raw, err := readWindowsPasswordLine(strings.NewReader("secx\bret\n\rignored"))
+	if err != nil {
+		t.Fatalf("read Windows password line: %v", err)
+	}
+	if string(raw) != "secret" {
+		t.Fatalf("password = %q, want secret", raw)
+	}
+}
+
+func TestReadWindowsPasswordLineReturnsFinalLineAtEOF(t *testing.T) {
+	raw, err := readWindowsPasswordLine(strings.NewReader("secret"))
+	if err != nil {
+		t.Fatalf("read Windows password line: %v", err)
+	}
+	if string(raw) != "secret" {
+		t.Fatalf("password = %q, want secret", raw)
+	}
+}
+
+func TestReadWindowsPasswordLineRejectsOversizedInput(t *testing.T) {
+	raw, err := readWindowsPasswordLine(bytes.NewReader(
+		bytes.Repeat([]byte{'x'}, maxSecretFileBytes+1),
+	))
+	if err == nil || !strings.Contains(err.Error(), "exceeds") {
+		t.Fatalf("read Windows password line error = %v", err)
+	}
+	if raw != nil {
+		t.Fatalf("oversized password remained in memory")
+	}
+}
+
+func TestReadWindowsPasswordLineReturnsReaderFailure(t *testing.T) {
+	expected := errors.New("injected read failure")
+	raw, err := readWindowsPasswordLine(&partialErrorReader{err: expected})
+	if !errors.Is(err, expected) {
+		t.Fatalf("read Windows password line error = %v", err)
+	}
+	if raw != nil {
+		t.Fatalf("unexpected password bytes: %q", raw)
+	}
+}
+
+type partialErrorReader struct {
+	err      error
+	returned bool
+}
+
+func (reader *partialErrorReader) Read(buffer []byte) (int, error) {
+	if !reader.returned {
+		reader.returned = true
+		buffer[0] = 's'
+		return 1, nil
+	}
+	return 0, reader.err
+}
+
+var _ io.Reader = &partialErrorReader{}

sdks/go/go.mod

@@ -4,4 +4,9 @@ go 1.21.0
 
 require github.com/pelletier/go-toml/v2 v2.4.3
 
-require github.com/tailscale/hujson v0.0.0-20221223112325-20486734a56a
+require (
+	github.com/tailscale/hujson v0.0.0-20221223112325-20486734a56a
+	golang.org/x/term v0.29.0
+)
+
+require golang.org/x/sys v0.30.0 // indirect

sdks/go/go.sum

@@ -4,3 +4,7 @@ github.com/pelletier/go-toml/v2 v2.4.3 h1:GTRvJQutkOSftxIFD5xw9aepkYNuPWmVJpffdD
 github.com/pelletier/go-toml/v2 v2.4.3/go.mod h1:2gIqNv+qfxSVS7cM2xJQKtLSTLUE9V8t9Stt+h56mCY=
 github.com/tailscale/hujson v0.0.0-20221223112325-20486734a56a h1:SJy1Pu0eH1C29XwJucQo73FrleVK6t4kYz4NVhp34Yw=
 github.com/tailscale/hujson v0.0.0-20221223112325-20486734a56a/go.mod h1:DFSS3NAGHthKo1gTlmEcSBiZrRJXi28rLNd/1udP1c8=
+golang.org/x/sys v0.30.0 h1:QjkSwP/36a20jFYWkSue1YwXzLmsV5Gfq7Eiy72C1uc=
+golang.org/x/sys v0.30.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
+golang.org/x/term v0.29.0 h1:L6pJp37ocefwRRtYPKSWOWzOtWSxVajvz2ldH/xi3iU=
+golang.org/x/term v0.29.0/go.mod h1:6bl4lRlvVuDgSf3179VpIxBF0o10JUpXWOnI7nErv7s=