fix(security): keep credentials off argv and plaintext transports

- M7: ResolveToken accepts the token via the HF_TOKEN env var (so it need
  not appear in argv, where it's visible in ps/shell history); the HTTP
  client refuses to send a token / API key over plaintext http:// to a
  non-loopback host (use https://). Loopback http is still allowed for
  local dev.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

internal/client/client.go

@@ -5,7 +5,9 @@ import (
 	"encoding/json"
 	"fmt"
 	"io"
+	"net"
 	"net/http"
+	neturl "net/url"
 	"strings"
 	"time"
 )
@@ -70,8 +72,39 @@ func (e *RequestError) Error() string {
 	return fmt.Sprintf("HTTP %d: %s", e.StatusCode, e.Body)
 }
 
+// guardPlaintextCreds refuses to transmit a token / API key over a plaintext
+// http:// connection to a non-loopback host (prevents credential interception).
+func (c *Client) guardPlaintextCreds() error {
+	if c.Token == "" && c.APIKey == "" {
+		return nil
+	}
+	u, err := neturl.Parse(c.BaseURL)
+	if err != nil || u.Scheme != "http" {
+		return nil // parse errors and https:// are fine
+	}
+	if isLoopbackHost(u.Hostname()) {
+		return nil
+	}
+	return fmt.Errorf("refusing to send credentials over plaintext http:// to non-loopback host %q — use an https:// base URL (hf config set-url ...)", u.Hostname())
+}
+
+// isLoopbackHost reports whether h is a loopback address or localhost name.
+func isLoopbackHost(h string) bool {
+	h = strings.ToLower(h)
+	if h == "localhost" || strings.HasSuffix(h, ".localhost") {
+		return true
+	}
+	if ip := net.ParseIP(h); ip != nil {
+		return ip.IsLoopback()
+	}
+	return false
+}
+
 // Do executes an HTTP request and returns the response body bytes.
 func (c *Client) Do(method, path string, body io.Reader) ([]byte, error) {
+	if err := c.guardPlaintextCreds(); err != nil {
+		return nil, err
+	}
 	url := c.BaseURL + path
 	req, err := http.NewRequest(method, url, body)
 	if err != nil {

internal/commands/auth.go

@@ -1,6 +1,9 @@
 package commands
 
 import (
+	"os"
+	"strings"
+
 	"git.hangman-lab.top/zhi/HarborForge.Cli/internal/mode"
 	"git.hangman-lab.top/zhi/HarborForge.Cli/internal/output"
 	"git.hangman-lab.top/zhi/HarborForge.Cli/internal/passmgr"
@@ -20,12 +23,17 @@ func ResolveToken(tokenFlag string) string {
 		}
 		return tok
 	}
-	// manual mode
+	// manual mode — prefer the explicit flag, else fall back to the HF_TOKEN
-	if tokenFlag == "" {
+	// env var so the token need not appear in argv (visible via `ps`/history).
-		output.Error("--token <token> required or execute this with pcexec")
+	if tokenFlag != "" {
-	}
 		return tokenFlag
 	}
+	if env := strings.TrimSpace(os.Getenv("HF_TOKEN")); env != "" {
+		return env
+	}
+	output.Error("--token <token> or HF_TOKEN env required, or execute this with pcexec")
+	return ""
+}
 
 // RejectTokenInPaddedCell checks if --token was passed in padded-cell mode
 // and terminates with the standard error message.