fix(weixin): fallback sync cursor store when home is unusable

pkg/channels/weixin/state.go

@@ -41,7 +41,24 @@ type contextTokensFile struct {
 }
 
 func picoclawHomeDir() string {
-	return config.GetHome()
+	if home := os.Getenv(config.EnvHome); home != "" {
+		return home
+	}
+
+	if userHome, err := os.UserHomeDir(); err == nil && userHome != "" {
+		home := filepath.Join(userHome, ".picoclaw")
+		syncDir := filepath.Join(home, "channels", "weixin", "sync")
+		mkErr := os.MkdirAll(syncDir, 0o700)
+		if mkErr == nil {
+			return home
+		}
+		logger.WarnCF("weixin", "Default picoclaw home is not writable; using temp directory for sync cursor", map[string]any{
+			"path":  home,
+			"error": mkErr.Error(),
+		})
+	}
+
+	return filepath.Join(os.TempDir(), "picoclaw")
 }
 
 func genWeixinAccountKey(cfg config.WeixinConfig) string {

pkg/channels/weixin/weixin_test.go

@@ -7,7 +7,9 @@ import (
 	"errors"
 	"io"
 	"net/http"
+	"os"
 	"path/filepath"
+	"runtime"
 	"testing"
 	"time"
 
@@ -269,6 +271,29 @@ func TestBuildWeixinSyncBufPathUsesPicoclawHome(t *testing.T) {
 	}
 }
 
+func TestBuildWeixinSyncBufPathFallsBackWhenHomeIsUnusable(t *testing.T) {
+	if runtime.GOOS == "windows" {
+		t.Skip("HOME handling differs on windows")
+	}
+
+	t.Setenv(config.EnvHome, "")
+	unusableHome := filepath.Join(t.TempDir(), "home-file")
+	if err := os.WriteFile(unusableHome, []byte("not-a-dir"), 0o600); err != nil {
+		t.Fatalf("WriteFile(unusableHome) error = %v", err)
+	}
+	t.Setenv("HOME", unusableHome)
+
+	wxCfg := config.WeixinConfig{
+		BaseURL: "https://ilinkai.weixin.qq.com/",
+	}
+	wxCfg.SetToken("token-123")
+	got := buildWeixinSyncBufPath(wxCfg)
+	wantDir := filepath.Join(os.TempDir(), "picoclaw", "channels", "weixin", "sync")
+	if filepath.Dir(got) != wantDir {
+		t.Fatalf("sync path dir = %q, want %q", filepath.Dir(got), wantDir)
+	}
+}
+
 func TestSessionPauseGuard(t *testing.T) {
 	ch := &WeixinChannel{
 		typingCache: make(map[string]typingTicketCacheEntry),