fix(config): allow lark-channel bind source override (#1154)

Change-Id: I406ea13e372e6bdd5f3d9d6210b04ebdf0354182

cmd/config/binder.go

@@ -389,10 +389,12 @@ func resolveHermesEnvPath() string {
 }
 
 // resolveLarkChannelConfigPath returns the path to lark-channel-bridge's
-// config.json. Mirrors the bridge's src/config/paths.ts which hardcodes
-// ~/.lark-channel/config.json with no env override — multi-instance is not
-// a supported scenario today.
+// source config. LARK_CHANNEL_CONFIG lets a host point bind at a projected
+// single-account config without changing lark-cli's target config directory.
 func resolveLarkChannelConfigPath() string {
+	if p := os.Getenv("LARK_CHANNEL_CONFIG"); strings.TrimSpace(p) != "" {
+		return expandHome(p)
+	}
 	home, err := vfs.UserHomeDir()
 	if err != nil || home == "" {
 		fmt.Fprintf(os.Stderr, "warning: unable to determine home directory: %v\n", err)

cmd/config/binder_test.go

@@ -4,6 +4,7 @@
 package config
 
 import (
+	"path/filepath"
 	"reflect"
 	"testing"
 
@@ -173,3 +174,27 @@ func TestSelectCandidate_AppIDFlag_WinsOverTUI(t *testing.T) {
 	}
 	assertCandidate(t, got, Candidate{AppID: "cli_b"})
 }
+
+func TestResolveLarkChannelConfigPath_Default(t *testing.T) {
+	home := t.TempDir()
+	t.Setenv("HOME", home)
+	t.Setenv("LARK_CHANNEL_CONFIG", "")
+
+	got := resolveLarkChannelConfigPath()
+	want := filepath.Join(home, ".lark-channel", "config.json")
+	if got != want {
+		t.Fatalf("resolveLarkChannelConfigPath() = %q, want %q", got, want)
+	}
+}
+
+func TestResolveLarkChannelConfigPath_EnvOverride(t *testing.T) {
+	home := t.TempDir()
+	t.Setenv("HOME", home)
+	t.Setenv("LARK_CHANNEL_CONFIG", "~/bridge/projection.json")
+
+	got := resolveLarkChannelConfigPath()
+	want := filepath.Join(home, "bridge", "projection.json")
+	if got != want {
+		t.Fatalf("resolveLarkChannelConfigPath() = %q, want %q", got, want)
+	}
+}