feat(copilot): finish configuration center

backend/internal/handler/api/v1/captain_preference_handler_test.go

@@ -175,3 +175,29 @@ func TestCaptainPreferencesInvalidAccountID(t *testing.T) {
 	w := f.request(http.MethodGet, "/api/v1/accounts/abc/captain/preferences", nil)
 	require.Equal(t, http.StatusBadRequest, w.Code, w.Body.String())
 }
+
+func TestCaptainPreferencesUpdateAndClearBehavior(t *testing.T) {
+	f := newCaptainPreferenceFixture(t)
+
+	w := f.request(http.MethodPut, f.path(""), map[string]any{
+		"behavior": map[string]any{
+			"tone":                   "friendly",
+			"language":               "auto",
+			"max_response_length":    750,
+			"custom_prompt_suffix":   "Use short steps",
+			"auto_label_enabled":     true,
+			"auto_follow_up_enabled": true,
+			"auto_reply_enabled":     false,
+		},
+	})
+	require.Equal(t, http.StatusOK, w.Code, w.Body.String())
+	behavior := decodeCaptainPreferencePayload(t, w)["behavior"].(map[string]any)
+	require.Equal(t, "Use short steps", behavior["custom_prompt_suffix"])
+
+	w = f.request(http.MethodPut, f.path(""), map[string]any{
+		"behavior": map[string]any{"custom_prompt_suffix": ""},
+	})
+	require.Equal(t, http.StatusOK, w.Code, w.Body.String())
+	behavior = decodeCaptainPreferencePayload(t, w)["behavior"].(map[string]any)
+	require.Equal(t, "", behavior["custom_prompt_suffix"])
+}