feat: settings dialog for update config (gear entry)

A low-key "⚙ 配置" button at the right end of the flow-tab row opens a settings
dialog to edit update_source / update_user / update_pass, with a test-connection
button that distinguishes "reachable & up to date" from "cannot connect".

- settings_dialog.py: pure-UI QDialog; password mask + show; test runs off the
  UI thread via load_manifest and reports the result
- update_service: add load_manifest() (raises on failure, unlike check_for_update)
- main_window: gear button, _open_settings persists via save_config and re-runs
  the update check; _update_found connected once to avoid duplicate banners
- tests: +2 for load_manifest

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/app/main_window.py

@@ -6,6 +6,7 @@ from pathlib import Path
 from PySide6.QtCore import Qt, QUrl, Signal
 from PySide6.QtGui import QDesktopServices
 from PySide6.QtWidgets import (
+    QDialog,
     QHBoxLayout,
     QLabel,
     QMainWindow,
@@ -26,6 +27,7 @@ from app.widgets.export_panel import ExportPanel
 from app.widgets.image_canvas import ImageCanvas
 from app.widgets.image_list_panel import ImageListPanel
 from app.widgets.queue_panel import QueuePanel
+from app.widgets.settings_dialog import SettingsDialog
 from app.widgets.template_panel import TemplatePanel
 from app.widgets.transform_panel import TransformPanel
 
@@ -108,8 +110,34 @@ class MainWindow(QMainWindow):
         layout.addWidget(self._tab_bar)
         layout.addStretch()
 
+        # Right-aligned utility entry — not a numbered workflow step (docs/07 §4.3)
+        self._settings_btn = QPushButton("⚙ 配置")
+        self._settings_btn.setObjectName("settingsBtn")
+        self._settings_btn.setCursor(Qt.PointingHandCursor)
+        self._settings_btn.clicked.connect(self._open_settings)
+        layout.addWidget(self._settings_btn)
+
         return container
 
+    def _open_settings(self):
+        """Open the settings dialog; persist + re-check on save (docs/07 §4.4)."""
+        dlg = SettingsDialog(
+            self,
+            update_source=self._config.get("update_source", ""),
+            update_user=self._config.get("update_user", ""),
+            update_pass=self._config.get("update_pass", ""),
+            current_version=APP_VERSION,
+        )
+        if dlg.exec() == QDialog.Accepted:
+            self._config.update(dlg.values())
+            save_config(self._config)
+            self._refresh_update_check()
+
+    def _refresh_update_check(self):
+        """Re-run the update check after the source/credentials changed."""
+        self._update_banner.setVisible(False)
+        self._start_update_check()
+
     # ------------------------------------------------------------------
     # Update notification (stage 2: notify-only, see docs/10-lan-update.md)
     # ------------------------------------------------------------------
@@ -117,6 +145,7 @@ class MainWindow(QMainWindow):
     def _create_update_banner(self):
         """A thin info bar shown when a newer version is found. Hidden by default."""
         self._update_info = None
+        self._update_found.connect(self._on_update_found)   # connect once
 
         bar = QWidget()
         bar.setObjectName("updateBanner")
@@ -149,13 +178,16 @@ class MainWindow(QMainWindow):
         return bar
 
     def _start_update_check(self):
-        """Check the configured update source for a newer version, off the UI thread."""
+        """Check the configured update source for a newer version, off the UI thread.
+
+        Safe to call again after the settings change; the result signal is
+        connected once in _create_update_banner, not here.
+        """
         source = self._config.get("update_source", "")
         if not source:
             return
         user = self._config.get("update_user", "")
         password = self._config.get("update_pass", "")
-        self._update_found.connect(self._on_update_found)
 
         def worker():
             try:
@@ -636,6 +668,15 @@ class MainWindow(QMainWindow):
             QTabBar#flowTabBar::tab:disabled {
                 color: #bbbbbb;
             }
+            #settingsBtn {
+                font-family: "Microsoft YaHei", "Segoe UI", sans-serif;
+                font-size: 12px;
+                color: #666666;
+                background: transparent;
+                border: none;
+                padding: 4px 14px;
+            }
+            #settingsBtn:hover { color: #0078d4; background: #e8f0fb; }
 
             /* Work splitter */
             QSplitter#workSplitter::handle {

src/app/widgets/settings_dialog.py

@@ -0,0 +1,146 @@
+"""Settings dialog: configure the online-update source and credentials.
+
+Pure UI — it never reads or writes the config file. The caller (main_window)
+injects the current values and persists the result via save_config
+(docs/05 §4.12, docs/07 §4.4).
+"""
+import logging
+import threading
+
+from PySide6.QtCore import Qt, Signal
+from PySide6.QtWidgets import (
+    QDialog,
+    QDialogButtonBox,
+    QFormLayout,
+    QHBoxLayout,
+    QLabel,
+    QLineEdit,
+    QPushButton,
+    QVBoxLayout,
+)
+
+from version import APP_VERSION
+from services.update_service import is_newer, load_manifest
+
+logger = logging.getLogger(__name__)
+
+
+class SettingsDialog(QDialog):
+    """Edit update_source / update_user / update_pass with a connection test."""
+
+    _test_done = Signal(str)   # result message, delivered to the UI thread
+
+    def __init__(self, parent=None, *, update_source="", update_user="",
+                 update_pass="", current_version=APP_VERSION):
+        super().__init__(parent)
+        self.setWindowTitle("设置")
+        self.setMinimumWidth(420)
+        self._current_version = current_version
+        self._setup_ui(update_source, update_user, update_pass)
+        self._test_done.connect(self._on_test_done)
+
+    # ── UI ───────────────────────────────────────────────────────────────────
+
+    def _setup_ui(self, source, user, password):
+        col = QVBoxLayout(self)
+        col.setSpacing(10)
+
+        form = QFormLayout()
+        form.setLabelAlignment(Qt.AlignRight)
+
+        self._source_edit = QLineEdit(source)
+        self._source_edit.setPlaceholderText("http://主机名/  或 manifest.json 地址")
+        form.addRow("更新地址", self._source_edit)
+
+        self._user_edit = QLineEdit(user)
+        form.addRow("账号", self._user_edit)
+
+        self._pass_edit = QLineEdit(password)
+        self._pass_edit.setEchoMode(QLineEdit.Password)
+        show_btn = QPushButton("显示")
+        show_btn.setCheckable(True)
+        show_btn.setFixedWidth(48)
+        show_btn.toggled.connect(self._toggle_password)
+        pass_row = QHBoxLayout()
+        pass_row.setContentsMargins(0, 0, 0, 0)
+        pass_row.addWidget(self._pass_edit, 1)
+        pass_row.addWidget(show_btn)
+        form.addRow("密码", pass_row)
+
+        col.addLayout(form)
+
+        # version + test row
+        test_row = QHBoxLayout()
+        test_row.addWidget(QLabel("当前版本 v{}".format(self._current_version)))
+        test_row.addStretch()
+        self._test_btn = QPushButton("测试连接")
+        self._test_btn.clicked.connect(self._on_test)
+        test_row.addWidget(self._test_btn)
+        col.addLayout(test_row)
+
+        self._result = QLabel("")
+        self._result.setObjectName("settingsResult")
+        self._result.setWordWrap(True)
+        col.addWidget(self._result)
+
+        hint = QLabel("提示：建议使用只读账号；生产环境请走 HTTPS（凭据为明文存储）。")
+        hint.setObjectName("settingsHint")
+        hint.setWordWrap(True)
+        col.addWidget(hint)
+
+        buttons = QDialogButtonBox(QDialogButtonBox.Save | QDialogButtonBox.Cancel)
+        buttons.button(QDialogButtonBox.Save).setText("保存")
+        buttons.button(QDialogButtonBox.Cancel).setText("取消")
+        buttons.accepted.connect(self.accept)
+        buttons.rejected.connect(self.reject)
+        col.addWidget(buttons)
+
+        self.setStyleSheet("""
+            #settingsHint { font-size: 11px; color: #999999; }
+            #settingsResult { font-size: 12px; color: #555555; }
+        """)
+
+    def _toggle_password(self, shown):
+        self._pass_edit.setEchoMode(QLineEdit.Normal if shown else QLineEdit.Password)
+
+    # ── public API ───────────────────────────────────────────────────────────
+
+    def values(self):
+        """Return the edited config values (caller persists them)."""
+        return {
+            "update_source": self._source_edit.text().strip(),
+            "update_user": self._user_edit.text(),
+            "update_pass": self._pass_edit.text(),
+        }
+
+    # ── connection test (off the UI thread) ──────────────────────────────────
+
+    def _on_test(self):
+        source = self._source_edit.text().strip()
+        if not source:
+            self._result.setText("请先填写更新地址。")
+            return
+        user, password = self._user_edit.text(), self._pass_edit.text()
+        self._test_btn.setEnabled(False)
+        self._result.setText("正在测试…")
+
+        def worker():
+            try:
+                data = load_manifest(source, user, password)
+                remote = str((data or {}).get("version", "")).strip()
+                if not remote:
+                    msg = "连接成功，但清单缺少版本号。"
+                elif is_newer(remote, self._current_version):
+                    msg = "发现新版本 v{}（当前 v{}）。".format(remote, self._current_version)
+                else:
+                    msg = "连接成功，已是最新（远端 v{}）。".format(remote)
+            except Exception as exc:   # surface any reachability/auth/format error
+                logger.info("Settings test failed: %s", exc)
+                msg = "连接失败：{}".format(exc)
+            self._test_done.emit(msg)
+
+        threading.Thread(target=worker, name="settings-test", daemon=True).start()
+
+    def _on_test_done(self, msg):
+        self._result.setText(msg)
+        self._test_btn.setEnabled(True)

src/services/update_service.py

@@ -119,6 +119,18 @@ def _load_local_manifest(update_source):
         return json.load(f)
 
 
+def load_manifest(update_source, update_user="", update_pass=""):
+    """Fetch and parse the manifest dict, RAISING on failure.
+
+    Unlike check_for_update (which swallows errors into None), this surfaces
+    reachability/auth/format errors — used by the settings "test connection"
+    button to distinguish "reachable & up to date" from "cannot connect".
+    """
+    if _is_http_source(update_source):
+        return _load_http_manifest(update_source, update_user, update_pass)
+    return _load_local_manifest(update_source)
+
+
 def check_for_update(
     update_source,
     current_version,