fix(titlebar): sync window width to panel-hidden state on startup

The titlebar's panel-toggle path physically shrinks the OS window by
320px per hidden panel (var(--w-left/right)) — but Tauri does NOT
persist window size across restarts (no tauri-plugin-window-state),
so a user who closed with panels hidden reopened at the full 1600px
default with a stretched-empty center column. Toggling a panel back
on then grew the window past 1600px because adjustWindowForPanel
works in deltas from the current size — every restart-then-show
cycle ballooned the window by another 320px on the affected axis.

Sync the window width to the persisted leftPanelHidden / rightPanelHidden
flags BEFORE invoke('show_main_window') reveals it. The window starts
with visible: false from tauri.conf.json, so the resize completes
during the same paint cycle that flips visibility — no flash.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: claude

src-ui/src/main.tsx

@@ -43,9 +43,42 @@ if (typeof document !== 'undefined' && document.fonts) {
 // Window starts with `visible: false` (see tauri.conf.json) to hide the
 // Windows-default chrome flash. Reveal it only after the first paint so
 // the first frame the user sees is the final themed UI.
+//
+// Before reveal, sync window width to the persisted panel-hidden state
+// (cc-left-hidden / cc-right-hidden). The titlebar's panel-toggle path
+// physically shrinks the window by 320px per panel, but Tauri does NOT
+// persist window size across restarts (no tauri-plugin-window-state).
+// Without this sync, a user who closed with panels hidden would reopen
+// at the full 1600px default with a stretched-empty center column, and
+// toggling a panel back on would grow the window past 1600px because
+// adjustWindowForPanel works in deltas from the current size. Keep
+// PANEL_WIDTH in sync with TitleBar.tsx and the --w-left/right CSS vars.
+async function syncWindowToPanelStateAndShow() {
+  try {
+    const leftHidden = localStorage.getItem('cc-left-hidden') === '1';
+    const rightHidden = localStorage.getItem('cc-right-hidden') === '1';
+    const hiddenCount = (leftHidden ? 1 : 0) + (rightHidden ? 1 : 0);
+    if (hiddenCount > 0) {
+      const { getCurrentWindow, PhysicalSize } = await import('@tauri-apps/api/window');
+      const w = getCurrentWindow();
+      if (!(await w.isMaximized())) {
+        const scale = await w.scaleFactor();
+        const shrinkPx = Math.round(320 * hiddenCount * scale);
+        const minWidthPx = Math.round(900 * scale); // matches tauri.conf.json minWidth
+        const size = await w.innerSize();
+        const targetW = Math.max(minWidthPx, size.width - shrinkPx);
+        if (targetW !== size.width) {
+          await w.setSize(new PhysicalSize(targetW, size.height));
+        }
+      }
+    }
+  } catch {}
+  invoke('show_main_window').catch(() => {});
+}
+
 requestAnimationFrame(() => {
   requestAnimationFrame(() => {
-    invoke('show_main_window').catch(() => {});
+    void syncWindowToPanelStateAndShow();
   });
 });