fix(tabs): re-evaluate auto-wrap on resize and on every full tab rebuild

Review polish on the desktop tab auto-wrap:

- Auto-wrap is purely width-driven, but updateTabOverflowMode() was only called at the
  tail of _renderSessionTabsImmediate (SSE content renders). Window resize — the primary
  trigger for tabs crossing the one-row overflow threshold — never re-evaluated it, so
  narrowing/widening the window left the wrap state stale until an unrelated status event
  fired a render. Call it from the debounced window-resize handler (no-op on
  mobile/tablet, where the method bails).

- Move the re-evaluation into _fullRenderSessionTabs() as well, so the incremental
  branch's two early `_fullRenderSessionTabs(); return;` paths (badge add/remove, which
  change tab width) and the manual two-rows toggle (applyTabWrapSettings → _fullRender…)
  re-evaluate too. The latter also fixes a transient where enabling manual two-rows while
  auto-wrap was on left both classes set (clipping folder tabs to 96px) until the next
  render.

- Add boundary cases to the policy test: exact fit and the +1 sub-pixel tolerance (no
  wrap), 2px over (wrap), and a single overflowing tab (no wrap).

Verified: tab-overflow test passes; tsc, check:frontend-syntax, check:public-assets,
prettier all clean.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/web/public/app.js

@@ -2765,6 +2765,12 @@ class CodemanApp {
 
     // Update connection lines after tabs change (positions may have shifted)
     this.updateConnectionLines();
+
+    // Re-evaluate desktop auto-wrap for every full rebuild, including the incremental
+    // branch's early `_fullRenderSessionTabs(); return;` paths and the manual two-rows
+    // toggle (applyTabWrapSettings calls this) which would otherwise leave a stale
+    // tabs-auto-wrap class until the next content render.
+    this.updateTabOverflowMode();
   }
 
   // Set up arrow key navigation for session tabs (accessibility)

src/web/public/mobile-handlers.js

@@ -139,6 +139,9 @@ const MobileDetection = {
       resizeTimeout = setTimeout(() => {
         this.updateBodyClass();
         this.updateAppHeight();
+        // Tab auto-wrap is width-driven, so it must re-evaluate on resize — the only
+        // other trigger is a tab content render. No-op on mobile/tablet (method bails).
+        if (typeof app !== 'undefined') app.updateTabOverflowMode?.();
       }, 100);
     };
     window.addEventListener('resize', this._resizeHandler);

test/tab-overflow.test.ts

@@ -48,4 +48,18 @@ describe('tab overflow layout policy', () => {
       })
     ).toBe(false);
   });
+
+  it('respects the boundary conditions (exact fit, +1 tolerance, and tabCount < 2)', () => {
+    const helper = loadTabOverflowHelper();
+    const base = { deviceType: 'desktop' as const, manualTwoRows: false, tabCount: 6 };
+
+    // Exact fit: no overflow, no wrap.
+    expect(helper.shouldAutoWrapTabs({ ...base, scrollWidth: 800, clientWidth: 800 })).toBe(false);
+    // Within the +1 sub-pixel tolerance: still no wrap.
+    expect(helper.shouldAutoWrapTabs({ ...base, scrollWidth: 801, clientWidth: 800 })).toBe(false);
+    // 2px over: wrap.
+    expect(helper.shouldAutoWrapTabs({ ...base, scrollWidth: 802, clientWidth: 800 })).toBe(true);
+    // A single overflowing tab must not wrap (need at least 2 to form a second row).
+    expect(helper.shouldAutoWrapTabs({ ...base, tabCount: 1, scrollWidth: 1400, clientWidth: 760 })).toBe(false);
+  });
 });