fix(ui): fellowship checkbox count, row-text + ListBox Flush doc corrections, promote probe findings to assertions

Mechanism SHOULD-FIX 4: SocialFellowshipPageController's class doc said
0x1000026B holds "all three visible option checkboxes" — the fixture and
the decomp both authors FOUR (Ignore Fellowship Requests / Auto-Accept
Requests / Share XP / Share Loot, 0x10000270-0x10000273). Corrected.

Mechanism SHOULD-FIX 9: SocialPanelRowText.FindDeepest's doc promised
"the deepest UiText descendant" but the implementation returns the LAST
match in pre-order traversal order, which only equals the deepest when
the subtree is a single chain. Both real row templates ARE single
chains today, so behavior is unaffected — the doc now describes what the
code actually does instead of a stronger guarantee it doesn't implement.

Blast SHOULD-FIX 5: UiTemplateListBox.Flush()'s doc only mentioned the
ContentHeight reset; UiScrollablePanel.ClearContent() also resets scroll
position to 0, which the sibling UiItemList.Flush() (same method name,
different semantics) does NOT do. Documented explicitly, including the
UX cost this creates for a scrolled-in Friends/Squelch roster once its
scrollbar is wired (this fix round's blast MF-1) — flagged for whoever
revisits Friends/Squelch scrolling next rather than silently fixed as an
unasked behavior change.

Mechanism SHOULD-FIX 3: SocialPanelLiveMountProbeTests printed two
headline findings (the 0x10000492-authored-twice count, page exclusivity
after ActivateTabBehavior) without ever asserting them — a future
importer regression collapsing/dropping an instance, or breaking
exclusivity, could not fail this test. Both are now real assertions
(Assert.Equal(2, passupCount); exactly one page Visible and it is
Allegiance).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/AcDream.App/UI/Layout/SocialFellowshipPageController.cs

@@ -16,7 +16,9 @@ namespace AcDream.App.UI.Layout;
 /// <c>m_pFellowship == null</c>, and vice-versa. Both are AUTHORED sibling
 /// containers of the fellowship page (<c>0x10000292</c>) — confirmed by the
 /// FA3 live-mount probe: <c>0x1000026B</c> holds the name-entry box, Create
-/// button, and all three visible option checkboxes; <c>0x10000275</c> holds
+/// button, and all FOUR visible option checkboxes (Ignore Fellowship
+/// Requests / Auto-Accept Requests / Share XP / Share Loot —
+/// <c>0x10000270</c>–<c>0x10000273</c>, fix-round mechanism SF-4); <c>0x10000275</c> holds
 /// the roster list and all six member-management buttons. A single
 /// <see cref="UiElement.Visible"/> toggle on each container is therefore the
 /// WHOLE empty-state swap; no per-child hiding is needed (closes lane-A

src/AcDream.App/UI/Layout/SocialPanelRowText.cs

@@ -16,9 +16,20 @@ namespace AcDream.App.UI.Layout;
 /// </summary>
 internal static class SocialPanelRowText
 {
-    /// <summary>Returns the deepest <see cref="UiText"/> descendant of
-    /// <paramref name="row"/> (pre-order, last match wins), or null if the
-    /// built row contains no text element at all.</summary>
+    /// <summary>
+    /// Returns the LAST <see cref="UiText"/> found by a pre-order walk of
+    /// <paramref name="row"/> (row itself, then each child's own subtree in
+    /// order), or null if the built row contains no text element at all.
+    /// <b>Fix-round mechanism SF-9:</b> this equals the truly DEEPEST match
+    /// only when the subtree is a single chain — both real row templates
+    /// (Friends <c>0x10000519</c>, Squelch <c>0x10000541</c>) ARE single
+    /// chains (row root -&gt; one Type-0xC text child -&gt; one more Type-0xC
+    /// text grandchild, per the FA3 live-mount probe), so this method's
+    /// actual "last match in traversal order" behavior and the class doc's
+    /// "deepest" framing agree for both templates in production today. A
+    /// row template with a BRANCHING subtree (multiple text leaves at
+    /// different depths) would expose the difference.
+    /// </summary>
     public static UiText? FindDeepest(UiElement row)
     {
         UiText? found = row as UiText;

src/AcDream.App/UI/UiTemplateListBox.cs

@@ -239,7 +239,10 @@ public sealed class UiTemplateListBox : UiDatElement
     /// <summary>
     /// Campaign FA slice FA3: removes every row previously added via
     /// <see cref="AddItemFromTemplateList"/>/<see cref="AddPrebuiltRow"/>, resetting
-    /// <see cref="ContentHeight"/> to 0 — the "Gap found" prerequisite lane A/D
+    /// <see cref="ContentHeight"/> to 0 AND the scroll position to 0
+    /// (<see cref="UiScrollablePanel.ClearContent"/> calls
+    /// <c>Scroll.SetScrollY(0)</c> — fix-round blast SF-5: the ORIGINAL doc here
+    /// only mentioned the height reset) — the "Gap found" prerequisite lane A/D
     /// flagged (docs/research/2026-08-11-fa-panel-structure.md §6.6: "no Flush, no
     /// selection model, no per-row instance-id"). Needed for a poll-and-rebuild
     /// binding (Friends/Squelch read-only lists) where the row COUNT can shrink
@@ -247,6 +250,20 @@ public sealed class UiTemplateListBox : UiDatElement
     /// grows the stack. A no-op, never allocating the viewport, when the box is
     /// still dormant (no row has ever been added) — mirrors every other dormancy
     /// guard on this class (see class doc).
+    ///
+    /// <para>
+    /// <b>Diverges from the sibling <see cref="UiItemList.Flush"/> it shares a
+    /// name with</b> (fix-round blast SF-5): that method does NOT touch scroll
+    /// position. For a poll-and-rebuild Friends/Squelch list, this means a user
+    /// scrolled partway into a long roster is yanked back to the top on every
+    /// server-side change (a friend's online status flips, etc.) — a real,
+    /// user-visible UX cost once <see cref="ScrollbarElementId"/> is actually
+    /// wired (it now is — see <see cref="AcDream.App.UI.Layout.SocialFriendsPageController"/>).
+    /// Not fixed here: doing so would require this class to preserve/re-clamp
+    /// the offset across a rebuild whose row COUNT can shrink, which is a
+    /// bigger behavior change than a fix-round doc correction should make
+    /// unasked; flagged for whoever revisits Friends/Squelch scrolling next.
+    /// </para>
     /// </summary>
     public void Flush() => _viewport?.ClearContent();
 }

tests/AcDream.App.Tests/UI/Layout/SocialPanelLiveMountProbeTests.cs

@@ -67,6 +67,11 @@ public sealed class SocialPanelLiveMountProbeTests
         tabs.ActivateTabBehavior();
         Assert.Empty(tabs.UnresolvedEntries);
 
+        // Fix-round mechanism SF-3: page exclusivity was activated but never
+        // asserted — the #372 class ("the panel mounts but the pages are
+        // wrong/blank") deserves a real assertion, not just a hope.
+        bool sawVisiblePage = false;
+        string? visiblePageName = null;
         foreach ((uint pageId, string name) in new[]
         {
             (0x10000513u, "Friends"),
@@ -77,9 +82,20 @@ public sealed class SocialPanelLiveMountProbeTests
         {
             UiElement? page = UiElement.FindDescendant(tabs, pageId);
             Console.WriteLine(
-                $"[socialprobe] page {name} 0x{pageId:X8} -> {(page is null ? "MISSING" : page.GetType().Name)}");
+                $"[socialprobe] page {name} 0x{pageId:X8} -> {(page is null ? "MISSING" : page.GetType().Name)} "
+                + $"Visible={page?.Visible}");
             Assert.NotNull(page);
+            if (page!.Visible)
+            {
+                Assert.False(
+                    sawVisiblePage,
+                    $"page exclusivity violated: both '{visiblePageName}' and '{name}' report Visible=true after ActivateTabBehavior()");
+                sawVisiblePage = true;
+                visiblePageName = name;
+            }
         }
+        Assert.True(sawVisiblePage, "no page reports Visible=true after ActivateTabBehavior()");
+        Assert.Equal("Allegiance", visiblePageName);
 
         // Fellowship empty/full frame pair.
         foreach ((uint id, string name) in new[]
@@ -116,6 +132,10 @@ public sealed class SocialPanelLiveMountProbeTests
         Assert.NotNull(allegiancePage);
         int passupCount = CountDescendants(allegiancePage!, 0x10000492u);
         Console.WriteLine($"[socialprobe] 0x10000492 occurrences under allegiance page = {passupCount}");
+        // Fix-round mechanism SF-3: this was printed but never asserted — a
+        // future importer change that collapses or drops one instance must
+        // fail this test, not just the log.
+        Assert.Equal(2, passupCount);
 
         // Tab button captions — non-empty (the #375 resolver class: a missing
         // string resolver renders blank captions even though the layout mounts).