fix #380: Chat tab opacity sliders were missing their retail row captions

Root cause: PlayerOptionPage::AddSliderOption never sets a row's own
name-label text — the "Inactive Opacity"/"Active Opacity" caption comes
from a SEPARATE DAT-resident runtime catalog (DID 0x78000000, resolved
via the same two-level DBCache::GetDIDFromEnumStatic master-map/submap
lookup ChatOptionsDatDefaults already uses for enum 0x16/category 2,
here for enum 0x15/category 2) that nothing in the codebase ever
queried, so both slider rows rendered with no caption at all.

Fix: new ChatOptionsDatCaptions.TryRead resolves the DID-0x78000000
catalog's per-property name/tooltip entries (matched by the same
owning-property enum ChatOptionsDatDefaults already keys its defaults
by) and ChatOptionsPageController.BuildOpacitySliders stamps each
slider's own row caption/tooltip from it — falling back to no text
(never invented English) if resolution fails. Regressed by
ChatOptionsPageControllerTests.
Bind_WiresEachSlidersOwnRowCaption_FromTheResolvedDatCatalog and the
companion Bind_MissingCaption_RendersNoText_NeverInventsEnglish case,
plus a live-mount probe (OptionsPanelLiveMountProbeTests.
ProbeChatOpacityCaptions) confirming the production TryRead call
resolves "Inactive Opacity"/"Active Opacity" against the real DAT.

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

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

@@ -107,6 +107,25 @@ public static class ChatOptionsPageController
     /// <summary>The slider leaf inside either slider row template's subtree.</summary>
     private const uint SliderElementId = 0x1000021Cu;
 
+    /// <summary>
+    /// #380 (2026-08-11, gate 4): the slider row's own NAME-CAPTION text
+    /// child ("Inactive Opacity" / "Active Opacity") — present on BOTH
+    /// template idx3 and idx6 (research doc §1.5's template array: "label
+    /// 0x1000021B + slider 0x1000021C", the SAME id
+    /// <see cref="ConfigOptionsPageController"/> already cites for its own
+    /// slider rows sharing this template pool). Retail's
+    /// <c>PlayerOptionPage::AddSliderOption</c> never sets this element's
+    /// text itself (byte-verified — no <c>StringInfo</c> write in its
+    /// pseudo-C body); the caption comes from
+    /// <c>UIOption_Slider::SetGameplayOptionProperty</c>'s own
+    /// <c>InqGameplayOptionNameAndTooltip</c> catalog lookup instead — see
+    /// <see cref="ChatOptionsDatCaptions"/>'s own doc for the full byte
+    /// trace. Nothing wired this element at all before #380 — the user's
+    /// literal complaint ("I also miss the text next to the bars for
+    /// Inactive and Active Opacity").
+    /// </summary>
+    private const uint SliderLabelElementId = 0x1000021Bu;
+
     /// <summary>Labelled slider template's low/high range-caption children
     /// (research doc §1.5's template array; present only on template idx 6).</summary>
     private const uint SliderRangeMinElementId = 0x1000021Eu;
@@ -199,7 +218,17 @@ public static class ChatOptionsPageController
         float DefaultOpacityDatDefault,
         float ActiveOpacityDatDefault,
         Func<int, ulong> CurrentFilter,
-        Action<int, ulong> SetFilter);
+        Action<int, ulong> SetFilter,
+        // #380: the two sliders' row captions/tooltips, resolved ONCE by the
+        // caller (RetailUiRuntime) via ChatOptionsDatCaptions — the SAME
+        // "resolve once, thread the pre-resolved value through Bindings"
+        // shape DefaultOpacityDatDefault/ActiveOpacityDatDefault already
+        // established for the value half of this exact DAT lookup family.
+        // Null when the DAT read failed or that entry's own StringInfo did
+        // not resolve — the row then renders with NO caption rather than
+        // invented English, matching this codebase's uniform degrade rule.
+        ChatOptionsDatCaptions.Caption DefaultOpacityCaption,
+        ChatOptionsDatCaptions.Caption ActiveOpacityCaption);
 
     /// <summary>
     /// Builds the General Options header + 2 sliders + 5 filter sections (header +
@@ -367,6 +396,16 @@ public static class ChatOptionsPageController
             SetRangeLabel(row2, SliderRangeMaxElementId, "ID_UI_Value_Opaque", resolveString);
         }
 
+        // #380: the row-name captions ("Inactive Opacity" / "Active
+        // Opacity") + tooltips — resolved once by the caller via
+        // ChatOptionsDatCaptions, threaded through Bindings exactly like the
+        // sibling DefaultOpacityDatDefault/ActiveOpacityDatDefault values.
+        // Element 0x1000021B is shared by BOTH templates (see its own doc).
+        if (row1 is not null)
+            SetOpacityCaption(row1, bindings.DefaultOpacityCaption, slider1);
+        if (row2 is not null)
+            SetOpacityCaption(row2, bindings.ActiveOpacityCaption, slider2);
+
         if (slider1 is null || slider2 is null)
             return;
 
@@ -431,6 +470,38 @@ public static class ChatOptionsPageController
         text.LinesProvider = () => new[] { new UiText.Line(label, text.DefaultColor) };
     }
 
+    /// <summary>
+    /// #380: sets one opacity slider row's own name-caption (element
+    /// <see cref="SliderLabelElementId"/>) + tooltip from a pre-resolved
+    /// <see cref="ChatOptionsDatCaptions.Caption"/> — the DAT-catalog
+    /// counterpart of <see cref="SetRangeLabel"/> (which resolves a
+    /// COMPILED symbol key; this resolves a RUNTIME DAT entry, so it takes
+    /// the already-resolved string rather than a key to hash). A null
+    /// <see cref="ChatOptionsDatCaptions.Caption.Name"/> leaves the row with
+    /// no caption rather than inventing English, matching every other
+    /// resolve-miss path in this controller. The tooltip attaches to the
+    /// SLIDER itself (the interactive/hoverable widget for this row — same
+    /// convention <see cref="ConfigOptionsPageController"/>'s own slider
+    /// rows use), not the caption text.
+    /// </summary>
+    private static void SetOpacityCaption(
+        UiElement row, ChatOptionsDatCaptions.Caption caption, UiScrollbar? slider)
+    {
+        if (UiElement.FindDescendant(row, SliderLabelElementId) is UiText text)
+        {
+            if (caption.Name is { Length: > 0 } name)
+                text.LinesProvider = () => new[] { new UiText.Line(name, text.DefaultColor) };
+            else
+                Console.WriteLine(
+                    "[D.2b] ChatOptionsPageController: opacity slider caption did not "
+                    + "resolve from the DAT name/tooltip catalog — the row renders with no "
+                    + "text rather than invented English.");
+        }
+
+        if (slider is not null && caption.Tooltip is { Length: > 0 } tooltip)
+            slider.TooltipText = tooltip;
+    }
+
     /// <summary>
     /// One per-window filter block: resolves the block template DIRECTLY through
     /// <paramref name="templateResolver"/> (NOT via