Merge branch 'main' into claude/eloquent-hugle-42119e

# Conflicts:
#	.gitignore

src/AcDream.Core/Rendering/RenderingDiagnostics.cs

@@ -271,6 +271,33 @@ public static class RenderingDiagnostics
     public static bool ProbeLightEnabled { get; set; } =
         Environment.GetEnvironmentVariable("ACDREAM_PROBE_LIGHT") == "1";
 
+    /// <summary>
+    /// A7.L1 (2026-07-06) per-cell light SET-COMPOSITION probe — the apparatus the
+    /// <c>[light]</c> counts could not provide (the #176/#177 discriminator: the bug
+    /// lived in set MEMBERSHIP, not counts). When true, the scoped
+    /// <c>LightManager.BuildPointLightSnapshot</c> emits ONE rate-limited
+    /// <c>[indoor-light]</c> line describing the visible-cell-scoped point-light pool
+    /// (see <see cref="EmitIndoorLight"/>):
+    /// <code>
+    /// [indoor-light] visibleCells=&lt;N&gt; pool=&lt;M&gt; cellLess=&lt;K&gt; registered=&lt;R&gt;
+    ///                droppedNonVisible=&lt;R-M&gt; byCell=[0x&lt;id&gt;:&lt;count&gt;,...]
+    /// </code>
+    /// This validates the A7 fix's load-bearing assumption end-to-end:
+    /// <list type="bullet">
+    ///   <item><description><c>cellLess==pool</c> (every pool light is CellId 0) ⇒
+    ///   cell tagging FAILED (ParentCellId not flowing) — scoping is a silent no-op.</description></item>
+    ///   <item><description><c>pool==cellLess</c> while <c>registered</c> is large in a
+    ///   LIT room ⇒ tagged CellIds never match the visible set (wrong id form) — the
+    ///   room would go dark.</description></item>
+    ///   <item><description><c>droppedNonVisible&gt;0</c> with <c>byCell</c> tracking the
+    ///   visible rooms ⇒ scoping WORKING (the under-room/through-floor lights are the
+    ///   dropped ones).</description></item>
+    /// </list>
+    /// Output-only, inert when off. Initial state from <c>ACDREAM_PROBE_INDOOR_LIGHT=1</c>.
+    /// </summary>
+    public static bool ProbeIndoorLightEnabled { get; set; } =
+        Environment.GetEnvironmentVariable("ACDREAM_PROBE_INDOOR_LIGHT") == "1";
+
     // Cell-change gate for EmitVis. The probe fires once per distinct root cell
     // so launch.log stays readable under motion (the per-frame call is a no-op
     // when the root is unchanged). Sentinel 0 = "no root yet" — the first real
@@ -451,6 +478,66 @@ public static class RenderingDiagnostics
         }
     }
 
+    // Wall-clock rate-limit gate for EmitIndoorLight (shares the 1 s interval).
+    private static long _lastIndoorLightEmitTicks;
+
+    /// <summary>
+    /// A7.L1 — emit ONE rate-limited <c>[indoor-light]</c> line describing the
+    /// visible-cell-scoped point-light pool: the SET COMPOSITION the <c>[light]</c>
+    /// counts can't show. Cheap no-op when <see cref="ProbeIndoorLightEnabled"/> is
+    /// false; otherwise fires at most once per second. Called from the scoped
+    /// <c>LightManager.BuildPointLightSnapshot</c> (visibleCells != null path).
+    /// </summary>
+    /// <param name="visibleCellCount">Size of the portal-flood visible-cell set this frame.</param>
+    /// <param name="allRegistered">Every registered light (<c>LightManager._all</c>).</param>
+    /// <param name="scopedSnapshot">The visible-cell-scoped point-light pool just built.</param>
+    public static void EmitIndoorLight(int visibleCellCount,
+        IReadOnlyList<AcDream.Core.Lighting.LightSource> allRegistered,
+        IReadOnlyList<AcDream.Core.Lighting.LightSource> scopedSnapshot)
+    {
+        if (!ProbeIndoorLightEnabled) return;
+
+        long now = DateTime.UtcNow.Ticks;
+        if (_lastIndoorLightEmitTicks != 0 && (now - _lastIndoorLightEmitTicks) < LightEmitIntervalTicks)
+            return;
+        _lastIndoorLightEmitTicks = now;
+
+        int registeredLitPoints = 0;
+        foreach (var l in allRegistered)
+            if (l.IsLit && l.Kind != AcDream.Core.Lighting.LightKind.Directional) registeredLitPoints++;
+
+        int pool = scopedSnapshot.Count;
+        int cellLess = 0;
+        var hist = new Dictionary<uint, int>();
+        foreach (var l in scopedSnapshot)
+        {
+            if (l.CellId == 0) cellLess++;
+            hist.TryGetValue(l.CellId, out var c);
+            hist[l.CellId] = c + 1;
+        }
+
+        var sb = new StringBuilder(220);
+        sb.Append("[indoor-light] visibleCells=").Append(visibleCellCount);
+        sb.Append(" pool=").Append(pool);
+        sb.Append(" cellLess=").Append(cellLess);
+        sb.Append(" registered=").Append(registeredLitPoints);
+        // Lights excluded by visibility scoping (retail: cells not in visible_cell_table
+        // contribute nothing) — the through-floor/under-room lights kept out of the pool.
+        sb.Append(" droppedNonVisible=").Append(registeredLitPoints - pool);
+        sb.Append(" byCell=[");
+        const int MaxCells = 12;
+        int shown = 0;
+        foreach (var kv in hist)
+        {
+            if (shown >= MaxCells) { sb.Append(",..."); break; }
+            if (shown > 0) sb.Append(',');
+            sb.Append("0x").Append(kv.Key.ToString("X8")).Append(':').Append(kv.Value);
+            shown++;
+        }
+        sb.Append(']');
+        Console.WriteLine(sb.ToString());
+    }
+
     private static bool _probeEnvCellEnabled =
         Environment.GetEnvironmentVariable("ACDREAM_PROBE_ENVCELL") == "1";