diff --git a/src/AcDream.App/Rendering/GameWindow.cs b/src/AcDream.App/Rendering/GameWindow.cs
index e7589c9..141f0ad 100644
--- a/src/AcDream.App/Rendering/GameWindow.cs
+++ b/src/AcDream.App/Rendering/GameWindow.cs
@@ -7138,6 +7138,10 @@ public sealed class GameWindow : IDisposable
                     $"cell=0x{cellId} visN={visCount} {visList}");
             }
 
+            // Phase A8 Task 9: increment the [draworder] frame counter once per render
+            // tick. Used by EmitDrawOrderProbe to attribute step transitions to a frame.
+            _phaseA8DrawOrderFrame++;
+
             // Lighting decisions (sun zeroed, indoor ambient applied) must
             // track the PLAYER's cell, not the camera's. In third-person
             // chase mode the camera enters interiors before the player body
@@ -10760,14 +10764,69 @@ public sealed class GameWindow : IDisposable
         }
     }
 
-    // ── Phase A8 probe stubs (Task 9 wires these up with real output) ────────
+    // ── Phase A8 Task 9 (2026-05-28): probe trail for RenderInsideOutAcdream ──
+    //
+    // Mandatory diagnostic infrastructure per the post-RR7 process rule
+    // "no visual-gate launch without probe data first" (handoff doc
+    // 2026-05-27-a8-rr7-reverted-wb-port-handoff.md).
+    //
+    // Gating:
+    //   [envcells]   — ACDREAM_PROBE_VIS=1  OR  ACDREAM_PROBE_ENVCELL=1
+    //   [stencil]    — ACDREAM_PROBE_VIS=1
+    //   [draworder]  — ACDREAM_PROBE_VIS=1
+    //   [buildings]  — ACDREAM_PROBE_VIS=1
+    //
+    // Acceptance criteria (read these FROM the launch log BEFORE asking
+    // the user for visual verification):
+    //   - [buildings] camBldgs=[0x...] non-empty when inside a cottage
+    //   - [envcells] cells>=1 tris>=1 filterCnt>=1 for at least one indoor frame
+    //   - [stencil] op=mark verts>0 fires per camera-building
+    //   - [draworder] shows steps 1 → 2 → 3 → 4 → 5{a,b,c,d} per indoor frame
+
+    private int _phaseA8DrawOrderFrame = 0;
+
+    private void EmitDrawOrderProbe(int step, char sub)
+    {
+        if (!AcDream.Core.Rendering.RenderingDiagnostics.ProbeVisibilityEnabled) return;
+        _gl!.GetInteger(Silk.NET.OpenGL.GLEnum.StencilTest, out int stOn);
+        _gl!.GetInteger(Silk.NET.OpenGL.GLEnum.DepthFunc, out int depthFn);
+        _gl!.GetBoolean(Silk.NET.OpenGL.GLEnum.DepthWritemask, out var depthMask);
+        string subStr = sub == ' ' ? "" : sub.ToString();
+        Console.WriteLine(
+            $"[draworder] frame={_phaseA8DrawOrderFrame} step={step}{subStr} " +
+            $"stencil={(stOn != 0 ? "on" : "off")} depthFn=0x{depthFn:X} depthMask={depthMask}");
+    }
+
+    private void EmitEnvCellProbe(int ourBldgs, int otherBldgs, int filterCnt)
+    {
+        if (!AcDream.Core.Rendering.RenderingDiagnostics.ProbeEnvCellEnabled) return;
+        var stats = _envCellRenderer?.Stats ?? default;
+        Console.WriteLine(
+            $"[envcells] cells={stats.CellsRendered} tris={stats.TrianglesDrawn} " +
+            $"ourBldgs={ourBldgs} otherBldgs={otherBldgs} filterCnt={filterCnt}");
+    }
+
+    private void EmitStencilProbe(string op)
+    {
+        if (!AcDream.Core.Rendering.RenderingDiagnostics.ProbeVisibilityEnabled) return;
+        if (_indoorStencilPipeline is null) return;
+        Console.WriteLine(
+            $"[stencil] op={op} bld=0x{_indoorStencilPipeline.LastStencilBuildingId:X8} " +
+            $"verts={_indoorStencilPipeline.LastStencilVertexCount}");
+    }
 
-    private void EmitDrawOrderProbe(int step, char sub) { /* Task 9 */ }
-    private void EmitEnvCellProbe(int ourBldgs, int otherBldgs, int filterCnt) { /* Task 9 */ }
-    private void EmitStencilProbe(string op) { /* Task 9 */ }
     private void EmitBuildingsProbe(uint visibilityCellId,
         System.Collections.Generic.List<AcDream.App.Rendering.Wb.Building> camBldgs,
-        System.Collections.Generic.List<AcDream.App.Rendering.Wb.Building> otherBldgs) { /* Task 9 */ }
+        System.Collections.Generic.List<AcDream.App.Rendering.Wb.Building> otherBldgs)
+    {
+        if (!AcDream.Core.Rendering.RenderingDiagnostics.ProbeVisibilityEnabled) return;
+        var ids = string.Join(",", camBldgs.ConvertAll(b => $"0x{b.BuildingId:X}"));
+        int totalKnown = 0;
+        foreach (var r in _buildingRegistries.Values) totalKnown += r.Count;
+        Console.WriteLine(
+            $"[buildings] camCell=0x{visibilityCellId:X8} " +
+            $"camBldgs=[{ids}] otherBldgs={otherBldgs.Count} totalKnown={totalKnown}");
+    }
 
     // ────────────────────────────────────────────────────────────────────────────
 
diff --git a/src/AcDream.Core/Rendering/RenderingDiagnostics.cs b/src/AcDream.Core/Rendering/RenderingDiagnostics.cs
index 421552c..95cdbe9 100644
--- a/src/AcDream.Core/Rendering/RenderingDiagnostics.cs
+++ b/src/AcDream.Core/Rendering/RenderingDiagnostics.cs
@@ -86,6 +86,23 @@ public static class RenderingDiagnostics
     public static bool ProbeVisibilityEnabled { get; set; } =
         Environment.GetEnvironmentVariable("ACDREAM_PROBE_VIS") == "1";
 
+    private static bool _probeEnvCellEnabled =
+        Environment.GetEnvironmentVariable("ACDREAM_PROBE_ENVCELL") == "1";
+
+    /// <summary>
+    /// Phase A8 Task 9 (2026-05-28): when true, RenderInsideOutAcdream's
+    /// <c>[envcells]</c> probe emits one line per indoor frame —
+    /// CellsRendered / TrianglesDrawn from <see cref="AcDream.App.Rendering.Wb"/>'s
+    /// <c>EnvCellRenderer.Stats</c> + ourBldgs/otherBldgs/filterCnt.
+    /// Also enabled implicitly when <see cref="ProbeVisibilityEnabled"/> is true.
+    /// Initial state from <c>ACDREAM_PROBE_ENVCELL=1</c>.
+    /// </summary>
+    public static bool ProbeEnvCellEnabled
+    {
+        get => _probeEnvCellEnabled || ProbeVisibilityEnabled;
+        set => _probeEnvCellEnabled = value;
+    }
+
     /// <summary>
     /// Master toggle. Reading reflects the AND of all five flags
     /// (true only when every probe is on). Writing cascades — setting