From 9d1c2c45e51361246bc38679347f4f35a7ab4f72 Mon Sep 17 00:00:00 2001
From: Erik <erik.nihlen@gmail.com>
Date: Sat, 11 Apr 2026 22:11:35 +0200
Subject: [PATCH] =?UTF-8?q?feat(app):=20Phase=20A.1=20=E2=80=94=20job=20+?=
 =?UTF-8?q?=20result=20records=20for=20LandblockStreamer?=
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LandblockStreamJob (Load/Unload) and LandblockStreamResult
(Loaded/Failed/Unloaded) are the channel payload types the next
task's LandblockStreamer will use. Separate file because they're
shared between the worker thread and the render thread and deserve
a focused home.

Folds in two carryover nits from the Task 1 fix review:
- Stale "radius + 1" comments in StreamingRegionTests updated to
  match the real radius+2 threshold (no numeric-assertion changes).
- Single-step recenter test now asserts Visible.Count == 25 and
  Resident.Count == 30, locking in the Visible/Resident semantic
  split behaviorally.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
---
 .../Streaming/LandblockStreamJob.cs           | 28 +++++++++++++++++++
 .../Streaming/StreamingRegionTests.cs         | 13 ++++++---
 2 files changed, 37 insertions(+), 4 deletions(-)
 create mode 100644 src/AcDream.App/Streaming/LandblockStreamJob.cs

diff --git a/src/AcDream.App/Streaming/LandblockStreamJob.cs b/src/AcDream.App/Streaming/LandblockStreamJob.cs
new file mode 100644
index 0000000..7542c68
--- /dev/null
+++ b/src/AcDream.App/Streaming/LandblockStreamJob.cs
@@ -0,0 +1,28 @@
+using AcDream.Core.World;
+
+namespace AcDream.App.Streaming;
+
+/// <summary>
+/// A job posted to <see cref="LandblockStreamer"/>'s inbox. Either a load
+/// (fetch this landblock from the dats and build its CPU-side mesh data)
+/// or an unload (release any state tied to this landblock on the render
+/// thread's next Tick drain).
+/// </summary>
+public abstract record LandblockStreamJob(uint LandblockId)
+{
+    public sealed record Load(uint LandblockId) : LandblockStreamJob(LandblockId);
+    public sealed record Unload(uint LandblockId) : LandblockStreamJob(LandblockId);
+}
+
+/// <summary>
+/// Outbox record the render thread drains. Either a successful load, a
+/// failed load (logged and ignored until region recenters off/back), or
+/// an unload notification (tells the render thread to release GPU state
+/// for this landblock id).
+/// </summary>
+public abstract record LandblockStreamResult(uint LandblockId)
+{
+    public sealed record Loaded(uint LandblockId, LoadedLandblock Landblock) : LandblockStreamResult(LandblockId);
+    public sealed record Failed(uint LandblockId, string Error) : LandblockStreamResult(LandblockId);
+    public sealed record Unloaded(uint LandblockId) : LandblockStreamResult(LandblockId);
+}
diff --git a/tests/AcDream.Core.Tests/Streaming/StreamingRegionTests.cs b/tests/AcDream.Core.Tests/Streaming/StreamingRegionTests.cs
index 767dd6d..d65b480 100644
--- a/tests/AcDream.Core.Tests/Streaming/StreamingRegionTests.cs
+++ b/tests/AcDream.Core.Tests/Streaming/StreamingRegionTests.cs
@@ -45,17 +45,22 @@ public class StreamingRegionTests
     [Fact]
     public void RecenterTo_SingleStepEast_LoadsColumn_NoUnloadsDueToHysteresis()
     {
-        // Radius 2 → unload threshold is radius+1 = 3.
+        // Radius 2 → unload threshold is radius+2 = 4.
         // Starting center (50,50) covers X in [48..52]. Step to (51,50):
         // new coverage X in [49..53]. New column is x=53 (5 entries).
-        // Departing column would be x=48, but |48-51| = 3 which equals the
-        // threshold, so it stays loaded (hysteresis keeps radius+1).
+        // Departing column x=48 is at distance |48-51| = 3, which is within
+        // the radius+2 threshold, so it stays loaded (hysteresis keeps radius+2).
         var region = new StreamingRegion(cx: 50, cy: 50, radius: 2);
 
         var diff = region.RecenterTo(51, 50);
 
         Assert.Equal(5, diff.ToLoad.Count);
         Assert.Empty(diff.ToUnload);
+        // Visible is strictly the 5×5 window around (51, 50).
+        Assert.Equal(25, region.Visible.Count);
+        // Resident includes the hysteresis-retained x=48 column (5 entries)
+        // plus the full new window, for 30 total.
+        Assert.Equal(30, region.Resident.Count);
     }
 
     [Fact]
@@ -63,7 +68,7 @@ public class StreamingRegionTests
     {
         // Starting (50,50) covers X in [48..52]. Step to (53,50):
         // new coverage X in [51..55]. New columns: x=53,54,55 (15 entries).
-        // x=48 is now 5 away → unload. x=49,50 still within radius+1 → keep.
+        // x=48 is now 5 away, > radius+2 = 4 → unload. x=49 is 4 away, not > 4 → keep. x=50 is 3 away, not > 4 → keep.
         var region = new StreamingRegion(cx: 50, cy: 50, radius: 2);
 
         var diff = region.RecenterTo(53, 50);