1 files changed, 68 insertions, 0 deletions
diff --git a/internal/game/owner_regression_test.go b/internal/game/owner_regression_test.go
new file mode 100644
index 0000000..1ccd25f
--- /dev/null
+++ b/internal/game/owner_regression_test.go
@@ -0,0 +1,68 @@
+package game
+
+// Single-owner serialization regressions: a full task queue applies
+// backpressure instead of bypassing the owner, and the owner-stop path
+// keeps its documented inline fallback for shutdown stragglers only.
+
+import (
+	"sync"
+	"testing"
+	"time"
+)
+
+// TestFullOwnerQueueAppliesBackpressure: when the owner's task queue is
+// full and the owner is blocked inside another task, run() must NOT execute
+// the new task inline on the caller's goroutine — that would mutate live
+// state concurrently with the owner. It blocks until the owner drains.
+func TestFullOwnerQueueAppliesBackpressure(t *testing.T) {
+	g := &Game{owner: newOwner()}
+	release := make(chan struct{})
+	started := make(chan struct{})
+	g.owner.submit(func() {
+		close(started)
+		<-release
+	})
+	<-started
+	var once sync.Once
+	t.Cleanup(func() {
+		once.Do(func() { close(release) })
+		g.stopOwner()
+	})
+
+	for i := 0; i < ownerTaskQueue; i++ {
+		if !g.owner.submit(func() {}) {
+			t.Fatal("setup: could not fill the owner queue")
+		}
+	}
+
+	ran := make(chan struct{})
+	go g.run(func() { close(ran) })
+	select {
+	case <-ran:
+		t.Fatal("task executed inline while the owner was still running other tasks")
+	case <-time.After(100 * time.Millisecond):
+	}
+
+	// Release the owner: the queued work drains and the blocked task runs.
+	once.Do(func() { close(release) })
+	select {
+	case <-ran:
+	case <-time.After(5 * time.Second):
+		t.Fatal("task never ran after the owner drained its queue")
+	}
+}
+
+// TestStoppedOwnerRunsStragglersInline: after the owner stops (graceful
+// shutdown), straggler submissions execute inline rather than blocking
+// forever — the documented admissions-closed behavior.
+func TestStoppedOwnerRunsStragglersInline(t *testing.T) {
+	g := &Game{owner: newOwner()}
+	g.stopOwner()
+	ran := make(chan struct{})
+	go g.run(func() { close(ran) })
+	select {
+	case <-ran:
+	case <-time.After(5 * time.Second):
+		t.Fatal("straggler task blocked forever after the owner stopped")
+	}
+}