diff --git a/tests/tools/test_gpu_scheduler.py b/tests/tools/test_gpu_scheduler.py
new file mode 100644
index 000000000..a4731bf42
--- /dev/null
+++ b/tests/tools/test_gpu_scheduler.py
@@ -0,0 +1,256 @@
+"""
+Tests for GPU Inference Scheduler.
+"""
+
+import pytest
+import tempfile
+import os
+from pathlib import Path
+
+from tools.gpu_scheduler import (
+    Priority,
+    ModelSpec,
+    InferenceJob,
+    InferenceScheduler,
+    MODEL_REGISTRY,
+)
+
+
+@pytest.fixture
+def scheduler():
+    """Create a scheduler with a temp database."""
+    with tempfile.TemporaryDirectory() as tmpdir:
+        db_path = Path(tmpdir) / "test_scheduler.db"
+        sched = InferenceScheduler(vram_budget_mb=32768, queue_db=str(db_path))
+        yield sched
+
+
+class TestPriority:
+    """Test priority ordering."""
+    
+    def test_priority_ordering(self):
+        """Realtime < Interactive < Batch."""
+        assert Priority.REALTIME < Priority.INTERACTIVE
+        assert Priority.INTERACTIVE < Priority.BATCH
+    
+    def test_priority_comparison(self):
+        """Lower value = higher priority."""
+        assert Priority.REALTIME.value == 1
+        assert Priority.INTERACTIVE.value == 2
+        assert Priority.BATCH.value == 3
+
+
+class TestModelSpec:
+    """Test model specifications."""
+    
+    def test_model_registry_has_models(self):
+        """Registry should have known models."""
+        assert "llama3_70b" in MODEL_REGISTRY
+        assert "sd_xl" in MODEL_REGISTRY
+        assert "mimo_v2_pro" in MODEL_REGISTRY
+    
+    def test_model_vram(self):
+        """Models should have VRAM requirements."""
+        llama = MODEL_REGISTRY["llama3_70b"]
+        assert llama.vram_mb > 0
+        assert llama.vram_mb == 40960  # 40GB
+
+
+class TestInferenceScheduler:
+    """Test the scheduler."""
+    
+    def test_init(self, scheduler):
+        """Scheduler should initialize."""
+        assert scheduler.vram_budget_mb == 32768
+        assert scheduler.gpu_state.total_vram_mb == 32768
+        assert len(scheduler.job_queue) == 0
+    
+    def test_submit_job(self, scheduler):
+        """Submit a job."""
+        job = scheduler.submit_job(
+            job_id="test-1",
+            project="playground",
+            model_name="llama3_8b",
+            priority=Priority.INTERACTIVE,
+        )
+        
+        assert job.job_id == "test-1"
+        assert job.status == "queued"
+        assert len(scheduler.job_queue) == 1
+    
+    def test_submit_unknown_model(self, scheduler):
+        """Submit with unknown model should raise."""
+        with pytest.raises(ValueError, match="Unknown model"):
+            scheduler.submit_job(
+                job_id="test-1",
+                project="playground",
+                model_name="nonexistent",
+            )
+    
+    def test_priority_ordering(self, scheduler):
+        """Jobs should be ordered by priority."""
+        scheduler.submit_job("batch-1", "harvester", "llama3_8b", Priority.BATCH)
+        scheduler.submit_job("rt-1", "lpm", "llama3_8b", Priority.REALTIME)
+        scheduler.submit_job("int-1", "playground", "llama3_8b", Priority.INTERACTIVE)
+        
+        # RT should be first
+        assert scheduler.job_queue[0].job_id == "rt-1"
+        assert scheduler.job_queue[1].job_id == "int-1"
+        assert scheduler.job_queue[2].job_id == "batch-1"
+    
+    def test_get_next_job(self, scheduler):
+        """Get next job should return highest priority."""
+        scheduler.submit_job("batch-1", "harvester", "llama3_8b", Priority.BATCH)
+        scheduler.submit_job("rt-1", "lpm", "llama3_8b", Priority.REALTIME)
+        
+        next_job = scheduler.get_next_job()
+        assert next_job.job_id == "rt-1"
+    
+    def test_start_job(self, scheduler):
+        """Start a job."""
+        job = scheduler.submit_job("test-1", "playground", "llama3_8b", Priority.INTERACTIVE)
+        success = scheduler.start_job(job)
+        
+        assert success
+        assert job.status == "loading"
+        assert job.started_at is not None
+        assert scheduler.gpu_state.used_vram_mb == 8192  # llama3_8b VRAM
+    
+    def test_complete_job(self, scheduler):
+        """Complete a job."""
+        job = scheduler.submit_job("test-1", "playground", "llama3_8b", Priority.INTERACTIVE)
+        scheduler.start_job(job)
+        scheduler.complete_job(job)
+        
+        assert job.status == "completed"
+        assert job.completed_at is not None
+        assert scheduler.gpu_state.used_vram_mb == 0
+        assert len(scheduler.job_queue) == 0
+        assert len(scheduler.completed_jobs) == 1
+    
+    def test_complete_job_with_error(self, scheduler):
+        """Complete a job with error."""
+        job = scheduler.submit_job("test-1", "playground", "llama3_8b", Priority.INTERACTIVE)
+        scheduler.start_job(job)
+        scheduler.complete_job(job, error="CUDA out of memory")
+        
+        assert job.status == "failed"
+        assert job.error == "CUDA out of memory"
+    
+    def test_vram_tracking(self, scheduler):
+        """VRAM should be tracked correctly."""
+        # Submit two small jobs
+        job1 = scheduler.submit_job("test-1", "playground", "llama3_8b", Priority.INTERACTIVE)
+        job2 = scheduler.submit_job("test-2", "playground", "llama3_8b", Priority.INTERACTIVE)
+        
+        # Start first
+        scheduler.start_job(job1)
+        assert scheduler.gpu_state.used_vram_mb == 8192
+        
+        # Start second (should work, still have room)
+        scheduler.start_job(job2)
+        assert scheduler.gpu_state.used_vram_mb == 16384
+        
+        # Complete first
+        scheduler.complete_job(job1)
+        assert scheduler.gpu_state.used_vram_mb == 8192
+    
+    def test_cpu_fallback(self, scheduler):
+        """CPU fallback when VRAM full."""
+        # Fill VRAM with two 16GB models (32GB total = our budget)
+        job1 = scheduler.submit_job("big-1", "lpm", "mimo_v2_pro", Priority.REALTIME)
+        scheduler.start_job(job1)
+        assert scheduler.gpu_state.used_vram_mb == 16384
+        
+        # Start another 16GB model (should work, exactly fills VRAM)
+        job2 = scheduler.submit_job("big-2", "playground", "mimo_v2_pro", Priority.INTERACTIVE)
+        scheduler.start_job(job2)
+        assert scheduler.gpu_state.used_vram_mb == 32768  # Full
+        
+        # Now try a third model - should get CPU fallback
+        job3 = scheduler.submit_job("big-3", "harvester", "mimo_v2_pro", Priority.BATCH)
+        next_job = scheduler.get_next_job()
+        
+        # Should get job3 with CPU fallback since VRAM is full
+        assert next_job.job_id == "big-3"
+        assert next_job.use_cpu_fallback
+    
+    def test_get_status(self, scheduler):
+        """Get scheduler status."""
+        scheduler.submit_job("test-1", "playground", "llama3_8b", Priority.INTERACTIVE)
+        scheduler.submit_job("test-2", "harvester", "llama3_8b", Priority.BATCH)
+        
+        status = scheduler.get_status()
+        
+        assert status["gpu"]["total_vram_mb"] == 32768
+        assert status["queue"]["pending"] == 2
+        assert status["queue"]["by_priority"]["INTERACTIVE"] == 1
+        assert status["queue"]["by_priority"]["BATCH"] == 1
+    
+    def test_register_model(self, scheduler):
+        """Register a custom model."""
+        custom = ModelSpec(name="Custom Model", vram_mb=4096)
+        scheduler.register_model("custom_model", custom)
+        
+        assert "custom_model" in MODEL_REGISTRY
+        
+        job = scheduler.submit_job("test-1", "playground", "custom_model")
+        assert job.model.vram_mb == 4096
+
+
+class TestCrossProjectScenarios:
+    """Test cross-project scenarios from the issue."""
+    
+    def test_video_forge_batch_plus_lpm_live(self, scheduler):
+        """
+        Video Forge batch + LPM live.
+        LPM should get priority, batch should queue.
+        """
+        # Video Forge batch job
+        vf_job = scheduler.submit_job(
+            "vf-batch-1", "video_forge", "sd_xl", Priority.BATCH
+        )
+        
+        # LPM live job (higher priority)
+        lpm_job = scheduler.submit_job(
+            "lpm-live-1", "lpm", "lpm_video", Priority.REALTIME
+        )
+        
+        # Next job should be LPM
+        next_job = scheduler.get_next_job()
+        assert next_job.job_id == "lpm-live-1"
+        assert next_job.priority == Priority.REALTIME
+    
+    def test_three_video_forge_jobs(self, scheduler):
+        """Three Video Forge jobs should queue sequentially."""
+        jobs = []
+        for i in range(3):
+            job = scheduler.submit_job(
+                f"vf-{i}", "video_forge", "sd_xl", Priority.BATCH
+            )
+            jobs.append(job)
+        
+        # Start first
+        scheduler.start_job(jobs[0])
+        assert scheduler.gpu_state.used_vram_mb == 8192
+        
+        # Second should queue (VRAM occupied)
+        next_job = scheduler.get_next_job()
+        assert next_job.job_id == "vf-1"
+    
+    def test_night_harvester_plus_playground(self, scheduler):
+        """Night harvester runs on idle cycles."""
+        harvester = scheduler.submit_job(
+            "harvest-1", "harvester", "llama3_8b", Priority.BATCH
+        )
+        playground = scheduler.submit_job(
+            "play-1", "playground", "sdxl_turbo", Priority.INTERACTIVE
+        )
+        
+        # Playground should get priority
+        next_job = scheduler.get_next_job()
+        assert next_job.job_id == "play-1"
+
+
+if __name__ == "__main__":
+    pytest.main([__file__, "-v"])