feat: add deterministic CPU/GPU benchmark runner slice

tests/test_performance_contract.py

@@ -4,7 +4,13 @@ from __future__ import annotations
 
 import json
 
-from meshnet_node.performance_contract import DEFAULT_CONTRACT, SCHEMA_VERSION, main
+from meshnet_node.performance_contract import (
+    BENCHMARK_SCHEMA_VERSION,
+    DEFAULT_CONTRACT,
+    SCHEMA_VERSION,
+    main,
+    run_performance_benchmark,
+)
 
 
 def test_default_contract_is_architecture_aligned_and_small():
@@ -82,3 +88,80 @@ def test_contract_cli_writes_json(tmp_path, capsys):
 
     assert written == DEFAULT_CONTRACT.to_dict()
     assert str(output) in capsys.readouterr().out
+
+
+def test_stub_benchmark_covers_every_lane_concurrency_and_metric():
+    """The runner exercises all four CPU/GPU lanes with the full metric set.
+
+    Tags: performance, benchmark, gguf
+    """
+    report = run_performance_benchmark()
+
+    assert report["schema_version"] == BENCHMARK_SCHEMA_VERSION
+    assert report["story_id"] == "DGR-001"
+    assert report["source"] == "stub-backend"
+    assert report["model_target"] == DEFAULT_CONTRACT.model_target.to_dict()
+    assert [lane["id"] for lane in report["lanes"]] == [
+        lane.id for lane in DEFAULT_CONTRACT.benchmark_lanes
+    ]
+    for lane in report["lanes"]:
+        assert [result["concurrency"] for result in lane["results"]] == [1, 4]
+        for result in lane["results"]:
+            assert set(result["metrics"]) == set(DEFAULT_CONTRACT.metrics)
+            assert result["metrics"]["failure_count"] == 0
+            assert result["metrics"]["decode_tok_per_sec"] > 0
+
+
+def test_stub_benchmark_is_deterministic():
+    """Two runs produce byte-identical reports; no clocks or randomness leak in.
+
+    Tags: performance, benchmark, deterministic
+    """
+    first = run_performance_benchmark()
+    second = run_performance_benchmark()
+
+    assert first == second
+    assert json.dumps(first, sort_keys=True) == json.dumps(second, sort_keys=True)
+
+
+def test_stub_benchmark_compares_gguf_against_safetensors_per_device():
+    """Each device gets a GGUF-vs-safetensors comparison and a stop-condition verdict.
+
+    Tags: performance, benchmark, gguf
+    """
+    report = run_performance_benchmark()
+
+    assert set(report["comparisons"]) == {"cpu", "gpu"}
+    cpu, gpu = report["comparisons"]["cpu"], report["comparisons"]["gpu"]
+    assert cpu["safetensors_lane"] == "transformers-safetensors-cpu"
+    assert cpu["gguf_lane"] == "llama-cpp-gguf-cpu"
+    assert cpu["memory_metric"] == "rss_bytes"
+    assert gpu["safetensors_lane"] == "transformers-safetensors-gpu"
+    assert gpu["gguf_lane"] == "llama-cpp-gguf-gpu"
+    assert gpu["memory_metric"] == "vram_bytes"
+    for comparison in (cpu, gpu):
+        assert comparison["decode_speedup"] > 1.0
+        assert comparison["artifact_bytes_ratio"] < 0.5
+        assert comparison["memory_bytes_ratio"] < 1.0
+        assert comparison["output_drift"] == 0.0
+        assert comparison["gguf_benefit"] is True
+    assert report["stop_condition"]["gguf_benefit"] is True
+    assert report["stop_condition"]["triggered"] is False
+    assert report["stop_condition"]["text"] == DEFAULT_CONTRACT.stop_condition
+
+
+def test_contract_cli_writes_benchmark_report(tmp_path, capsys):
+    """--benchmark-out emits the stub benchmark report next to the contract.
+
+    Tags: performance, benchmark, artifact
+    """
+    contract_out = tmp_path / "performance-contract.json"
+    benchmark_out = tmp_path / "artifacts" / "stub-benchmark-report.json"
+
+    assert main(["--json-out", str(contract_out), "--benchmark-out", str(benchmark_out)]) == 0
+    report = json.loads(benchmark_out.read_text(encoding="utf-8"))
+
+    assert report == run_performance_benchmark()
+    output = capsys.readouterr().out
+    assert str(contract_out) in output
+    assert str(benchmark_out) in output