diff --git a/packages/tracker/meshnet_tracker/test_runner.py b/packages/tracker/meshnet_tracker/test_runner.py
index e9725da..fdd8b6d 100644
--- a/packages/tracker/meshnet_tracker/test_runner.py
+++ b/packages/tracker/meshnet_tracker/test_runner.py
@@ -57,6 +57,7 @@ DEFAULT_MAX_LOG_LINES = 4000
 _MAX_LINE_CHARS = 4000
 DEFAULT_COLLECT_TIMEOUT = 120.0
 DEFAULT_RUN_TIMEOUT = 1800.0
+PYTHON_ENV_VAR = "MESHNET_PYTHON"
 
 _NODE_ID_RE = re.compile(r"^[\w./\[\]:,= @-]+$")
 
@@ -98,6 +99,23 @@ def _real_inference_enabled() -> bool:
     return os.environ.get(REAL_INFERENCE_ENV_VAR) == "1"
 
 
+def _test_python() -> str:
+    """Return the project interpreter configured by the machine env file.
+
+    The tracker may run from a lightweight service environment while the test
+    suite needs the project's full environment (including SDK dependencies).
+    ``meshnet_tracker.cli`` loads ``.env.<hostname>`` before constructing the
+    server, so use its explicit interpreter selection for child pytest runs.
+    Direct users of ``TestRunManager`` retain the normal interpreter fallback.
+    """
+    configured = os.environ.get(PYTHON_ENV_VAR, "").strip()
+    if configured:
+        python = Path(configured).expanduser()
+        if python.is_file() and os.access(python, os.X_OK):
+            return str(python)
+    return sys.executable
+
+
 class TestRunManager:
     """Collects pytest node IDs and runs one fixed target at a time."""
 
@@ -145,7 +163,7 @@ class TestRunManager:
             if self._collected_at is not None and not refresh:
                 return self._collection_snapshot_locked()
 
-        cmd = [sys.executable, "-m", "pytest", "--collect-only", "-q", "-p", "no:cacheprovider"]
+        cmd = [_test_python(), "-m", "pytest", "--collect-only", "-q", "-p", "no:cacheprovider"]
         if not _real_inference_enabled():
             for name in sorted(
                 p.name for p in (self.repo_root / "tests").glob("test_real_*.py")
@@ -216,7 +234,7 @@ class TestRunManager:
         with self._lock:
             if self._run is not None and self._run["status"] == "running":
                 raise RunInProgressError("a test run is already in progress")
-            cmd = [sys.executable, "-m", "pytest", "-q", "-p", "no:cacheprovider", *pytest_args]
+            cmd = [_test_python(), "-m", "pytest", "-q", "-p", "no:cacheprovider", *pytest_args]
             self._stdout = deque(maxlen=self.max_log_lines)
             self._stderr = deque(maxlen=self.max_log_lines)
             process = subprocess.Popen(  # noqa: S603 — fixed argv, no shell
diff --git a/tests/test_real_model_backend.py b/tests/test_real_model_backend.py
index 57a6db1..75c31b5 100644
--- a/tests/test_real_model_backend.py
+++ b/tests/test_real_model_backend.py
@@ -15,7 +15,7 @@ import pytest
 from meshnet_node.model_backend import (
     InsufficientVRAMError,
     PartialModelLoadUnsupported,
-    ShardCacheMiss,
+    KVCacheMiss,
     TensorPayload,
     TorchModelShard,
     _call_layer,
@@ -629,7 +629,7 @@ def test_shard_cache_decode_miss_is_explicit():
     torch = pytest.importorskip("torch")
     shard = _fake_cache_shard(torch)
 
-    with pytest.raises(ShardCacheMiss):
+    with pytest.raises(KVCacheMiss):
         shard._run_layers(
             torch.zeros((1, 1, 2), dtype=torch.bfloat16),
             torch.ones((1, 5), dtype=torch.long),
diff --git a/tests/test_tracker_test_runner.py b/tests/test_tracker_test_runner.py
index ea01d47..5198b0e 100644
--- a/tests/test_tracker_test_runner.py
+++ b/tests/test_tracker_test_runner.py
@@ -6,6 +6,7 @@ constructed without an explicit ``repo_root``.
 """
 
 import json
+import sys
 import time
 import urllib.error
 import urllib.request
@@ -16,7 +17,7 @@ import pytest
 from meshnet_tracker.accounts import AccountStore
 from meshnet_tracker.server import TrackerServer
 from meshnet_tracker.test_runner import TestRunManager as RunManager
-from meshnet_tracker.test_runner import discover_repo_root
+from meshnet_tracker.test_runner import _test_python, discover_repo_root
 
 
 def _make_repo(tmp_path: Path) -> Path:
@@ -119,6 +120,16 @@ def test_enable_flag_constructs_runner_against_real_repo(monkeypatch):
     assert (tracker._test_runner.repo_root / "tests" / "conftest.py").is_file()
 
 
+def test_runner_uses_configured_project_python(monkeypatch, tmp_path):
+    python = tmp_path / "python"
+    python.touch(mode=0o755)
+    monkeypatch.setenv("MESHNET_PYTHON", str(python))
+    assert _test_python() == str(python)
+
+    monkeypatch.setenv("MESHNET_PYTHON", str(tmp_path / "missing-python"))
+    assert _test_python() == sys.executable
+
+
 def test_collection_lists_tests_and_excludes_real_inference(tmp_path, monkeypatch):
     monkeypatch.delenv("MESHNET_ENABLE_REAL_INFERENCE_TESTS", raising=False)
     tracker, port, admin, _user = _start_tracker(tmp_path)