diff --git a/src/coverage_gate.py b/src/coverage_gate.py
index d13c9f8..664fb68 100644
--- a/src/coverage_gate.py
+++ b/src/coverage_gate.py
@@ -53,6 +53,7 @@ import json
 import logging
 import os
 import subprocess
+import sys
 
 from .config import settings
 from .git_worktree import ensure_worktree, get_worktree_path
@@ -140,8 +141,11 @@ def measure_coverage(repo: str, branch: str) -> float | None:
     except OSError:
         pass
 
+    # Use the SAME interpreter that runs the orchestrator (sys.executable), not a
+    # bare "python" — the prod container / CI runner expose "python3", and the
+    # pytest-cov plugin lives in exactly this interpreter's environment.
     cmd = [
-        "python", "-m", "pytest", "tests/",
+        sys.executable, "-m", "pytest", "tests/",
         "--cov=src",
         f"--cov-report=json:{cov_json}",
         "--cov-report=",  # suppress the terminal cov report (json only)