diff --git a/tests/test_anchor_prg.py b/tests/test_anchor_prg.py
index 7129974..cc6bdbf 100644
--- a/tests/test_anchor_prg.py
+++ b/tests/test_anchor_prg.py
@@ -311,6 +311,11 @@ def test_phi_prg_rejects_non_int_dim_h():
 
 def test_module_exports_version_string():
     assert PHI_PRG_VERSION == "phi-prg-v1-hmac-sha512"
+    # versioned-default discipline (calculator-test-patterns.md §2):
+    # "v1" substring present so future major-version rotations
+    # (v2-blake3-expansion etc.) are detectable at the call site
+    # without string-comparing module paths.
+    assert "v1" in PHI_PRG_VERSION
 
 
 def test_placeholder_seed_is_32_bytes():
diff --git a/tests/test_phi_alignment_probe.py b/tests/test_phi_alignment_probe.py
index b0b54d3..9853b62 100644
--- a/tests/test_phi_alignment_probe.py
+++ b/tests/test_phi_alignment_probe.py
@@ -180,6 +180,11 @@ def test_alignment_report_round_trips_via_asdict():
 
 def test_module_exports_thresholds_and_version():
     assert PROBE_VERSION == "phi-alignment-v1-lanczos"
+    # versioned-default discipline (calculator-test-patterns.md §2):
+    # "v1" substring present so future major-version rotations are
+    # detectable at the call site without string-comparing module
+    # paths.
+    assert "v1" in PROBE_VERSION
     assert STRUCTURAL_ALIGNMENT_RATIO_FLOOR == 1.5
     assert ANTI_ALIGNED_RATIO_CEILING == 0.7
     assert DEFAULT_K_TOP == 100
diff --git a/tests/test_v8_fork_score.py b/tests/test_substrate_fork_score.py
similarity index 89%
rename from tests/test_v8_fork_score.py
rename to tests/test_substrate_fork_score.py
index 92d7032..0aa5805 100644
--- a/tests/test_v8_fork_score.py
+++ b/tests/test_substrate_fork_score.py
@@ -14,6 +14,8 @@ Covers:
 from __future__ import annotations
 
 import json
+import subprocess
+import sys
 from pathlib import Path
 
 import pytest
@@ -505,3 +507,56 @@ def test_score_is_dict_serializable():
     encoded = json.dumps(sf.to_dict(), default=str)
     decoded = json.loads(encoded)
     assert decoded["verdict"] == sf.verdict
+
+
+# ---------------------------------------------------------------------
+# Real subprocess-mode CLI test (calculator-test-patterns.md §6).
+# The in-process build_parser() tests above catch argparse-shape drift
+# but NOT entry-point / module-loading / sys.argv drift. fox's
+# test_cli_baseline_runs_clean in test_t3_bound_calculator.py is the
+# exemplar; this test mirrors that pattern for `arborist substrate score`.
+# ---------------------------------------------------------------------
+
+
+def test_cli_substrate_score_subprocess_invocation(tmp_path):
+    """Real subprocess-mode invocation of `arborist substrate score`.
+
+    Catches drift at the entry-point + module-loading layer that the
+    in-process build_parser() tests would miss — e.g. a refactor that
+    breaks the console-script in pyproject.toml, or that introduces a
+    sys.argv-handling bug.
+
+    Pattern: docs/calculator-test-patterns.md §6 + the substrate
+    rename's three-defect lesson (85be5eb fork_score.py import,
+    209d670 Makefile bench-fork-score, b320e27 .gitlab-ci.yml job).
+    """
+    parent_path = tmp_path / "parent.json"
+    child_path = tmp_path / "child.json"
+    out_path = tmp_path / "report.json"
+    _write_bench_result(parent_path, {
+        "5s": {"syntax": {"parse_pass_rate": 0.80}},
+        "5t": {}, "5f": {},
+    })
+    _write_bench_result(child_path, {
+        "5s": {"syntax": {"parse_pass_rate": 0.85}},
+        "5t": {}, "5f": {},
+    })
+
+    cmd = [
+        sys.executable, "-m", "arborist.cli",
+        "substrate", "score",
+        "--parent", str(parent_path),
+        "--child", str(child_path),
+        "--out", str(out_path),
+    ]
+    out = subprocess.run(
+        cmd, capture_output=True, text=True, check=True,
+        cwd="/home/fox/git/arborist",
+    )
+    # Exit code 0 = ACCEPT or MARGINAL per ScoredFork verdict
+    # discipline. Subprocess.run(check=True) already asserts it.
+    assert out_path.exists(), "expected --out artifact written"
+    artifact = json.loads(out_path.read_text())
+    assert "score" in artifact
+    assert "verdict" in artifact
+    assert artifact["verdict"] in {"ACCEPT", "MARGINAL", "REJECT"}