test: check pinned source manifests against their own commits

Historical-evidence pins (dfg_re100 / jet_circle_cv / refined_dfg manifests)
now compare each recorded digest with the file at the recorded commit, read
with git, instead of with today's working tree. Missing history (no git,
shallow clone, installed copy) raises HistoryUnavailable and the test is
reported as skipped with that reason, never passed. Receipt/plan logic tests
take the selected manifest directly, so their assertions run again; the
pinned modes' mismatch rejections stay as negative controls.

V1 (run_jet_circle_cv) keeps its pinned mode and gains --current-checkout:
it records HEAD, the src tree and per-file hashes labelled as current
checkout, never as the frozen qualification, and requires a clean tree.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/unit/test_refined_dfg.py

@@ -12,12 +12,30 @@ import run_refined_dfg as r
 h, periodic = r.helpers(r.DEFAULT_SOURCE)
 
 
+def historical_manifest(collision="SRT", observation_mode="last_base_step"):
+    """The manifest verify_source would select, without hashing the working tree.
+
+    Receipt/plan logic tests use it; source integrity is checked once in test_source_pin.
+    """
+    name = ("source_manifest_window.json" if observation_mode == "window" else
+            "source_manifest.json" if collision == "SRT" else "source_manifest_mrt.json")
+    return json.loads((r.HERE / "data/refined_dfg" / name).read_text())
+
+
 def test_source_pin():
-    historical = json.loads((r.HERE / "data/refined_dfg/source_manifest.json").read_text())
+    historical = historical_manifest("SRT")
     assert historical["commit"].startswith("cd3a657")
-    mrt_history = json.loads((r.HERE / "data/refined_dfg/source_manifest_mrt.json").read_text())
+    mrt_history = historical_manifest("MRT")
     assert mrt_history["commit"].startswith("3ea131e")
-    assert r.verify_source(r.DEFAULT_SOURCE, "MRT", "window")["commit"].startswith("a233c90")
+    assert historical_manifest("MRT", "window")["commit"].startswith("a233c90")
+    from source_provenance import HistoryUnavailable, historical_sha256
+    for manifest in (historical, mrt_history, historical_manifest("MRT", "window")):
+        try:  # historical integrity: each manifest matches the tree of its own commit
+            actual = historical_sha256(r.DEFAULT_SOURCE, manifest["commit"], manifest["sha256"])
+        except HistoryUnavailable as error:
+            unittest.TestCase().skipTest(f"historical integrity NOT checked: {error}")
+        assert actual == manifest["sha256"], manifest["commit"]
+    # Negative controls: the pinned modes refuse a working tree that differs from their pin.
     with unittest.TestCase().assertRaisesRegex(RuntimeError, "Source mismatch"):
         r.verify_source(r.DEFAULT_SOURCE, "MRT")
     with unittest.TestCase().assertRaisesRegex(RuntimeError, "Source mismatch"):
@@ -143,12 +161,13 @@ def test_axis_specific_sampling_phase():
 
 def test_full_requires_completed_pilot():
     with unittest.TestCase().assertRaisesRegex(ValueError, "pilot-results"):
-        r.verify_pilot(None, r.verify_source(r.DEFAULT_SOURCE, "MRT", "window"))
+        r.verify_pilot(None, historical_manifest("MRT", "window"))
 
 
 def pilot_fixture(path, observation_mode="window", jet_scenario="none", case_selection="both", uniform_diameter=80, placement="wide"):
     """Synthetic contract fixture only; never a physical result or run receipt."""
-    manifest = (r.verify_source(r.DEFAULT_SOURCE, "MRT", "window", jet_scenario)
+    manifest = ((historical_manifest("MRT", "window") if jet_scenario == "none" else
+                 r.verify_source(r.DEFAULT_SOURCE, "MRT", "window", jet_scenario))
                 if observation_mode == "window" else
                 json.loads((r.HERE / "data/refined_dfg/source_manifest_mrt.json").read_text()))
     selection = dict(case_selection=case_selection, uniform_diameter=uniform_diameter, placement=placement)
@@ -348,7 +367,7 @@ def test_record_actual_checkout_separately():
     actual = checkout_provenance(r.DEFAULT_SOURCE)
     assert len(actual["checkout_revision"]) == 40
     assert isinstance(actual["checkout_dirty"], bool)
-    assert r.verify_source(r.DEFAULT_SOURCE, "MRT", "window")["production_origin_commit"].startswith("d930")
+    assert historical_manifest("MRT", "window")["production_origin_commit"].startswith("d930")
 
 
 def test_window_plan_preserves_physics():
@@ -358,7 +377,7 @@ def test_window_plan_preserves_physics():
         assert baseline.pop("observation_mode") == "last_base_step"
         assert window.pop("observation_mode") == "window"
         assert baseline == window
-        assert r.verify_source(r.DEFAULT_SOURCE, collision, "window")["observation_mode"] == "window"
+        assert historical_manifest(collision, "window")["observation_mode"] == "window"
     with unittest.TestCase().assertRaises(ValueError):
         r.verify_source(r.DEFAULT_SOURCE, "MRT", "unknown")