fix(evidence): stabilize real Pi authoring

harness/tests/test_evidence_cli.py

@@ -14,6 +14,32 @@ def test_evidence_authoring_commands_are_distinct_from_runtime_preprocessing():
     assert "validate" in result.output
 
 
+def test_evidence_prepare_failure_identifies_the_source_file(monkeypatch, tmp_path):
+    from tht.cli import evidence_cmd
+    from tht.evidence import EvidencePreparationError
+
+    monkeypatch.setattr(evidence_cmd, "_canonical_worktree", lambda root: root)
+    monkeypatch.setattr(
+        evidence_cmd,
+        "prepare_workspace_evidence",
+        lambda *args, **kwargs: (_ for _ in ()).throw(
+            EvidencePreparationError("pi_restructure_invalid", "source/domain/patient.md")
+        ),
+    )
+
+    result = CliRunner().invoke(app, ["evidence", "prepare", str(tmp_path), "--json"])
+
+    assert result.exit_code == 1
+    assert result.stderr == ""
+    assert json.loads(result.stdout) == {
+        "code": "pi_restructure_invalid",
+        "operation": "evidence_prepare",
+        "schemaVersion": 1,
+        "sourceFile": "source/domain/patient.md",
+        "status": "failed",
+    }
+
+
 def test_evidence_resolve_json_is_pristine(monkeypatch, tmp_path):
     from tht.cli import evidence_cmd
     from tht.evidence.authoring import EvidenceResolutionReport