fix(evidence): stabilize real Pi authoring

harness/tests/test_evidence_authoring.py

@@ -1,4 +1,5 @@
 import hashlib
+import threading
 import unicodedata
 
 import pytest
@@ -348,6 +349,40 @@ def test_prepare_changed_source_uses_one_model_call_and_applies_a_valid_batch(tm
     assert validate_workspace_evidence(tmp_path).publishable is True
 
 
+def test_prepare_can_issue_independent_source_calls_concurrently(tmp_path):
+    source_text = "I pazienti sotto i 18 anni sono pediatrici."
+    _write_workspace(tmp_path, _evidence(source_text), source_text)
+    source_root = tmp_path / "evidence" / "source" / "domain"
+    changed_text = source_text + "\nRegola revisionata.\n"
+    (source_root / "patient.md").write_text(changed_text, encoding="utf-8")
+    (source_root / "second.md").write_text(changed_text, encoding="utf-8")
+    barrier = threading.Barrier(2)
+
+    class ConcurrentRestructurer:
+        def __init__(self):
+            self.requests = []
+
+        def restructure(self, request):
+            self.requests.append(request)
+            barrier.wait(timeout=2)
+            return (_candidate(title=f"Unit {request.source_file}"),)
+
+    restructurer = ConcurrentRestructurer()
+
+    report = prepare_workspace_evidence(
+        tmp_path,
+        restructurer=restructurer,
+        git_status=lambda _: (),
+        max_workers=2,
+    )
+
+    assert report.model_calls == 2
+    assert sorted(request.source_file for request in restructurer.requests) == [
+        "source/domain/patient.md",
+        "source/domain/second.md",
+    ]
+
+
 def test_prepare_unchanged_source_skips_model_and_does_not_write(tmp_path):
     source_text = "I pazienti sotto i 18 anni sono pediatrici."
     _write_workspace(tmp_path, _evidence(source_text), source_text)