Select phase-specific working context and retain auditable source evidence

tests/test_diagnosis_builder.py

@@ -218,7 +218,7 @@ def test_legacy_rejection_upgrades_next_attempt_without_rewriting_context(invest
     assert build(builder).status=='REJECTED'
     assert adapter.requests[0]['prompt_version']=='diagnosis_v1'
     assert build(builder).status=='COMPLETED'
-    assert adapter.requests[1]['prompt_version']=='diagnosis_v4'
+    assert adapter.requests[1]['prompt_version']=='diagnosis_v5'
     received=restore(json.loads(adapter.requests[1]['messages'][1]['content'])['input'])
     assert received['validation_feedback'][0]['code']=='DIAGNOSIS_SELECTION'
     assert build(builder).reused and adapter.calls==2