Persist cumulative investigation briefs and trim live bookkeeping

scripts/study_investigation_context.py

@@ -135,11 +135,44 @@ def measure(path):
             'largest_evidence_example':example, 'samples':rows}
 
 
+def measure_migration(path):
+    """Actual v13 migration view; no made-up historical working summaries."""
+    rows = []
+    with PackageReader(path) as reader:
+        for ref in reader.files:
+            if not (ref.startswith('analysis/investigation/') and '/contexts/' in ref):
+                continue
+            context = json.loads(reader.read_bytes(ref))
+            if context.get('prompt_version') not in {'investigation_project_v11','investigation_project_v12'}:
+                continue
+            def sizes(request):
+                system, prefix, live = GeminiProvider._messages(request, stable_case_context=True)
+                return {'message_bytes':sum(len(m['content'].encode('utf8')) for m in request['messages']),
+                        'prefix_bytes':size([system,prefix]), 'live_bytes':size(live)}
+            rows.append({'context':ref, 'old':sizes(build_prompt(context)),
+                'v13_migration':sizes(build_prompt(dict(context,prompt_version='investigation_project_v13')))})
+    old = sum(r['old']['live_bytes'] for r in rows)
+    new = sum(r['v13_migration']['live_bytes'] for r in rows)
+    return {'measurement':'production_v13_migration_offline', 'samples':rows,
+            'old_live_bytes':old, 'new_live_bytes':new,
+            'live_reduction_percent':round(100*(1-new/old),2) if old else None,
+            'limitations':['No old note history removed: historical runs have no persisted working brief.',
+                'Includes actual v13 schema/instructions; no invented working summaries.',
+                'No paid requests or token/quality claim.']}
+
+
 def main():
     parser = argparse.ArgumentParser(description=__doc__)
     parser.add_argument('package', type=Path)
     parser.add_argument('--output', required=True, type=Path)
+    parser.add_argument('--production-v13', action='store_true', help='Measure actual v13 migration instead of speculative views')
     args = parser.parse_args()
+    if args.production_v13:
+        report = measure_migration(args.package)
+        args.output.parent.mkdir(parents=True, exist_ok=True)
+        args.output.write_text(json.dumps(report, ensure_ascii=False, indent=2)+'\n', encoding='utf8')
+        print(json.dumps({k:v for k,v in report.items() if k!='samples'}))
+        return
     report = {'study':'offline_investigation_context_v1',
         'limitations':['Not a runnable prompt protocol; production unchanged.',
             'No quality test or token/cost claim; bytes are UTF-8.',