Add utilization diagnostics and correction ledger

docs/public-contract.md

@@ -13,6 +13,7 @@ This contract covers:
 - stable validator key identifiers in report/diagnostics records
 - prompt metadata identifiers in diagnostics
 - diagnostics directory behavior
+- utilization diagnostics and correction-ledger artifact presence/pathing in diagnostics metadata
 - stdout/stderr and exit-code behavior
 - secret redaction guarantees
 - compatibility and deprecation policy
@@ -92,6 +93,7 @@ Current values:
 `--report-json` output and diagnostics run-dir `report.json` use the same report schema metadata.
 
 Validator decision/rejection records in reports use stable validator keys in `validator_name`.
+Report diagnostics metadata includes artifact-path fields for utilization diagnostics and correction ledger when diagnostics initialization succeeds.
 
 ## Diagnostics directory behavior
 
@@ -99,6 +101,8 @@ When diagnostics directory creation succeeds, Audita writes run artifacts includ
 - invocation metadata
 - redacted effective config
 - transcript/normalization/chunking artifacts
+- utilization diagnostics (`utilization-diagnostics.json`)
+- correction ledger (`correction-ledger.json`)
 - report and failure error log (when applicable)
 - module/LLM diagnostics artifacts as available