Document feedback-aware validation retries

docs/consumers/subprocess.md

@@ -69,6 +69,13 @@ lanes. The caller decides which lane IDs are required for its own work and
 which are optional; it should make that decision explicitly rather than infer
 failure from the receipt counts alone.
 
+When complete validation is required, also require receipt
+`validation_status: approved` and inspect `validation_summaries`. A successful
+run with `validation_status: incomplete` contains a structurally valid result
+that advanced after validator execution could not complete under the configured
+`warn_continue` policy. It is not reusable checkpoint state and should not be
+silently treated as fully reviewed by the caller.
+
 ## Preserve Provenance And Handle Data Carefully
 
 Keep the receipt with the published `manifest.json`, and retain