Guarantee bounded mutation receipts

docs/USER_MANUAL.md

@@ -614,6 +614,12 @@ The older create-and-append tools remain supported for interactive proposal cons
 For update, move, and delete operations it captures the synchronized current node hash when
 `expected_content_hash` is omitted.
 
+MCP mutations are preflighted against the configured response limit. Small mutations keep their
+full response. Large successful mutations return a compact or minimum version-1 receipt with
+`mutation_committed = true` and the exact current changeset hash. A preflight size failure has
+`mutation_committed = false`; it is safe to correct the request or policy before retrying. A
+committed mutation is never reported as `result_too_large`.
+
 Active changeset listing includes draft and ready proposals. Stale work remains available through
 an explicit `status="stale"` query for rebase decisions. Applied and abandoned proposals are
 terminal history, remain available by status or history request, and no longer block new proposals