Add bounded generation transition receipts

docs/COMPATIBILITY.md

@@ -79,6 +79,12 @@ Milestone 0 preserves:
   Context and changeset MCP reads accept optional limits and opaque generation-bound cursors.
   Direct Python changeset methods and the ordinary CLI context command retain full legacy results
   when pagination is not requested.
+- Latest-generation-diff receipt schema version 1. The additive `generation-diff` CLI command and
+  `docforge_get_generation_diff` MCP read accept only optional pagination fields. They record one
+  primary-graph transition and do not create a history store or expose Logic details.
+- Latest-generation-diff page schema version 1. Pages use one top-level pagination object and a
+  nested `receipt_header`. `stored_receipt_hash` names the complete stored receipt. Opaque cursors
+  may be restarted after a server or receipt change and are not durable public identifiers.
 
 Indexes, attestations, extraction caches, previews, and rendered artifacts are disposable. A schema
 change may rebuild them. Canonical project content and stored proposals may not be silently
@@ -99,6 +105,10 @@ must retain `load_projection()` as their independent clean-build and equivalence
 Project adapters remain explicitly composed. Generic DocForge does not discover arbitrary adapter
 modules or choose a project globally.
 
+The supported generation-diff Python boundary is `ProjectIndex.generation_diff()`. Helpers in the
+`docforge.generation_diff` module implement the disposable publication contract and are internal;
+they are not frozen as adapter-authoring imports.
+
 ## Preserved no-AST binding
 
 `docforge-mcp --project-root /project --no-ast` is a stable shorthand for the