Add serializable project commands

docs/spec/07-implementation-phases-todo.md

@@ -359,7 +359,8 @@ Tasks:
   forward/inverse payloads
 - [x] add optimistic checks when appending a revision
 - route domain writes and history records through one shared transaction
-- model serializable domain command descriptions outside React
+- define concrete serializable domain command descriptions and executors
+  outside React
 - persist undo/redo eligibility on the server
 - add named and periodic logical project snapshots
 - restore a historical snapshot as a new revision
@@ -369,6 +370,8 @@ Implemented foundation:
 
 - projects start at revision zero and advance monotonically
 - each revision has one separately stored logical change set
+- forward and inverse changes use complete, versioned JSON command envelopes
+- invalid or lossy command payloads are rejected before persistence
 - revision metadata, change-set payloads and the project counter are committed
   in one SQLite transaction
 - a stale expected revision produces no history writes