Persist authored Age generation plans (#31)

README.md

@@ -92,10 +92,13 @@ outputs a Descriptive Book once the title, cover, and Link Panel are present.
 Inputs are consumed only when the result is taken.
 
 The completed book receives its Age identity when assembled. With only a Link
-Panel, it describes a randomly generated Age. Its writing is stored on the
-book; the Descriptive Book screen's turned pages show ordered symbols and
-unresolved IDs. Until Milestone 5, symbols do not affect generation and written
-books use the same random Age fallback. The Descriptive Book screen follows
+Panel, it describes a randomly generated Age. Authored writing is compiled once
+into a versioned, server-owned Age plan. The plan freezes the Age seed, resolved
+symbol meanings, page order, and runtime profile, so later data-pack changes do
+not reinterpret an existing Age. An authored terrain page selects its runtime
+profile; other symbol effects are scheduled for later Milestone 5 slices. The
+writing is also stored on the book; the Descriptive Book screen's turned pages
+show ordered symbols and unresolved IDs. The Descriptive Book screen follows
 Legacy's book spread: the title and Age details are on the left, the destination
 preview is on the right, and clicks in the bottom corners turn pages. Ordered
 symbol pages appear before the final blank spread; their pictograms await