Complete milestone 3 book previews and Age generators

README.md

@@ -28,21 +28,22 @@ right-clicking with an empty hand. Sneak-right-click with an empty hand to take
 the book back and restore the vanilla lectern. Breaking a Book Stand drops both
 the stored book and a vanilla lectern.
 
-Bound Linking Books request a server-validated 32-by-32-by-32 snapshot around
-their destination. The book keeps its target-centered close-up framing as a
-rotating Ponder scene on the left page, backed by the
-destination biome's sky color. The snapshot is visual only; the server
-independently validates every link.
+Bound Linking Books show a rotating Ponder snapshot when Create is installed.
+Without Create, they use a built-in animated linking panel tinted by the
+destination sky. The server independently validates every link.
 
 ## Descriptive Book
 
 Open a page-free Descriptive Book, name its Age, and press Create. Rivencraft
-assigns the book a permanent Age UUID, creates a dedicated vanilla-like runtime
-dimension, and prepares a five-by-five cobblestone arrival platform at the
+assigns the book a permanent Age UUID, selects a deterministic base terrain,
+creates a dedicated runtime dimension, and prepares a five-by-five cobblestone
+arrival platform at the
 highest suitable nearby terrain. Solid blocks and tree leaves are valid
 footing. Candidate columns are scanned from the top down so cave floors are not
 selected, and fluid-covered columns are excluded. If no suitable surface is
 available, the platform is generated at Y=63. Reopen the book and click its preview to travel.
+The book cannot reopen while its Age is being generated, whether held or on a
+Book Stand. Once creation finishes, reopening shows the written book.
 Copies of the written book continue to resolve to the same persistent Age
 across server restarts.
 
@@ -50,6 +51,10 @@ New Age dimension folders use a Minecraft-safe lowercase form of the assigned
 name. Conflicts receive incrementing suffixes such as `_2` and `_3`; existing
 Age folders are never renamed.
 
+Page-free Ages deterministically select one of six base terrains inspired by
+Mystcraft Legacy: Standard, Amplified, Island, Cave, Flat, or Void. The chosen
+profile is saved with the Age and does not change when the server restarts.
+
 Linking creates a bound Return Link to the exact source position and orientation
 according to the configured Return Link policy.
 
@@ -61,9 +66,18 @@ server config to `ON_CREATION` (default), `ALWAYS`, or `DISABLED`.
 - A Java 21 JDK
 - Minecraft 1.21.1
 - NeoForge 21.1.251 or newer in the 21.1 line
-- Ponder 1.0.82 for Minecraft 1.21.1 (client)
 - Dynamic Dimensions AR Edition 0.9.1 and Bad Packets 0.8.2 (client and server)
 
+Create is optional. When installed, Rivencraft uses its Ponder renderer for
+book previews when Immersive Portals is absent. Immersive Portals is also
+optional and takes priority in the default `AUTO` mode, providing a live
+rotating destination view. Its Explore button enables WASD and jump/sneak
+camera movement plus left-drag camera look; right-click returns to the rotating
+view. Without either integration, Rivencraft uses its built-in animated linking
+panel. Clients can set `book_preview.mode` in
+`rivencraft-client.toml` to `AUTO`, `IMMERSIVE_PORTALS`, `PONDER`, or `LEGACY`.
+Unavailable optional renderers safely fall back to `LEGACY`.
+
 ## Build and run
 
 ```shell