New claims: open another claim once one is paid off, travel between them (t3)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/DESIGN.md

@@ -232,6 +232,22 @@ above, including:
   Items piling up under a block stay a thing to build around (a belt or an open drop), and the
   Saw's text says so.
 
+- **A world that lasts: deep ore, rock that pays, Huge worlds, new claims (t3, 2026-10-24).**
+  The owner found worlds small and quickly mined out, so the only way on was a new game. Keep the
+  bot and drill at today's pace and add more to find instead:
+  - Deeper is richer: ore gets more common the deeper you dig, about 4.7x the ore in a Medium
+    world (coal and copper ~5x, iron, zinc and tin ~4.5-5x, silver and gold ~3.4x, kept lower for
+    their price). The top quarter of the underground is unchanged; copper also forms in deep stone
+    and granite, coal in basalt, tin deeper. Lenses grow from lower noise thresholds only:
+    stretching the noise with depth sheared it into diagonal streaks.
+  - Waste rock pays: grinding granite and basalt finds about twice the ore, and builders order
+    granite and basalt rubble in bulk.
+  - A Huge size (6144 x 2048); saves are gzip-compressed (a Medium save went from 29 MB to 0.4 MB).
+  - New claims: once a claim is paid off, open another for $5,000 down and twice the last debt
+    ($40,000, $80,000, ...). Money, bag, upgrades, discoveries, milestones and stats belong to the
+    career and come along; buildings stay on their claim and wait (they don't run) until you
+    travel back from the notebook's Claims page.
+
 - **Clay bricks come from a Brick press (t28, 2026-10-24).** A hopper block like the Saw: every
   8 clay lumps on top become a Green brick below, and a Green brick fires into a Brick above about
   900°C (any fire). 2 Bricks build a brick wall block; builders order them. The owner found it odd