Improve generation and lifecycle safety

- Reduce terrain, noise, hydrology, and decorator sampling overhead.
- Reduce object transaction allocations while preserving rollback behavior.
- Optimize structure placement and cave anchor sampling.
- Parallelize Studio cache warmup and protect world entry and hotload recovery.
- Validate pack fingerprints and publish pack replacements atomically.
- Notify modded operators about outdated packs without synchronizing pack data.
- Harden world creation, loading, evacuation, and teleport failure recovery.
- Coalesce queued region flushes while preserving chunk save ordering.
- Remove obsolete mantle, pack, and cave planning code.
- Add regression tests and reusable gameplay fixtures.

adapters/bukkit/plugin/src/test/gameplay/noise.mjs

@@ -0,0 +1,48 @@
+import { readFile } from 'node:fs/promises'
+import path from 'node:path'
+
+export default {
+  name: 'iris-noise',
+  description: 'Verify expression and interpolated noise produce varied, bounded terrain visible to a player.',
+  async run(context) {
+    const source = await readFile(path.join(context.server.directory, '.server-source'), 'utf8')
+    context.expect(/^isolated=true\s*$/m.test(source), 'Noise generation requires an isolated instance')
+    await context.step('create a world with expression and Clover noise', async () => {
+      const response = await context.command('/iris create name=noise_probe type=noise-fixture seed=78264193',
+        /Successfully created your world|Failed to create/, 180000)
+      context.expect(response.includes('Successfully created your world'), response)
+    })
+    await context.step('client observes bounded terrain with varying heights', async () => {
+      let columns = 0
+      let minimum = Infinity
+      let maximum = -Infinity
+      await context.waitUntil(() => {
+        columns = 0
+        minimum = Infinity
+        maximum = -Infinity
+        const center = context.bot.entity.position.floored()
+        for (let x = -8; x <= 8; x++) {
+          for (let z = -8; z <= 8; z++) {
+            let surface = null
+            for (let y = 60; y <= 100; y++) {
+              const position = center.offset(x, y - center.y, z)
+              const block = context.bot.blockAt(position)
+              if (!block) return false
+              if (block.name === 'lime_wool') {
+                if (surface !== null || context.bot.blockAt(position.offset(0, 1, 0))?.name !== 'air') return false
+                surface = y
+              }
+            }
+            if (surface === null || surface < 64 || surface > 96) return false
+            columns++
+            minimum = Math.min(minimum, surface)
+            maximum = Math.max(maximum, surface)
+          }
+        }
+        return columns === 289 && maximum - minimum >= 3
+      }, { label: '289 noise columns with bounded, varied surfaces', timeoutMs: 60000, intervalMs: 250 })
+      context.expect(columns === 289 && maximum - minimum >= 3, 'Client verified noise terrain', { columns, minimum, maximum })
+      context.report.noiseTerrain = { columns, minimum, maximum }
+    })
+  }
+}