Phase 5: breeding with Cobbreeding, Ditto a rare Deep Dark find

Adrian (2026-10-31): add Cobbreeding without a gate; only Ditto should
be rare, in an endgame area or gated behind something else.

- Cobbreeding 2.4.1 (Modrinth only) and Cloth Config (client) in the
  pack; Cobblebase's hatchery takes Cobbreeding's eggs.
- Ditto moved from Button Isle to the Deep Dark with both of Cobblemon's
  entries (rare in slime chunks, ultra-rare elsewhere): zone_spawns.py
  pins take {"zone", "all_entries"}; Deep Dark target +1, Button Isle -1
  so no other line moved; Southwold and Frostpeak guardians pinned (they
  tie on base stats and flipped between runs).
- HMs' Trainer Ditto is made uncatchable; it still trades.
- check_deps.py skips other-side dependencies; Cobbreeding's harmless
  client-mixin log line allowlisted.
- Self-tests cobbreeding_eggs_fit_the_hatchery, trainer_ditto_cant_be_caught;
  docs, balance table, Phase 5 checklist.

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

mod/src/main/kotlin/dev/cobblesurvival/CobbleSurvival.kt

@@ -14,6 +14,7 @@ import dev.cobblesurvival.progress.Gates
 import dev.cobblesurvival.selftest.SelfTest
 import dev.cobblesurvival.world.OnlyPokemon
 import dev.cobblesurvival.world.SharedLoot
+import dev.cobblesurvival.world.SpecialPokemon
 import dev.cobblesurvival.zone.Guardians
 import dev.cobblesurvival.zone.InZoneCondition
 import dev.cobblesurvival.zone.LevelPressure
@@ -77,6 +78,7 @@ class CobbleSurvival {
         Catching.register()
         Wanderers.register()
         SharedLoot.register()
+        SpecialPokemon.register()
         ZoneHazards.register()
         LevelPressure.register()
         SelfTest.register()

mod/src/main/kotlin/dev/cobblesurvival/selftest/BreedingTests.kt

@@ -0,0 +1,47 @@
+package dev.cobblesurvival.selftest
+
+import dev.cobblesurvival.world.SpecialPokemon
+import net.minecraft.core.registries.BuiltInRegistries
+import net.minecraft.resources.ResourceLocation
+import net.minecraft.world.item.ItemStack
+import net.minecraft.world.item.Items
+
+/**
+ * Breeding (Adrian, 2026-10-31): Cobbreeding is in, open from the start, and its eggs are what Cobblebase's hatchery
+ * takes (Cobblebase finds them through its own bridge, by reflection). Ditto is a rare Deep Dark find, so HMs' visiting
+ * Trainer Ditto can't be caught.
+ */
+object BreedingTests {
+    private val EGG = ResourceLocation.parse("cobbreeding:pokemon_egg")
+    private const val BRIDGE = "notlown.cobblebase.core.CobbreedingBridge"
+
+    fun all() = listOf(
+        SelfTestCase("cobbreeding_eggs_fit_the_hatchery", 20, ::eggsFitTheHatchery),
+        SelfTestCase("trainer_ditto_cant_be_caught", 40, ::trainerDittoCantBeCaught),
+    )
+
+    private fun eggsFitTheHatchery(s: Scenario) {
+        val egg = BuiltInRegistries.ITEM.get(EGG)
+        s.check(egg != Items.AIR) { "Cobbreeding isn't installed: no $EGG" }
+        val type = Class.forName(BRIDGE)
+        val bridge = type.getField("INSTANCE").get(null)
+        s.check(type.getMethod("isLoaded").invoke(bridge) as Boolean) { "Cobblebase doesn't see Cobbreeding" }
+        s.check(type.getMethod("isPokemonEgg", ItemStack::class.java).invoke(bridge, ItemStack(egg)) as Boolean) {
+            "Cobblebase's hatchery doesn't take Cobbreeding's eggs"
+        }
+        s.helper.succeed()
+    }
+
+    private fun trainerDittoCantBeCaught(s: Scenario) {
+        s.player()
+        val pokemon = s.pokemon("ditto", 20)
+        pokemon.persistentData.putBoolean("dittohms_trainer", true)
+        val ordinary = s.pokemon("ditto", 20)
+        s.wild(pokemon, s.at(4.5, 1.0, 4.5))
+        s.wild(ordinary, s.at(10.5, 1.0, 10.5))
+        s.helper.startSequence()
+            .thenWaitUntil { s.check(pokemon.isUncatchable()) { "HMs' Trainer Ditto can be caught" } }
+            .thenExecute { s.check(!ordinary.isUncatchable() && !SpecialPokemon.isTrainerDitto(ordinary)) { "an ordinary wild Ditto became uncatchable" } }
+            .thenSucceed()
+    }
+}

mod/src/main/kotlin/dev/cobblesurvival/selftest/SelfTest.kt

@@ -54,7 +54,7 @@ object SelfTest {
     private val cases: List<SelfTestCase> get() =
         PermadeathTests.all() + SurvivalRulesTests.all() + ZoneTests.all() + HazardTests.all() + GuardianTests.all() +
             VeinTests.all() + OreNodeTests.all() + DropTests.all() + ProgressionTests.all() +
-            CatchingTests.all() + WorldRulesTests.all() + FieldMoveTests.all() + ShoulderTests.all() + BaseLootTests.all()
+            CatchingTests.all() + WorldRulesTests.all() + FieldMoveTests.all() + ShoulderTests.all() + BaseLootTests.all() + BreedingTests.all()
 
     private var running: List<Scenario> = emptyList()
     private var forced: List<ChunkPos> = emptyList()

mod/src/main/kotlin/dev/cobblesurvival/world/SpecialPokemon.kt

@@ -1,17 +1,43 @@
 package dev.cobblesurvival.world
 
+import com.cobblemon.mod.common.entity.pokemon.PokemonEntity
 import com.cobblemon.mod.common.pokemon.Pokemon
+import com.cobblemon.mod.common.pokemon.properties.UncatchableProperty
 import dev.cobblesurvival.zone.Guardians
+import net.minecraft.server.TickTask
+import net.minecraft.server.level.ServerLevel
+import net.neoforged.neoforge.common.NeoForge
+import net.neoforged.neoforge.event.entity.EntityJoinLevelEvent
 
 /**
  * Wild Pokémon that the island's rules for wild Pokémon (strays despawning, hunting weaker trainers) leave alone:
  * guardians, anything uncatchable, and other mods' characters that are Pokémon underneath, such as Cobblemon HMs'
  * visiting Trainer Ditto, which sells TMs.
+ *
+ * The Trainer Ditto is also made uncatchable (Adrian, 2026-10-31: Ditto, which breeds with anything, is a rare find in
+ * the Deep Dark; a Ditto visiting every half hour would hand them out early). It still trades.
  */
 object SpecialPokemon {
     /** Cobblemon HMs marks its Trainer Ditto with this in the Pokémon's persistent data. */
     private const val HMS_TRAINER = "dittohms_trainer"
 
+    fun register() {
+        NeoForge.EVENT_BUS.addListener(::onEntityJoin)
+    }
+
     fun isExempt(pokemon: Pokemon): Boolean =
-        pokemon.isUncatchable() || pokemon.persistentData.contains(Guardians.TAG) || pokemon.persistentData.contains(HMS_TRAINER)
+        pokemon.isUncatchable() || pokemon.persistentData.contains(Guardians.TAG) || isTrainerDitto(pokemon)
+
+    fun isTrainerDitto(pokemon: Pokemon): Boolean = pokemon.persistentData.contains(HMS_TRAINER)
+
+    /** Checked a tick later, since HMs may mark its trader after the entity joins. */
+    private fun onEntityJoin(event: EntityJoinLevelEvent) {
+        val entity = event.entity as? PokemonEntity ?: return
+        val level = event.level as? ServerLevel ?: return
+        level.server.tell(TickTask(level.server.tickCount + 1) { keepTrainerDittoFree(entity.pokemon) })
+    }
+
+    fun keepTrainerDittoFree(pokemon: Pokemon) {
+        if (isTrainerDitto(pokemon) && !pokemon.isUncatchable()) UncatchableProperty.uncatchable().apply(pokemon)
+    }
 }