Phase 2c (roster gate): dilute single-boss elite pools

Each zone's elite pool was a single SpawnWeight=1 over-tier boss, so
InterruptElite bracket rolls auto-picked that boss 100% of the time.
The post-2b tier-lethality trace named these one-shots (Warchief, Hag,
Roper, Young Red Dragon) as the dominant remaining death source.

Promotes one mid-tier alt per zone to IsElite (underforge gets two
since fire_elemental was itself a non-elite killer). Boss SW=1 stays;
alt SW 3-4 gives the boss ~17-25% elite-roll share. pickZoneEnemy also
excludes IsElite from the standard pool, so promotion softens standard
encounters by one mid-difficulty entry — each zone still has 3-4
standard entries left. Crypt-Valdris already dual-elite, untouched.

Promotions: worg, owlbear, aboleth_thrall, vampire_spawn,
salamander+fire_elemental, drow_elite_warrior, night_hag,
dragonborn_cultist, hezrou.

Phase 1 matrix delta (200 trials/cell, Fighter, centerline):
  goblin_warrens: 0% → 3.0% completion (first non-zero T1 reading)
  sunken_temple:  0% → 0.5%
  dragons_lair:   death 100% → 60% (40% starve — different failure)
  underdark:      death 100% → 90% (10% starve)
  feywild:        death 100% → 92% (8% starve)
  T3 cells still 100% death — next pass is global supply/threat levers.

Tier-lethality trace shows Drow Elite Warrior + Dragonborn Cultist
spawning and being winnable, with arcs stretching to 7-10 encounters
instead of fresh-entry one-shots.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

gogobee_expedition_difficulty.md

@@ -156,15 +156,47 @@ target the cascade path that's now mostly resolved; they have no
 remaining death-fraction to convert. Phase 2c (roster dilution) is
 justified rather than premature.
 
-### Phase 2c — roster gate (next)
+### Phase 2c — roster gate (shipped)
 
-Promote softer mid-tier monsters to `IsElite: true` in zones whose
+Promoted one mid-tier alt to `IsElite: true` in every zone whose elite
-elite pool is a single tier-disproportionate boss (warchief / hag /
+pool was a single SpawnWeight=1 boss (`internal/plugin/dnd_zone.go`).
-roper / dragon are all SpawnWeight=1 alone in their elite pool, so
+The boss stays in the pool; weighted dilution means the InterruptElite
-an InterruptElite bracket roll = 100% pick of the over-tier boss).
+bracket no longer auto-picks the over-tier boss. `pickZoneEnemy` also
-Diluting the elite pool with one or two softer alternates at higher
+excludes the promoted entry from the standard pool, lowering standard
-SpawnWeight lets the fighter sometimes face a winnable elite,
+encounter difficulty by removing one mid-difficulty option from
-without removing the over-tier boss as a possible spawn.
+non-elite brackets (acceptable: each zone still has 3-4 standard
+entries left). Crypt-Valdris was already dual-elite (wight + flameskull)
+and was left alone.
+
+| zone               | promoted alt          | boss (untouched)   |
+|--------------------|-----------------------|--------------------|
+| goblin_warrens     | worg (SW=3)           | hobgoblin_warchief |
+| forest_shadows     | owlbear (SW=4)        | green_hag          |
+| sunken_temple      | aboleth_thrall (SW=3) | water_elemental    |
+| manor_blackspire   | vampire_spawn (SW=3)  | revenant           |
+| underforge         | salamander (SW=3) + fire_elemental (SW=3) | helmed_horror |
+| underdark          | drow_elite_warrior (SW=4) | roper          |
+| feywild_crossing   | night_hag (SW=3)      | fomorian           |
+| dragons_lair       | dragonborn_cultist (SW=3) | young_red_dragon |
+| abyss_portal       | hezrou (SW=4)         | marilith           |
+
+**Phase 1 matrix delta (200 trials/cell, Fighter, tier centerline):**
+goblin_warrens 0% → **3.0%** completion (first non-zero T1 reading
+since Phase 0); sunken_temple 0% → 0.5%; dragons_lair death% **100% →
+60%** with 40% now starve (fighter survives the elite-spawn path long
+enough to run out of supplies — different failure mode); underdark
+death% 100% → 90% (10% starve); feywild_crossing 100% → 92% death
+(8% starve). T3 manor_blackspire / underforge still 100% death — the
+remaining death pressure there is the post-2b chained-standard path,
+not the elite roll.
+
+Tier-lethality trace cross-check (`Phase2_TierLethality`) shows the
+new alt-elites actually spawning and being winnable: underdark trial
+1 now opens with `Drow Elite Warrior` (won), reaches the Roper at
+turn 6, retreats, then dies on a Hook Horror nick — a substantively
+longer arc than the pre-2c fresh-entry Roper one-shot. Dragons_lair
+trials similarly show `Dragonborn Cultist` as a winnable elite stop
+before the dragon roll lands.
 
 Stat-block tuning of the bosses themselves is off-limits per the
 Phase 3 constraint (bestiary is shared across systems).

internal/plugin/dnd_zone.go

@@ -220,7 +220,7 @@ func zoneGoblinWarrens() ZoneDefinition {
 			{BestiaryID: "goblin_sneak", SpawnWeight: 7},
 			{BestiaryID: "goblin_archer", SpawnWeight: 6},
 			{BestiaryID: "hobgoblin_grunt", SpawnWeight: 5},
-			{BestiaryID: "worg", SpawnWeight: 3},
+			{BestiaryID: "worg", SpawnWeight: 3, IsElite: true},
 			{BestiaryID: "goblin_shaman", SpawnWeight: 2},
 			{BestiaryID: "hobgoblin_warchief", SpawnWeight: 1, IsElite: true},
 		},
@@ -310,7 +310,7 @@ func zoneForestShadows() ZoneDefinition {
 		Enemies: []ZoneEnemy{
 			{BestiaryID: "dire_wolf", SpawnWeight: 6},
 			{BestiaryID: "bandit_captain", SpawnWeight: 4},
-			{BestiaryID: "owlbear", SpawnWeight: 4},
+			{BestiaryID: "owlbear", SpawnWeight: 4, IsElite: true},
 			{BestiaryID: "dryad_corrupted", SpawnWeight: 3},
 			{BestiaryID: "displacer_beast", SpawnWeight: 3},
 			{BestiaryID: "green_hag", SpawnWeight: 1, IsElite: true},
@@ -356,7 +356,7 @@ func zoneSunkenTemple() ZoneDefinition {
 			{BestiaryID: "kuo_toa", SpawnWeight: 7},
 			{BestiaryID: "kuo_toa_whip", SpawnWeight: 4},
 			{BestiaryID: "merrow", SpawnWeight: 4},
-			{BestiaryID: "aboleth_thrall", SpawnWeight: 3},
+			{BestiaryID: "aboleth_thrall", SpawnWeight: 3, IsElite: true},
 			{BestiaryID: "water_elemental", SpawnWeight: 1, IsElite: true},
 		},
 		Boss: ZoneBoss{
@@ -403,7 +403,7 @@ func zoneManorBlackspire() ZoneDefinition {
 			{BestiaryID: "poltergeist", SpawnWeight: 5},
 			{BestiaryID: "banshee", SpawnWeight: 3},
 			{BestiaryID: "wraith", SpawnWeight: 3},
-			{BestiaryID: "vampire_spawn", SpawnWeight: 3},
+			{BestiaryID: "vampire_spawn", SpawnWeight: 3, IsElite: true},
 			{BestiaryID: "revenant", SpawnWeight: 1, IsElite: true},
 		},
 		Boss: ZoneBoss{
@@ -449,8 +449,8 @@ func zoneUnderforge() ZoneDefinition {
 			{BestiaryID: "magmin", SpawnWeight: 6},
 			{BestiaryID: "azer", SpawnWeight: 5},
 			{BestiaryID: "flameskull", SpawnWeight: 4},
-			{BestiaryID: "salamander", SpawnWeight: 3},
+			{BestiaryID: "salamander", SpawnWeight: 3, IsElite: true},
-			{BestiaryID: "fire_elemental", SpawnWeight: 3},
+			{BestiaryID: "fire_elemental", SpawnWeight: 3, IsElite: true},
 			{BestiaryID: "helmed_horror", SpawnWeight: 1, IsElite: true},
 		},
 		Boss: ZoneBoss{
@@ -495,7 +495,7 @@ func zoneUnderdark() ZoneDefinition {
 		MaxRooms:   10,
 		Enemies: []ZoneEnemy{
 			{BestiaryID: "drow", SpawnWeight: 7},
-			{BestiaryID: "drow_elite_warrior", SpawnWeight: 4},
+			{BestiaryID: "drow_elite_warrior", SpawnWeight: 4, IsElite: true},
 			{BestiaryID: "drow_mage", SpawnWeight: 3},
 			{BestiaryID: "mind_flayer", SpawnWeight: 2},
 			{BestiaryID: "hook_horror", SpawnWeight: 4},
@@ -545,7 +545,7 @@ func zoneFeywildCrossing() ZoneDefinition {
 			{BestiaryID: "will_o_wisp", SpawnWeight: 5},
 			{BestiaryID: "quickling", SpawnWeight: 5},
 			{BestiaryID: "green_hag", SpawnWeight: 4},
-			{BestiaryID: "night_hag", SpawnWeight: 3},
+			{BestiaryID: "night_hag", SpawnWeight: 3, IsElite: true},
 			{BestiaryID: "fomorian", SpawnWeight: 1, IsElite: true},
 		},
 		Boss: ZoneBoss{
@@ -590,7 +590,7 @@ func zoneDragonsLair() ZoneDefinition {
 			{BestiaryID: "kobold", SpawnWeight: 7},
 			{BestiaryID: "guard_drake", SpawnWeight: 5},
 			{BestiaryID: "kobold_scale_sorcerer", SpawnWeight: 4},
-			{BestiaryID: "dragonborn_cultist", SpawnWeight: 3},
+			{BestiaryID: "dragonborn_cultist", SpawnWeight: 3, IsElite: true},
 			{BestiaryID: "young_red_dragon", SpawnWeight: 1, IsElite: true},
 		},
 		Boss: ZoneBoss{
@@ -637,7 +637,7 @@ func zoneAbyssPortal() ZoneDefinition {
 		Enemies: []ZoneEnemy{
 			{BestiaryID: "quasit", SpawnWeight: 6},
 			{BestiaryID: "vrock", SpawnWeight: 5},
-			{BestiaryID: "hezrou", SpawnWeight: 4},
+			{BestiaryID: "hezrou", SpawnWeight: 4, IsElite: true},
 			{BestiaryID: "nalfeshnee", SpawnWeight: 2},
 			{BestiaryID: "marilith", SpawnWeight: 1, IsElite: true},
 		},