Adv 2.0 D&D Phase 11 D6: boss phase-two narration

Wires the eight prewritten *PhaseTwoLines pools (Valdris / HollowKing /
Aldric / Thyrak / Ilvaras / Thornmother / Infernax / Belaxath) into
resolveBossRoom. When the combat event log shows enemy HP crossing the
zone's PhaseTwoAt threshold, a TwinBee phase-two callout is injected
between the boss-stat header and the win/loss line. Bosses without a
phase-two transition (Grol, Aboleth) are unaffected.

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

internal/plugin/dnd_zone_cmd.go

@@ -448,6 +448,12 @@ func (p *AdventurePlugin) resolveBossRoom(userID id.UserID, run *DungeonRun, zon
 
 	var b strings.Builder
 	b.WriteString(fmt.Sprintf("👑 **Boss — %s** (HP %d, AC %d)\n", monster.Name, monster.HP, monster.AC))
+	if phaseTwoCrossedInEvents(result.Events, result.EnemyStartHP, zone.Boss.PhaseTwoAt) {
+		if line := bossPhaseTwoLine(zone.ID, run.RunID, run.CurrentRoom); line != "" {
+			b.WriteString(line)
+			b.WriteString("\n")
+		}
+	}
 	if !result.PlayerWon {
 		_, _ = applyMoodEvent(run.RunID, MoodEventPlayerDeath)
 		_ = abandonZoneRun(userID)

internal/plugin/dnd_zone_narration.go

@@ -214,6 +214,61 @@ func bossSignaturePool(zoneID ZoneID) []string {
 	return nil
 }
 
+// bossPhaseTwoPool returns the zone-boss phase-two callout pool — the
+// line surfaced when the boss crosses its PhaseTwoAt HP threshold mid-fight.
+// Returns nil for bosses with no phase-two transition (Grol, Aboleth).
+func bossPhaseTwoPool(zoneID ZoneID) []string {
+	switch zoneID {
+	case ZoneCryptValdris:
+		return flavor.ValdrisPhaseTwoLines
+	case ZoneForestShadows:
+		return flavor.HollowKingPhaseTwoLines
+	case ZoneManorBlackspire:
+		return flavor.AldricPhaseTwoLines
+	case ZoneUnderforge:
+		return flavor.ThyrakPhaseTwoLines
+	case ZoneUnderdark:
+		return flavor.IlvarasPhaseTwoLines
+	case ZoneFeywildCrossing:
+		return flavor.ThornmotherPhaseTwoLines
+	case ZoneDragonsLair:
+		return flavor.InfernaxPhaseTwoLines
+	case ZoneAbyssPortal:
+		return flavor.BelaxathPhaseTwoLines
+	}
+	return nil
+}
+
+// bossPhaseTwoLine renders the zone-specific phase-two transition line.
+// Empty string when the zone has no phase-two pool.
+func bossPhaseTwoLine(zoneID ZoneID, runID string, roomIdx int) string {
+	pool := bossPhaseTwoPool(zoneID)
+	if len(pool) == 0 {
+		return ""
+	}
+	line := pickLineDeterministic(pool, runID, roomIdx^0x71F4A2D3)
+	if line == "" {
+		return ""
+	}
+	return "🎭 **TwinBee:** " + line
+}
+
+// phaseTwoCrossedInEvents reports whether enemy HP crossed the
+// PhaseTwoAt fraction of startHP at any point in the events log. Returns
+// false when threshold <= 0 (no phase 2) or startHP <= 0.
+func phaseTwoCrossedInEvents(events []CombatEvent, startHP int, threshold float64) bool {
+	if threshold <= 0 || startHP <= 0 {
+		return false
+	}
+	cutoff := int(float64(startHP) * threshold)
+	for _, ev := range events {
+		if ev.EnemyHP <= cutoff {
+			return true
+		}
+	}
+	return false
+}
+
 // eliteRoomEntryPool returns the zone-specific elite-room atmospheric
 // pool. Returns nil when the zone has no dedicated elite prose.
 func eliteRoomEntryPool(zoneID ZoneID) []string {

internal/plugin/dnd_zone_narration_test.go

@@ -445,3 +445,58 @@ func TestRoomEntryPool_Tier4And5PrependsZoneSpecific(t *testing.T) {
 		}
 	}
 }
+
+// ── Phase 11 D6 — boss phase-two narration ──────────────────────────────────
+
+func TestBossPhaseTwoPool_RoutesEightZones(t *testing.T) {
+	cases := map[ZoneID]int{
+		ZoneCryptValdris:    len(flavor.ValdrisPhaseTwoLines),
+		ZoneForestShadows:   len(flavor.HollowKingPhaseTwoLines),
+		ZoneManorBlackspire: len(flavor.AldricPhaseTwoLines),
+		ZoneUnderforge:      len(flavor.ThyrakPhaseTwoLines),
+		ZoneUnderdark:       len(flavor.IlvarasPhaseTwoLines),
+		ZoneFeywildCrossing: len(flavor.ThornmotherPhaseTwoLines),
+		ZoneDragonsLair:     len(flavor.InfernaxPhaseTwoLines),
+		ZoneAbyssPortal:     len(flavor.BelaxathPhaseTwoLines),
+	}
+	for z, want := range cases {
+		got := bossPhaseTwoPool(z)
+		if len(got) == 0 || len(got) != want {
+			t.Errorf("%s phase-two pool len mismatch: got %d, want %d", z, len(got), want)
+		}
+	}
+	// Bosses without a phase-two transition return nil.
+	for _, z := range []ZoneID{ZoneGoblinWarrens, ZoneSunkenTemple} {
+		if got := bossPhaseTwoPool(z); got != nil {
+			t.Errorf("%s should not have a phase-two pool (no PhaseTwoAt)", z)
+		}
+	}
+}
+
+func TestBossPhaseTwoLine_PrependsTwinBee(t *testing.T) {
+	line := bossPhaseTwoLine(ZoneCryptValdris, "run-d6", 4)
+	if !strings.HasPrefix(line, "🎭 **TwinBee:**") {
+		t.Errorf("phase-two line missing TwinBee prefix: %q", line)
+	}
+	if bossPhaseTwoLine(ZoneGoblinWarrens, "run-d6", 4) != "" {
+		t.Errorf("Grol has no phase-two pool — expected empty string")
+	}
+}
+
+func TestPhaseTwoCrossedInEvents(t *testing.T) {
+	startHP := 100
+	threshold := 0.5
+	events := []CombatEvent{{EnemyHP: 80}, {EnemyHP: 60}, {EnemyHP: 40}}
+	if !phaseTwoCrossedInEvents(events, startHP, threshold) {
+		t.Errorf("expected crossing at EnemyHP=40 (cutoff=50)")
+	}
+	if phaseTwoCrossedInEvents(events[:2], startHP, threshold) {
+		t.Errorf("did not cross 50%% by event 2 (EnemyHP=60); should be false")
+	}
+	if phaseTwoCrossedInEvents(events, startHP, 0) {
+		t.Errorf("threshold 0 means no phase 2 — should be false")
+	}
+	if phaseTwoCrossedInEvents(events, 0, threshold) {
+		t.Errorf("startHP 0 — should be false (degenerate)")
+	}
+}