N5 review fixes: protect keys from Robbie, fire epilogue on autopilot, atomic finale reward

Five correctness fixes from a code review of the N5 branch:

- Robbie no longer sweeps/sells cross-zone keys (Type "key"), which
  permanently broke the vault unlock they exist to open.
- Robbie's gift tier now reads the canonical DnD level, not the frozen
  legacy CombatLevel that pegged every gift at tier 1.
- Boss epilogue (D1b) now fires on the compact autopilot boss resolve —
  the primary long-expedition path — not just manual !fight. Deduped the
  two manual sites into a shared writeBossEpilogue helper.
- Finale reward latches epilogue_cleared before granting the Legendary +
  title, so a failed/late write can't make the reward repeatable.
- Misty arc beat's occupied-slot guard moved above the counter increment,
  so a contended pending slot defers the encounter instead of consuming a
  5/15/30 beat forever.

Claude-Session: https://claude.ai/code/session_017mEwUmmS7aQTP2NQXj6rUa

internal/plugin/adventure_flavor_campaign.go

@@ -269,6 +269,17 @@ func bossEpilogueLine(zoneID ZoneID) string {
 	return bossEpilogues[zoneID]
 }
 
+// writeBossEpilogue appends a zone's campaign capstone (if any) to a
+// victory narration. Shared by every boss-down render path — the manual
+// turn-based finishes (finishCombatSession, finishPartyWin) and the compact
+// autopilot boss resolve — so the D1b epilogue fires no matter how the boss
+// was cleared. Caller gates on "this was a boss, not an elite".
+func writeBossEpilogue(b *strings.Builder, zoneID ZoneID) {
+	if ep := bossEpilogueLine(zoneID); ep != "" {
+		b.WriteString("\n" + ep + "\n")
+	}
+}
+
 // twinBeeJournalReactions are TwinBee's morning/digest reactions to pages found
 // during the day — first-person, implicit subject, he/him, one line, curious,
 // never expository (feedback_twinbee_voice, feedback_twinbee_is_male). Picked
@@ -463,6 +474,15 @@ func (p *AdventurePlugin) finishEpilogueWin(userID id.UserID, alreadyCleared boo
 		return "_The throne stays empty. You came to be sure. You are sure._"
 	}
 
+	// Latch the once-only flag BEFORE handing out the Legendary + title, so a
+	// failed write (or a crash) can never leave the reward repeatable. If the
+	// latch fails, skip the grant entirely — the player re-enters uncleared and
+	// can try again, rather than pocketing a second Legendary on the retry.
+	if err := markEpilogueClearedDB(userID); err != nil {
+		slog.Error("epilogue: mark cleared failed", "user", userID, "err", err)
+		return "_The account won't quite close — the ledger jams. Try `!expedition start epilogue` again._"
+	}
+
 	var b strings.Builder
 	b.WriteString("🎖️ **The account is closed.** You are named **" + finaleTitle + "** — the one who unhoused the Hollow King.\n")
 	if mi, ok := pickMagicItemForRarity(RarityLegendary, nil); ok {
@@ -481,9 +501,6 @@ func (p *AdventurePlugin) finishEpilogueWin(userID id.UserID, alreadyCleared boo
 			}
 		}
 	}
-	if err := markEpilogueClearedDB(userID); err != nil {
-		slog.Error("epilogue: mark cleared failed", "user", userID, "err", err)
-	}
 
 	if gr := gamesRoom(); gr != "" {
 		if dn, _ := loadDisplayName(userID); dn != "" {

internal/plugin/adventure_npcs.go

@@ -131,6 +131,15 @@ func (p *AdventurePlugin) npcFireEncounter(userID id.UserID, npc string) {
 		return
 	}
 
+	// Don't consume the encounter — or its one-shot arc beat — if the player is
+	// already mid-interaction (shop, treasure, another NPC). Bail before
+	// touching MistyEncounterCount so a contended slot defers the whole
+	// encounter to a later fire instead of durably advancing the counter past
+	// a 5/15/30 threshold and losing that beat forever.
+	if _, occupied := p.pending.Load(string(userID)); occupied {
+		return
+	}
+
 	now := time.Now().UTC()
 
 	var opening, prompt string
@@ -165,11 +174,6 @@ func (p *AdventurePlugin) npcFireEncounter(userID id.UserID, npc string) {
 		slog.Error("player_meta: npc last_seen dual-write failed", "user", userID, "npc", npc, "err", err)
 	}
 
-	// Don't overwrite an existing pending interaction (shop, treasure, etc.)
-	if _, occupied := p.pending.Load(string(userID)); occupied {
-		return
-	}
-
 	// Set pending interaction — NPC encounters stay valid until end of UTC day
 	endOfDay := time.Date(now.Year(), now.Month(), now.Day(), 0, 0, 0, 0, time.UTC).Add(24 * time.Hour)
 	p.pending.Store(string(userID), &advPendingInteraction{

internal/plugin/adventure_robbie.go

@@ -171,7 +171,10 @@ func (p *AdventurePlugin) robbieVisitPlayer(userID id.UserID, displayName string
 	if err == nil {
 		char.RobbieVisitCount++
 		if char.RobbieVisitCount%robbieGiftEveryNVisits == 0 {
-			if gifts := consumableCache(robbieGiftTier(char.CombatLevel), 1); len(gifts) > 0 {
+			// Use the canonical DnD level (like the arena's tier gate), not the
+			// frozen legacy CombatLevel — that snapshots at 1–3 once D&D setup
+			// completes, so reading it here would peg every gift at tier 1.
+			if gifts := consumableCache(robbieGiftTier(arenaDnDLevelOrZero(userID)), 1); len(gifts) > 0 {
 				if err := addAdvInventoryItem(userID, gifts[0]); err == nil {
 					leftGift = &gifts[0]
 				}
@@ -200,10 +203,12 @@ func (p *AdventurePlugin) robbieVisitPlayer(userID id.UserID, displayName string
 func robbieQualifyingItems(inv []AdvItem, equip map[EquipmentSlot]*AdvEquipment) []AdvItem {
 	var result []AdvItem
 	for _, item := range inv {
-		// Never touch Arena gear, cards, or consumables. Consumables are a
-		// player-curated stockpile (crafted or dropped); selling them is an
-		// explicit decision the player must make themselves.
-		if item.Type == "ArenaGear" || item.Type == "card" || item.Type == "consumable" {
+		// Never touch Arena gear, cards, consumables, or keys. Consumables are
+		// a player-curated stockpile (crafted or dropped); selling them is an
+		// explicit decision the player must make themselves. Keys are cross-zone
+		// unlock tokens (N5/D4) that must persist in inventory to open their
+		// vault later — sweeping one permanently breaks that unlock.
+		if item.Type == "ArenaGear" || item.Type == "card" || item.Type == "consumable" || item.Type == "key" {
 			continue
 		}
 

internal/plugin/combat_cmd.go

@@ -382,9 +382,7 @@ func (p *AdventurePlugin) finishCombatSession(userID id.UserID, sess *CombatSess
 			b.WriteString(drop + "\n")
 		}
 		if !elite {
-			if ep := bossEpilogueLine(zone.ID); ep != "" {
-				b.WriteString("\n" + ep + "\n")
-			}
+			writeBossEpilogue(&b, zone.ID)
 		}
 		if bossOnExpedition {
 			// The boss is the expedition's climax. Frame the close-out as

internal/plugin/combat_party_finish.go

@@ -119,9 +119,7 @@ func (p *AdventurePlugin) finishPartyWin(
 			}
 		}
 		if !elite {
-			if ep := bossEpilogueLine(zone.ID); ep != "" {
-				b.WriteString("\n" + ep + "\n")
-			}
+			writeBossEpilogue(&b, zone.ID)
 		}
 		switch {
 		case bossOnExpedition && seat == 0:

internal/plugin/dnd_zone_cmd.go

@@ -1130,6 +1130,13 @@ func (p *AdventurePlugin) resolveCombatRoom(userID id.UserID, run *DungeonRun, z
 			ob.WriteString("\n")
 			ob.WriteString(line)
 		}
+		// D1b campaign capstone. The compact autopilot resolves boss rooms
+		// itself (the primary long-expedition path), so the epilogue has to
+		// fire here too — otherwise almost every player clears the boss
+		// without ever seeing it.
+		if isBoss {
+			writeBossEpilogue(&ob, zone.ID)
+		}
 		outcome = ob.String()
 		return
 	}