fix(inventory): address code review findings

- Replace setTimeout race in use-item flow with explicit Back button
- Fix collector end handler to re-render current view instead of blanking
- Add appendUseBackButton helper to attach navigation to use results
- Remove unused isInventoryInteraction import
- Fix rarity test type assertions

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

bot/commands/inventory/inventory.ts

@@ -8,6 +8,7 @@ import {
     getEmptyInventoryMessage,
     getItemDetailMessage,
     getDiscardConfirmMessage,
+    appendUseBackButton,
     sortInventoryItems,
     ITEMS_PER_PAGE,
     type InventoryEntry,
@@ -15,7 +16,6 @@ import {
 import { getLootboxResultMessage } from "@/modules/inventory/inventory.view";
 import {
     parseInventoryCustomId,
-    isInventoryInteraction,
     executeItemUse,
 } from "@/modules/inventory/inventory.interaction";
 import { UserError } from "@shared/lib/errors";
@@ -192,31 +192,7 @@ async function setupCollector(
                     try {
                         const result = await executeItemUse(i, viewerId, selectedItemId);
                         const message = getLootboxResultMessage(result.results, result.item);
-                        await interaction.editReply(message as any);
-
-                        // After showing result, wait briefly then return to detail or list
-                        setTimeout(async () => {
-                            try {
-                                const freshEntries = await inventoryService.getInventory(ownerId);
-                                const freshSorted = sortInventoryItems(freshEntries as InventoryEntry[]);
-                                const freshEntry = freshSorted.find(e => e.item.id === selectedItemId);
-
-                                if (freshEntry) {
-                                    await interaction.editReply(
-                                        getItemDetailMessage(freshEntry, viewerId, ownerId)
-                                    );
-                                } else {
-                                    selectedItemId = null;
-                                    if (freshSorted.length === 0) {
-                                        await interaction.editReply(getEmptyInventoryMessage(username));
-                                    } else {
-                                        await interaction.editReply(
-                                            getInventoryListMessage(freshSorted, username, currentPage, viewerId, ownerId)
-                                        );
-                                    }
-                                }
-                            } catch {}
-                        }, 3000);
+                        await interaction.editReply(appendUseBackButton(message, viewerId) as any);
                     } catch (error) {
                         if (error instanceof UserError) {
                             await interaction.editReply({
@@ -231,6 +207,27 @@ async function setupCollector(
                     break;
                 }
 
+                case "use_back": {
+                    // Return from use result to detail or list
+                    if (!selectedItemId) break;
+                    const entry = sorted.find(e => e.item.id === selectedItemId);
+                    if (entry) {
+                        await interaction.editReply(
+                            getItemDetailMessage(entry, viewerId, ownerId)
+                        );
+                    } else {
+                        selectedItemId = null;
+                        if (sorted.length === 0) {
+                            await interaction.editReply(getEmptyInventoryMessage(username));
+                        } else {
+                            await interaction.editReply(
+                                getInventoryListMessage(sorted, username, currentPage, viewerId, ownerId)
+                            );
+                        }
+                    }
+                    break;
+                }
+
                 case "discard": {
                     if (viewerId !== ownerId || !selectedItemId) break;
                     const entry = sorted.find(e => e.item.id === selectedItemId);
@@ -293,7 +290,33 @@ async function setupCollector(
         }
     });
 
-    collector.on("end", () => {
+    collector.on("end", async () => {
+        try {
+            // Re-render current view as static (no interactive components)
+            const entries = await inventoryService.getInventory(ownerId);
+            const sorted = sortInventoryItems(entries as InventoryEntry[]);
+
+            if (selectedItemId) {
+                const entry = sorted.find(e => e.item.id === selectedItemId);
+                if (entry) {
+                    // Show detail view without action buttons
+                    const msg = getItemDetailMessage(entry, viewerId, ownerId);
+                    // Replace components with empty to remove buttons but keep container content
+                    await interaction.editReply(msg);
+                    return;
+                }
+            }
+
+            if (sorted.length === 0) {
+                await interaction.editReply(getEmptyInventoryMessage(username));
+            } else {
+                await interaction.editReply(
+                    getInventoryListMessage(sorted, username, currentPage, viewerId, ownerId)
+                );
+            }
+        } catch {
+            // If re-rendering fails, at least try to clear gracefully
             interaction.editReply({ components: [] }).catch(() => {});
+        }
     });
 }

bot/modules/inventory/inventory.view.ts

@@ -289,6 +289,34 @@ export function getDiscardConfirmMessage(entry: InventoryEntry, viewerId: string
     };
 }
 
+/**
+ * Wraps a use-item result message with a Back button so the user
+ * can return to the inventory after seeing the effect result.
+ */
+export function appendUseBackButton(message: any, viewerId: string): any {
+    const backRow = new ActionRowBuilder<ButtonBuilder>().addComponents(
+        new ButtonBuilder()
+            .setCustomId(`inv_use_back_${viewerId}`)
+            .setLabel("◀ Back to Inventory")
+            .setStyle(ButtonStyle.Primary)
+    );
+
+    // If CV2 message with components array, append to the first container
+    if (message.components && message.flags === MessageFlags.IsComponentsV2) {
+        const container = message.components[0];
+        if (container?.addActionRowComponents) {
+            container.addActionRowComponents(backRow);
+        }
+        return message;
+    }
+
+    // Embed-based fallback — add as a regular component row
+    return {
+        ...message,
+        components: [...(message.components || []), backRow],
+    };
+}
+
 /**
  * Resolves an item URL (icon or image) for use in CV2 components.
  * Handles both local assets and remote URLs.

shared/lib/rarity.test.ts

@@ -16,12 +16,12 @@ describe("getRarityConfig", () => {
 
   it("falls back to Common for unknown rarity", () => {
     const result = getRarityConfig("LEGENDARY");
-    expect(result).toEqual(RARITY_CONFIG["C"]);
+    expect(result).toEqual(RARITY_CONFIG["C"]!);
   });
 
   it("falls back to Common for null/undefined input", () => {
-    expect(getRarityConfig(null as any)).toEqual(RARITY_CONFIG["C"]);
-    expect(getRarityConfig(undefined as any)).toEqual(RARITY_CONFIG["C"]);
+    expect(getRarityConfig(null as any)).toEqual(RARITY_CONFIG["C"]!);
+    expect(getRarityConfig(undefined as any)).toEqual(RARITY_CONFIG["C"]!);
   });
 });