fix firing heldItemChanged, add type (#3625)

* fix firing heldItemChanged, add type

* test: add tests for heldItemChanged event, fix missing argument

Add internal tests verifying heldItemChanged fires with the correct item
when the held slot is updated via set_slot and via direct updateSlot.

Also fix the new updateSlot listener to pass bot.heldItem as the event
argument, matching the existing updateHeldItem behavior and the type
definition.

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

* Retrigger CI

* test: add external test for heldItemChanged event

Verifies that the heldItemChanged event fires with the correct item
when the held slot contents are changed via server-side inventory update.

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

---------

Co-authored-by: Claude <claude@anthropic.com>
Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: zardoy

index.d.ts

@@ -162,6 +162,7 @@ export interface BotEvents {
   bossBarDeleted: (bossBar: BossBar) => Promise<void> | void
   bossBarUpdated: (bossBar: BossBar) => Promise<void> | void
   resourcePack: (url: string, hash?: string, uuid?: string) => Promise<void> | void
+  heldItemChanged: (newItem: Item | null) => Promise<void> | void
   particle: (particle: Particle) => Promise<void> | void
 }
 
@@ -386,8 +387,8 @@ export interface Bot extends TypedEmitter<BotEvents> {
     times?: number
   ) => Promise<void>
 
-  
-  
+
+
   setCommandBlock: (pos: Vec3, command: string, options: CommandBlockOptions) => void
 
   clickWindow: (

lib/plugins/inventory.js

@@ -547,7 +547,7 @@ function inject (bot, { hideErrors }) {
     }
     const window = bot.currentWindow || bot.inventory
 
-    assert.ok(mode >= 0 && mode <= 4)
+    assert.ok(mode >= 0 && mode <= 6)
     const actionId = createActionNumber()
 
     const click = {
@@ -734,6 +734,11 @@ function inject (bot, { hideErrors }) {
     const newItem = Item.fromNotch(packet.contents)
     bot._setSlot(packet.slotId, newItem)
   })
+  bot.inventory.on('updateSlot', (index) => {
+    if (index === bot.quickBarSlot + bot.inventory.hotbarStart) {
+      bot.emit('heldItemChanged', bot.heldItem)
+    }
+  })
   bot._client.on('window_items', (packet) => {
     const window = packet.windowId === 0 ? bot.inventory : bot.currentWindow
     if (!window || window.id !== packet.windowId) {

test/externalTests/heldItemChanged.js

@@ -0,0 +1,28 @@
+const assert = require('assert')
+const { onceWithCleanup } = require('../../lib/promise_utils')
+
+module.exports = () => async (bot) => {
+  await bot.test.becomeCreative()
+  await bot.test.clearInventory()
+  await bot.test.wait(100)
+
+  // Give the bot a stone in the held slot (slot 36 = first hotbar slot)
+  const stoneId = bot.registry.itemsByName.stone.id
+  const diamondId = bot.registry.itemsByName.diamond.id
+
+  // Put stone in the current held slot
+  await bot.test.setInventorySlot(bot.quickBarSlot + bot.inventory.hotbarStart, new (require('prismarine-item')(bot.registry))(stoneId, 1))
+  await bot.test.wait(100)
+  assert.strictEqual(bot.heldItem.type, stoneId, 'should be holding stone')
+
+  // Now change the held slot contents to diamond and verify heldItemChanged fires
+  const heldItemPromise = onceWithCleanup(bot, 'heldItemChanged', {
+    timeout: 5000
+  })
+  await bot.test.setInventorySlot(bot.quickBarSlot + bot.inventory.hotbarStart, new (require('prismarine-item')(bot.registry))(diamondId, 1))
+
+  const [newItem] = await heldItemPromise
+  assert(newItem, 'heldItemChanged should fire with the new item')
+  assert.strictEqual(newItem.type, diamondId, 'new item should be diamond')
+  assert.strictEqual(bot.heldItem.type, diamondId, 'bot.heldItem should reflect diamond')
+}

test/internalTest.js

@@ -968,6 +968,63 @@ for (const supportedVersion of mineflayer.testedVersions) {
       })
     })
 
+    describe('heldItemChanged', () => {
+      it('emits heldItemChanged when the held slot is updated via set_slot', (done) => {
+        const Item = require('prismarine-item')(supportedVersion)
+        const QUICK_BAR_SLOT = 0
+        const HOTBAR_START = 36
+        const stoneId = registry.itemsByName.stone.id
+        const stoneItem = new Item(stoneId, 1)
+        const notchItem = Item.toNotch(stoneItem)
+
+        server.on('playerJoin', (client) => {
+          client.write('login', bot.test.generateLoginPacket())
+          client.write('held_item_slot', { slot: QUICK_BAR_SLOT })
+
+          // Wait for the held_item_slot to be processed, then listen for the
+          // heldItemChanged triggered by the set_slot update to the held slot
+          setTimeout(() => {
+            bot.once('heldItemChanged', (newItem) => {
+              assert.ok(newItem, 'heldItemChanged should provide the new item')
+              assert.strictEqual(newItem.type, stoneId)
+              done()
+            })
+            client.write('set_slot', {
+              windowId: 0,
+              slot: HOTBAR_START + QUICK_BAR_SLOT,
+              item: notchItem
+            })
+          }, 100)
+        })
+      })
+
+      it('emits heldItemChanged via updateSlot on the inventory', (done) => {
+        const Item = require('prismarine-item')(supportedVersion)
+        const QUICK_BAR_SLOT = 0
+        const stoneId = registry.itemsByName.stone.id
+        const stoneItem = new Item(stoneId, 1)
+
+        server.on('playerJoin', (client) => {
+          client.write('login', bot.test.generateLoginPacket())
+          client.write('held_item_slot', { slot: QUICK_BAR_SLOT })
+
+          setTimeout(() => {
+            bot.once('heldItemChanged', (newItem) => {
+              assert.ok(newItem, 'heldItemChanged should provide the new item')
+              assert.strictEqual(newItem.type, stoneId)
+              done()
+            })
+            // Directly call updateSlot on the inventory to simulate
+            // the set_player_inventory code path
+            bot.inventory.updateSlot(
+              QUICK_BAR_SLOT + bot.inventory.hotbarStart,
+              stoneItem
+            )
+          }, 100)
+        })
+      })
+    })
+
     describe('tablist', () => {
       it('handles newlines in header and footer', (done) => {
         const HEADER = 'asd\ndsa'