refactor(platform): organize mixins into category directories

Move 136 prototype mixins under mixins/domain, json-export, and
runtime/* so the package root stays navigable. Manifest assign order
is unchanged; apply-platform-mixins and runtime registry paths updated.

Co-authored-by: Cursor <[email protected]>

mixins/domain/slash-mixin.js

@@ -0,0 +1,110 @@
+'use strict'
+
+const slashMixin = {
+  _slashCommandGossipKeys: null,
+  _slashRegistryHealWatermark: null,
+  _slashUsageHealWatermark: null,
+
+  _initSlashMixinState () {
+    if (!this._slashCommandGossipKeys) {
+      this._slashCommandGossipKeys = new Set()
+    }
+  },
+
+  _shouldGossipSlashCommand (row) {
+    this._initSlashMixinState()
+    if (!row?.guildId || !row?.name) return true
+    const hash = `${row.guildId}:${row.name}:${row.description || ''}:${row.optionsJson || ''}:${row.defaultMemberPermissions ?? ''}:${row.builtin ? 1 : 0}:${row.updatedAt || row.createdAt || 0}`
+    if (this._slashCommandGossipKeys.has(hash)) return false
+    this._slashCommandGossipKeys.add(hash)
+    if (this._slashCommandGossipKeys.size > 8192) {
+      const first = this._slashCommandGossipKeys.values().next().value
+      if (first) this._slashCommandGossipKeys.delete(first)
+    }
+    return true
+  },
+
+  async _healSlashRegistryOnPartition (guildId) {
+    const gid = guildId || this.guild?.guild?.id || null
+    const span = this.log.time('slash.heal', {
+      spanKind: 'slash.heal',
+      guildId: gid,
+      slice: 'registry'
+    })
+    try {
+      if (!gid || !this.slashCommands?.list) {
+        span.end({ relisted: 0, skipped: true })
+        return { relisted: 0, skipped: true }
+      }
+      const rows = await this.slashCommands.list().catch(() => [])
+      let relisted = 0
+      for (const row of rows) {
+        if (row.guildId && row.guildId !== gid) continue
+        const gossipRow = {
+          id: row.id,
+          guildId: row.guildId,
+          name: row.name,
+          description: row.description,
+          optionsJson: row.options?.length ? JSON.stringify(row.options) : row.optionsJson || null,
+          applicationId: row.applicationId,
+          defaultMemberPermissions: row.defaultMemberPermissions ?? null,
+          builtin: !!row.builtin,
+          createdAt: row.createdAt
+        }
+        if (this._shouldGossipSlashCommand(gossipRow) && this.guild?.gossipSlashCommand) {
+          this.guild.gossipSlashCommand(gossipRow)
+          relisted++
+        }
+      }
+      const watermark = Date.now()
+      this._slashRegistryHealWatermark = watermark
+      span.end({ relisted, watermark, commandCount: rows.length })
+      return { relisted, watermark, commandCount: rows.length }
+    } catch (err) {
+      this.log.error('slash.heal error', {
+        guildId: gid,
+        slice: 'registry',
+        error: err?.message || String(err)
+      })
+      span.fail(err)
+      return { relisted: 0, error: err?.message || String(err) }
+    }
+  },
+
+  async _healSlashUsageCursorOnPartition (guildId) {
+    const gid = guildId || this.guild?.guild?.id || null
+    const span = this.log.time('slash.create', {
+      spanKind: 'slash.create',
+      guildId: gid,
+      context: 'heal.usage'
+    })
+    try {
+      if (!gid) {
+        span.end({ relisted: 0, skipped: true, slashCommandCount: 0 })
+        return { relisted: 0, skipped: true }
+      }
+      const list = this.slashCommands ? await this.slashCommands.list().catch(() => []) : []
+      const watermark = Date.now()
+      this._slashUsageHealWatermark = watermark
+      span.end({
+        relisted: 0,
+        watermark,
+        slashCommandCount: list.length,
+        customCount: list.filter((r) => !r.builtin).length,
+        guildCount: (this.guilds || []).length,
+        activeChannelId: this.activeChannelId || null
+      })
+      return { relisted: 0, watermark, slashCommandCount: list.length }
+    } catch (err) {
+      this.log.error('slash.create error', {
+        guildId: gid,
+        context: 'heal.usage',
+        error: err?.message || String(err)
+      })
+      span.fail(err)
+      return { relisted: 0, error: err?.message || String(err) }
+    }
+  }
+}
+
+module.exports = { slashMixin }