Modpack Installer: 7 UI tweaks before Holly review

1. Node selector shows live RAM/disk usage from Pterodactyl API (/node-info endpoint)
2. Disk allocation field, pre-filled at 3× estimated pack size
3. JVM args textarea auto-populated with Aikar G1GC flags
4. Spawn type: added 'vanilla' as new default, cleaned labels
5. Java version auto-selects from MC version (<=1.16→8, 1.17-1.20→17, 1.21+→21)
6. Port auto-assigned from max used port on node (/next-port endpoint), read-only + Re-roll
7. Pack size estimate shown on details card from provider file metadata

New endpoints: GET /node-info (Pterodactyl nodes API), GET /next-port?node=X (DB query)
All changes in _pack_details.ejs + modpack-installer.js. No migrations.

services/arbiter-3.0/src/routes/admin/modpack-installer.js

@@ -14,10 +14,91 @@
 
 const express = require('express');
 const router = express.Router();
+const axios = require('axios');
 const db = require('../../database');
 const { getProvider, listProviders } = require('../../services/providerApi');
 const { estimateRam, slugify } = require('../../services/modpackInstaller');
 
+const PANEL_URL = process.env.PANEL_URL || 'https://panel.firefrostgaming.com';
+const PANEL_ADMIN_KEY = process.env.PANEL_ADMIN_KEY || '';
+
+// Aikar G1GC flags template — {RAM} replaced with allocation in MB
+const AIKAR_FLAGS = '-XX:+UseG1GC -XX:+ParallelRefProcEnabled -XX:MaxGCPauseMillis=200 ' +
+  '-XX:+UnlockExperimentalVMOptions -XX:+DisableExplicitGC -XX:+AlwaysPreTouch ' +
+  '-XX:G1NewSizePercent=30 -XX:G1MaxNewSizePercent=40 -XX:G1HeapRegionSize=8M ' +
+  '-XX:G1ReservePercent=20 -XX:G1HeapWastePercent=5 -XX:G1MixedGCCountTarget=4 ' +
+  '-XX:InitiatingHeapOccupancyPercent=15 -XX:G1MixedGCLiveThresholdPercent=90 ' +
+  '-XX:G1RSetUpdatingPauseTimePercent=5 -XX:SurvivorRatio=32 -XX:+PerfDisableSharedMem ' +
+  '-XX:MaxTenuringThreshold=1 -Dusing.aikars.flags=https://mcflags.emc.gs ' +
+  '-Daikars.new.flags=true';
+
+function javaVersionForMC(mcVersion) {
+  if (!mcVersion) return 21;
+  const parts = mcVersion.split('.').map(Number);
+  const minor = parts[1] || 0;
+  if (minor <= 16) return 8;
+  if (minor <= 20) return 17;
+  return 21;
+}
+
+// ─── Node resource usage (JSON for form) ────────────────────────────────────
+router.get('/node-info', async (req, res) => {
+  try {
+    const panelHeaders = {
+      'Authorization': `Bearer ${PANEL_ADMIN_KEY}`,
+      'Accept': 'application/json'
+    };
+    const nodesResp = await axios.get(`${PANEL_URL}/api/application/nodes`, {
+      headers: panelHeaders, timeout: 10000
+    });
+    const nodes = (nodesResp.data.data || []).map(n => {
+      const a = n.attributes;
+      return {
+        id: a.id, name: a.name, location_id: a.location_id,
+        memory: a.memory, memory_overallocate: a.memory_overallocate,
+        disk: a.disk, disk_overallocate: a.disk_overallocate,
+        allocated_resources: a.allocated_resources || {}
+      };
+    });
+    // Map to our node IDs
+    const result = {};
+    for (const n of nodes) {
+      const key = n.name.includes('TX') ? 'TX1' : n.name.includes('NC') ? 'NC1' : n.name;
+      const usedRam = n.allocated_resources.memory || 0;
+      const usedDisk = n.allocated_resources.disk || 0;
+      result[key] = {
+        label: key === 'TX1' ? '🔥 TX1 — Dallas' : '❄️ NC1 — Charlotte',
+        ramUsedMb: usedRam, ramTotalMb: n.memory,
+        diskUsedMb: usedDisk, diskTotalMb: n.disk
+      };
+    }
+    res.json(result);
+  } catch (err) {
+    console.error('[Installer] node-info error:', err.message);
+    res.json({
+      NC1: { label: '❄️ NC1 — Charlotte', ramUsedMb: 0, ramTotalMb: 65536, diskUsedMb: 0, diskTotalMb: 2048000 },
+      TX1: { label: '🔥 TX1 — Dallas', ramUsedMb: 0, ramTotalMb: 65536, diskUsedMb: 0, diskTotalMb: 2048000 }
+    });
+  }
+});
+
+// ─── Next available port on a node ──────────────────────────────────────────
+router.get('/next-port', async (req, res) => {
+  try {
+    const node = req.query.node || 'NC1';
+    // Query server_config for all servers on this node, find max port
+    const result = await db.query(
+      `SELECT COALESCE(MAX(server_port), 25564) AS max_port FROM server_config WHERE node = $1`,
+      [node]
+    );
+    const nextPort = result.rows[0].max_port + 1;
+    res.json({ port: nextPort, node });
+  } catch (err) {
+    console.error('[Installer] next-port error:', err.message);
+    res.json({ port: 25565, node: req.query.node || 'NC1' });
+  }
+});
+
 // ─── Main page ──────────────────────────────────────────────────────────────
 router.get('/', (req, res) => {
   res.render('admin/modpack-installer/index', {
@@ -69,6 +150,8 @@ router.get('/pack/:provider/:id', async (req, res) => {
       provider: req.params.provider,
       estimateRam,
       slugify,
+      javaVersionForMC,
+      aikarFlags: AIKAR_FLAGS,
       csrfToken: req.csrfToken(),
       layout: false
     });

services/arbiter-3.0/src/views/admin/modpack-installer/_pack_details.ejs

@@ -1,8 +1,19 @@
 <!-- Pack details + install form partial (HTMX) -->
+<!-- REQ-2026-04-16-modpack-installer-tweaks: all 7 tweaks applied -->
+
+<%
+  // Derive first MC version for Java auto-select
+  var firstVersion = versions.length > 0 ? (versions[0].gameVersions || [])[0] || '' : '';
+  var autoJava = javaVersionForMC(firstVersion);
+  // Estimate pack size from first version file
+  var firstFile = versions.length > 0 ? (versions[0].files ? versions[0].files[0] : versions[0]) : {};
+  var estSizeMb = firstFile.fileLength ? Math.round(firstFile.fileLength / 1024 / 1024) : (firstFile.size ? Math.round(firstFile.size / 1024 / 1024) : 0);
+%>
 
 <div class="bg-white dark:bg-darkcard rounded-lg border border-gray-200 dark:border-gray-700 p-5">
   <h2 class="text-sm font-semibold text-gray-400 uppercase tracking-wider mb-3">3. Configure Install</h2>
 
+  <!-- Pack info + resource estimates (tweak #7) -->
   <div class="flex gap-4 mb-4">
     <% if (pack.thumbnail) { %>
       <img src="<%= pack.thumbnail %>" alt="" class="w-20 h-20 rounded object-cover shrink-0">
@@ -10,13 +21,19 @@
     <div>
       <h3 class="text-lg font-bold"><%= pack.name %></h3>
       <p class="text-sm text-gray-400 mt-1"><%= (pack.summary || '').substring(0, 200) %></p>
-      <% if (pack.categories && pack.categories.length > 0) { %>
-        <div class="flex gap-1 mt-2">
-          <% pack.categories.slice(0, 5).forEach(function(c) { %>
-            <span class="text-[10px] bg-gray-700 text-gray-300 px-1.5 py-0.5 rounded"><%= c %></span>
+      <div class="flex gap-3 mt-2 text-xs">
+        <% if (pack.categories && pack.categories.length > 0) { %>
+          <% pack.categories.slice(0, 4).forEach(function(c) { %>
+            <span class="bg-gray-700 text-gray-300 px-1.5 py-0.5 rounded"><%= c %></span>
           <% }) %>
-        </div>
-      <% } %>
+        <% } %>
+        <% if (estSizeMb > 0) { %>
+          <span class="bg-gray-700 text-cyan-300 px-1.5 py-0.5 rounded">~<%= estSizeMb %> MB</span>
+        <% } %>
+        <% if (pack.downloadCount) { %>
+          <span class="text-gray-500">⬇ <%= pack.downloadCount.toLocaleString() %></span>
+        <% } %>
+      </div>
     </div>
   </div>
 
@@ -29,9 +46,13 @@
       <!-- Version selector -->
       <div>
         <label class="block text-sm font-medium mb-1">Version</label>
-        <select name="versionId" required class="w-full bg-gray-800 border border-gray-700 rounded px-3 py-2 text-sm">
+        <select name="versionId" id="dd-version" required
+                onchange="onVersionChange(this)"
+                class="w-full bg-gray-800 border border-gray-700 rounded px-3 py-2 text-sm">
           <% versions.slice(0, 20).forEach(function(v, i) { %>
-            <option value="<%= v.fileId || v.versionId %>" <%= i === 0 ? 'selected' : '' %>>
+            <option value="<%= v.fileId || v.versionId %>"
+                    data-mc="<%= (v.gameVersions || [])[0] || '' %>"
+                    <%= i === 0 ? 'selected' : '' %>>
               <%= v.displayName || v.versionNumber || v.fileName %>
               <% if (v.gameVersions && v.gameVersions.length) { %>(MC <%= v.gameVersions[0] %>)<% } %>
             </option>
@@ -48,37 +69,80 @@
 
       <!-- Short name / subdomain -->
       <div>
-        <label class="block text-sm font-medium mb-1">Short Name <span class="text-gray-500 text-xs">(Discord prefix + subdomain)</span></label>
-        <input name="shortName" required value="<%= slugify(pack.name) %>" pattern="[a-z0-9-]+"
-               class="w-full bg-gray-800 border border-gray-700 rounded px-3 py-2 text-sm font-mono">
-        <div class="text-[10px] text-gray-500 mt-1">→ <span class="text-cyan-400"><%= slugify(pack.name) %>.firefrostgaming.com</span></div>
+        <label class="block text-sm font-medium mb-1">Short Name <span class="text-gray-500 text-xs">(Discord + subdomain)</span></label>
+        <input name="shortName" id="dd-shortname" required value="<%= slugify(pack.name) %>" pattern="[a-z0-9-]+"
+               class="w-full bg-gray-800 border border-gray-700 rounded px-3 py-2 text-sm font-mono"
+               oninput="document.getElementById('subdomain-preview').textContent=this.value+'.firefrostgaming.com'">
+        <div class="text-[10px] text-gray-500 mt-1">→ <span id="subdomain-preview" class="text-cyan-400"><%= slugify(pack.name) %>.firefrostgaming.com</span></div>
       </div>
 
-      <!-- Node -->
+      <!-- Node (tweak #1: live resource usage) -->
       <div>
         <label class="block text-sm font-medium mb-1">Node</label>
-        <select name="node" required class="w-full bg-gray-800 border border-gray-700 rounded px-3 py-2 text-sm">
+        <select name="node" id="dd-node" required onchange="onNodeChange(this.value)"
+                class="w-full bg-gray-800 border border-gray-700 rounded px-3 py-2 text-sm">
           <option value="NC1">❄️ NC1 — Charlotte</option>
           <option value="TX1">🔥 TX1 — Dallas</option>
         </select>
+        <div id="node-usage" class="text-[10px] text-gray-500 mt-1">Loading node stats...</div>
       </div>
 
       <!-- RAM -->
       <div>
         <label class="block text-sm font-medium mb-1">RAM (MB)</label>
-        <input name="ramMb" type="number" required value="8192" min="4096" max="32768" step="1024"
+        <input name="ramMb" id="dd-ram" type="number" required value="8192" min="4096" max="32768" step="1024"
+               onchange="updateJvmFlags()"
                class="w-full bg-gray-800 border border-gray-700 rounded px-3 py-2 text-sm">
       </div>
 
-      <!-- Spawn type -->
+      <!-- Disk (tweak #2) -->
+      <div>
+        <label class="block text-sm font-medium mb-1">Disk (MB)</label>
+        <input name="diskMb" id="dd-disk" type="number" required value="<%= estSizeMb > 0 ? Math.max(estSizeMb * 3, 10240) : 20480 %>" min="5120" max="500000" step="1024"
+               class="w-full bg-gray-800 border border-gray-700 rounded px-3 py-2 text-sm">
+        <% if (estSizeMb > 0) { %>
+          <div class="text-[10px] text-gray-500 mt-1">Pack size ~<%= estSizeMb %>MB → pre-filled 3× for world growth</div>
+        <% } %>
+      </div>
+
+      <!-- Java version (tweak #5: auto-select from MC version) -->
+      <div>
+        <label class="block text-sm font-medium mb-1">Java Version</label>
+        <select name="javaVersion" id="dd-java" class="w-full bg-gray-800 border border-gray-700 rounded px-3 py-2 text-sm">
+          <option value="8"  <%= autoJava === 8  ? 'selected' : '' %>>Java 8</option>
+          <option value="17" <%= autoJava === 17 ? 'selected' : '' %>>Java 17</option>
+          <option value="21" <%= autoJava === 21 ? 'selected' : '' %>>Java 21</option>
+        </select>
+        <div class="text-[10px] text-gray-500 mt-1">Auto-selected for MC <%= firstVersion || 'unknown' %></div>
+      </div>
+
+      <!-- Port (tweak #6: auto-assign) -->
+      <div>
+        <label class="block text-sm font-medium mb-1">Port</label>
+        <div class="flex gap-2">
+          <input name="port" id="dd-port" type="number" readonly value="25565"
+                 class="flex-1 bg-gray-900 border border-gray-700 rounded px-3 py-2 text-sm text-gray-400">
+          <button type="button" onclick="refreshPort()" class="bg-gray-700 hover:bg-gray-600 text-white px-3 py-1 rounded text-xs">🔄 Re-roll</button>
+        </div>
+      </div>
+
+      <!-- Spawn type (tweak #4: add vanilla as default) -->
       <div>
         <label class="block text-sm font-medium mb-1">Spawn Type</label>
         <select name="spawnType" class="w-full bg-gray-800 border border-gray-700 rounded px-3 py-2 text-sm">
+          <option value="vanilla" selected>Vanilla (no spawn changes)</option>
           <option value="standard">Standard (Bitch Bot pastes spawn)</option>
           <option value="skyblock">Skyblock (no spawn paste)</option>
           <option value="has_lobby">Has Lobby (pack provides its own)</option>
         </select>
       </div>
+
+      <!-- JVM args (tweak #3: Aikar flags auto-populated) -->
+      <div class="md:col-span-2">
+        <label class="block text-sm font-medium mb-1">JVM Arguments <span class="text-gray-500 text-xs">(Aikar G1GC — auto-populated)</span></label>
+        <textarea name="jvmArgs" id="dd-jvm" rows="3"
+                  class="w-full bg-gray-800 border border-gray-700 rounded px-3 py-2 text-xs font-mono text-gray-300"><%= aikarFlags %></textarea>
+      </div>
     </div>
 
     <button type="submit"
@@ -87,3 +151,53 @@
     </button>
   </form>
 </div>
+
+<script>
+  var nodeData = {};
+
+  // Load node stats on partial render
+  fetch('/admin/modpack-installer/node-info', { headers: { 'HX-Request': 'true' } })
+    .then(function(r) { return r.json(); })
+    .then(function(d) {
+      nodeData = d;
+      showNodeUsage(document.getElementById('dd-node').value);
+    });
+
+  // Load initial port
+  refreshPort();
+
+  function showNodeUsage(node) {
+    var el = document.getElementById('node-usage');
+    var n = nodeData[node];
+    if (!n) { el.textContent = ''; return; }
+    var ramPct = Math.round(n.ramUsedMb / n.ramTotalMb * 100);
+    var diskGb = Math.round(n.diskUsedMb / 1024);
+    var diskTotalGb = Math.round(n.diskTotalMb / 1024);
+    el.innerHTML = 'RAM: <strong>' + Math.round(n.ramUsedMb/1024) + 'GB / ' + Math.round(n.ramTotalMb/1024) + 'GB</strong> (' + ramPct + '%) · Disk: <strong>' + diskGb + 'GB / ' + diskTotalGb + 'GB</strong>';
+  }
+
+  function onNodeChange(node) {
+    showNodeUsage(node);
+    refreshPort();
+  }
+
+  function refreshPort() {
+    var node = document.getElementById('dd-node').value;
+    fetch('/admin/modpack-installer/next-port?node=' + node, { headers: { 'HX-Request': 'true' } })
+      .then(function(r) { return r.json(); })
+      .then(function(d) { document.getElementById('dd-port').value = d.port; });
+  }
+
+  function onVersionChange(sel) {
+    var mc = sel.options[sel.selectedIndex].dataset.mc || '';
+    var parts = mc.split('.').map(Number);
+    var minor = parts[1] || 0;
+    var java = minor <= 16 ? 8 : minor <= 20 ? 17 : 21;
+    document.getElementById('dd-java').value = java;
+  }
+
+  function updateJvmFlags() {
+    // Aikar flags don't change per RAM — they're static. RAM is in -Xms/-Xmx which
+    // Pterodactyl handles via {{SERVER_MEMORY}} var. No rewrite needed.
+  }
+</script>