diff --git a/tools/gateway-chat.html b/tools/gateway-chat.html
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+<!doctype html>
+<html lang="en">
+<head>
+<meta charset="utf-8">
+<meta name="viewport" content="width=device-width, initial-scale=1">
+<title>Gateway Chat — light LiteLLM playground</title>
+<!--
+  Single-file chat playground for the LiteLLM gateway (10.250.50.70:4000).
+  Zero dependencies, zero backend: open it in a browser (file:// is fine) or
+  serve statically. The gateway sends permissive CORS, so the browser talks to
+  it directly. It deliberately NEVER sends a `tools` field, sidestepping the
+  vLLM "tools must not be an empty array" bug that breaks the LiteLLM UI
+  playground for vLLM-backed models. Settings persist in localStorage.
+-->
+<style>
+  :root{--bg:#0f1115;--panel:#171a21;--ink:#e6e9ef;--muted:#8b93a7;--acc:#5b8cff;--line:#262b36;--user:#1f6feb22;--warn:#ff6b6b}
+  *{box-sizing:border-box}
+  body{margin:0;font:14px/1.55 system-ui,sans-serif;background:var(--bg);color:var(--ink);display:flex;height:100vh}
+  #side{width:330px;min-width:330px;background:var(--panel);border-right:1px solid var(--line);padding:14px;overflow:auto}
+  #main{flex:1;display:flex;flex-direction:column;min-width:0}
+  h1{font-size:13px;text-transform:uppercase;letter-spacing:.08em;color:var(--muted);margin:0 0 12px}
+  label{display:block;font-size:11px;text-transform:uppercase;letter-spacing:.05em;color:var(--muted);margin:10px 0 4px}
+  input,textarea,select{width:100%;background:#0c0e13;color:var(--ink);border:1px solid var(--line);border-radius:6px;padding:7px 8px;font:inherit}
+  textarea{resize:vertical}
+  #sys{min-height:130px;font-family:ui-monospace,monospace;font-size:12px}
+  .row{display:flex;gap:8px}.row>*{flex:1}
+  #log{flex:1;overflow:auto;padding:18px;display:flex;flex-direction:column;gap:14px}
+  .msg{max-width:840px}
+  .msg .who{font-size:11px;text-transform:uppercase;letter-spacing:.05em;color:var(--muted);margin-bottom:3px}
+  .msg .body{white-space:pre-wrap;word-wrap:break-word}
+  .msg.user .body{background:var(--user);border:1px solid #1f6feb55;border-radius:8px;padding:8px 10px}
+  .msg .reason{white-space:pre-wrap;color:var(--muted);font-size:12.5px;border-left:2px solid var(--line);padding-left:10px;margin-bottom:6px}
+  #composer{border-top:1px solid var(--line);padding:12px 18px;display:flex;gap:10px;background:var(--panel)}
+  #inp{flex:1;min-height:42px;max-height:220px}
+  button{background:var(--acc);color:#fff;border:0;border-radius:6px;padding:0 16px;font:inherit;font-weight:600;cursor:pointer}
+  button.ghost{background:transparent;color:var(--muted);border:1px solid var(--line)}
+  button:disabled{opacity:.5;cursor:default}
+  .err{color:var(--warn);font-family:ui-monospace,monospace;font-size:12px;white-space:pre-wrap}
+  .hint{font-size:11px;color:var(--muted);margin-top:8px}
+  code{font-family:ui-monospace,monospace}
+</style>
+</head>
+<body>
+  <aside id="side">
+    <h1>Gateway Chat</h1>
+    <label>Base URL</label>
+    <input id="base" placeholder="http://10.250.50.70:4000/v1">
+    <label>API key</label>
+    <input id="key" type="password" placeholder="sk-…">
+    <label>Model</label>
+    <input id="model" list="models" placeholder="mistral-small-4">
+    <datalist id="models">
+      <option>granite-4.1-8b</option>
+      <option>mistral-small-4</option>
+      <option>mistral-small-4-reasoning</option>
+      <option>qwen3.6-35b-a3b</option>
+      <option>qwen3.6-35b-a3b-thinking</option>
+      <option>selene-1-mini-8b</option>
+      <option>glm-5.1</option>
+      <option>glm-4.7</option>
+    </datalist>
+    <label>System prompt</label>
+    <textarea id="sys" placeholder="You are a helpful assistant."></textarea>
+    <div class="row">
+      <div><label>Temperature</label><input id="temp" type="number" step="0.05" value="1"></div>
+      <div><label>Max tokens</label><input id="max" type="number" step="1" value="1024"></div>
+    </div>
+    <div class="hint">Settings persist locally. No <code>tools</code> field is ever sent. Reasoning models show their <code>reasoning_content</code> above the answer.</div>
+  </aside>
+  <main id="main">
+    <div id="log"></div>
+    <div id="composer">
+      <textarea id="inp" placeholder="Message…  (Enter to send · Shift+Enter for newline)"></textarea>
+      <button id="send">Send</button>
+      <button id="reset" class="ghost" title="Clear conversation">Reset</button>
+    </div>
+  </main>
+<script>
+const $ = id => document.getElementById(id);
+const cfg = ['base','key','model','sys','temp','max'];
+cfg.forEach(k => { const v = localStorage.getItem('gc_'+k); if (v !== null) $(k).value = v; });
+if (!$('base').value) $('base').value = 'http://10.250.50.70:4000/v1';
+cfg.forEach(k => $(k).addEventListener('input', e => localStorage.setItem('gc_'+k, e.target.value)));
+
+let history = [];            // [{role:'user'|'assistant', content}]
+const log = $('log');
+
+function addMsg(who, cls){
+  const wrap = document.createElement('div'); wrap.className = 'msg ' + cls;
+  const h = document.createElement('div'); h.className = 'who'; h.textContent = who;
+  const r = document.createElement('div'); r.className = 'reason'; r.style.display = 'none';
+  const b = document.createElement('div'); b.className = 'body';
+  wrap.append(h, r, b); log.append(wrap); log.scrollTop = log.scrollHeight;
+  return { wrap, reason:r, body:b };
+}
+function showErr(text){ const m = addMsg('error','err'); m.body.className = 'err'; m.body.textContent = text; }
+
+async function send(){
+  const text = $('inp').value.trim(); if (!text) return;
+  $('inp').value = '';
+  history.push({ role:'user', content:text });
+  addMsg('you','user').body.textContent = text;
+
+  const messages = [];
+  const sys = $('sys').value.trim();
+  if (sys) messages.push({ role:'system', content:sys });
+  messages.push(...history);
+
+  const body = {
+    model: $('model').value.trim() || 'mistral-small-4',
+    messages,
+    temperature: parseFloat($('temp').value),
+    max_tokens: parseInt($('max').value, 10),
+    stream: true
+    // intentionally NO `tools` — vLLM 400s on an empty array.
+  };
+
+  const out = addMsg(body.model, 'assistant');
+  let content = '', reasoning = '';
+  $('send').disabled = true;
+  try {
+    const res = await fetch($('base').value.replace(/\/+$/,'') + '/chat/completions', {
+      method:'POST',
+      headers:{ 'Content-Type':'application/json', 'Authorization':'Bearer ' + $('key').value },
+      body: JSON.stringify(body)
+    });
+    if (!res.ok){ showErr('HTTP ' + res.status + '\n' + await res.text()); out.wrap.remove(); return; }
+    const reader = res.body.getReader(); const dec = new TextDecoder(); let buf = '';
+    for(;;){
+      const { done, value } = await reader.read(); if (done) break;
+      buf += dec.decode(value, { stream:true });
+      const lines = buf.split('\n'); buf = lines.pop();
+      for (const line of lines){
+        const t = line.trim(); if (!t.startsWith('data:')) continue;
+        const payload = t.slice(5).trim(); if (payload === '[DONE]') continue;
+        let j; try { j = JSON.parse(payload); } catch { continue; }
+        const d = (j.choices && j.choices[0] && j.choices[0].delta) || {};
+        if (d.reasoning_content){ reasoning += d.reasoning_content; out.reason.style.display = 'block'; out.reason.textContent = reasoning; }
+        if (d.content){ content += d.content; out.body.textContent = content; }
+        log.scrollTop = log.scrollHeight;
+      }
+    }
+    history.push({ role:'assistant', content });
+  } catch (e){
+    showErr(String(e)); out.wrap.remove();
+  } finally {
+    $('send').disabled = false;
+  }
+}
+
+$('send').addEventListener('click', send);
+$('inp').addEventListener('keydown', e => { if (e.key === 'Enter' && !e.shiftKey){ e.preventDefault(); send(); } });
+$('reset').addEventListener('click', () => { history = []; log.innerHTML = ''; });
+</script>
+</body>
+</html>
