diff --git a/routes/codex_routes.py b/routes/codex_routes.py
index e11965c35..52ff2949a 100644
--- a/routes/codex_routes.py
+++ b/routes/codex_routes.py
@@ -46,8 +46,12 @@ def _ssh_prefix_for_task(task: dict) -> tuple[str, str]:
     shell metacharacters in ``remoteHost`` is rejected with 400 rather than
     injected.
     """
-    host = validate_remote_host((task.get("remoteHost") or "").strip() or None) or ""
-    ssh_port = validate_ssh_port((task.get("sshPort") or "").strip() or None) or ""
+    raw_host = task.get("remoteHost")
+    raw_port = task.get("sshPort")
+    host_value = str(raw_host).strip() if raw_host is not None else None
+    port_value = str(raw_port).strip() if raw_port is not None else None
+    host = validate_remote_host(host_value or None) or ""
+    ssh_port = validate_ssh_port(port_value or None) or ""
     port_flag = f"-p {ssh_port} " if ssh_port and ssh_port != "22" else ""
     return host, port_flag
 
diff --git a/routes/cookbook_routes.py b/routes/cookbook_routes.py
index af25dd8e8..ea15a22c3 100644
--- a/routes/cookbook_routes.py
+++ b/routes/cookbook_routes.py
@@ -1284,6 +1284,11 @@ def setup_cookbook_routes() -> APIRouter:
         # LOCAL execution on a native-Windows host never uses tmux (detached
         # process path below), regardless of the UI-supplied platform.
         local_windows = IS_WINDOWS and not remote
+        if is_windows and remote and "diffusion_server.py" in req.cmd:
+            raise HTTPException(
+                400,
+                "Remote Windows Diffusers serving is not supported yet; use local Windows or a Linux remote server.",
+            )
 
         if not is_windows and not local_windows and not await _binary_available("tmux", remote, req.ssh_port):
             return {
diff --git a/static/js/cookbookServe.js b/static/js/cookbookServe.js
index f3b5842b2..33d56ef3c 100644
--- a/static/js/cookbookServe.js
+++ b/static/js/cookbookServe.js
@@ -116,13 +116,28 @@ function _selectedServeTarget(panel) {
     : (server?.name || 'local server');
   return {
     host,
-    port: host ? (_getPort(host) || server?.port || '') : '',
+    port: host ? (server?.port || _getPort(host) || '') : '',
+    env: server?.env || '',
     venv,
     platform: server?.platform || _envState.platform || '',
     label,
   };
 }
 
+function _remoteWindowsDiffusersUnsupported(target) {
+  return !!(target?.host && target?.platform === 'windows');
+}
+
+function _backendChoicesForTarget(target) {
+  if (target?.platform === 'windows') {
+    if (_remoteWindowsDiffusersUnsupported(target)) return [['llamacpp','llama.cpp']];
+    return [['llamacpp','llama.cpp'],['diffusers','Diffusers']];
+  }
+  return _isMetal()
+    ? [['llamacpp','llama.cpp'],['ollama','Ollama']]
+    : [['vllm','vLLM'],['sglang','SGLang'],['llamacpp','llama.cpp'],['ollama','Ollama'],['diffusers','Diffusers']];
+}
+
 async function _fetchServeRuntimePackage(panel, backend) {
   const packageByBackend = {
     vllm: 'vllm',
@@ -529,13 +544,14 @@ function _rerenderCachedModels() {
       const ss = (_byRepo[repo] && typeof _byRepo[repo] === 'object')
         ? _byRepo[repo]
         : (_lastUsed || (_isLegacyFlat ? _allSs : {}));
+      const _serveTarget = _selectedServeTarget();
+      const _backendChoices = _backendChoicesForTarget(_serveTarget);
+      const _allowedBackends = new Set(_backendChoices.map(([v]) => v));
       const detectedBackend = _detectBackend(m).backend;
-      const _allowedBackends = new Set(_isWindows()
-        ? ['llamacpp', 'diffusers']
-        : (_isMetal() ? ['llamacpp', 'ollama'] : ['vllm', 'sglang', 'llamacpp', 'ollama', 'diffusers']));
-      const defaultBackend = (ss._forceBackend && ss.backend && _allowedBackends.has(ss.backend))
+      let defaultBackend = (ss._forceBackend && ss.backend && _allowedBackends.has(ss.backend))
         ? ss.backend
         : detectedBackend;
+      if (!_allowedBackends.has(defaultBackend)) defaultBackend = _backendChoices[0]?.[0] || detectedBackend;
       const savedMatchesBackend = !!ss._forceBackend || (ss.backend || 'vllm') === detectedBackend;
       const sv = (k, def) => (ss[k] !== undefined && savedMatchesBackend) ? ss[k] : def;
       const defaultTp = defaultBackend === 'llamacpp' ? '1' : sv('tp', '1');
@@ -607,12 +623,6 @@ function _rerenderCachedModels() {
       }
       // Row 1: Backend + Server + Env
       panelHtml += `<div class="hwfit-serve-row">`;
-      const _backendChoices = _isWindows()
-        ? [['llamacpp','llama.cpp'],['diffusers','Diffusers']]
-        : _isMetal()
-        // Diffusers (diffusion_server.py) is CUDA-only — omit it on Metal.
-        ? [['llamacpp','llama.cpp'],['ollama','Ollama']]
-        : [['vllm','vLLM'],['sglang','SGLang'],['llamacpp','llama.cpp'],['ollama','Ollama'],['diffusers','Diffusers']];
       const backendOpts = _backendChoices.map(([v,l]) => `<option value="${v}"${defaultBackend===v?' selected':''}>${l}</option>`).join('');
       // Custom Backend picker — native <select> can't host SVG inside
       // options, so we render a button + menu that show the backend logo
@@ -1971,6 +1981,12 @@ function _rerenderCachedModels() {
           else serveState[el.dataset.field] = el.value;
         });
         serveState.backend = serveState.backend || (_detectBackend(m).backend) || 'vllm';
+        const launchTarget = _selectedServeTarget(panel);
+        if (serveState.backend === 'diffusers' && _remoteWindowsDiffusersUnsupported(launchTarget)) {
+          _restoreLaunchBtn();
+          uiModule.showToast('Diffusers serving is not supported on remote Windows servers yet. Use local Windows or a Linux server.', 9000);
+          return;
+        }
 
         // Pre-launch: check our own task list for a serve already running
         // on this host. Offer to stop+launch as the default action — the
@@ -1979,7 +1995,7 @@ function _rerenderCachedModels() {
         // common case instantly without waiting for a network round-trip.
         try {
           const _runningMod = await import('./cookbookRunning.js');
-          const _hostStr = _envState.remoteHost || '';
+          const _hostStr = launchTarget.host || '';
           const _active = (_runningMod._loadTasks ? _runningMod._loadTasks() : []).filter(t =>
             t && t.type === 'serve'
             && (t.remoteHost || '') === _hostStr
@@ -2033,12 +2049,11 @@ function _rerenderCachedModels() {
           || (serveState.backend === 'diffusers');
         if (_needsGpu) {
           try {
-            const _probeHost = (_envState.remoteHost || '').trim();
+            const _probeHost = (launchTarget.host || '').trim();
             const _probeParams = new URLSearchParams();
             if (_probeHost) {
               _probeParams.set('host', _probeHost);
-              const _sp = (_serverByVal?.(_envState.remoteServerKey || _probeHost) || {}).port;
-              if (_sp) _probeParams.set('ssh_port', _sp);
+              if (launchTarget.port) _probeParams.set('ssh_port', launchTarget.port);
             }
             const _probeRes = await fetch('/api/cookbook/gpus' + (_probeParams.toString() ? '?' + _probeParams : ''), { credentials: 'same-origin' });
             const _probeData = await _probeRes.json();
@@ -2071,10 +2086,10 @@ function _rerenderCachedModels() {
             || launchCmd.match(/OLLAMA_HOST=[^:\s]+:(\d{2,5})\b/);
           const _port = _portMatch ? _portMatch[1] : '';
           if (_port) {
-            const _portHost = (_envState.remoteHost || '').trim();
+            const _portHost = (launchTarget.host || '').trim();
             const _checkInner = `ss -tlnp 2>/dev/null | awk '$4 ~ /:${_port}$/ {print; exit}' || netstat -tlnp 2>/dev/null | awk '$4 ~ /:${_port}$/ {print; exit}'`;
             const _cmd = _portHost
-              ? `ss h ${_portHost} <<<"" 2>/dev/null; ssh -o ConnectTimeout=4 -o StrictHostKeyChecking=no ${_portHost} ${JSON.stringify(_checkInner)}`
+              ? `ssh -o ConnectTimeout=4 -o StrictHostKeyChecking=no ${_sshPrefix(launchTarget.port)}${_portHost} ${JSON.stringify(_checkInner)}`
               : _checkInner;
             const _res = await fetch('/api/shell/exec', {
               method: 'POST', credentials: 'same-origin',
@@ -2131,20 +2146,8 @@ function _rerenderCachedModels() {
         // Resolve the target host from the visible Server dropdown — the reliable
         // source. Relying on _envState.remoteHost silently sent serves to Local
         // when that value was stale/empty. Pass it explicitly to the launcher.
-        let serveHost = _envState.remoteHost || '';
-        let _srvEnv = '', _srvEnvPath = '';
-        const _ssEl = document.getElementById('hwfit-server-select') || document.getElementById('hwfit-dl-server');
-        if (_ssEl && _ssEl.value != null) {
-          if (_ssEl.value === 'local') serveHost = '';
-          else {
-            const _srv = _serverByVal?.(_ssEl.value) || _envState.servers[parseInt(_ssEl.value)];
-            if (_srv) {
-              serveHost = _srv.host;
-              _srvEnv = _srv.env || '';
-              _srvEnvPath = _srv.envPath || '';
-            }
-          }
-        }
+        let serveHost = launchTarget.host || '';
+        let _srvEnv = launchTarget.env || '', _srvEnvPath = launchTarget.venv || '';
         // The venv field wins; otherwise fall back to the env configured for the
         // selected server in Settings, so the activation isn't silently dropped
         // when the field is left blank (the per-server venv wasn't being applied).
diff --git a/tests/test_codex_ssh_host_validation.py b/tests/test_codex_ssh_host_validation.py
index f376e71e5..6e05c2146 100644
--- a/tests/test_codex_ssh_host_validation.py
+++ b/tests/test_codex_ssh_host_validation.py
@@ -68,6 +68,14 @@ def test_valid_remote_builds_port_flag():
     assert port_flag == "-p 2222 "
 
 
+def test_integer_ssh_port_in_stored_task_normalizes_without_crashing():
+    host, port_flag = codex_routes._ssh_prefix_for_task(
+        {"remoteHost": "user@box", "sshPort": 2222}
+    )
+    assert host == "user@box"
+    assert port_flag == "-p 2222 "
+
+
 def test_default_ssh_port_omits_flag():
     host, port_flag = codex_routes._ssh_prefix_for_task(
         {"remoteHost": "box", "sshPort": "22"}
diff --git a/tests/test_cookbook_cpu_only_serve.py b/tests/test_cookbook_cpu_only_serve.py
index b46c3e080..d7039404c 100644
--- a/tests/test_cookbook_cpu_only_serve.py
+++ b/tests/test_cookbook_cpu_only_serve.py
@@ -38,11 +38,14 @@ def test_diffusers_is_not_blocked_on_windows_dependencies_panel():
     assert "new Set(['diffusers'" not in text
 
 
-def test_diffusers_is_available_on_windows_serve_panel():
+def test_diffusers_is_available_only_on_local_windows_serve_panel():
     text = SERVE_SRC.read_text(encoding="utf-8")
 
-    assert "? ['llamacpp', 'diffusers']" in text
-    assert "? [['llamacpp','llama.cpp'],['diffusers','Diffusers']]" in text
+    assert "function _remoteWindowsDiffusersUnsupported(target)" in text
+    assert "return !!(target?.host && target?.platform === 'windows');" in text
+    assert "if (_remoteWindowsDiffusersUnsupported(target)) return [['llamacpp','llama.cpp']];" in text
+    assert "return [['llamacpp','llama.cpp'],['diffusers','Diffusers']];" in text
+    assert "Diffusers serving is not supported on remote Windows servers yet." in text
 
 
 def test_windows_diffusers_uses_python_not_python3():
diff --git a/tests/test_cookbook_remote_windows_diffusers.py b/tests/test_cookbook_remote_windows_diffusers.py
new file mode 100644
index 000000000..b4236e076
--- /dev/null
+++ b/tests/test_cookbook_remote_windows_diffusers.py
@@ -0,0 +1,57 @@
+import asyncio
+
+import pytest
+from fastapi import HTTPException
+from starlette.requests import Request
+
+import routes.cookbook_routes as cookbook_routes
+from routes.cookbook_helpers import ServeRequest
+
+
+def _route_endpoint(path: str, method: str):
+    router = cookbook_routes.setup_cookbook_routes()
+    for route in router.routes:
+        if route.path == path and method in route.methods:
+            return route.endpoint
+    raise AssertionError(f"{method} {path} route not found")
+
+
+def _admin_request() -> Request:
+    request = Request(
+        {
+            "type": "http",
+            "method": "POST",
+            "path": "/api/model/serve",
+            "headers": [],
+            "state": {},
+        }
+    )
+    request.state.current_user = "admin"
+    return request
+
+
+@pytest.mark.asyncio
+async def test_remote_windows_diffusers_is_rejected_before_runner_launch(monkeypatch):
+    monkeypatch.setattr(cookbook_routes, "require_admin", lambda request: None)
+    calls = []
+
+    async def fail_if_shell_runs(*args, **kwargs):
+        calls.append((args, kwargs))
+        raise AssertionError("remote Windows Diffusers should fail before shell launch")
+
+    monkeypatch.setattr(asyncio, "create_subprocess_shell", fail_if_shell_runs)
+
+    endpoint = _route_endpoint("/api/model/serve", "POST")
+    req = ServeRequest(
+        repo_id="diffusers/example",
+        cmd="python scripts/diffusion_server.py --model diffusers/example --port 8100",
+        remote_host="winbox",
+        platform="windows",
+    )
+
+    with pytest.raises(HTTPException) as exc:
+        await endpoint(_admin_request(), req)
+
+    assert exc.value.status_code == 400
+    assert "Remote Windows Diffusers" in str(exc.value.detail)
+    assert calls == []
diff --git a/tests/test_cookbook_same_host_server_profiles_js.py b/tests/test_cookbook_same_host_server_profiles_js.py
index de9649fd6..13f7d2db4 100644
--- a/tests/test_cookbook_same_host_server_profiles_js.py
+++ b/tests/test_cookbook_same_host_server_profiles_js.py
@@ -36,10 +36,22 @@ def test_cookbook_submodules_resolve_visible_profile_selection():
     assert "_serverByVal(_envState.remoteServerKey || remoteHost)" in HWFIT
     assert "hk: _currentServerValue()" in HWFIT
     assert "sel.value = _currentServerValue();" in HWFIT
-    assert "_serverByVal?.(_ssEl.value)" in SERVE
+    assert "_serverByVal?.(select.value)" in SERVE
     assert "_serverByVal?.(val)" in SERVE
     assert "_serverByVal?.(_es.remoteServerKey || _es.remoteHost || '')" in SERVE
-    assert "_serverByVal?.(_envState.remoteServerKey || _probeHost)" in SERVE
+    assert "port: host ? (server?.port || _getPort(host) || '') : ''" in SERVE
+
+
+def test_serve_launch_preflights_use_selected_target_and_port():
+    launch_target = "const launchTarget = _selectedServeTarget(panel);"
+    assert launch_target in SERVE
+    assert "const _hostStr = launchTarget.host || '';" in SERVE
+    assert "const _probeHost = (launchTarget.host || '').trim();" in SERVE
+    assert "if (launchTarget.port) _probeParams.set('ssh_port', launchTarget.port);" in SERVE
+    assert "const _portHost = (launchTarget.host || '').trim();" in SERVE
+    assert "StrictHostKeyChecking=no ${_sshPrefix(launchTarget.port)}${_portHost}" in SERVE
+    assert "let serveHost = launchTarget.host || '';" in SERVE
+    assert SERVE.index(launch_target) < SERVE.index("const _runningMod = await import('./cookbookRunning.js');")
 
 
 def test_running_tab_resolves_profile_key_not_first_host():