diff --git a/CHANGELOG.md b/CHANGELOG.md
index c75a2334..d3be963b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,11 @@
 # Hermes Web UI -- Changelog
 
+## [Unreleased]
+
+### Fixed
+
+- **bug(cron): clarify one-shot schedule deletion semantics** ([#2031](https://github.com/nesquena/hermes-webui/issues/2031)). The Scheduled Jobs form now makes the Hermes Agent cron contract visible: recurring jobs should use `every 30m` or a cron expression, while bare durations/dates such as `30m`, `2h`, or `2026-05-11T08:00` create one-shot jobs that are removed after they run. Adds a live warning under the Schedule input when the entered value matches the one-shot forms.
+
 ## [v0.51.39] — 2026-05-10 — Release O (4-PR contributor batch — Railway docker fix + Stop-button race + provider resolver + live context tracking)
 
 ### Fixed
diff --git a/static/i18n.js b/static/i18n.js
index a625dcd9..2dec4953 100644
--- a/static/i18n.js
+++ b/static/i18n.js
@@ -1011,7 +1011,8 @@ const LOCALES = {
     cron_name_label: 'Name',
     cron_name_placeholder: 'Optional',
     cron_schedule_label: 'Schedule',
-    cron_schedule_hint: "Cron expression or shorthand like 'every 1h'.",
+    cron_schedule_hint: "Use 'every 1h' or a cron expression for recurring jobs. Bare durations like '30m' run once.",
+    cron_schedule_once_warning: "Duration forms like '30m' run once and are removed after running. Use 'every 30m' to keep a recurring job.",
     cron_prompt_label: 'Prompt',
     cron_deliver_label: 'Deliver output to',
     cron_deliver_local: 'Local (save output only)',
@@ -2095,7 +2096,8 @@ const LOCALES = {
     cron_name_label: '名前',
     cron_name_placeholder: '任意',
     cron_schedule_label: 'スケジュール',
-    cron_schedule_hint: "Cron 式または 'every 1h' のような短縮形。",
+    cron_schedule_hint: "繰り返し実行には 'every 1h' または Cron 式を使います。'30m' のような期間だけの指定は 1 回だけ実行されます。",
+    cron_schedule_once_warning: "'30m' のような期間指定は 1 回だけ実行され、実行後に削除されます。繰り返すには 'every 30m' を使ってください。",
     cron_prompt_label: 'プロンプト',
     cron_deliver_label: '出力先',
     cron_deliver_local: 'ローカル (出力を保存のみ)',
@@ -2985,7 +2987,8 @@ const LOCALES = {
     cron_name_label: 'Имя',
     cron_name_placeholder: 'Необязательно',
     cron_schedule_label: 'Расписание',
-    cron_schedule_hint: "Cron-выражение или сокращение, например 'every 1h'.",
+    cron_schedule_hint: "Для повторяющихся заданий используйте 'every 1h' или cron-выражение. Простые интервалы вроде '30m' выполняются один раз.",
+    cron_schedule_once_warning: "Интервалы вроде '30m' выполняются один раз и удаляются после запуска. Используйте 'every 30m' для повторяющегося задания.",
     cron_prompt_label: 'Запрос',
     cron_deliver_label: 'Доставлять вывод',
     cron_deliver_local: 'Локально (только сохранение)',
@@ -3990,7 +3993,8 @@ const LOCALES = {
     cron_name_label: 'Nombre',
     cron_name_placeholder: 'Opcional',
     cron_schedule_label: 'Programación',
-    cron_schedule_hint: "Expresión cron o abreviatura como 'every 1h'.",
+    cron_schedule_hint: "Usa 'every 1h' o una expresión cron para trabajos recurrentes. Duraciones como '30m' se ejecutan una sola vez.",
+    cron_schedule_once_warning: "Las duraciones como '30m' se ejecutan una vez y se eliminan después de correr. Usa 'every 30m' para mantener un trabajo recurrente.",
     cron_prompt_label: 'Prompt',
     cron_deliver_label: 'Entregar salida a',
     cron_deliver_local: 'Local (solo guardar salida)',
@@ -4741,7 +4745,8 @@ const LOCALES = {
     cron_duplicated: 'Aufgabe dupliziert (pausiert)',
     cron_name_placeholder: 'Optional',
     cron_schedule_label: 'Zeitplan',
-    cron_schedule_hint: "Cron-Ausdruck oder Kurzform wie 'every 1h'.",
+    cron_schedule_hint: "Für wiederkehrende Aufgaben 'every 1h' oder einen Cron-Ausdruck verwenden. Reine Dauern wie '30m' laufen einmal.",
+    cron_schedule_once_warning: "Dauerangaben wie '30m' laufen einmal und werden nach der Ausführung entfernt. Verwende 'every 30m' für eine wiederkehrende Aufgabe.",
     cron_prompt_label: 'Prompt',
     cron_deliver_label: 'Ausgabe senden an',
     cron_deliver_local: 'Lokal (nur speichern)',
@@ -6022,7 +6027,8 @@ const LOCALES = {
     cron_name_label: '名称',
     cron_name_placeholder: '可选',
     cron_schedule_label: '计划',
-    cron_schedule_hint: "Cron 表达式或简写，例如 'every 1h'。",
+    cron_schedule_hint: "循环任务请用 'every 1h' 或 Cron 表达式。像 '30m' 这样的裸时长只会运行一次。",
+    cron_schedule_once_warning: "像 '30m' 这样的时长写法只会运行一次，并在运行后移除。要保留循环任务，请使用 'every 30m'。",
     cron_prompt_label: '提示词',
     cron_deliver_label: '输出位置',
     cron_deliver_local: '本地（仅保存输出）',
@@ -7236,7 +7242,8 @@ const LOCALES = {
     // Cron labels
     cron_name_label: '任務名稱',
     cron_schedule_label: '排程',
-    cron_schedule_hint: '例如: 0 9 * * *, every 2h, 30m',
+    cron_schedule_hint: "循環任務請用 'every 1h' 或 Cron 表達式。像 '30m' 這樣的裸時長只會執行一次。",
+    cron_schedule_once_warning: "像 '30m' 這樣的時長寫法只會執行一次，並在執行後移除。要保留循環任務，請使用 'every 30m'。",
     cron_prompt_label: '提示',
     cron_deliver_label: '發送至',
     cron_deliver_local: '僅本地儲存',
@@ -8142,7 +8149,8 @@ const LOCALES = {
     cron_name_label: 'Nome',
     cron_name_placeholder: 'Opcional',
     cron_schedule_label: 'Agendamento',
-    cron_schedule_hint: "Expressão Cron ou shorthand como 'every 1h'.",
+    cron_schedule_hint: "Use 'every 1h' ou uma expressão Cron para tarefas recorrentes. Durações como '30m' rodam uma vez.",
+    cron_schedule_once_warning: "Durações como '30m' rodam uma vez e são removidas após executar. Use 'every 30m' para manter uma tarefa recorrente.",
     cron_prompt_label: 'Prompt',
     cron_deliver_label: 'Entregar output para',
     cron_deliver_local: 'Local (salvar output apenas)',
@@ -9192,7 +9200,8 @@ const LOCALES = {
     cron_name_label: 'Name',
     cron_name_placeholder: 'Optional',
     cron_schedule_label: 'Schedule',
-    cron_schedule_hint: "Cron expression or shorthand like 'every 1h'.",
+    cron_schedule_hint: "Use 'every 1h' or a cron expression for recurring jobs. Bare durations like '30m' run once.",
+    cron_schedule_once_warning: "Duration forms like '30m' run once and are removed after running. Use 'every 30m' to keep a recurring job.",
     cron_prompt_label: 'Prompt',
     cron_deliver_label: 'Deliver output to',
     cron_deliver_local: 'Local (save output only)',
diff --git a/static/panels.js b/static/panels.js
index 7f73e503..86075f1b 100644
--- a/static/panels.js
+++ b/static/panels.js
@@ -231,6 +231,26 @@ function _isRecurringCronJob(job) {
   return kind === 'cron' || kind === 'interval';
 }
 
+function _cronScheduleKindForInput(value) {
+  const schedule = String(value || '').trim();
+  if (!schedule) return '';
+  const lower = schedule.toLowerCase();
+  if (lower.startsWith('every ')) return 'interval';
+  if (lower.startsWith('@')) return 'cron';
+  const parts = schedule.split(/\s+/);
+  if (parts.length >= 5 && parts.slice(0, 5).every(p => /^[\d*\-,/]+$/.test(p))) return 'cron';
+  if (schedule.includes('T') || /^\d{4}-\d{2}-\d{2}/.test(schedule)) return 'once';
+  if (/^\d+\s*(m|min|mins|minute|minutes|h|hr|hrs|hour|hours|d|day|days)$/i.test(schedule)) return 'once';
+  return '';
+}
+
+function _syncCronScheduleWarning() {
+  const input = $('cronFormSchedule');
+  const warning = $('cronFormScheduleOnceWarning');
+  if (!input || !warning) return;
+  warning.style.display = _cronScheduleKindForInput(input.value) === 'once' ? '' : 'none';
+}
+
 function _hasUnlimitedRepeat(job) {
   return !!(job && job.repeat && job.repeat.times == null);
 }
@@ -722,6 +742,7 @@ function _renderCronForm({ name, schedule, prompt, deliver, profile, no_agent=fa
           <label for="cronFormSchedule">${esc(t('cron_schedule_label') || 'Schedule')}</label>
           <input type="text" id="cronFormSchedule" value="${esc(schedule || '')}" placeholder="0 9 * * *  —  every 1h  —  @daily" autocomplete="off" required>
           <div class="detail-form-hint">${esc(t('cron_schedule_hint') || "Cron expression or shorthand like 'every 1h'.")}</div>
+          <div id="cronFormScheduleOnceWarning" class="detail-form-warning cron-once-warning" style="display:none">${esc(t('cron_schedule_once_warning') || "Duration forms like '30m' run once and are removed after running. Use 'every 30m' to keep a recurring job.")}</div>
         </div>
         <div class="detail-form-row ${isNoAgent ? 'cron-no-agent-prompt-row' : ''}">
           <label for="cronFormPrompt">${esc(t('cron_prompt_label') || 'Prompt')}</label>
@@ -759,6 +780,12 @@ function _renderCronForm({ name, schedule, prompt, deliver, profile, no_agent=fa
   if (empty) empty.style.display = 'none';
   _setCronHeaderButtons(isEdit ? 'edit' : 'create');
   _renderCronSkillTags();
+  const scheduleEl = $('cronFormSchedule');
+  if (scheduleEl) {
+    scheduleEl.addEventListener('input', _syncCronScheduleWarning);
+    scheduleEl.addEventListener('change', _syncCronScheduleWarning);
+    _syncCronScheduleWarning();
+  }
   const focusEl = $('cronFormName');
   if (focusEl) focusEl.focus();
 }
diff --git a/static/style.css b/static/style.css
index 2e438f37..b1ce4985 100644
--- a/static/style.css
+++ b/static/style.css
@@ -3216,6 +3216,8 @@ main.main > .main-view:not([id="mainChat"]):not([id="mainSettings"]) .main-view-
 .detail-form-row input:disabled{opacity:.6;cursor:not-allowed;}
 .detail-form-row textarea{resize:vertical;font-family:'SF Mono',ui-monospace,SFMono-Regular,Menlo,monospace;font-size:12px;}
 .detail-form-row .detail-form-hint{font-size:11px;color:var(--muted);line-height:1.5;}
+.detail-form-warning{font-size:11px;line-height:1.5;border:1px solid rgba(245,158,11,.35);background:rgba(245,158,11,.1);color:rgba(245,158,11,.98);border-radius:8px;padding:8px 10px;}
+.cron-once-warning{margin-top:2px;}
 .detail-form-row label.detail-form-check{display:flex;align-items:center;gap:8px;font-size:13px;color:var(--text);cursor:pointer;font-weight:400;}
 .detail-form-row label.detail-form-check input{accent-color:var(--accent,var(--link));}
 .detail-form-error{font-size:12px;color:var(--error,#e05);padding:8px 10px;border:1px solid color-mix(in srgb,var(--error,#e05) 35%,transparent);background:color-mix(in srgb,var(--error,#e05) 8%,transparent);border-radius:8px;line-height:1.5;}
diff --git a/tests/test_issue2031_cron_once_visibility.py b/tests/test_issue2031_cron_once_visibility.py
new file mode 100644
index 00000000..9bc00aea
--- /dev/null
+++ b/tests/test_issue2031_cron_once_visibility.py
@@ -0,0 +1,82 @@
+"""Regression coverage for #2031 one-shot cron schedule visibility."""
+
+import json
+import shutil
+import subprocess
+from pathlib import Path
+
+import pytest
+
+
+ROOT = Path(__file__).resolve().parent.parent
+PANELS_JS = ROOT / "static" / "panels.js"
+STYLE_CSS = ROOT / "static" / "style.css"
+I18N_JS = ROOT / "static" / "i18n.js"
+NODE = shutil.which("node")
+
+pytestmark = pytest.mark.skipif(NODE is None, reason="node not on PATH")
+
+
+def _cron_schedule_source() -> str:
+    src = PANELS_JS.read_text(encoding="utf-8")
+    start = src.find("function _cronScheduleKindForInput")
+    if start < 0:
+        pytest.fail("_cronScheduleKindForInput is missing")
+    end = src.find("function _hasUnlimitedRepeat", start)
+    if end < 0:
+        pytest.fail("_cronScheduleKindForInput must stay near the cron schedule helpers")
+    return src[start:end]
+
+
+def _run_node(script: str) -> str:
+    proc = subprocess.run(
+        [NODE, "-e", script],
+        check=True,
+        capture_output=True,
+        text=True,
+    )
+    return proc.stdout.strip()
+
+
+def test_cron_schedule_input_classifier_flags_agent_one_shot_forms():
+    script = _cron_schedule_source() + r"""
+const cases = {
+  "30m": _cronScheduleKindForInput("30m"),
+  "2h": _cronScheduleKindForInput("2h"),
+  "1 day": _cronScheduleKindForInput("1 day"),
+  "2026-05-11": _cronScheduleKindForInput("2026-05-11"),
+  "2026-05-11T08:00": _cronScheduleKindForInput("2026-05-11T08:00"),
+  "every 30m": _cronScheduleKindForInput("every 30m"),
+  "Every 2h": _cronScheduleKindForInput("Every 2h"),
+  "0 9 * * *": _cronScheduleKindForInput("0 9 * * *"),
+  "not_a_schedule": _cronScheduleKindForInput("not_a_schedule"),
+};
+console.log(JSON.stringify(cases));
+"""
+    kinds = json.loads(_run_node(script))
+
+    assert kinds["30m"] == "once"
+    assert kinds["2h"] == "once"
+    assert kinds["1 day"] == "once"
+    assert kinds["2026-05-11"] == "once"
+    assert kinds["2026-05-11T08:00"] == "once"
+    assert kinds["every 30m"] == "interval"
+    assert kinds["Every 2h"] == "interval"
+    assert kinds["0 9 * * *"] == "cron"
+    assert kinds["not_a_schedule"] == ""
+
+
+def test_cron_form_surfaces_one_shot_warning_copy_and_styles():
+    panels = PANELS_JS.read_text(encoding="utf-8")
+    style = STYLE_CSS.read_text(encoding="utf-8")
+    i18n = I18N_JS.read_text(encoding="utf-8")
+
+    assert "id=\"cronFormScheduleOnceWarning\"" in panels
+    assert "cron_schedule_once_warning" in panels
+    assert "_syncCronScheduleWarning" in panels
+    assert "addEventListener('input', _syncCronScheduleWarning" in panels
+    assert "addEventListener('change', _syncCronScheduleWarning" in panels
+
+    assert ".cron-once-warning" in style
+    assert i18n.count("cron_schedule_once_warning") >= 9
+    assert "Duration forms like '30m' run once" in i18n