diff --git a/.changeset/condition-builder-cel-editor.md b/.changeset/condition-builder-cel-editor.md
new file mode 100644
index 000000000..2da59e5f5
--- /dev/null
+++ b/.changeset/condition-builder-cel-editor.md
@@ -0,0 +1,23 @@
+---
+"@object-ui/app-shell": minor
+---
+
+Studio: CEL lint + field autocomplete for condition predicates (#1582).
+
+`ConditionBuilder`'s raw-expression escape hatch — a bare `<textarea>` — is
+replaced by `CelPredicateField`, so every surface that authors a condition
+through it gains inline syntax/semantic validation and field-name autocomplete
+on the canonical `@objectstack/formula` engine:
+
+- field-level `visibleWhen` / `readonlyWhen` / `requiredWhen` (SchemaForm's
+  `condition` widget auto-maps `/When$/` properties),
+- action `visible` / `disabled` (ActionDefaultInspector),
+- every other `condition`-widget property (`visibleOn`, `predicate`, …).
+
+The no-code [subject][op][value] builder path is unchanged; only the "Expression"
+mode is upgraded. An invalid predicate now surfaces a readable inline error
+instead of failing silently at runtime. English + Chinese labels.
+
+This completes the objectui side of #1582 — the CEL assists it asked for now
+cover the field `*When` inputs (and, since the previous change, view
+`conditionalFormatting` conditions).
diff --git a/packages/app-shell/src/views/metadata-admin/i18n.ts b/packages/app-shell/src/views/metadata-admin/i18n.ts
index 4b6b605ef..7561b2f7b 100644
--- a/packages/app-shell/src/views/metadata-admin/i18n.ts
+++ b/packages/app-shell/src/views/metadata-admin/i18n.ts
@@ -445,6 +445,9 @@ const ENGINE_STRINGS_EN: Record<string, string> = {
   'engine.inspector.view.cf.remove': 'Remove rule',
   'engine.inspector.view.cf.moveUp': 'Move up',
   'engine.inspector.view.cf.moveDown': 'Move down',
+  // ConditionBuilder raw-expression mode (CEL editor, #1582)
+  'engine.condition.celLabel': 'CEL expression',
+  'engine.condition.advancedHint': 'Advanced expression — Builder only supports simple AND/OR conditions.',
   'engine.inspector.view.type.grid': 'Table / List',
   'engine.inspector.view.type.kanban': 'Kanban',
   'engine.inspector.view.type.calendar': 'Calendar',
@@ -1768,6 +1771,9 @@ const ENGINE_STRINGS_ZH: Record<string, string> = {
   'engine.inspector.view.cf.remove': '删除规则',
   'engine.inspector.view.cf.moveUp': '上移',
   'engine.inspector.view.cf.moveDown': '下移',
+  // ConditionBuilder 裸表达式模式（CEL 编辑器，#1582）
+  'engine.condition.celLabel': 'CEL 表达式',
+  'engine.condition.advancedHint': '高级表达式 —— 搭建器仅支持简单的 AND/OR 条件。',
   'engine.inspector.view.type.grid': '表格 / 列表',
   'engine.inspector.view.type.kanban': '看板',
   'engine.inspector.view.type.calendar': '日历',
diff --git a/packages/app-shell/src/views/metadata-admin/inspectors/ConditionBuilder.test.tsx b/packages/app-shell/src/views/metadata-admin/inspectors/ConditionBuilder.test.tsx
new file mode 100644
index 000000000..431dc4709
--- /dev/null
+++ b/packages/app-shell/src/views/metadata-admin/inspectors/ConditionBuilder.test.tsx
@@ -0,0 +1,102 @@
+// Copyright (c) 2025 ObjectStack. Licensed under the Apache-2.0 license.
+
+/**
+ * ConditionBuilder raw-expression mode = CEL editor (#1582).
+ *
+ * The bare <textarea> escape hatch is replaced by CelPredicateField, so the
+ * surfaces that route conditions through this builder — field-level
+ * `visibleWhen`/`readonlyWhen`/`requiredWhen` (via SchemaForm's condition
+ * widget) and action `visible`/`disabled` (ActionDefaultInspector) — get
+ * inline lint + field autocomplete on the canonical engine.
+ */
+
+import * as React from 'react';
+import { describe, it, expect, afterEach } from 'vitest';
+import { render, screen, cleanup, fireEvent, waitFor } from '@testing-library/react';
+import userEvent from '@testing-library/user-event';
+import { ConditionBuilder } from './ConditionBuilder';
+import { __setCelFormulaLoader } from '../celAuthoring';
+
+afterEach(() => {
+  cleanup();
+  __setCelFormulaLoader(undefined);
+});
+
+const FIELDS = [
+  { name: 'status', label: 'Status' },
+  { name: 'amount', label: 'Amount' },
+];
+
+/** Controlled harness: `record.status in [...]` can't round-trip through the
+ * no-code builder, so the component opens in RAW mode. */
+function Harness({ initial }: { initial: string }) {
+  const [v, setV] = React.useState(initial);
+  return (
+    <div>
+      <ConditionBuilder label="Visible when" value={v} onCommit={setV} objectName="invoice" fields={FIELDS} />
+      <pre data-testid="committed">{v}</pre>
+    </div>
+  );
+}
+
+const RAW_INIT = "record.status in ['sent', 'paid']";
+
+describe('ConditionBuilder raw mode — CEL editor (#1582)', () => {
+  it('renders the CEL editor (not a bare textarea) and commits edits', () => {
+    render(<Harness initial={RAW_INIT} />);
+    // CelPredicateField's textarea is a combobox (autocomplete host).
+    const ta = screen.getByRole('combobox') as HTMLTextAreaElement;
+    expect(ta.value).toBe(RAW_INIT);
+
+    fireEvent.change(ta, { target: { value: "record.amount > 100" } });
+    expect(screen.getByTestId('committed').textContent).toBe('record.amount > 100');
+  });
+
+  it('surfaces a lint error inline for an invalid predicate', async () => {
+    __setCelFormulaLoader(() =>
+      Promise.resolve({
+        validateExpression: () => ({
+          ok: false,
+          errors: [{ message: 'Unknown variable: statuss' }],
+          warnings: [],
+        }),
+      }),
+    );
+    // `in [...]` can't round-trip the no-code builder → opens in raw mode.
+    render(<Harness initial={"statuss in ['open']"} />);
+    await waitFor(
+      () => expect(screen.getByText(/Unknown variable: statuss/i)).toBeInTheDocument(),
+      { timeout: 3000 },
+    );
+  });
+
+  it("autocompletes the object's field names as you type", async () => {
+    __setCelFormulaLoader(() =>
+      Promise.resolve({
+        validateExpression: () => ({ ok: true, errors: [], warnings: [] }),
+        introspectScope: () => ({
+          fields: ['status', 'amount'],
+          roots: ['record', 'current_user'],
+          functions: ['has'],
+        }),
+      }),
+    );
+    const user = userEvent.setup();
+    render(<Harness initial={RAW_INIT} />);
+    const ta = screen.getByRole('combobox') as HTMLTextAreaElement;
+    await user.clear(ta);
+    await user.type(ta, 'sta');
+    const option = await screen.findByRole('option', { name: /status/i }, { timeout: 3000 });
+    expect(option).toBeTruthy();
+  });
+
+  it('keeps the no-code builder path for simple conditions (unchanged)', () => {
+    const { container } = render(<Harness initial={"record.status == 'open'"} />);
+    // Round-trippable → builder mode: no CEL textarea, the compiled CEL chip is
+    // shown instead. (Builder-mode Selects are also role=combobox, so assert on
+    // the textarea element specifically.)
+    expect(container.querySelector('textarea')).toBeNull();
+    // Compiled-CEL chip + the harness <pre> both echo the value.
+    expect(screen.getAllByText("record.status == 'open'").length).toBeGreaterThanOrEqual(1);
+  });
+});
diff --git a/packages/app-shell/src/views/metadata-admin/inspectors/ConditionBuilder.tsx b/packages/app-shell/src/views/metadata-admin/inspectors/ConditionBuilder.tsx
index e989d535a..724a01e96 100644
--- a/packages/app-shell/src/views/metadata-admin/inspectors/ConditionBuilder.tsx
+++ b/packages/app-shell/src/views/metadata-admin/inspectors/ConditionBuilder.tsx
@@ -22,6 +22,8 @@ import {
 } from '@object-ui/components';
 import { Plus, X, Code2, ListFilter } from 'lucide-react';
 import { useObjectFields } from '../previews/useObjectFields';
+import { CelPredicateField } from '../CelPredicateField';
+import { t, useMetadataLocale } from '../i18n';
 
 type Op = '==' | '!=' | '>' | '<' | '>=' | '<=' | 'truthy' | 'falsy';
 
@@ -125,6 +127,14 @@ export function ConditionBuilder({ label, value, onCommit, objectName, fields: f
       .map((f) => ({ value: `record.${f.name}`, label: `record.${f.name}` }));
     return [...fieldOpts, ...CONTEXT_SUBJECTS];
   }, [fields]);
+  // The raw-expression editor's CEL assists (#1582): field-existence lint +
+  // autocomplete need the bare field-name catalog and a locale-bound `t`.
+  const locale = useMetadataLocale();
+  const tLocal = React.useCallback((k: string) => t(k, locale), [locale]);
+  const fieldNames = React.useMemo(
+    () => fields.filter((f) => !f.hidden).map((f) => f.name),
+    [fields],
+  );
 
   const init = React.useMemo(() => initFrom(value), []); // first mount only
   const [rows, setRowsState] = React.useState<Row[]>(init.rows);
@@ -168,17 +178,21 @@ export function ConditionBuilder({ label, value, onCommit, objectName, fields: f
             <ListFilter className="h-3 w-3" /> Builder
           </button>
         </div>
-        <textarea
+        {/* CEL editor with inline lint + field autocomplete (#1582) — the same
+            author-time assists the RLS policy editor gets, on the canonical
+            @objectstack/formula engine. Replaces the bare <textarea>. */}
+        <CelPredicateField
+          label={tLocal('engine.condition.celLabel')}
           value={value}
-          onChange={(e) => { lastEmitted.current = e.target.value; onCommit(e.target.value); }}
+          onChange={(v) => { lastEmitted.current = v; onCommit(v); }}
           disabled={disabled}
-          spellCheck={false}
-          rows={2}
-          placeholder="CEL expression, e.g. record.status != 'done' && user.isAdmin"
-          className="w-full rounded border border-input bg-background px-2 py-1.5 text-xs font-mono outline-none focus:ring-1 focus:ring-primary resize-y disabled:opacity-60"
+          placeholder="record.status != 'done' && user.isAdmin"
+          objectName={objectName}
+          fieldNames={fieldNames}
+          t={tLocal}
         />
         {value && !parse(value) && (
-          <div className="text-[10px] text-muted-foreground/70">Advanced expression — Builder only supports simple AND/OR conditions.</div>
+          <div className="text-[10px] text-muted-foreground/70">{tLocal('engine.condition.advancedHint')}</div>
         )}
       </div>
     );