@@ -0,0 +1,19 @@
+---
+'@objectstack/objectql': patch
+---
+
+fix(objectql)!: the in-process engine refuses a projection whose every column is unknown, as it refuses an empty one (#27165)
+
+Clause-②: no (narrowing) — `ObjectQL.find` / `findOne` refuse a `fields` list naming only columns the object does not have, which they read before as every column. Nothing is widened.
+Metadata-protocol: none
+
+<!-- adr-0087: not-required (no-migration-prescription) No key of any schema is added, removed, renamed or re-shaped, and no export or type changes: the engine already refused an empty projection, and a projection that its unknown-column tolerance empties is now judged the same way. There is nothing for a migration to rewrite and no tombstone. -->
+
+**BREAKING** accept-set narrowing at the in-process read entry (`@objectstack/objectql`).
+
+- **Before.** `find` / `findOne` drop a requested plain column the object does not have. When that left nothing, they fell back to every column: `engine.find(object, { fields: ['nope'] })` answered every column, owner, organization and audit columns included, and the caller was not told. The REST door refuses the same request.
+- **Now.** That case is an empty projection and gets the empty projection's refusal, before any driver read: `status: 400`, `code: 'VALIDATION_ERROR'`, the declaration's words (`Name at least one field`), and the message names the columns that were asked for.
+- **Unchanged.** A mix of known and unknown columns still projects the known ones and drops the rest. An absent or `null` `fields` still reads every column. A host whose object has no registered field map is not judged.
+- **Who sees it.** A plugin, hook, flow or other in-process caller whose projection names only columns the object lacks, for example a typo or a column from another object. No in-repo caller does.
+
+**The remedy.** Name at least one column the object has, or leave `fields` out to read every column.
@@ -322,6 +322,10 @@ This object form of a field node isn't wired up for top-level `fields` projectio
 object's schema is registered, the engine's unknown-field filter compares each entry against
 the schema's field names via `String(f)`, so an object entry never matches and is silently
 dropped from the projection — the aliased field is simply missing from results, no error.
+That holds only while some other entry is known: when **every** top-level `fields` entry is
+unknown (object-form entries included), `engine.find()` / `findOne()` refuse the read with
+`400 VALIDATION_ERROR` naming the requested columns, instead of reading every column. A mix of
+known and unknown entries still drops the unknown ones and projects the rest.
 
 Dotted relationship paths (`'owner.name'`) fare no better: the unknown-field filter validates
 only the **head** segment and keeps the path, but there is no populate step anywhere in the
 
@@ -36,6 +36,16 @@
  * the bare foreign key when a sub-read throws, so the refusal would reach the
  * caller as a silently unexpanded field. Judged here, before the parent read,
  * it reaches the caller as a refusal.
+ *
+ * ## A projection emptied by the unknown-column tolerance
+ *
+ * [#27165] `find` / `findOne` drop a requested plain column the object does not
+ * have (the #7589 tolerance). When that leaves nothing, the projection is
+ * empty, and it gets this same refusal, naming what was asked for. Before, the
+ * engine fell back to every column there, so `fields: ['nope']` answered wider
+ * than any named projection. A mix of known and unknown columns keeps the
+ * tolerance. An `expand` entry needs no judgement of its own here: its
+ * sub-read always names `id`, which is never dropped.
  */
 
 import { EngineQueryOptionsSchema } from '@objectstack/spec/data';
@@ -48,9 +58,17 @@ function projectionNamesNoField(): string | undefined {
   return declaredRefusal;
 }
 
-function refuseEmptyProjection(object: string, operation: 'find' | 'findOne', param: string): never {
+function refuseEmptyProjection(
+  object: string,
+  operation: 'find' | 'findOne',
+  param: string,
+  requested: readonly unknown[] = [],
+): never {
+  const dropped = requested.length > 0
+    ? `, and none of them is a field of '${object}' (an unknown column is dropped from a projection)`
+    : '';
   const err: any = new Error(
-    `ObjectQL.${operation}('${object}') names no field in ${param}: got []. The query was not run: `
+    `ObjectQL.${operation}('${object}') names no field in ${param}: got ${JSON.stringify(requested)}${dropped}. The query was not run: `
     + 'an empty projection was read as no projection, which answers every column. '
     + `${projectionNamesNoField()}, or leave the projection out to read every column.`,
   );
@@ -93,3 +111,16 @@ export function assertProjectionNamesAField(
   if (Array.isArray(query.fields) && query.fields.length === 0) refuseEmptyProjection(object, operation, "'fields'");
   assertExpandProjections(object, operation, query.expand, '');
 }
+
+/**
+ * [#27165] Refuse a projection the unknown-column tolerance emptied: every
+ * entry of `requested` named a column `object` does not have. Same refusal as
+ * `fields: []`, naming what was asked for.
+ */
+export function refuseProjectionOfUnknownColumns(
+  object: string,
+  operation: 'find' | 'findOne',
+  requested: readonly unknown[],
+): never {
+  return refuseEmptyProjection(object, operation, "'fields'", requested);
+}
@@ -216,3 +216,48 @@ describe('[#27008] the in-process engine refuses an empty projection', () => {
     expect(row).toEqual({ title: 'Ship', project_id: { name: 'Apollo' } });
   });
 });
+
+/**
+ * [#27165] A projection that is empty AFTER the unknown-plain-column tolerance
+ * dropped every entry is an empty projection, and is refused with the same
+ * refusal. Before, `find(obj, { fields: ['nope'] })` dropped `nope` (the #7589
+ * tolerance) and then fell back to every column: a narrower request answered
+ * wider. The tolerance itself stays for a mix of known and unknown columns.
+ */
+describe('[#27165] a projection whose every column is unknown is an empty projection', () => {
+  let engine: ObjectQL;
+  let reads: Array<{ object: string; fields: unknown }>;
+
+  beforeEach(async () => {
+    engine = new ObjectQL();
+    const made = makeDriver();
+    reads = made.reads;
+    engine.registerDriver(made.driver, true);
+    await engine.init();
+    engine.registry.registerObject(projectObject, 'test-package');
+    engine.registry.registerObject(taskObject, 'test-package');
+  });
+
+  it('find with only unknown columns is refused 400 VALIDATION_ERROR, naming them, before any driver read', async () => {
+    const answer = await wireAnswer(engine.find('task_27008', { fields: ['nope', 'nada'] }));
+    expect(answer).toMatchObject({ status: 400, code: 'VALIDATION_ERROR' });
+    expect(answer.message).toContain(declaredRefusal());
+    expect(answer.message).toMatch(/^ObjectQL\.find\('task_27008'\) names no field in 'fields': got \["nope","nada"\]/);
+    expect(reads).toEqual([]);
+  });
+
+  it('findOne with only unknown columns is refused the same way, before any driver read', async () => {
+    const answer = await wireAnswer(engine.findOne('task_27008', { where: { id: 't1' }, fields: ['nope'] }));
+    expect(answer).toMatchObject({ status: 400, code: 'VALIDATION_ERROR' });
+    expect(answer.message).toContain(declaredRefusal());
+    expect(answer.message).toMatch(/^ObjectQL\.findOne\('task_27008'\) names no field in 'fields': got \["nope"\]/);
+    expect(reads).toEqual([]);
+  });
+
+  it('CONTROL: a mix of known and unknown columns keeps the tolerance and projects the known ones', async () => {
+    const [row] = await engine.find('task_27008', { fields: ['nope', 'title'] });
+    expect(row).toEqual({ title: 'Ship' });
+    const one = await engine.findOne('task_27008', { where: { id: 't1' }, fields: ['nope', 'title'] });
+    expect(one).toEqual({ title: 'Ship' });
+  });
+});
@@ -302,7 +302,7 @@ import {
 // each body the members it reads (`CountAggregateHost`).
 import { count, rejectCredentialAggregation } from './engine-count-aggregate.js';
 import { assertGroupByNamesNoJsonStoredField } from './group-by-structured-json-door.js';
-import { assertProjectionNamesAField } from './empty-projection-door.js';
+import { assertProjectionNamesAField, refuseProjectionOfUnknownColumns } from './empty-projection-door.js';
 import { assertAggregationFieldTypesAccepted } from './aggregate-field-type-door.js';
 import { assertRecordCurrencyAggregatesGrouped } from './record-currency-aggregate-door.js';
 import { assertRecordCurrencyCodes, touchesRecordCurrency } from './validation/record-currency-code.js';
@@ -13634,10 +13634,10 @@ export class ObjectQL implements IObjectQLEngine {
       // Whole names, no head-splitting: only plain entries reach here (the
       // dotted refusal above fired on anything carrying a '.').
       const filtered = ast.fields.filter(f => known.has(f));
-      // Guard against an empty projection — fall back to `*` so the
-      // request still returns rows. An empty SELECT list would either
-      // 400 in Postgres or silently project nothing.
-      ast.fields = filtered.length > 0 ? filtered : undefined;
+      // [#27165] Nothing left is an empty projection, refused as `fields: []`
+      // is — never read as every column.
+      if (filtered.length === 0) refuseProjectionOfUnknownColumns(object, 'find', ast.fields);
+      ast.fields = filtered;
     }
 
     const opCtx: OperationContext = {
@@ -13940,7 +13940,9 @@ export class ObjectQL implements IObjectQLEngine {
       // in schema.fields (matches `find()` behavior, one list).
       const known = new Set<string>([...Object.keys(_findOneSchema.fields), ...PLATFORM_PROVISIONED_COLUMNS]);
       const filtered = ast.fields.filter(f => known.has(f));
-      ast.fields = filtered.length > 0 ? filtered : undefined;
+      // [#27165] Same refusal as `find`.
+      if (filtered.length === 0) refuseProjectionOfUnknownColumns(objectName, 'findOne', ast.fields);
+      ast.fields = filtered;
     }
 
     const opCtx: OperationContext = {
 
@@ -1783,14 +1783,17 @@ describe('#4226 — sort / select / expand on the list path (real ObjectQL engin
         for (const r of rows) expect(Object.keys(r).sort()).toEqual(['title']);
     });
 
-    it('[#7589 GUARD] a projection of ONLY unknown plain columns still falls back to every field', async () => {
-        // The `SELECT *` fallback itself, pinned as KEPT for the plain case:
-        // this is the documented tolerance the ruling preserves, not a defect
-        // this card missed. (The DOTTED route into this same fallback is what
-        // was closed above.)
-        const rows: any[] = await engine.find('showcase_task', { fields: ['no_such_field'] });
-        expect(rows).toHaveLength(5);
-        expect(Object.keys(rows[0])).toEqual(expect.arrayContaining(['id', 'title', 'status']));
+    it('[#27165] a projection of ONLY unknown plain columns is an empty projection, refused', async () => {
+        // The `SELECT *` fallback this guard pinned as KEPT is closed by its
+        // own ruling (#27165 triage): a projection the tolerance empties is an
+        // empty projection, refused as `fields: []` is (#27008), never read as
+        // every column. The tolerance itself stays for a mixed projection
+        // (the guard above).
+        const err: any = await engine
+            .find('showcase_task', { fields: ['no_such_field'] })
+            .then(() => null, (e: unknown) => e);
+        expect(err).toMatchObject({ status: 400, code: 'VALIDATION_ERROR' });
+        expect(err.message).toMatch(/names no field in 'fields': got \["no_such_field"\]/);
     });
 
     it('[#7589 GUARD] `engine.findOne` keeps the same plain tolerance', async () => {
 
@@ -203,11 +203,11 @@ describe.each<Behaviour>(['whole row', 'projection', 'ladder'])(
     });
 
     it('door: an explicit projection naming ONLY a retired column', async () => {
-      // The engine's unknown-plain tolerance drops the name and reads the
-      // default projection; it must not read every column.
-      const rows = await h.engine.find(CONTACT, { fields: ['mailing_street'] });
-      expect(rows[0]).toMatchObject({ id: 'con_1', name: 'Ada' });
-      expectNoRetiredColumn(rows);
+      // The engine's unknown-plain tolerance drops the name, which leaves an
+      // empty projection: [#27165] refused, as `fields: []` is, so the
+      // retired column is never read and no row is served.
+      const err: any = await h.engine.find(CONTACT, { fields: ['mailing_street'] }).then(() => null, (e: unknown) => e);
+      expect(err).toMatchObject({ status: 400, code: 'VALIDATION_ERROR' });
     });
 
     it('door: expand — the related record is the related object\'s declared fields', async () => {