@@ -0,0 +1,16 @@
+---
+'@objectstack/metadata-core': patch
+'@objectstack/metadata-protocol': patch
+'@objectstack/objectql': patch
+---
+
+fix(metadata-protocol): load-time diagnostics no longer report "`picklist` and `options` cannot both be declared" on a field that declares only `picklist`
+
+Clause-②: no
+Metadata-protocol: none
+
+A select field that names a shared list (`picklist: 'industry'`) is served with the list's options written beside `picklist`, and the diagnostics judged that served copy, so every shared-picklist field of every app was reported as declaring both keys: in an item's `_diagnostics`, in the list read's, and in `GET /meta/diagnostics` (Setup › All Metadata Types). They now judge the field as its author wrote it.
+
+- **The rule stands.** A field that authors both `picklist` and `options` is still reported, with the same message and severity, at `fields.NAME.options`.
+- **What `/meta` serves is unchanged.** A picklist-bound field is still served with `picklist` and the resolved `options`.
+- **How the two are told apart.** The picklist resolution marks the options array it derives; `@objectstack/metadata-core` exports `markResolvedPicklistOptions` and `isResolvedPicklistOptions`, and the diagnostics leave a marked array out of the judgement. The mark is not part of any response or stored row.
@@ -133,3 +133,9 @@ export * from './object-field-type.js';
 // `view` write in `@objectstack/metadata-protocol`; both read this one rule, so
 // a form withdrawn by either declared switch is withdrawn everywhere.
 export * from './anonymous-form-intake.js';
+
+// [#26886] The mark on an `options` array resolved from a shared picklist,
+// shared by the resolution (`@objectstack/objectql`'s lean core closure) and the
+// load-time diagnostics (`@objectstack/metadata-protocol`), so the diagnostics
+// judge a field as its author wrote it.
+export * from './resolved-picklist-options.js';
@@ -0,0 +1,39 @@
+// Copyright (c) 2026 ObjectStack. Licensed under the Apache-2.0 license.
+
+/**
+ * #26886 — the mark on options resolved from a shared picklist rides the array
+ * itself and nothing else: never a JSON key, never on a copy. A copy reads as
+ * authored, so a reader of it reports a diagnostic rather than missing one.
+ */
+import { describe, expect, it } from 'vitest';
+import { isResolvedPicklistOptions, markResolvedPicklistOptions } from './resolved-picklist-options.js';
+
+describe('resolved picklist options mark', () => {
+  it('marks the array it is given, in place, and only that array', () => {
+    const options = [{ label: 'Tech', value: 'tech' }];
+    expect(markResolvedPicklistOptions(options)).toBe(options);
+    expect(isResolvedPicklistOptions(options)).toBe(true);
+    expect(isResolvedPicklistOptions(markResolvedPicklistOptions(options))).toBe(true);
+    expect(isResolvedPicklistOptions([{ label: 'Tech', value: 'tech' }])).toBe(false);
+    expect(isResolvedPicklistOptions(undefined)).toBe(false);
+  });
+
+  it('is invisible to JSON and to key enumeration', () => {
+    const options = markResolvedPicklistOptions([{ label: 'Tech', value: 'tech' }]);
+    expect(JSON.stringify({ options })).toBe('{"options":[{"label":"Tech","value":"tech"}]}');
+    expect(Object.keys(options)).toEqual(['0']);
+    expect(Object.getOwnPropertySymbols(options).map((s) => Object.getOwnPropertyDescriptor(options, s)?.enumerable)).toEqual([false]);
+  });
+
+  it('does not survive a copy of the array', () => {
+    const options = markResolvedPicklistOptions([{ label: 'Tech', value: 'tech' }]);
+    expect(isResolvedPicklistOptions(options.map((o) => ({ ...o })))).toBe(false);
+    expect(isResolvedPicklistOptions([...options])).toBe(false);
+    expect(isResolvedPicklistOptions(JSON.parse(JSON.stringify(options)))).toBe(false);
+  });
+
+  it('survives a copy of the field that holds it', () => {
+    const field = { picklist: 'industry', options: markResolvedPicklistOptions([{ label: 'Tech', value: 'tech' }]) };
+    expect(isResolvedPicklistOptions({ ...field }.options)).toBe(true);
+  });
+});
@@ -0,0 +1,45 @@
+// Copyright (c) 2026 ObjectStack. Licensed under the Apache-2.0 license.
+
+/**
+ * [#26886] The mark on an `options` array the runtime RESOLVED from a shared
+ * picklist, as opposed to one an author wrote on the field.
+ *
+ * A field authors `picklist: '<name>'` and no `options`; every object read
+ * serves it with the list's options written beside `picklist` (the registry's
+ * picklist resolution in `@objectstack/objectql`). The load-time diagnostics in
+ * `@objectstack/metadata-protocol` judge what the author wrote, so the field
+ * schema's rule refusing `picklist` and `options` together must not read the
+ * copy the runtime wrote. The resolution marks the array it derived and the
+ * diagnostics leave only a marked array out.
+ *
+ * Here because both sides need the one spelling: the diagnostics live in
+ * `@objectstack/metadata-protocol`, which `@objectstack/objectql` depends on,
+ * and the resolution sits in the lean `@objectstack/objectql/core` closure,
+ * which must not import `@objectstack/metadata-protocol` (ADR-0076 D2). Both
+ * already declare this package.
+ *
+ * The mark is a non-enumerable property, so no response, stored row or JSON
+ * key ever carries it, and it is keyed with `Symbol.for` so every loaded copy
+ * of a package reads the one mark. A copy of the array (`.map`, a spread, a
+ * JSON round trip) does not carry it: whoever reads the copy sees authored
+ * options, so the failure direction is a reported diagnostic, never a missed one.
+ */
+
+const RESOLVED_PICKLIST_OPTIONS = Symbol.for('@objectstack/metadata-core:resolved-picklist-options');
+
+/**
+ * Mark an `options` array as resolved from a shared picklist rather than
+ * authored on the field. Returns the same array.
+ */
+export function markResolvedPicklistOptions<T extends object>(options: T): T {
+  if (!Object.prototype.hasOwnProperty.call(options, RESOLVED_PICKLIST_OPTIONS)) {
+    Object.defineProperty(options, RESOLVED_PICKLIST_OPTIONS, { value: true });
+  }
+  return options;
+}
+
+/** `true` when `options` is an array {@link markResolvedPicklistOptions} marked. */
+export function isResolvedPicklistOptions(options: unknown): boolean {
+  return Array.isArray(options)
+    && (options as unknown as Record<symbol, unknown>)[RESOLVED_PICKLIST_OPTIONS] === true;
+}
@@ -0,0 +1,81 @@
+// Copyright (c) 2026 ObjectStack. Licensed under the Apache-2.0 license.
+
+/**
+ * #26886 — load-time diagnostics judge a picklist-bound field as its author
+ * wrote it, never with the `options` the runtime resolved onto it.
+ *
+ * Every object read serves a field that authors `picklist: '<name>'` with the
+ * list's options written beside it, and the field schema refuses `picklist`
+ * and `options` together. Judging the served copy flagged every shared-picklist
+ * field of every app. The resolution marks the array it derived
+ * (`markResolvedPicklistOptions`), and only a marked array is left out of the
+ * judgement:
+ *
+ *  - a field naming only a picklist, served with resolved options: clean;
+ *  - a field that AUTHORS both keys (an unmarked array): still flagged, with
+ *    the rule's own message, at `fields.NAME.options`;
+ *  - a field with inline `options` only: clean, before and after.
+ *
+ * The mark never reaches a response or a memo key: a marked document and an
+ * unmarked one with the same JSON are two verdicts.
+ */
+import { describe, expect, it } from 'vitest';
+import { markResolvedPicklistOptions } from '@objectstack/metadata-core';
+import { computeMetadataDiagnostics, decorateMetadataItem } from './metadata-diagnostics.js';
+
+const BOTH_KEYS = '`picklist` and `options` cannot both be declared';
+
+const resolved = () => markResolvedPicklistOptions([{ label: 'Tech', value: 'tech' }]);
+const authored = () => [{ label: 'Tech', value: 'tech' }];
+
+function objectWith(fields: Record<string, unknown>) {
+    return { name: 'pk_probe', label: 'Probe', fields: { name: { name: 'name', type: 'text', label: 'Name' }, ...fields } };
+}
+
+const industry = (options: unknown[]) =>
+    ({ name: 'industry', type: 'select', label: 'Industry', picklist: 'industry', options });
+
+function bothKeysPaths(diagnostics: ReturnType<typeof computeMetadataDiagnostics>): string[] {
+    return (diagnostics?.errors ?? []).filter((e) => e.message.startsWith(BOTH_KEYS)).map((e) => e.path);
+}
+
+describe('diagnostics — options resolved from a shared picklist', () => {
+    it('a field naming only a picklist, served with its resolved options, is clean', () => {
+        expect(computeMetadataDiagnostics('object', objectWith({ industry: industry(resolved()) }))).toEqual({ valid: true });
+    });
+
+    it('a field that authors `options` beside `picklist` is still flagged, at its options path', () => {
+        const diagnostics = computeMetadataDiagnostics('object', objectWith({ industry: industry(authored()) }));
+        expect(diagnostics?.valid).toBe(false);
+        expect(bothKeysPaths(diagnostics)).toEqual(['fields.industry.options']);
+    });
+
+    it('a field with inline `options` only is clean', () => {
+        const inline = { name: 'stage', type: 'select', label: 'Stage', options: [{ label: 'Open', value: 'open' }] };
+        expect(computeMetadataDiagnostics('object', objectWith({ stage: inline }))).toEqual({ valid: true });
+    });
+
+    it('a marked array on a field with no `picklist` is judged as written', () => {
+        // A one-character option value is refused; left out, nothing would be.
+        const stray = { name: 'stage', type: 'select', label: 'Stage', options: markResolvedPicklistOptions([{ label: 'X', value: 'x' }]) };
+        const diagnostics = computeMetadataDiagnostics('object', objectWith({ stage: stray }));
+        expect(diagnostics?.errors?.map((e) => e.path)).toEqual(['fields.stage.options.0.value']);
+    });
+
+    it('a marked and an unmarked document with the same JSON are two verdicts, in either order', () => {
+        const marked = objectWith({ industry: industry(resolved()) });
+        const unmarked = objectWith({ industry: industry(authored()) });
+        expect(JSON.stringify(marked)).toBe(JSON.stringify(unmarked));
+        expect(bothKeysPaths(computeMetadataDiagnostics('object', unmarked))).toEqual(['fields.industry.options']);
+        expect(computeMetadataDiagnostics('object', marked)).toEqual({ valid: true });
+        expect(bothKeysPaths(computeMetadataDiagnostics('object', unmarked))).toEqual(['fields.industry.options']);
+    });
+
+    it('the served item keeps both keys and carries no trace of the mark', () => {
+        const served = decorateMetadataItem('object', objectWith({ industry: industry(resolved()) })) as any;
+        expect(served._diagnostics).toEqual({ valid: true });
+        expect(served.fields.industry).toMatchObject({ picklist: 'industry', options: [{ label: 'Tech', value: 'tech' }] });
+        expect(JSON.parse(JSON.stringify(served.fields.industry))).toEqual(industry(authored()));
+        expect(Object.keys(served.fields.industry.options)).toEqual(['0']);
+    });
+});
@@ -41,6 +41,8 @@ import { redactMetadataItem } from './metadata-redaction.js';
 // runtime gate's own answer, so the publish verdict below is re-spelled
 // against the same prefix the gate wrote it with.
 import { stackKeyForType } from '@objectstack/lint/runtime';
+// [#26886] The resolution's mark on options it derived from a shared picklist.
+import { isResolvedPicklistOptions } from '@objectstack/metadata-core';
 import type { RuntimeAuthoringIssue } from '@objectstack/spec/api';
 
 /**
@@ -175,6 +177,52 @@ function copyDiagnostics(verdict: MetadataDiagnostics): MetadataDiagnostics {
     return copy;
 }
 
+// ---------------------------------------------------------------------------
+// [#26886] Options the runtime resolved from a shared picklist
+// ---------------------------------------------------------------------------
+//
+// A field authors `picklist: '<name>'` and no `options`; every object read
+// serves it with the list's options written beside `picklist` (the registry's
+// picklist resolution, `PicklistServedFieldSchema`). Diagnostics judge what the
+// author wrote, so the field schema's rule that refuses `picklist` and
+// `options` together must not read the copy the runtime wrote: it flagged
+// every picklist-bound field of every app.
+//
+// The resolution therefore MARKS the options array it derived
+// (`markResolvedPicklistOptions`, `@objectstack/metadata-core`), and only a
+// marked array is left out here. A field that authored its own `options`
+// beside `picklist` arrives unmarked and is still flagged, with the same
+// message and severity. The mark is a non-enumerable property, so it is no
+// part of the memo key either: the key is the content of the candidate the
+// mark has already shaped.
+
+function withoutResolvedOptions(field: unknown): unknown {
+    if (!field || typeof field !== 'object') return field;
+    const { picklist, options } = field as { picklist?: unknown; options?: unknown };
+    if (typeof picklist !== 'string' || !isResolvedPicklistOptions(options)) return field;
+    const { options: _resolved, ...authored } = field as Record<string, unknown>;
+    return authored;
+}
+
+/**
+ * A document with the resolved `options` left out of every picklist-bound
+ * field of its name-keyed `fields` (the only spelling the object schema
+ * accepts). By reference when no field carries resolved options.
+ */
+function withoutResolvedPicklistOptions(document: unknown): unknown {
+    if (!document || typeof document !== 'object') return document;
+    const fields = (document as { fields?: unknown }).fields;
+    if (!fields || typeof fields !== 'object' || Array.isArray(fields)) return document;
+    let next: Record<string, unknown> | undefined;
+    for (const [name, field] of Object.entries(fields as Record<string, unknown>)) {
+        const judged = withoutResolvedOptions(field);
+        if (judged === field) continue;
+        next ??= { ...(fields as Record<string, unknown>) };
+        next[name] = judged;
+    }
+    return next ? { ...(document as object), fields: next } : document;
+}
+
 /**
  * Compute spec diagnostics for a single metadata document.
  *
@@ -224,7 +272,10 @@ export function computeMetadataDiagnostics(
     // says. Same class as #6810 (`indexed`), different remedy — that key did
     // not belong on the served body at all and left at its injection site,
     // whereas this one is read by the UI and belongs on the response.
-    const candidate = stripReadDecorations(item);
+    // [#26886] …and judge each picklist-bound field as its author wrote it:
+    // the `options` the runtime resolved onto it are not part of that shape
+    // ({@link withoutResolvedPicklistOptions}).
+    const candidate = withoutResolvedPicklistOptions(stripReadDecorations(item));
 
     // [#25783] A document parsed before against this same schema is answered
     // from the memo — see "The verdict memo" above.
 
@@ -31,6 +31,11 @@
  * validator refuses every value of the field instead of accepting any.
  */
 
+// The mark that tells the load-time diagnostics these options were resolved
+// here, not authored: they judge what the author wrote, and the field schema
+// refuses `picklist` and `options` together.
+import { isResolvedPicklistOptions, markResolvedPicklistOptions } from '@objectstack/metadata-core';
+
 /** One option, as `SelectOptionSchema` declares it (only `value` is read here). */
 export interface PicklistOptionLike {
   value: string | number | boolean;
@@ -133,7 +138,15 @@ function resolveField(field: unknown, resolve: (picklist: string) => readonly Pi
   const picklist = (field as { picklist?: unknown }).picklist;
   if (typeof picklist !== 'string' || picklist.length === 0) return field;
   const options = resolve(picklist);
-  if (options) return { ...(field as object), options: options.map((o) => ({ ...o })) };
+  if (options) {
+    const resolved = options.map((o) => ({ ...o }));
+    // Marked as derived unless the body brought `options` of its own: a field
+    // that AUTHORS both keys is still told so. A body that is itself a served
+    // copy (marked) stays marked.
+    const carried = (field as { options?: unknown }).options;
+    if (carried === undefined || isResolvedPicklistOptions(carried)) markResolvedPicklistOptions(resolved);
+    return { ...(field as object), options: resolved };
+  }
   // Unresolved: drop any options the body carried, so a stale served copy
   // cannot stand in for the list. The validator refuses every value of a
   // picklist-bound field that has none.
 
@@ -184,3 +184,52 @@ describe('picklist — the protocol object read and the authoring door', () => {
         expect(err.message).toContain('`picklist` and `options` cannot both be declared');
     });
 });
+
+// [#26886] Every door that shows a load-time diagnostic judges a
+// picklist-bound field as its author wrote it: the item's `_diagnostics`, the
+// list's, and `GET /meta/diagnostics`. The read itself keeps serving both keys.
+describe('picklist — the load-time diagnostics judge the authored field, not the served copy', () => {
+    const BOTH_KEYS = '`picklist` and `options` cannot both be declared';
+    let protocol: ObjectStackProtocolImplementation;
+
+    beforeEach(async () => {
+        const engine = new ObjectQL();
+        engine.registerDriver(makeStubDriver().driver, true);
+        await engine.init();
+        engine.registry.registerObject(sysMetadataObject);
+        for (const o of [SysMetadataHistoryObject, SysMetadataAuditObject, SysMetadataCommitObject]) engine.registry.registerObject(o as any);
+        engine.registerApp({
+            id: 'com.test.lists', name: 'lists',
+            picklists: [{ name: 'industry', label: 'Industry', options: [{ label: 'Tech', value: 'tech' }] }],
+            objects: [{
+                name: 'pd_obj', label: 'Probe', sharingModel: 'public_read_write',
+                fields: {
+                    name: { name: 'name', type: 'text', label: 'Name' },
+                    industry: { name: 'industry', type: 'select', label: 'Industry', picklist: 'industry' },
+                    stage: { name: 'stage', type: 'select', label: 'Stage', options: [{ label: 'Open', value: 'open' }] },
+                    both: { name: 'both', type: 'select', label: 'Both', picklist: 'industry', options: [{ label: 'Own', value: 'own' }] },
+                },
+            }],
+        } as any);
+        protocol = new ObjectStackProtocolImplementation(engine);
+    });
+
+    const bothKeysPaths = (diagnostics: any): string[] =>
+        (diagnostics?.errors ?? []).filter((e: any) => String(e.message).startsWith(BOTH_KEYS)).map((e: any) => e.path);
+
+    it('the item read: only the field that authored both keys is flagged, and both keys are still served', async () => {
+        const served: any = await protocol.getMetaItem({ type: 'object', name: 'pd_obj' } as any);
+        expect(served.item.fields.industry).toMatchObject({ picklist: 'industry', options: [{ label: 'Tech', value: 'tech' }] });
+        expect(bothKeysPaths(served.item._diagnostics)).toEqual(['fields.both.options']);
+        expect(served.item._diagnostics.errors.map((e: any) => e.path)).toEqual(['fields.both.options']);
+    });
+
+    it('the list read and `GET /meta/diagnostics` agree with the item read', async () => {
+        const listed: any = await protocol.getMetaItems({ type: 'object' } as any);
+        const item = (listed.items ?? listed).find((i: any) => i.name === 'pd_obj');
+        expect(bothKeysPaths(item._diagnostics)).toEqual(['fields.both.options']);
+        const sweep: any = await (protocol as any).getMetaDiagnostics({ type: 'object' });
+        const entry = sweep.entries.find((e: any) => e.name === 'pd_obj');
+        expect(entry.diagnostics.errors.map((e: any) => e.path)).toEqual(['fields.both.options']);
+    });
+});