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+---
+'@objectstack/metadata-protocol': patch
+---
+
+fix(metadata-protocol): the item reads take an item's ADR-0010 `_lock` from the same resolution the write doors enforce, so the read envelope and the doors agree on the artifact layer too (#21738)
+
+Clause-②: no
+
+The `_lock` gate of the write doors (save, publish, rollback, delete) resolves an item's lock from two layers in order: the packaged artifact's `_lock`, unless it is `'none'`, then the stored `sys_metadata` row's. The two item reads did not use that resolution. `getMetaItem` took the lock from its served document, onto which `mergeArtifactProtection` had copied any declared artifact `_lock`, `'none'` included. `getMetaItemLayered` (`GET /api/v1/meta/:type/:name/layers`) took it from the code layer whenever one existed. Now the gate, both reads' envelopes, the served body's lock fields and the `getMetaDiagnostics` per-type `locked` count all call one resolution, `resolveItemLock`.
+
+**Read answers that change**, on both kernel topologies:
+
+- An artifact that declares `_lock: 'none'` over a stored row that declares a lock (env-wide, or the organization's own row) now reads with the stored row's lock in `getMetaItem` and `getMetaItemLayered`. Under `'full'`, that is `editable: false` and `deletable: false`. The served body's `_lock`, the `getMetaItems` list item's `_lock` and the diagnostics `locked` count say the same. The doors already refused these writes with `403 ITEM_LOCKED`. An artifact's `'none'` declares no lock; it does not override an administrator's stored lock.
+- `getMetaItemLayered` for a packaged item whose artifact declares no `_lock`, under a stored row that declares one, now reads the stored row's lock, as `getMetaItem` and the doors already did. Before, it read `lock: 'none'`, `editable: true`.
+- `lockReason`, `lockSource` and `lockDocsUrl` are the binding layer's. When no layer binds, they are absent: a reason explains a refusal, and there is none. Before, they were whatever the served document carried, so an explicit `'none'` artifact's reason was reported. For the same reason, an explicit `'none'` artifact's `_lock`, `_lockReason`, `_lockSource` and `_lockDocsUrl` are no longer copied onto a stored row's served body.
+- A `_lock` that only a copy the doors never read declares is no longer reported as binding. Examples are a MetadataService copy the dev watcher reloaded after boot, and an item registered at runtime with no package. Such an item now reads as the doors answer it.
+
+**Unchanged.** Every write-door verdict, refusal code and refusal text: the gate still reads the stored row only when the artifact's lock does not bind, so a packaged lock is still answered without a store read. `provenance`, `packageId` and `packageVersion` on both reads, and the artifact's `_packageId`, `_packageVersion` and `_provenance` on served bodies. Which stored row each read serves. The one declared difference between the reads and the gate also stays: the reads still serve a row stored under the type's other (plural) spelling when no canonical row is in scope, and the gate does not read it. No export, accepted input, key or error code changes.
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+// Copyright (c) 2026 ObjectStack. Licensed under the Apache-2.0 license.
+
+/**
+ * [#21738, ADR-0010 §3.3 / §5] THE item-lock resolution: the one answer to
+ * "which ADR-0010 `_lock` binds this item?", taken by every caller that
+ * enforces a lock or reports one.
+ *
+ *  - The write doors' `_lock` gate (`getEffectiveLock` in `protocol.ts`, behind
+ *    save, publish, rollback, delete and the package publish's promotion)
+ *    reads its layers through {@link resolveItemLockLazily}.
+ *  - Both item reads' protection envelope (`getMetaItem`,
+ *    `getMetaItemLayered`, through `servedLockState`) and the per-type
+ *    `locked` count of `getMetaDiagnostics` call {@link resolveItemLock}.
+ *  - The lock family a served body carries (`mergeArtifactProtection`) calls
+ *    it too, so a body never states a lock the envelope does not report.
+ *
+ * Before this module the reads took their lock from two derivations of their
+ * own, and neither was the door's:
+ *
+ *  1. `mergeArtifactProtection` copied any declared artifact `_lock` over the
+ *     stored row's, an explicit `'none'` included. A packaged item whose
+ *     artifact declared `'none'` under a stored row declaring `'full'` read
+ *     `editable: true` while the door refused the save with `ITEM_LOCKED`.
+ *  2. `getMetaItemLayered` read the lock off `code ?? overlay`, so a packaged
+ *     item whose artifact declared no lock read unlocked under a stored row
+ *     declaring one, while `getMetaItem` and the door said locked.
+ *
+ * ## The rule
+ *
+ * The layers are read in {@link ITEM_LOCK_LAYERS} order. The first layer whose
+ * declared `_lock` is not `'none'` binds, and the answer carries that layer's
+ * lock and its prose (`_lockReason`, `_lockDocsUrl`, `_lockSource`). A layer
+ * that declares `'none'`, or declares nothing, does not bind. `'none'` declares
+ * no lock: it is not a grant over a lower layer's lock (the triage ruling on
+ * #21738: an artifact's explicit `'none'` leaves an administrator's stored lock
+ * binding, because letting it override would widen the door). When no layer
+ * binds, the answer is `'none'` with no prose: a lock reason explains a
+ * refusal, and there is none to explain.
+ *
+ * ## The layers ARE the resolution's inputs, by name
+ *
+ * {@link ITEM_LOCK_LAYERS} is both the precedence and the parameter set. The
+ * resolver iterates it, the input types are derived from it, and the
+ * acceptance pin (`protocol.lock-one-resolution.test.ts`) generates its rows
+ * from it. A layer added here without an axis there turns that pin's
+ * completeness check red, naming the layer.
+ *
+ * ⛔ Not a policy of its own. Each caller decides which document it hands each
+ * layer: the door hands the canonical-spelling, package-agnostic row; the reads
+ * hand the row they serve (see `findServedOverlayRow` for the one declared
+ * difference between the two).
+ */
+import { extractProtection, type MetadataLock, type MetadataLockSource } from '@objectstack/spec/kernel';
+
+/**
+ * The layers an item's lock can come from, in precedence order:
+ *
+ *  - `artifact`: the item a code package's loader registered (ADR-0010 §3.3,
+ *    "an overlay cannot loosen a packaged lock");
+ *  - `overlay`: the stored `sys_metadata` row (ADR-0005), as the caller
+ *    resolved it.
+ */
+export const ITEM_LOCK_LAYERS = Object.freeze(['artifact', 'overlay'] as const);
+
+/** One of {@link ITEM_LOCK_LAYERS}. */
+export type ItemLockLayer = (typeof ITEM_LOCK_LAYERS)[number];
+
+/** Per layer, the document that layer contributes, or `undefined` when it has none. */
+export type ItemLockLayers = { readonly [L in ItemLockLayer]: unknown };
+
+/** The resolution's answer. */
+export interface ItemLock {
+    /** The binding lock, or `'none'` when no layer binds. */
+    readonly lock: MetadataLock;
+    /** The binding layer's `_lockReason`. */
+    readonly lockReason: string | undefined;
+    /** The binding layer's `_lockDocsUrl`. */
+    readonly lockDocsUrl: string | undefined;
+    /** The binding layer's declared `_lockSource`. */
+    readonly lockSource: MetadataLockSource | undefined;
+    /** The layer whose lock binds, or `undefined` when none does. */
+    readonly layer: ItemLockLayer | undefined;
+}
+
+const UNLOCKED: ItemLock = Object.freeze({
+    lock: 'none',
+    lockReason: undefined,
+    lockDocsUrl: undefined,
+    lockSource: undefined,
+    layer: undefined,
+});
+
+/**
+ * Resolve the item's lock from the documents its layers contribute.
+ * See this module's header for the rule.
+ */
+export function resolveItemLock(layers: ItemLockLayers): ItemLock {
+    for (const layer of ITEM_LOCK_LAYERS) {
+        const declared = extractProtection(layers[layer]);
+        if (declared.lock !== 'none') {
+            return {
+                lock: declared.lock,
+                lockReason: declared.lockReason,
+                lockDocsUrl: declared.lockDocsUrl,
+                lockSource: declared.lockSource,
+                layer,
+            };
+        }
+    }
+    return UNLOCKED;
+}
+
+/**
+ * {@link resolveItemLock}, reading each layer only when no layer above it
+ * binds. The answer is the same; what this saves is the reads below a binding
+ * layer. The write doors use it, so a packaged lock is answered without a
+ * `sys_metadata` read, and a store that cannot be read never turns a packaged
+ * lock's `ITEM_LOCKED` into a 503.
+ *
+ * A reader's failure propagates: each caller owns its #5532 / #5706
+ * discrimination.
+ */
+export async function resolveItemLockLazily(read: {
+    readonly [L in ItemLockLayer]: () => unknown | Promise<unknown>;
+}): Promise<ItemLock> {
+    const layers = Object.fromEntries(ITEM_LOCK_LAYERS.map((layer) => [layer, undefined])) as Record<ItemLockLayer, unknown>;
+    for (const layer of ITEM_LOCK_LAYERS) {
+        layers[layer] = await read[layer]();
+        const answer = resolveItemLock(layers);
+        if (answer.layer !== undefined) return answer;
+    }
+    return UNLOCKED;
+}