@@ -15,7 +15,9 @@
  * code and installed packages are listed last: they open for browsing, and each
  * card points at the routes that customize one (objectui#11808). Writability is
  * the server's verdict read by packages-io (`PkgEntry.writable`, ADR-0070 D2),
- * and the server's write gate stays the authority.
+ * and the server's write gate stays the authority. Each read-only base's card
+ * says what this deployment changed on it, "n customized, m switched off"
+ * (ADR-0146 D3), from the server's per-package customization read.
  */
 
 import * as React from 'react';
@@ -28,6 +30,8 @@ import { t, tFormat, useMetadataLocale } from '../metadata-admin/i18n.js';
 import { PackageFormDialog } from '../metadata-admin/PackageFormDialog.js';
 import { isMarketplaceEnabled } from '../../runtime-config.js';
 import { fetchPackages, duplicatePackage, isSpecPackageId, type PkgEntry } from './packages-io.js';
+import { fetchPackageCustomizationCounts, type PackageCustomizationCounts } from './packageCustomizations-io.js';
+import { customizationPackageId, isCustomizationPackage } from '@objectstack/spec/kernel';
 import { PackageIdInput } from './PackageIdInput.js';
 import { studioOrgScopePath } from './studioScope.js';
 import { STUDIO_NEW_PARAM, STUDIO_NEW_PACKAGE_VALUE } from './studioNewPackage.js';
@@ -64,6 +68,18 @@ export const packagedAutomationPath = () =>
 /** objectui#11863 — how many recent packages the landing lists: one row of cards. */
 const RECENT_PACKAGES_SHOWN = 3;
 
+/**
+ * ADR-0146 D3 — one read-only base's customization line, by the state of its
+ * read. No entry means the read has not answered: the line shows no number.
+ */
+type CustomizationLine =
+  | { kind: 'read'; counts: PackageCustomizationCounts }
+  | { kind: 'failed'; message: string };
+
+/** A package's Studio address on one pillar, the way `open` below spells it. */
+const studioPillarPath = (packageId: string, pillar: 'data' | 'automations') =>
+  `/studio/${encodeURIComponent(packageId)}/${pillar}`;
+
 export function BuilderLanding(): React.ReactElement {
   const navigate = useNavigate();
   const locale = useMetadataLocale();
@@ -123,6 +139,100 @@ export function BuilderLanding(): React.ReactElement {
   const writable = pkgs?.filter((p) => p.writable) ?? [];
   const readonly = pkgs?.filter((p) => !p.writable) ?? [];
 
+  // ADR-0146 D3 — each read-only BASE's card carries "n customized, m switched
+  // off", the server's counts (`GET /packages/:id/customizations`), one read
+  // per card drawn. A pair (`<base>.custom`) draws no line and is never sent:
+  // the route refuses its id. The page does not wait for these reads. The
+  // effect is keyed on the joined ids, the primitive it reads (ui/AGENTS.md #10).
+  const customizationTargetKey = readonly
+    .filter((p) => !isCustomizationPackage(p.id))
+    .map((p) => p.id)
+    .join('\n');
+  const [customizationLines, setCustomizationLines] = React.useState<Record<string, CustomizationLine>>({});
+  React.useEffect(() => {
+    if (!customizationTargetKey) return;
+    let cancelled = false;
+    for (const id of customizationTargetKey.split('\n')) {
+      fetchPackageCustomizationCounts(id).then(
+        (counts) => {
+          if (!cancelled) setCustomizationLines((prev) => ({ ...prev, [id]: { kind: 'read', counts } }));
+        },
+        (e: unknown) => {
+          const message = e instanceof Error ? e.message : String(e);
+          if (!cancelled) setCustomizationLines((prev) => ({ ...prev, [id]: { kind: 'failed', message } }));
+        },
+      );
+    }
+    return () => {
+      cancelled = true;
+    };
+  }, [customizationTargetKey]);
+  // The pair is linked only when the package list holds it: a base with no
+  // pair has nothing to open, and the read never creates one.
+  const listedIds = new Set(pkgs?.map((p) => p.id) ?? []);
+  const listedPairOf = (baseId: string): string | null => {
+    const pair = customizationPackageId(baseId);
+    return pair.ok && listedIds.has(pair.value) ? pair.value : null;
+  };
+
+  const renderCustomizationLine = (baseId: string): React.ReactNode => {
+    if (isCustomizationPackage(baseId)) return null;
+    const line = customizationLines[baseId];
+    const lineClass = 'text-[10px] leading-4 text-muted-foreground';
+    if (!line) {
+      return (
+        <p data-testid="studio-landing-customizations" data-state="loading" className={lineClass}>
+          {t('engine.studio.landing.customizations.loading', locale)}
+        </p>
+      );
+    }
+    if (line.kind === 'failed') {
+      // Never a "0": the read did not answer. The server's sentence is the title.
+      return (
+        <p
+          data-testid="studio-landing-customizations"
+          data-state="failed"
+          title={line.message}
+          className={`${lineClass} italic opacity-80`}
+        >
+          {t('engine.studio.landing.customizations.failed', locale)}
+        </p>
+      );
+    }
+    const pair = listedPairOf(baseId);
+    const customized = tFormat('engine.studio.landing.customizations.customized', locale, {
+      customized: line.counts.customized,
+    });
+    const linkClass = 'hover:text-foreground hover:underline';
+    return (
+      <p data-testid="studio-landing-customizations" data-state="read" className={lineClass}>
+        {pair ? (
+          <Link
+            to={studioPillarPath(pair, 'data')}
+            title={tFormat('engine.studio.landing.customizations.pairTitle', locale, { pair })}
+            data-testid="studio-landing-customizations-pair"
+            className={linkClass}
+          >
+            {customized}
+          </Link>
+        ) : (
+          <span>{customized}</span>
+        )}
+        {t('engine.studio.landing.customizations.separator', locale)}
+        <Link
+          to={studioPillarPath(baseId, 'automations')}
+          title={t('engine.studio.landing.customizations.switchedOffTitle', locale)}
+          data-testid="studio-landing-customizations-switched-off"
+          className={linkClass}
+        >
+          {tFormat('engine.studio.landing.customizations.switchedOff', locale, {
+            switchedOff: line.counts.switchedOff,
+          })}
+        </Link>
+      </p>
+    );
+  };
+
   // Duplicate (ADR-0070 D4) clones a writable BASE into a new writable package,
   // the "duplicate base" gesture, and drops the user straight into the copy's
   // builder. It is offered on writable bases only. A read-only code or
@@ -384,12 +494,13 @@ export function BuilderLanding(): React.ReactElement {
                     <Lock className="h-2.5 w-2.5" /> {t('engine.studio.pkg.readonly', locale)}
                   </span>
                 </button>
-                <div className="border-t px-3 py-1.5">
+                <div className="flex flex-col gap-1 border-t px-3 py-1.5">
+                  {renderCustomizationLine(p.id)}
                   <Link
                     to={overlayPath(p.id)}
                     title={t('engine.studio.landing.overlayTitle', locale)}
                     data-testid="studio-landing-overlay"
-                    className="inline-flex items-center gap-1 text-[10px] text-muted-foreground hover:text-foreground hover:underline"
+                    className="inline-flex self-start items-center gap-1 text-[10px] text-muted-foreground hover:text-foreground hover:underline"
                   >
                     {/* objectui#12513 — the link leaves Studio for Setup: its
                         name says where it goes, the arrow that it goes out. */}
 
@@ -0,0 +1,71 @@
+// Copyright (c) 2026 ObjectStack. Licensed under the Apache-2.0 license.
+
+/**
+ * The per-package customization read the Studio landing draws on each
+ * read-only base's card (ADR-0146 D3: one line per package, "n customized,
+ * m switched off").
+ *
+ * The numbers are the server's: `GET /api/v1/packages/:id/customizations`
+ * (ADR-0146 D8 item 4) answers, for one installed base, the items its paired
+ * `<base>.custom` package overrides, the members that pair adds to the base's
+ * objects and the base's items switched off in this deployment, each with its
+ * count. This reader computes no count of its own: "customized" is the served
+ * `counts.overrides` plus the served `counts.extensions`, the two kinds of
+ * change the pair carries, and "switched off" is the served
+ * `counts.switchedOff`.
+ *
+ * The answer is judged by the route's own declaration,
+ * `GetPackageCustomizationsResponseSchema` (strict at every level): an answer
+ * it refuses is a failed read, never a count read out of an off-contract body.
+ * A failure carries the server's sentence by the rule every package reader in
+ * this folder uses (`readEnvelopeFailureText`), else `HTTP <status>`.
+ *
+ * ⛔ A pair id is never sent: the route refuses one by its shape
+ * (`400 VALIDATION_ERROR` naming its base), so this reader refuses it first,
+ * without a request.
+ */
+
+import { GetPackageCustomizationsResponseSchema } from '@objectstack/spec/api';
+import { isCustomizationPackage } from '@objectstack/spec/kernel';
+import { readEnvelopeFailureText } from '../../utils/apiErrorEnvelope.js';
+
+/** What the landing draws for one base: two served numbers. */
+export interface PackageCustomizationCounts {
+  /** Served overrides plus served extensions of the base's pair. */
+  customized: number;
+  /** Served switched-off items of the base. */
+  switchedOff: number;
+}
+
+/** The route of the read, for one base package id. */
+export const packageCustomizationsUrl = (baseId: string) =>
+  `/api/v1/packages/${encodeURIComponent(baseId)}/customizations`;
+
+/**
+ * Read one installed base's customization counts.
+ *
+ * Rejects with the server's sentence on a failed read, and with a sentence of
+ * its own on an answer the route's declaration refuses; resolves only with
+ * counts the server served.
+ */
+export async function fetchPackageCustomizationCounts(baseId: string): Promise<PackageCustomizationCounts> {
+  if (isCustomizationPackage(baseId)) {
+    throw new Error(`Package '${baseId}' is a customization package: customizations are read for its base.`);
+  }
+  const res = await fetch(packageCustomizationsUrl(baseId), {
+    credentials: 'include',
+    headers: { Accept: 'application/json' },
+    cache: 'no-store',
+  });
+  const payload = (await res.json().catch(() => null)) as Record<string, unknown> | null;
+  if (!res.ok) {
+    throw new Error(readEnvelopeFailureText(payload) ?? `HTTP ${res.status}`);
+  }
+  // The dispatcher envelope `{ success, data }`; the declaration is the `data`.
+  const parsed = GetPackageCustomizationsResponseSchema.safeParse(payload?.data);
+  if (!parsed.success) {
+    throw new Error(`The customization read for '${baseId}' answered a body its declaration refuses.`);
+  }
+  const { counts } = parsed.data;
+  return { customized: counts.overrides + counts.extensions, switchedOff: counts.switchedOff };
+}
@@ -3183,6 +3183,15 @@ const STUDIO_EN: Record<string, string> = {
   'engine.studio.landing.overlay': 'Open in Setup',
   'engine.studio.landing.overlayTitle': 'Open this package’s metadata: each type shows whether it accepts an environment overlay',
   'engine.studio.landing.marketplace': 'Or install a template app from the marketplace',
+  // ADR-0146 D3 — a read-only base's card says what this deployment changed on
+  // it, from the server's per-package customization read.
+  'engine.studio.landing.customizations.customized': '{customized} customized',
+  'engine.studio.landing.customizations.separator': ', ',
+  'engine.studio.landing.customizations.switchedOff': '{switchedOff} switched off',
+  'engine.studio.landing.customizations.loading': 'Reading customizations…',
+  'engine.studio.landing.customizations.failed': 'Couldn’t read customizations',
+  'engine.studio.landing.customizations.pairTitle': 'Open the customization package {pair} in Studio',
+  'engine.studio.landing.customizations.switchedOffTitle': 'Open this package’s Automations, where its items are switched on and off',
   // objectui#11553 — the package-less scope: the organization's own flows.
   'engine.studio.landing.orgHeading': 'Not in a package',
   'engine.studio.org.name': 'Organization flows',
 
@@ -2825,6 +2825,13 @@ const STUDIO_ZH: Record<string, string> = {
   'engine.studio.landing.overlay': '在设置中打开',
   'engine.studio.landing.overlayTitle': '打开该软件包的元数据：每种类型都会标明是否接受环境覆盖',
   'engine.studio.landing.marketplace': '或从应用市场安装一个模板应用',
+  'engine.studio.landing.customizations.customized': '已定制 {customized} 项',
+  'engine.studio.landing.customizations.separator': '，',
+  'engine.studio.landing.customizations.switchedOff': '已停用 {switchedOff} 项',
+  'engine.studio.landing.customizations.loading': '正在读取定制…',
+  'engine.studio.landing.customizations.failed': '无法读取定制',
+  'engine.studio.landing.customizations.pairTitle': '在 Studio 中打开定制包 {pair}',
+  'engine.studio.landing.customizations.switchedOffTitle': '打开该软件包的自动化，在那里启用或停用其中的项',
   // objectui#11553 — the package-less scope: the organization's own flows.
   'engine.studio.landing.orgHeading': '不属于软件包',
   'engine.studio.org.name': '组织流程',