diff --git a/.changeset/lint-label-case-localized-guard.md b/.changeset/lint-label-case-localized-guard.md
new file mode 100644
index 0000000000..25fd2527f0
--- /dev/null
+++ b/.changeset/lint-label-case-localized-guard.md
@@ -0,0 +1,13 @@
+---
+"@objectstack/cli": minor
+---
+
+`os lint` no longer crashes on a localized label.
+
+`convention/label-case` indexed its argument (`label[0].toUpperCase()`) on a parameter annotated `string`, while every call site reaches it through `any`-typed config walking and the spec does not require a label to be a string: `I18nLabelSchema` is `z.union([z.string(), InlineLocaleMapSchema])`. On the map form `label[0]` is `undefined`, the rule threw a `TypeError`, and the throw escaped `lintConfig` into the command's catch-all — so an author who localized an app label or a list-view label could not lint the project at all. Every face exited 1 with `Cannot read properties of undefined (reading 'toUpperCase')`, naming no rule, no path and no remedy, on input `ObjectStackDefinitionSchema` parses clean.
+
+The rule now checks `typeof label === 'string'` first. Two of the four carriers it walks accept the inline locale map — `apps[].label` (`AppSchema`) and a view's `list` / `listViews.*` labels (`ListViewShapeSchema`); the other two are `z.string()` and reject the map at the schema door (`objects[].label`, `objects[].fields.*.label`).
+
+**Nothing about a plain string label moves.** Same warning, same message, same `fix`, same path, on all four carriers — that is pinned per carrier rather than asserted.
+
+**The rule deliberately says nothing about a localized label**, rather than resolving the map and case-checking one of its entries. Case is a property of a literal, and deciding which locale entry a case verdict is taken against is a product call, not a lint call. Widening the rule that way is a separate change.
diff --git a/packages/cli/src/commands/lint.ts b/packages/cli/src/commands/lint.ts
index d6c14bb15f..611e6613c3 100644
--- a/packages/cli/src/commands/lint.ts
+++ b/packages/cli/src/commands/lint.ts
@@ -98,7 +98,31 @@ function checkLabelExists(item: any, path: string, kind: string): LintIssue | nu
   return null;
 }
 
-function checkLabelCase(label: string, path: string): LintIssue | null {
+// A label is not required to be a string. `I18nLabelSchema` (spec
+// `ui/i18n.zod`) is `z.union([z.string(), InlineLocaleMapSchema])`, and it is
+// the label primitive the whole `ui/` tree imports — so of the four carriers
+// this rule is called on, two accept the inline locale map:
+// `views[].list.label` / `views[].listViews.*.label` (`ListViewShapeSchema`)
+// and `apps[].label` (`AppSchema`). The other two are `z.string()` and reject
+// the map at the schema door (`objects[].label`, `objects[].fields.*.label`).
+//
+// Every call site reaches this function through `any`-typed config walking, so
+// the annotation below used to say `string` and be wrong: on a map,
+// `label[0]` is `undefined` and `undefined.toUpperCase()` threw. The throw
+// escaped `lintConfig` into the command's catch-all, so an author who
+// localized an app or list-view label could not lint the project at all —
+// every face exited 1 naming no rule, no path and no remedy, on input
+// `ObjectStackDefinitionSchema` parses clean.
+//
+// ⛔ The guard deliberately says NOTHING about a localized label rather than
+// resolving the map and case-checking an entry. Case is a property of a
+// literal; picking WHICH locale entry a case verdict is taken against is a
+// product decision (`resolveI18nLabel` exists, but which entry is
+// authoritative for a lint verdict is not this rule's to answer). Widening
+// the rule to localized labels is an extension, filed separately; this guard
+// is the floor, and it leaves the string branch below byte-identical.
+function checkLabelCase(label: unknown, path: string): LintIssue | null {
+  if (typeof label !== 'string') return null;
   if (label && label[0] !== label[0].toUpperCase()) {
     return {
       severity: 'warning',
@@ -111,7 +135,11 @@ function checkLabelCase(label: string, path: string): LintIssue | null {
   return null;
 }
 
-function getViewLabel(view: any, viewPath: string): { label?: string; path: string } {
+// ⚠️ `label` is `unknown`, not `string`: it is read straight off `any`-typed
+// config and `ListViewShapeSchema.label` is `I18nLabelSchema`, so the value
+// can legitimately be an inline locale map. Annotating it `string` here is
+// what let the map reach `checkLabelCase`'s indexing unchecked.
+function getViewLabel(view: any, viewPath: string): { label?: unknown; path: string } {
   if (view?.list?.label) {
     return { label: view.list.label, path: `${viewPath}.list.label` };
   }
diff --git a/packages/cli/test/lint-label-case-localized.test.ts b/packages/cli/test/lint-label-case-localized.test.ts
new file mode 100644
index 0000000000..08b547b126
--- /dev/null
+++ b/packages/cli/test/lint-label-case-localized.test.ts
@@ -0,0 +1,235 @@
+// Copyright (c) 2026 ObjectStack. Licensed under the Apache-2.0 license.
+
+/**
+ * `convention/label-case` must not crash `os lint` on a localized label.
+ *
+ * ## What this file pins, and how each half can fail
+ *
+ * The rule indexed its argument (`label[0].toUpperCase()`) on a parameter
+ * annotated `string` that every call site reaches through `any`-typed config
+ * walking. `I18nLabelSchema` is `z.union([z.string(), InlineLocaleMapSchema])`,
+ * so on the map form `label[0]` is `undefined` and the rule threw — out of
+ * `lintConfig`, into the command's catch-all, exit 1 on every face with a
+ * message naming no rule, no path and no remedy.
+ *
+ * Two independent properties, and neither one covers the other:
+ *
+ *  1. **NO MOVE** — the check on a plain string label is unchanged. This is
+ *     the property that makes a guard the uncontroversial floor, so it is
+ *     pinned per carrier rather than asserted in prose. Falsified by any guard
+ *     that also swallows strings (a `typeof` typo, an early return placed
+ *     above the string branch, or the guard inverted to
+ *     `typeof label === 'string'`): every lowercase row below stops
+ *     reporting.
+ *  2. **NO CRASH** — a localized label is walked without throwing, on every
+ *     carrier whose schema accepts the map. Falsified by removing the guard:
+ *     each of those rows throws a `TypeError` instead of returning issues.
+ *
+ * ## Why the carriers are enumerated rather than sampled
+ *
+ * The filed mutation sweep hit exactly two paths (`apps.0.label`,
+ * `views.0.list.label`) because the fixture it swept had exactly those two.
+ * The class is the set of call sites, not the set of sweep hits:
+ * `lintConfig` calls this rule from four places, and the schema decides which
+ * of them can carry a map —
+ *
+ *   | call site                       | governing schema                        | map?  |
+ *   | `objects[].label`               | `ObjectSchema.label` — `z.string()`     | no    |
+ *   | `objects[].fields.*.label`      | field base — `z.string()`               | no    |
+ *   | `views[].list{,Views.*}.label`  | `ListViewShapeSchema` — `I18nLabelSchema` | yes |
+ *   | `apps[].label`                  | `AppSchema.label` — `I18nLabelSchema`   | yes   |
+ *
+ * — which is why `views[].listViews.*.label` is pinned below even though no
+ * sweep ever reached it: it is the same primitive behind a second path, and
+ * `getViewLabel` only falls through to it when `list.label` is absent.
+ *
+ * ## What the rule now SAYS about a localized label: nothing
+ *
+ * Deliberately. Case is a property of a literal; deciding which locale entry a
+ * case verdict is taken against is a product call this card does not make. So
+ * the localized rows assert the ABSENCE of a `convention/label-case` issue —
+ * if someone later widens the rule to resolve the map, these are the
+ * assertions that must be rewritten on purpose rather than silently satisfied.
+ */
+
+import { describe, expect, it } from 'vitest';
+import { ObjectStackDefinitionSchema, normalizeStackInput } from '@objectstack/spec';
+import { lintConfig } from '../src/commands/lint';
+import { scoreMetadata } from '../src/lint/score';
+
+const MANIFEST = {
+  id: 'todo',
+  namespace: 'todo',
+  version: '1.0.0',
+  name: 'Todo',
+  type: 'app' as const,
+};
+
+/** The card's own fixture value, plus the sweep's literal hit value. */
+const LOCALIZED = { en: 'Todos', 'zh-CN': '待办' };
+const EMPTY_MAP = {};
+
+const caseIssues = (issues: { rule: string }[]) =>
+  issues.filter((i) => i.rule === 'convention/label-case');
+
+/** `objects[]` needs fields to avoid drowning the label rows in structure issues. */
+const objectWith = (label: unknown) => ({
+  name: 'invoice',
+  label,
+  fields: { name: { type: 'text', label: 'Invoice Number' } },
+});
+
+const objectWithFieldLabel = (label: unknown) => ({
+  name: 'invoice',
+  label: 'Invoice',
+  fields: { name: { type: 'text', label } },
+});
+
+const stackWithApp = (label: unknown) => ({
+  manifest: MANIFEST,
+  apps: [{ name: 'todo_app', label }],
+});
+
+const stackWithListLabel = (label: unknown) => ({
+  manifest: MANIFEST,
+  views: [{ name: 'invoice_views', object: 'invoice', list: { label, type: 'grid', columns: ['name'] } }],
+});
+
+const stackWithNamedListLabel = (label: unknown) => ({
+  manifest: MANIFEST,
+  views: [{
+    name: 'invoice_views',
+    object: 'invoice',
+    listViews: { all: { label, type: 'grid', columns: ['name'] } },
+  }],
+});
+
+describe('convention/label-case — the plain-string check does not move', () => {
+  // Falsification for every row: a guard that swallows strings as well as
+  // maps makes the lowercase rows report nothing and this whole block red.
+  const rows: [string, unknown, string][] = [
+    ['objects[].label', { objects: [objectWith('invoice')] }, 'objects[0].label'],
+    ['objects[].fields.*.label', { objects: [objectWithFieldLabel('invoice number')] }, 'objects[0].fields.name.label'],
+    ['views[].list.label', stackWithListLabel('accounts'), 'views[0].list.label'],
+    ['views[].listViews.*.label', stackWithNamedListLabel('all accounts'), 'views[0].listViews.all.label'],
+    ['apps[].label', stackWithApp('todos'), 'apps[0].label'],
+  ];
+
+  for (const [carrier, config, path] of rows) {
+    it(`still warns on a lowercase string at ${carrier}`, () => {
+      const issues = caseIssues(lintConfig(config as any));
+      expect(issues).toHaveLength(1);
+      expect(issues[0]).toEqual({
+        severity: 'warning',
+        rule: 'convention/label-case',
+        message: expect.stringContaining('should start with an uppercase letter'),
+        path,
+        fix: expect.any(String),
+      });
+    });
+  }
+
+  it('carries the label verbatim in the message and the capitalized value in `fix`', () => {
+    // The message/fix wording is what an author reads, so it is pinned whole
+    // on one row rather than left to `stringContaining` everywhere.
+    const [issue] = caseIssues(lintConfig(stackWithApp('todos') as any));
+    expect(issue).toMatchObject({
+      message: 'Label "todos" should start with an uppercase letter',
+      fix: 'Todos',
+    });
+  });
+
+  it('stays silent on an already-uppercase string', () => {
+    expect(caseIssues(lintConfig(stackWithApp('Todos') as any))).toEqual([]);
+  });
+
+  it('stays silent on a label whose first character has no case (unchanged)', () => {
+    // `'1st quarter'[0].toUpperCase()` === `'1'`, so the rule never fired here
+    // and must still not. A guard written as `label.length && ...` would keep
+    // this green; one written as "warn unless the first char is uppercase"
+    // would flip it. That is the distinction this row protects.
+    expect(caseIssues(lintConfig(stackWithApp('1st quarter') as any))).toEqual([]);
+  });
+});
+
+describe('convention/label-case — a localized label is walked, not indexed', () => {
+  // Falsification for every row: drop the `typeof label !== 'string'` guard
+  // and each of these throws `TypeError: Cannot read properties of undefined
+  // (reading 'toUpperCase')` instead of returning.
+  const rows: [string, (label: unknown) => unknown][] = [
+    ['apps[].label', stackWithApp],
+    ['views[].list.label', stackWithListLabel],
+    ['views[].listViews.*.label', stackWithNamedListLabel],
+  ];
+
+  for (const [carrier, build] of rows) {
+    it(`does not throw on an inline locale map at ${carrier}`, () => {
+      expect(() => lintConfig(build(LOCALIZED) as any)).not.toThrow();
+    });
+
+    it(`does not throw on an EMPTY locale map at ${carrier}`, () => {
+      // `{}` is the value the filed sweep actually mutated in, and it is a
+      // valid `InlineLocaleMapSchema` (a `z.record` with no entries).
+      expect(() => lintConfig(build(EMPTY_MAP) as any)).not.toThrow();
+    });
+
+    it(`reports no case verdict for the localized label at ${carrier}`, () => {
+      expect(caseIssues(lintConfig(build(LOCALIZED) as any))).toEqual([]);
+    });
+
+    it(`does not report the localized label as MISSING at ${carrier}`, () => {
+      // The other failure mode a careless guard produces: treat a non-string
+      // as absent and emit `required/label`, which would be a NEW error on a
+      // schema-valid config — the opposite of leaving behaviour where it was.
+      const issues = lintConfig(build(LOCALIZED) as any) as { rule: string }[];
+      expect(issues.filter((i) => i.rule === 'required/label')).toEqual([]);
+    });
+  }
+
+  it('does not throw on a non-string, non-map label either', () => {
+    // Schema-INVALID input (no label carrier accepts a number), so this is
+    // not the defect's class — but the guard is written on the type, not on
+    // the map shape, and a linter that dies on bad input still cannot report
+    // the bad input. Falsified by a guard spelled `if (isLocaleMap(label))`.
+    expect(() => lintConfig(stackWithApp(42) as any)).not.toThrow();
+    expect(caseIssues(lintConfig(stackWithApp(42) as any))).toEqual([]);
+  });
+});
+
+describe('the localized fixtures are schema-VALID — this is not bad input', () => {
+  // Falsification: if any of these stopped parsing, the crash rows above
+  // would be pinning a diagnostic degrading on bad input (acceptable) rather
+  // than a tool that cannot walk a supported authoring shape (the defect).
+  const stacks: [string, unknown][] = [
+    ['apps[].label', stackWithApp(LOCALIZED)],
+    ['views[].list.label', stackWithListLabel(LOCALIZED)],
+    ['views[].listViews.*.label', stackWithNamedListLabel(LOCALIZED)],
+    ['apps[].label, empty map', stackWithApp(EMPTY_MAP)],
+  ];
+
+  for (const [carrier, stack] of stacks) {
+    it(`${carrier} parses clean`, () => {
+      const parsed = ObjectStackDefinitionSchema.safeParse(normalizeStackInput(stack as any));
+      expect(parsed.success).toBe(true);
+    });
+  }
+
+  it('CONTROL: a number label does NOT parse, so the parse check discriminates', () => {
+    const parsed = ObjectStackDefinitionSchema.safeParse(normalizeStackInput(stackWithApp(42) as any));
+    expect(parsed.success).toBe(false);
+  });
+});
+
+describe('the scorer reaches a verdict on a localized stack', () => {
+  // The join with the swallowed-crash repair one module over: that repair
+  // makes `scoreMetadata` REFUSE when a rule throws. With the guard there is
+  // no throw, so the refusal must not fire here. Falsification: drop the
+  // guard and `lintError` is set, `valid` is false, `grade` is 'F'.
+  it('scores it without a lint crash', () => {
+    const r = scoreMetadata(stackWithApp(LOCALIZED));
+    expect(r.lintError).toBeUndefined();
+    expect(r.valid).toBe(true);
+    expect(r.counts.schemaErrors).toBe(0);
+    expect(r.grade).not.toBe('F');
+  });
+});
diff --git a/packages/cli/test/score-lint-crash.test.ts b/packages/cli/test/score-lint-crash.test.ts
index 559cbb3995..ef90e28958 100644
--- a/packages/cli/test/score-lint-crash.test.ts
+++ b/packages/cli/test/score-lint-crash.test.ts
@@ -6,12 +6,15 @@
  *
  * ## Why the linter is mocked here rather than driven
  *
- * The crash IS reachable on a schema-valid stack — a localized `label`
+ * The crash WAS reachable on a schema-valid stack — a localized `label`
  * (`{ en: …, 'zh-CN': … }`) on an app, or on a view's `list`, parses clean and
- * makes the label-case rule throw a `TypeError`. That is a defect in the rule,
- * filed on its own; pinning it here would make this suite depend on a bug
- * staying unfixed, and the day someone repairs the rule these assertions would
- * go green for the wrong reason — or be deleted to make them pass.
+ * made the label-case rule throw a `TypeError`. That was a defect in the rule,
+ * filed and fixed on its own (`convention/label-case` now guards on
+ * `typeof label === 'string'`; the pins live in
+ * `lint-label-case-localized.test.ts`). Pinning it here would have made this
+ * suite depend on a bug staying unfixed — and that day has since come: the
+ * repair landed, and had these assertions been driven through the real rule
+ * they would now be green for the wrong reason, or deleted to make them pass.
  *
  * What this file pins is the SCORER's contract, which holds for any throw from
  * any rule: a crash is recorded, never swallowed into `issues: []`. So the