diff --git a/manifests/install-components.json b/manifests/install-components.json
index 039d55cf..0cc630a1 100644
--- a/manifests/install-components.json
+++ b/manifests/install-components.json
@@ -531,31 +531,31 @@
       "family": "locale",
       "description": "Japanese (ja-JP) translated reference docs installed to ~/.claude/docs/ja-JP/.",
       "modules": [
-        "docs-ja-JP"
+        "docs-ja-jp"
       ]
     },
     {
-      "id": "locale:zh-CN",
+      "id": "locale:zh-cn",
       "family": "locale",
       "description": "Simplified Chinese (zh-CN) translated reference docs installed to ~/.claude/docs/zh-CN/.",
       "modules": [
-        "docs-zh-CN"
+        "docs-zh-cn"
       ]
     },
     {
-      "id": "locale:ko-KR",
+      "id": "locale:ko-kr",
       "family": "locale",
       "description": "Korean (ko-KR) translated reference docs installed to ~/.claude/docs/ko-KR/.",
       "modules": [
-        "docs-ko-KR"
+        "docs-ko-kr"
       ]
     },
     {
-      "id": "locale:pt-BR",
+      "id": "locale:pt-br",
       "family": "locale",
       "description": "Brazilian Portuguese (pt-BR) translated reference docs installed to ~/.claude/docs/pt-BR/.",
       "modules": [
-        "docs-pt-BR"
+        "docs-pt-br"
       ]
     },
     {
@@ -575,19 +575,19 @@
       ]
     },
     {
-      "id": "locale:vi-VN",
+      "id": "locale:vi-vn",
       "family": "locale",
       "description": "Vietnamese (vi-VN) translated reference docs installed to ~/.claude/docs/vi-VN/.",
       "modules": [
-        "docs-vi-VN"
+        "docs-vi-vn"
       ]
     },
     {
-      "id": "locale:zh-TW",
+      "id": "locale:zh-tw",
       "family": "locale",
       "description": "Traditional Chinese (zh-TW) translated reference docs installed to ~/.claude/docs/zh-TW/.",
       "modules": [
-        "docs-zh-TW"
+        "docs-zh-tw"
       ]
     }
   ]
diff --git a/manifests/install-modules.json b/manifests/install-modules.json
index 4cf7e709..5f9c8754 100644
--- a/manifests/install-modules.json
+++ b/manifests/install-modules.json
@@ -695,7 +695,7 @@
       "stability": "stable"
     },
     {
-      "id": "docs-ja-JP",
+      "id": "docs-ja-jp",
       "kind": "docs",
       "description": "Japanese (ja-JP) translated reference docs for agents, commands, skills, and rules.",
       "paths": [
@@ -710,7 +710,7 @@
       "stability": "stable"
     },
     {
-      "id": "docs-zh-CN",
+      "id": "docs-zh-cn",
       "kind": "docs",
       "description": "Simplified Chinese (zh-CN) translated reference docs for agents, commands, skills, and rules.",
       "paths": [
@@ -725,7 +725,7 @@
       "stability": "stable"
     },
     {
-      "id": "docs-ko-KR",
+      "id": "docs-ko-kr",
       "kind": "docs",
       "description": "Korean (ko-KR) translated reference docs for agents, commands, skills, and rules.",
       "paths": [
@@ -740,7 +740,7 @@
       "stability": "stable"
     },
     {
-      "id": "docs-pt-BR",
+      "id": "docs-pt-br",
       "kind": "docs",
       "description": "Brazilian Portuguese (pt-BR) translated reference docs for agents, commands, skills, and rules.",
       "paths": [
@@ -785,7 +785,7 @@
       "stability": "stable"
     },
     {
-      "id": "docs-vi-VN",
+      "id": "docs-vi-vn",
       "kind": "docs",
       "description": "Vietnamese (vi-VN) translated reference docs for agents, commands, skills, and rules.",
       "paths": [
@@ -800,7 +800,7 @@
       "stability": "stable"
     },
     {
-      "id": "docs-zh-TW",
+      "id": "docs-zh-tw",
       "kind": "docs",
       "description": "Traditional Chinese (zh-TW) translated reference docs for agents, commands, skills, and rules.",
       "paths": [
diff --git a/package.json b/package.json
index 72d9735d..af498b8f 100644
--- a/package.json
+++ b/package.json
@@ -56,6 +56,14 @@
     "agent.yaml",
     "agents/",
     "commands/",
+    "docs/ja-JP/",
+    "docs/ko-KR/",
+    "docs/pt-BR/",
+    "docs/ru/",
+    "docs/tr/",
+    "docs/vi-VN/",
+    "docs/zh-CN/",
+    "docs/zh-TW/",
     "hooks/",
     "install.ps1",
     "install.sh",
diff --git a/schemas/install-components.schema.json b/schemas/install-components.schema.json
index c77878da..d72f41b0 100644
--- a/schemas/install-components.schema.json
+++ b/schemas/install-components.schema.json
@@ -26,7 +26,7 @@
         "properties": {
           "id": {
             "type": "string",
-            "pattern": "^(baseline|lang|framework|capability|agent|skill):[a-z0-9-]+$"
+            "pattern": "^(baseline|lang|framework|capability|agent|skill|locale):[a-z0-9-]+$"
           },
           "family": {
             "type": "string",
@@ -36,7 +36,8 @@
               "framework",
               "capability",
               "agent",
-              "skill"
+              "skill",
+              "locale"
             ]
           },
           "description": {
diff --git a/schemas/install-modules.schema.json b/schemas/install-modules.schema.json
index 12573377..252f8e82 100644
--- a/schemas/install-modules.schema.json
+++ b/schemas/install-modules.schema.json
@@ -26,7 +26,8 @@
               "hooks",
               "platform",
               "orchestration",
-              "skills"
+              "skills",
+              "docs"
             ]
           },
           "description": {
diff --git a/scripts/ci/validate-install-manifests.js b/scripts/ci/validate-install-manifests.js
index 26c4c5ad..7f1f4f24 100644
--- a/scripts/ci/validate-install-manifests.js
+++ b/scripts/ci/validate-install-manifests.js
@@ -21,6 +21,7 @@ const COMPONENT_FAMILY_PREFIXES = {
   language: 'lang:',
   framework: 'framework:',
   capability: 'capability:',
+  locale: 'locale:',
 };
 
 function readJson(filePath, label) {
@@ -163,9 +164,12 @@ function validateInstallManifests() {
 
   if (profiles.full) {
     const fullModules = new Set(profiles.full.modules);
-    for (const moduleId of moduleIds) {
-      if (!fullModules.has(moduleId)) {
-        console.error(`ERROR: full profile is missing module ${moduleId}`);
+    for (const module of modules) {
+      if (module.kind === 'docs' && module.defaultInstall === false) {
+        continue;
+      }
+      if (!fullModules.has(module.id)) {
+        console.error(`ERROR: full profile is missing module ${module.id}`);
         hasErrors = true;
       }
     }
diff --git a/scripts/lib/install-executor.js b/scripts/lib/install-executor.js
index d7a5e4ee..a8311fc1 100644
--- a/scripts/lib/install-executor.js
+++ b/scripts/lib/install-executor.js
@@ -555,6 +555,12 @@ function createLegacyCompatInstallPlan(options = {}) {
   const sourceRoot = options.sourceRoot || getSourceRoot();
   const projectRoot = options.projectRoot || process.cwd();
   const target = options.target || 'claude';
+  const includeComponentIds = Array.isArray(options.includeComponentIds)
+    ? [...options.includeComponentIds]
+    : [];
+  const excludeComponentIds = Array.isArray(options.excludeComponentIds)
+    ? [...options.excludeComponentIds]
+    : [];
 
   validateLegacyTarget(target);
 
@@ -571,14 +577,14 @@ function createLegacyCompatInstallPlan(options = {}) {
     target,
     profileId: null,
     moduleIds: selection.moduleIds,
-    includeComponentIds: [],
-    excludeComponentIds: [],
+    includeComponentIds,
+    excludeComponentIds,
     legacyLanguages: selection.legacyLanguages,
     legacyMode: true,
     requestProfileId: null,
     requestModuleIds: [],
-    requestIncludeComponentIds: [],
-    requestExcludeComponentIds: [],
+    requestIncludeComponentIds: includeComponentIds,
+    requestExcludeComponentIds: excludeComponentIds,
     mode: 'legacy-compat',
   });
 }
diff --git a/scripts/lib/install-manifests.js b/scripts/lib/install-manifests.js
index 14e6769b..c27d5e23 100644
--- a/scripts/lib/install-manifests.js
+++ b/scripts/lib/install-manifests.js
@@ -18,17 +18,17 @@ const SUPPORTED_LOCALES = Object.freeze(['ja', 'zh-CN', 'ko-KR', 'pt-BR', 'ru',
 const LOCALE_ALIAS_TO_COMPONENT_ID = Object.freeze({
   'ja': 'locale:ja',
   'ja-JP': 'locale:ja',
-  'zh-CN': 'locale:zh-CN',
-  'zh': 'locale:zh-CN',
-  'ko-KR': 'locale:ko-KR',
-  'ko': 'locale:ko-KR',
-  'pt-BR': 'locale:pt-BR',
-  'pt': 'locale:pt-BR',
+  'zh-CN': 'locale:zh-cn',
+  'zh': 'locale:zh-cn',
+  'ko-KR': 'locale:ko-kr',
+  'ko': 'locale:ko-kr',
+  'pt-BR': 'locale:pt-br',
+  'pt': 'locale:pt-br',
   'ru': 'locale:ru',
   'tr': 'locale:tr',
-  'vi-VN': 'locale:vi-VN',
-  'vi': 'locale:vi-VN',
-  'zh-TW': 'locale:zh-TW',
+  'vi-VN': 'locale:vi-vn',
+  'vi': 'locale:vi-vn',
+  'zh-TW': 'locale:zh-tw',
 });
 
 function listSupportedLocales() {
diff --git a/scripts/lib/install/request.js b/scripts/lib/install/request.js
index 52a79e1e..4cf5c043 100644
--- a/scripts/lib/install/request.js
+++ b/scripts/lib/install/request.js
@@ -62,7 +62,11 @@ function parseInstallArgs(argv) {
       }
       index += 1;
     } else if (arg === '--locale') {
-      parsed.locale = args[index + 1] || null;
+      const locale = args[index + 1] || '';
+      if (!locale || locale.startsWith('--')) {
+        throw new Error('Missing value for --locale');
+      }
+      parsed.locale = locale;
       index += 1;
     } else if (arg === '--dry-run') {
       parsed.dryRun = true;
@@ -85,6 +89,7 @@ function normalizeInstallRequest(options = {}) {
     ? options.config
     : null;
   const profileId = options.profileId || config?.profileId || null;
+  const target = options.target || config?.target || 'claude';
   const moduleIds = validateInstallModuleIds(
     dedupeStrings([...(config?.moduleIds || []), ...(options.moduleIds || [])])
   );
@@ -95,9 +100,15 @@ function normalizeInstallRequest(options = {}) {
       `Unsupported locale: "${locale}". Supported locales: ${listSupportedLocales().join(', ')}`
     );
   }
-  const includeComponentIds = dedupeStrings([
+  if (locale && target !== 'claude') {
+    throw new Error('--locale can only be used with --target claude');
+  }
+  const requestedIncludeComponentIds = dedupeStrings([
     ...(config?.includeComponentIds || []),
     ...(options.includeComponentIds || []),
+  ]);
+  const includeComponentIds = dedupeStrings([
+    ...requestedIncludeComponentIds,
     ...(localeComponentId ? [localeComponentId] : []),
   ]);
   const excludeComponentIds = dedupeStrings([
@@ -108,13 +119,16 @@ function normalizeInstallRequest(options = {}) {
     ...(Array.isArray(options.legacyLanguages) ? options.legacyLanguages : []),
     ...(Array.isArray(options.languages) ? options.languages : []),
   ]).map(language => language.toLowerCase()));
-  const target = options.target || config?.target || 'claude';
   const hasManifestBaseSelection = Boolean(profileId) || moduleIds.length > 0 || includeComponentIds.length > 0;
+  const hasNonLocaleManifestSelection = Boolean(profileId)
+    || moduleIds.length > 0
+    || requestedIncludeComponentIds.length > 0
+    || excludeComponentIds.length > 0;
   const usingManifestMode = hasManifestBaseSelection || excludeComponentIds.length > 0;
 
-  if (usingManifestMode && legacyLanguages.length > 0) {
+  if (hasNonLocaleManifestSelection && legacyLanguages.length > 0) {
     throw new Error(
-      'Legacy language arguments cannot be combined with --profile, --modules, --with, --without, --locale, or manifest config selections'
+      'Legacy language arguments cannot be combined with --profile, --modules, --with, --without, or manifest config selections'
     );
   }
 
@@ -123,7 +137,9 @@ function normalizeInstallRequest(options = {}) {
   }
 
   return {
-    mode: usingManifestMode ? 'manifest' : 'legacy-compat',
+    mode: legacyLanguages.length > 0
+      ? 'legacy-compat'
+      : (usingManifestMode ? 'manifest' : 'legacy-compat'),
     target,
     profileId,
     moduleIds,
diff --git a/scripts/lib/install/runtime.js b/scripts/lib/install/runtime.js
index 91a340c8..55f55bfb 100644
--- a/scripts/lib/install/runtime.js
+++ b/scripts/lib/install/runtime.js
@@ -28,6 +28,8 @@ function createInstallPlanFromRequest(request, options = {}) {
     return createLegacyCompatInstallPlan({
       target: request.target,
       legacyLanguages: request.legacyLanguages,
+      includeComponentIds: request.includeComponentIds,
+      excludeComponentIds: request.excludeComponentIds,
       projectRoot: options.projectRoot,
       homeDir: options.homeDir,
       claudeRulesDir: options.claudeRulesDir,
diff --git a/tests/lib/install-request.test.js b/tests/lib/install-request.test.js
index 18e0ec37..614c8ee2 100644
--- a/tests/lib/install-request.test.js
+++ b/tests/lib/install-request.test.js
@@ -52,6 +52,29 @@ function runTests() {
     assert.deepStrictEqual(parsed.languages, []);
   })) passed++; else failed++;
 
+  if (test('parses --locale argument', () => {
+    const parsed = parseInstallArgs([
+      'node',
+      'scripts/install-apply.js',
+      '--locale', 'ja'
+    ]);
+
+    assert.strictEqual(parsed.locale, 'ja');
+    assert.deepStrictEqual(parsed.languages, []);
+  })) passed++; else failed++;
+
+  if (test('requires a --locale value', () => {
+    assert.throws(
+      () => parseInstallArgs([
+        'node',
+        'scripts/install-apply.js',
+        '--locale',
+        '--dry-run'
+      ]),
+      /Missing value for --locale/
+    );
+  })) passed++; else failed++;
+
   if (test('normalizes legacy language installs into a canonical request', () => {
     const request = normalizeInstallRequest({
       target: 'claude',
@@ -67,6 +90,69 @@ function runTests() {
     assert.strictEqual(request.profileId, null);
   })) passed++; else failed++;
 
+  if (test('normalizes locale-only installs as manifest component requests', () => {
+    const request = normalizeInstallRequest({
+      target: 'claude',
+      profileId: null,
+      moduleIds: [],
+      includeComponentIds: [],
+      excludeComponentIds: [],
+      languages: [],
+      locale: 'ja',
+    });
+
+    assert.strictEqual(request.mode, 'manifest');
+    assert.strictEqual(request.target, 'claude');
+    assert.deepStrictEqual(request.includeComponentIds, ['locale:ja']);
+    assert.deepStrictEqual(request.legacyLanguages, []);
+  })) passed++; else failed++;
+
+  if (test('allows legacy language installs to include a locale component', () => {
+    const request = normalizeInstallRequest({
+      target: 'claude',
+      profileId: null,
+      moduleIds: [],
+      includeComponentIds: [],
+      excludeComponentIds: [],
+      languages: ['typescript'],
+      locale: 'ja-JP',
+    });
+
+    assert.strictEqual(request.mode, 'legacy-compat');
+    assert.deepStrictEqual(request.legacyLanguages, ['typescript']);
+    assert.deepStrictEqual(request.includeComponentIds, ['locale:ja']);
+  })) passed++; else failed++;
+
+  if (test('rejects unsupported locale codes', () => {
+    assert.throws(
+      () => normalizeInstallRequest({
+        target: 'claude',
+        profileId: null,
+        moduleIds: [],
+        includeComponentIds: [],
+        excludeComponentIds: [],
+        languages: [],
+        locale: 'fr',
+      }),
+      /Unsupported locale/
+    );
+  })) passed++; else failed++;
+
+  if (test('rejects --locale for non-Claude targets', () => {
+    assert.throws(
+      () => normalizeInstallRequest({
+        target: 'cursor',
+        profileId: null,
+        moduleIds: [],
+        includeComponentIds: [],
+        excludeComponentIds: [],
+        languages: [],
+        locale: 'ja',
+      }),
+      /--locale can only be used with --target claude/
+    );
+  })) passed++; else failed++;
+
   if (test('normalizes manifest installs into a canonical request', () => {
     const request = normalizeInstallRequest({
       target: 'cursor',
diff --git a/tests/lib/locale-install.test.js b/tests/lib/locale-install.test.js
new file mode 100644
index 00000000..6e108b18
--- /dev/null
+++ b/tests/lib/locale-install.test.js
@@ -0,0 +1,172 @@
+/**
+ * Tests for --locale translated docs installs.
+ */
+
+const assert = require('assert');
+const fs = require('fs');
+const os = require('os');
+const path = require('path');
+const { execFileSync } = require('child_process');
+
+const {
+  listInstallComponents,
+  resolveInstallPlan,
+} = require('../../scripts/lib/install-manifests');
+
+function normalizePlanPath(value) {
+  return String(value || '').replace(/\\/g, '/');
+}
+
+function runInstallApply(args, options = {}) {
+  const scriptPath = path.join(__dirname, '..', '..', 'scripts', 'install-apply.js');
+  return execFileSync('node', [scriptPath, ...args], {
+    cwd: options.cwd || process.cwd(),
+    env: { ...process.env, ...(options.env || {}) },
+    encoding: 'utf8',
+    maxBuffer: 16 * 1024 * 1024,
+    stdio: ['pipe', 'pipe', 'pipe'],
+  });
+}
+
+function test(name, fn) {
+  try {
+    fn();
+    console.log(`  \u2713 ${name}`);
+    return true;
+  } catch (error) {
+    console.log(`  \u2717 ${name}`);
+    console.log(`    Error: ${error.message}`);
+    return false;
+  }
+}
+
+function runTests() {
+  console.log('\n=== Testing --locale translated docs installs ===\n');
+
+  let passed = 0;
+  let failed = 0;
+
+  if (test('component catalog includes locale entries', () => {
+    const components = listInstallComponents({ family: 'locale' });
+    assert.ok(components.some(component => component.id === 'locale:ja'));
+    assert.ok(components.some(component => component.id === 'locale:zh-cn'));
+    assert.ok(components.every(component => component.family === 'locale'));
+  })) passed++; else failed++;
+
+  if (test('locale component resolves to the translated docs module', () => {
+    const homeDir = fs.mkdtempSync(path.join(os.tmpdir(), 'locale-plan-'));
+    try {
+      const plan = resolveInstallPlan({
+        includeComponentIds: ['locale:ja'],
+        target: 'claude',
+        homeDir,
+      });
+
+      assert.deepStrictEqual(plan.selectedModuleIds, ['docs-ja-jp']);
+      assert.ok(
+        plan.operations.some(operation => (
+          normalizePlanPath(operation.sourceRelativePath) === 'docs/ja-JP'
+          && normalizePlanPath(operation.destinationPath).endsWith('/.claude/docs/ja-JP')
+        )),
+        'Should map docs/ja-JP to ~/.claude/docs/ja-JP'
+      );
+    } finally {
+      fs.rmSync(homeDir, { recursive: true, force: true });
+    }
+  })) passed++; else failed++;
+
+  if (test('end-to-end: --locale ja dry-run includes docs-ja-jp operations', () => {
+    const homeDir = fs.mkdtempSync(path.join(os.tmpdir(), 'locale-dry-run-'));
+    const projectDir = fs.mkdtempSync(path.join(os.tmpdir(), 'locale-dry-run-project-'));
+
+    try {
+      const output = runInstallApply([
+        '--locale', 'ja',
+        '--dry-run',
+        '--json',
+      ], {
+        cwd: projectDir,
+        env: { HOME: homeDir },
+      });
+      const json = JSON.parse(output);
+
+      assert.strictEqual(json.plan.mode, 'manifest');
+      assert.deepStrictEqual(json.plan.includedComponentIds, ['locale:ja']);
+      assert.deepStrictEqual(json.plan.selectedModuleIds, ['docs-ja-jp']);
+      assert.ok(
+        json.plan.operations.some(operation => (
+          normalizePlanPath(operation.sourceRelativePath) === 'docs/ja-JP/README.md'
+          && normalizePlanPath(operation.destinationPath).endsWith('/.claude/docs/ja-JP/README.md')
+        )),
+        'Should copy translated README into ~/.claude/docs/ja-JP'
+      );
+    } finally {
+      fs.rmSync(homeDir, { recursive: true, force: true });
+      fs.rmSync(projectDir, { recursive: true, force: true });
+    }
+  })) passed++; else failed++;
+
+  if (test('end-to-end: legacy language plus --locale keeps legacy install and docs', () => {
+    const homeDir = fs.mkdtempSync(path.join(os.tmpdir(), 'locale-legacy-dry-run-'));
+    const projectDir = fs.mkdtempSync(path.join(os.tmpdir(), 'locale-legacy-dry-run-project-'));
+
+    try {
+      const output = runInstallApply([
+        'typescript',
+        '--locale', 'ja',
+        '--dry-run',
+        '--json',
+      ], {
+        cwd: projectDir,
+        env: { HOME: homeDir },
+      });
+      const json = JSON.parse(output);
+
+      assert.strictEqual(json.plan.mode, 'legacy-compat');
+      assert.deepStrictEqual(json.plan.legacyLanguages, ['typescript']);
+      assert.ok(json.plan.includedComponentIds.includes('locale:ja'));
+      assert.ok(json.plan.selectedModuleIds.includes('framework-language'));
+      assert.ok(json.plan.selectedModuleIds.includes('docs-ja-jp'));
+    } finally {
+      fs.rmSync(homeDir, { recursive: true, force: true });
+      fs.rmSync(projectDir, { recursive: true, force: true });
+    }
+  })) passed++; else failed++;
+
+  if (test('end-to-end: --locale ja installs translated docs side-by-side', () => {
+    const homeDir = fs.mkdtempSync(path.join(os.tmpdir(), 'locale-install-'));
+    const projectDir = fs.mkdtempSync(path.join(os.tmpdir(), 'locale-install-project-'));
+
+    try {
+      runInstallApply([
+        '--locale', 'ja',
+      ], {
+        cwd: projectDir,
+        env: { HOME: homeDir },
+      });
+
+      const claudeRoot = path.join(homeDir, '.claude');
+      assert.ok(
+        fs.existsSync(path.join(claudeRoot, 'docs', 'ja-JP', 'README.md')),
+        'Should install Japanese README under docs/ja-JP'
+      );
+      assert.ok(
+        !fs.existsSync(path.join(claudeRoot, 'skills', 'ecc', 'configure-ecc', 'SKILL.md')),
+        'Locale-only install should not install English skills'
+      );
+
+      const statePath = path.join(claudeRoot, 'ecc', 'install-state.json');
+      const state = JSON.parse(fs.readFileSync(statePath, 'utf8'));
+      assert.deepStrictEqual(state.request.includeComponents, ['locale:ja']);
+      assert.deepStrictEqual(state.resolution.selectedModules, ['docs-ja-jp']);
+    } finally {
+      fs.rmSync(homeDir, { recursive: true, force: true });
+      fs.rmSync(projectDir, { recursive: true, force: true });
+    }
+  })) passed++; else failed++;
+
+  console.log(`\nResults: Passed: ${passed}, Failed: ${failed}`);
+  process.exit(failed > 0 ? 1 : 0);
+}
+
+runTests();