diff --git a/.github/workflows/validate.yml b/.github/workflows/validate.yml
index 8a375774..b3ae480a 100644
--- a/.github/workflows/validate.yml
+++ b/.github/workflows/validate.yml
@@ -44,10 +44,5 @@ jobs:
       - name: Install dependencies
         run: pnpm install --frozen-lockfile=false --ignore-scripts
 
-      - name: Install pipx (for JSON schema validation)
-        run: |
-          python3 -m pip install --user pipx
-          python3 -m pipx ensurepath
-
       - name: Run pre-commit hooks against the full tree
         run: pnpm exec lefthook run pre-commit --all-files --force
diff --git a/lefthook.yml b/lefthook.yml
index 1277fc94..7821aa66 100644
--- a/lefthook.yml
+++ b/lefthook.yml
@@ -4,50 +4,21 @@ pre-commit:
     json-validity:
       glob: "**/*.json"
       run: |
-        has_schema_validator=0
-        if command -v pipx >/dev/null 2>&1; then
-          has_schema_validator=1
+        if ! command -v node >/dev/null 2>&1; then
+          echo "❌ node not available; cannot validate JSON"
+          exit 1
         fi
-        for f in {files}; do
-          [ -f "$f" ] || continue
-          if ! jq empty "$f" >/dev/null 2>&1; then
-            echo "❌ invalid JSON: $f"
-            exit 1
-          fi
-          schema=""
-          case "$f" in
-            *.claude-plugin/plugin.json|*/.claude-plugin/plugin.json)
-              schema="https://www.schemastore.org/claude-code-plugin-manifest.json" ;;
-            *.claude-plugin/marketplace.json|*/.claude-plugin/marketplace.json)
-              schema="https://www.schemastore.org/claude-code-marketplace.json" ;;
-            *.claude/settings.json|*.claude/settings.local.json|*/.claude/settings.json|*/.claude/settings.local.json)
-              schema="https://www.schemastore.org/claude-code-settings.json" ;;
-          esac
-          if [ -n "$schema" ] && [ "$has_schema_validator" = "1" ]; then
-            if ! pipx run check-jsonschema --schemafile "$schema" "$f" >/dev/null 2>&1; then
-              pipx run check-jsonschema --schemafile "$schema" "$f"
-              echo "❌ schema validation failed: $f against $schema"
-              exit 1
-            fi
-          fi
-        done
+        node scripts/validate-json.mjs {files}
     yaml-validity:
       glob: "**/*.{yml,yaml}"
       exclude:
         - "plugins/*/skills/*/assets/**"
       run: |
-        if ! command -v python3 >/dev/null 2>&1; then
-          echo "ℹ️  python3 not available; skipping yaml-validity"
-          exit 0
-        fi
-        if ! python3 -c "import yaml" >/dev/null 2>&1; then
-          echo "ℹ️  python3 yaml module not available; skipping yaml-validity"
-          exit 0
+        if ! command -v node >/dev/null 2>&1; then
+          echo "❌ node not available; cannot validate YAML"
+          exit 1
         fi
-        for f in {files}; do
-          [ -f "$f" ] || continue
-          python3 -c "import yaml; yaml.safe_load(open('$f'))" 2>/dev/null || { echo "❌ invalid YAML: $f"; exit 1; }
-        done
+        node scripts/validate-yaml.mjs {files}
     skill-frontmatter:
       glob: "plugins/*/skills/*/SKILL.md"
       run: |
diff --git a/package.json b/package.json
index e8606bee..8aa3446b 100644
--- a/package.json
+++ b/package.json
@@ -33,6 +33,9 @@
   "devDependencies": {
     "@commitlint/cli": "^21.0.2",
     "@commitlint/config-conventional": "^21.0.2",
+    "ajv": "8.20.0",
+    "ajv-formats": "3.0.1",
+    "js-yaml": "4.2.0",
     "lefthook": "^2.1.9"
   }
 }
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index d9a5efc9..2aaaa136 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -14,6 +14,15 @@ importers:
       '@commitlint/config-conventional':
         specifier: ^21.0.2
         version: 21.0.2
+      ajv:
+        specifier: 8.20.0
+        version: 8.20.0
+      ajv-formats:
+        specifier: 3.0.1
+        version: 3.0.1(ajv@8.20.0)
+      js-yaml:
+        specifier: 4.2.0
+        version: 4.2.0
       lefthook:
         specifier: ^2.1.9
         version: 2.1.9
@@ -120,6 +129,14 @@ packages:
   '@types/node@25.3.5':
     resolution: {integrity: sha512-oX8xrhvpiyRCQkG1MFchB09f+cXftgIXb3a7UUa4Y3wpmZPw5tyZGTLWhlESOLq1Rq6oDlc8npVU2/9xiCuXMA==}
 
+  ajv-formats@3.0.1:
+    resolution: {integrity: sha512-8iUql50EUR+uUcdRQ3HDqa6EVyo3docL8g5WJ3FNcWmu62IbkGUue/pEyLBW8VGKKucTPgqeks4fIU1DA4yowQ==}
+    peerDependencies:
+      ajv: ^8.0.0
+    peerDependenciesMeta:
+      ajv:
+        optional: true
+
   ajv@8.20.0:
     resolution: {integrity: sha512-Thbli+OlOj+iMPYFBVBfJ3OmCAnaSyNn4M1vz9T6Gka5Jt9ba/HIR56joy65tY6kx/FCF5VXNB819Y7/GUrBGA==}
 
@@ -519,6 +536,10 @@ snapshots:
     dependencies:
       undici-types: 7.18.2
 
+  ajv-formats@3.0.1(ajv@8.20.0):
+    optionalDependencies:
+      ajv: 8.20.0
+
   ajv@8.20.0:
     dependencies:
       fast-deep-equal: 3.1.3
diff --git a/scripts/validate-json.mjs b/scripts/validate-json.mjs
new file mode 100755
index 00000000..b43af257
--- /dev/null
+++ b/scripts/validate-json.mjs
@@ -0,0 +1,229 @@
+#!/usr/bin/env node
+// JSON validator for framework files. It always checks JSON syntax, validates
+// Claude metadata against SchemaStore when available, and falls back to local
+// structural checks if remote schemas cannot be loaded.
+
+import { access, readFile } from "node:fs/promises";
+import path from "node:path";
+import Ajv from "ajv";
+import addFormats from "ajv-formats";
+
+const ROOT = process.cwd();
+const INPUTS = process.argv.slice(2).filter((file) => file !== "--");
+const SCHEMA_TIMEOUT_MS = 10_000;
+const ajv = new Ajv({ allErrors: true, strict: false });
+addFormats(ajv);
+const errors = [];
+const warnings = [];
+const schemaCache = new Map();
+
+const SCHEMAS = {
+  pluginManifest: "https://www.schemastore.org/claude-code-plugin-manifest.json",
+  marketplace: "https://www.schemastore.org/claude-code-marketplace.json",
+  claudeSettings: "https://www.schemastore.org/claude-code-settings.json",
+};
+
+function fail(file, message) {
+  errors.push(`${file}: ${message}`);
+}
+
+function warn(file, message) {
+  warnings.push(`${file}: ${message}`);
+}
+
+function isObject(value) {
+  return value !== null && typeof value === "object" && !Array.isArray(value);
+}
+
+function requireString(file, object, key) {
+  if (typeof object[key] !== "string" || object[key].trim() === "") {
+    fail(file, `missing or invalid string field '${key}'`);
+  }
+}
+
+function requireStringArray(file, object, key) {
+  if (!Array.isArray(object[key]) || object[key].some((value) => typeof value !== "string" || value.trim() === "")) {
+    fail(file, `missing or invalid string array '${key}'`);
+  }
+}
+
+async function pathExists(file, relativePath, label, baseDir = path.dirname(path.join(ROOT, file))) {
+  try {
+    await access(path.resolve(baseDir, relativePath));
+  } catch {
+    fail(file, `${label} does not exist: ${relativePath}`);
+  }
+}
+
+function schemaFor(file) {
+  if (file.endsWith(".claude-plugin/plugin.json") || file.includes("/.claude-plugin/plugin.json")) {
+    return { type: "pluginManifest", url: SCHEMAS.pluginManifest };
+  }
+  if (file.endsWith(".claude-plugin/marketplace.json") || file.includes("/.claude-plugin/marketplace.json")) {
+    return { type: "marketplace", url: SCHEMAS.marketplace };
+  }
+  if (file.endsWith(".claude/settings.json") || file.endsWith(".claude/settings.local.json") || file.includes("/.claude/settings.")) {
+    return { type: "claudeSettings", url: SCHEMAS.claudeSettings };
+  }
+  return null;
+}
+
+async function loadSchemaValidator(url) {
+  if (schemaCache.has(url)) return schemaCache.get(url);
+
+  const validatorPromise = (async () => {
+    const controller = new AbortController();
+    const timeout = setTimeout(() => controller.abort(), SCHEMA_TIMEOUT_MS);
+
+    try {
+      const response = await fetch(url, { signal: controller.signal });
+      if (!response.ok) {
+        throw new Error(`HTTP ${response.status}`);
+      }
+      const schema = await response.json();
+      return ajv.compile(schema);
+    } finally {
+      clearTimeout(timeout);
+    }
+  })();
+
+  schemaCache.set(url, validatorPromise);
+  return validatorPromise;
+}
+
+function formatSchemaError(error) {
+  const location = error.instancePath || "/";
+  const message = error.message ?? "schema validation failed";
+  return `${location} ${message}`;
+}
+
+async function validateAgainstRemoteSchema(file, data, schema) {
+  let validator;
+  try {
+    validator = await loadSchemaValidator(schema.url);
+  } catch (error) {
+    warn(file, `could not load ${schema.url}; using local fallback (${error.message})`);
+    return false;
+  }
+
+  if (!validator(data)) {
+    for (const error of validator.errors ?? []) {
+      fail(file, formatSchemaError(error));
+    }
+  }
+  return true;
+}
+
+async function validatePluginManifestFallback(file, data) {
+  for (const key of ["name", "version", "description", "repository", "homepage", "license"]) {
+    requireString(file, data, key);
+  }
+  if (!isObject(data.author)) {
+    fail(file, "missing or invalid object field 'author'");
+  } else {
+    requireString(file, data.author, "name");
+  }
+  requireStringArray(file, data, "skills");
+  const pluginRoot = path.dirname(path.dirname(path.join(ROOT, file)));
+  for (const skillPath of data.skills ?? []) {
+    await pathExists(file, skillPath, "skill path", pluginRoot);
+  }
+  if (data.agents !== undefined) {
+    requireStringArray(file, data, "agents");
+    for (const agentPath of data.agents ?? []) {
+      await pathExists(file, agentPath, "agent path", pluginRoot);
+    }
+  }
+  if (data.keywords !== undefined) {
+    requireStringArray(file, data, "keywords");
+  }
+}
+
+async function validateMarketplaceFallback(file, data) {
+  for (const key of ["name", "version", "description"]) {
+    requireString(file, data, key);
+  }
+  if (!isObject(data.owner)) {
+    fail(file, "missing or invalid object field 'owner'");
+  } else {
+    requireString(file, data.owner, "name");
+  }
+  if (!Array.isArray(data.plugins) || data.plugins.length === 0) {
+    fail(file, "missing or invalid non-empty array 'plugins'");
+    return;
+  }
+  const names = new Set();
+  for (const [index, plugin] of data.plugins.entries()) {
+    const label = `plugins[${index}]`;
+    if (!isObject(plugin)) {
+      fail(file, `${label} must be an object`);
+      continue;
+    }
+    for (const key of ["name", "version", "source", "description"]) {
+      if (typeof plugin[key] !== "string" || plugin[key].trim() === "") {
+        fail(file, `${label}.${key} must be a non-empty string`);
+      }
+    }
+    if (names.has(plugin.name)) fail(file, `duplicate plugin name: ${plugin.name}`);
+    names.add(plugin.name);
+    if (typeof plugin.strict !== "boolean") fail(file, `${label}.strict must be boolean`);
+    if (typeof plugin.recommended !== "boolean") fail(file, `${label}.recommended must be boolean`);
+    if (typeof plugin.source === "string") await pathExists(file, plugin.source, `${label}.source`, ROOT);
+  }
+}
+
+function validateClaudeSettingsFallback(file, data) {
+  if (data.extraKnownMarketplaces !== undefined && !isObject(data.extraKnownMarketplaces)) {
+    fail(file, "extraKnownMarketplaces must be an object when present");
+  }
+  if (data.enabledPlugins !== undefined) {
+    if (!isObject(data.enabledPlugins)) {
+      fail(file, "enabledPlugins must be an object when present");
+    } else {
+      for (const [name, enabled] of Object.entries(data.enabledPlugins)) {
+        if (typeof enabled !== "boolean") fail(file, `enabledPlugins.${name} must be boolean`);
+      }
+    }
+  }
+}
+
+async function validateWithLocalFallback(file, data, type) {
+  if (type === "pluginManifest") {
+    await validatePluginManifestFallback(file, data);
+  } else if (type === "marketplace") {
+    await validateMarketplaceFallback(file, data);
+  } else if (type === "claudeSettings") {
+    validateClaudeSettingsFallback(file, data);
+  }
+}
+
+async function validate(file) {
+  let data;
+  try {
+    data = JSON.parse(await readFile(path.join(ROOT, file), "utf8"));
+  } catch (error) {
+    fail(file, `invalid JSON (${error.message})`);
+    return;
+  }
+
+  const schema = schemaFor(file);
+  if (!schema) return;
+
+  const usedRemoteSchema = await validateAgainstRemoteSchema(file, data, schema);
+  if (!usedRemoteSchema) await validateWithLocalFallback(file, data, schema.type);
+}
+
+for (const file of INPUTS) {
+  await validate(file);
+}
+
+if (errors.length > 0) {
+  console.error(errors.map((error) => `❌ ${error}`).join("\n"));
+  process.exit(1);
+}
+
+if (warnings.length > 0) {
+  console.warn(warnings.map((warning) => `⚠️  ${warning}`).join("\n"));
+}
+
+console.log(`JSON validation passed for ${INPUTS.length} file(s).`);
diff --git a/scripts/validate-yaml.mjs b/scripts/validate-yaml.mjs
new file mode 100755
index 00000000..e667e2f3
--- /dev/null
+++ b/scripts/validate-yaml.mjs
@@ -0,0 +1,23 @@
+#!/usr/bin/env node
+// Validates YAML syntax using the repository's Node dependency, avoiding Python in hooks.
+
+import { readFile } from "node:fs/promises";
+import yaml from "js-yaml";
+
+const files = process.argv.slice(2).filter((file) => file !== "--");
+const errors = [];
+
+for (const file of files) {
+  try {
+    yaml.load(await readFile(file, "utf8"), { filename: file });
+  } catch (error) {
+    errors.push(`${file}: ${error.message}`);
+  }
+}
+
+if (errors.length > 0) {
+  console.error(errors.map((error) => `❌ ${error}`).join("\n"));
+  process.exit(1);
+}
+
+console.log(`YAML validation passed for ${files.length} file(s).`);