feat: add UV runtime support in manifest v0.4

Add UV as a new server type for Python extensions that use UV runtime
for dependency management instead of bundling dependencies.

Schema changes (v0.4):
- Add "uv" to server.type enum
- Make mcp_config optional (not needed for UV type)
- UV extensions rely on pyproject.toml for dependencies

Documentation:
- Add UV runtime section to MANIFEST.md explaining benefits and usage
- Update README.md to recommend UV runtime for Python
- Add complete hello-world-uv example

Benefits of UV runtime:
- Cross-platform support (Windows/macOS/Linux, Intel/ARM)
- Small bundle size (~100 KB vs 5-10 MB)
- Handles compiled dependencies portably
- No user Python installation required

Example manifest:
{
  "manifest_version": "0.4",
  "server": {
    "type": "uv",
    "entry_point": "src/server.py"
  }
}

Co-authored-by: Joan <joan@anthropic.com>

src/schemas_loose/0.4.ts

@@ -0,0 +1,151 @@
+import * as z from "zod";
+
+export const MANIFEST_VERSION = "0.4";
+
+const LOCALE_PLACEHOLDER_REGEX = /\$\{locale\}/i;
+const BCP47_REGEX = /^[A-Za-z0-9]{2,8}(?:-[A-Za-z0-9]{1,8})*$/;
+const ICON_SIZE_REGEX = /^\d+x\d+$/;
+
+export const McpServerConfigSchema = z.object({
+  command: z.string(),
+  args: z.array(z.string()).optional(),
+  env: z.record(z.string(), z.string()).optional(),
+});
+
+export const McpbManifestAuthorSchema = z.object({
+  name: z.string(),
+  email: z.string().email().optional(),
+  url: z.string().url().optional(),
+});
+
+export const McpbManifestRepositorySchema = z.object({
+  type: z.string(),
+  url: z.string().url(),
+});
+
+export const McpbManifestPlatformOverrideSchema =
+  McpServerConfigSchema.partial();
+
+export const McpbManifestMcpConfigSchema = McpServerConfigSchema.extend({
+  platform_overrides: z
+    .record(z.string(), McpbManifestPlatformOverrideSchema)
+    .optional(),
+});
+
+export const McpbManifestServerSchema = z.object({
+  type: z.enum(["python", "node", "binary", "uv"]),
+  entry_point: z.string(),
+  // mcp_config is optional for UV type (UV handles execution)
+  mcp_config: McpbManifestMcpConfigSchema.optional(),
+});
+
+export const McpbManifestCompatibilitySchema = z
+  .object({
+    claude_desktop: z.string().optional(),
+    platforms: z.array(z.enum(["darwin", "win32", "linux"])).optional(),
+    runtimes: z
+      .object({
+        python: z.string().optional(),
+        node: z.string().optional(),
+      })
+      .optional(),
+  })
+  .passthrough();
+
+export const McpbManifestToolSchema = z.object({
+  name: z.string(),
+  description: z.string().optional(),
+});
+
+export const McpbManifestPromptSchema = z.object({
+  name: z.string(),
+  description: z.string().optional(),
+  arguments: z.array(z.string()).optional(),
+  text: z.string(),
+});
+
+export const McpbUserConfigurationOptionSchema = z.object({
+  type: z.enum(["string", "number", "boolean", "directory", "file"]),
+  title: z.string(),
+  description: z.string(),
+  required: z.boolean().optional(),
+  default: z
+    .union([z.string(), z.number(), z.boolean(), z.array(z.string())])
+    .optional(),
+  multiple: z.boolean().optional(),
+  sensitive: z.boolean().optional(),
+  min: z.number().optional(),
+  max: z.number().optional(),
+});
+
+export const McpbManifestLocalizationSchema = z
+  .object({
+    resources: z
+      .string()
+      .regex(
+        LOCALE_PLACEHOLDER_REGEX,
+        'resources must include a "${locale}" placeholder',
+      ),
+    default_locale: z
+      .string()
+      .regex(
+        BCP47_REGEX,
+        "default_locale must be a valid BCP 47 locale identifier",
+      ),
+  })
+  .passthrough();
+
+export const McpbManifestIconSchema = z
+  .object({
+    src: z.string(),
+    size: z
+      .string()
+      .regex(
+        ICON_SIZE_REGEX,
+        'size must be in the format "WIDTHxHEIGHT" (e.g., "16x16")',
+      ),
+    theme: z.string().min(1).optional(),
+  })
+  .passthrough();
+
+export const McpbManifestSchema = z
+  .object({
+    $schema: z.string().optional(),
+    dxt_version: z
+      .literal(MANIFEST_VERSION)
+      .optional()
+      .describe("@deprecated Use manifest_version instead"),
+    manifest_version: z.literal(MANIFEST_VERSION).optional(),
+    name: z.string(),
+    display_name: z.string().optional(),
+    version: z.string(),
+    description: z.string(),
+    long_description: z.string().optional(),
+    author: McpbManifestAuthorSchema,
+    repository: McpbManifestRepositorySchema.optional(),
+    homepage: z.string().url().optional(),
+    documentation: z.string().url().optional(),
+    support: z.string().url().optional(),
+    icon: z.string().optional(),
+    icons: z.array(McpbManifestIconSchema).optional(),
+    screenshots: z.array(z.string()).optional(),
+    localization: McpbManifestLocalizationSchema.optional(),
+    server: McpbManifestServerSchema,
+    tools: z.array(McpbManifestToolSchema).optional(),
+    tools_generated: z.boolean().optional(),
+    prompts: z.array(McpbManifestPromptSchema).optional(),
+    prompts_generated: z.boolean().optional(),
+    keywords: z.array(z.string()).optional(),
+    license: z.string().optional(),
+    privacy_policies: z.array(z.string().url()).optional(),
+    compatibility: McpbManifestCompatibilitySchema.optional(),
+    user_config: z
+      .record(z.string(), McpbUserConfigurationOptionSchema)
+      .optional(),
+    _meta: z.record(z.string(), z.record(z.string(), z.any())).optional(),
+  })
+  .passthrough()
+  .refine((data) => !!(data.dxt_version || data.manifest_version), {
+    message:
+      "Either 'dxt_version' (deprecated) or 'manifest_version' must be provided",
+  });

src/schemas_loose/index.ts

@@ -1,3 +1,4 @@
 export * as v0_1 from "./0.1.js";
 export * as v0_2 from "./0.2.js";
 export * as v0_3 from "./0.3.js";
+export * as v0_4 from "./0.4.js";