diff --git a/packages/devframe/src/adapters/__tests__/dev.test.ts b/packages/devframe/src/adapters/__tests__/dev.test.ts
index 3f15e9d9..39729ded 100644
--- a/packages/devframe/src/adapters/__tests__/dev.test.ts
+++ b/packages/devframe/src/adapters/__tests__/dev.test.ts
@@ -5,6 +5,7 @@ import { join } from 'node:path'
 import { defineDevframe } from 'devframe'
 import { createRpcClient } from 'devframe/rpc/client'
 import { createWsRpcChannel } from 'devframe/rpc/transports/ws-client'
+import { createWsOriginRegistry } from 'devframe/rpc/transports/ws-server'
 import { open } from 'devframe/utils/open'
 import { getPort } from 'get-port-please'
 import { describe, expect, it, vi } from 'vitest'
@@ -31,6 +32,19 @@ function makeTmpDist(): string {
   return dir
 }
 
+async function connectRaw(url: string, origin?: string): Promise<'open' | 'closed'> {
+  return await new Promise((resolve) => {
+    const ws = new WebSocket(url, origin ? { headers: { origin } } : undefined)
+    ws.on('open', () => {
+      ws.close()
+      resolve('open')
+    })
+    ws.on('error', () => resolve('closed'))
+    ws.on('unexpected-response', () => resolve('closed'))
+    ws.on('close', () => resolve('closed'))
+  })
+}
+
 describe('adapters/dev', () => {
   it('createDevServer starts, exposes __connection.json, and closes', async () => {
     const distDir = makeTmpDist()
@@ -256,6 +270,99 @@ describe('adapters/dev', () => {
     }
   })
 
+  it('allowedOrigins: default stays loopback-only', async () => {
+    const devframe = defineDevframe({
+      id: 'devframe-origins-default',
+      name: 'Origins Default',
+      version: '0.0.0',
+      packageName: 'devframe-test',
+      homepage: 'https://example.test',
+      description: 'Test devframe.',
+      setup: () => {},
+    })
+    const host = '127.0.0.1'
+    const port = await getPort({ port: 19450, host })
+    const handle = await createDevServer(devframe, { host, port, openBrowser: false })
+
+    try {
+      await expect(connectRaw(`ws://${host}:${port}/__ws`)).resolves.toBe('open')
+      await expect(connectRaw(`ws://${host}:${port}/__ws`, `http://${host}:12345`)).resolves.toBe('open')
+      await expect(connectRaw(`ws://${host}:${port}/__ws`, 'http://evil.example')).resolves.toBe('closed')
+    }
+    finally {
+      await handle.close()
+    }
+  })
+
+  it('allowedOrigins: an array of extra origins is honored on top of the loopback default', async () => {
+    const devframe = defineDevframe({
+      id: 'devframe-origins-array',
+      name: 'Origins Array',
+      version: '0.0.0',
+      packageName: 'devframe-test',
+      homepage: 'https://example.test',
+      description: 'Test devframe.',
+      setup: () => {},
+    })
+    const host = '127.0.0.1'
+    const port = await getPort({ port: 19440, host })
+    const handle = await createDevServer(devframe, {
+      host,
+      port,
+      openBrowser: false,
+      allowedOrigins: ['http://evil.example'],
+    })
+
+    try {
+      await expect(connectRaw(`ws://${host}:${port}/__ws`, 'http://evil.example')).resolves.toBe('open')
+      // Still rejects an origin that's neither loopback nor allowlisted.
+      await expect(connectRaw(`ws://${host}:${port}/__ws`, 'http://other.example')).resolves.toBe('closed')
+    }
+    finally {
+      await handle.close()
+    }
+  })
+
+  it('allowedOrigins: a WsOriginRegistry gates the upgrade end-to-end', async () => {
+    const devframe = defineDevframe({
+      id: 'devframe-origins-registry',
+      name: 'Origins Registry',
+      version: '0.0.0',
+      packageName: 'devframe-test',
+      homepage: 'https://example.test',
+      description: 'Test devframe.',
+      setup: () => {},
+    })
+    const host = '127.0.0.1'
+    const port = await getPort({ port: 19430, host })
+    const origin = 'chrome-extension://abcdefghijklmnop'
+    const registry = createWsOriginRegistry({
+      validateOrigin: value => value.startsWith('chrome-extension://'),
+    })
+    const handle = await createDevServer(devframe, {
+      host,
+      port,
+      openBrowser: false,
+      allowedOrigins: registry,
+    })
+
+    try {
+      // Unregistered, the registry rejects the same origin it'll accept below.
+      await expect(connectRaw(`ws://${host}:${port}/__ws`, origin)).resolves.toBe('closed')
+
+      const params = new URLSearchParams({
+        devframe_viewer_origin: origin,
+        devframe_viewer_origin_token: registry.token,
+      })
+      expect(registry.registerFromUrl(`/__connection.json?${params}`)).toBe(origin)
+
+      await expect(connectRaw(`ws://${host}:${port}/__ws`, origin)).resolves.toBe('open')
+    }
+    finally {
+      await handle.close()
+    }
+  })
+
   it('createDevServer runs in bridge mode when no distDir is configured', async () => {
     const devframe = defineDevframe({
       id: 'devframe-test-nodist',
diff --git a/packages/devframe/src/adapters/dev.ts b/packages/devframe/src/adapters/dev.ts
index aa549b9c..59881515 100644
--- a/packages/devframe/src/adapters/dev.ts
+++ b/packages/devframe/src/adapters/dev.ts
@@ -1,4 +1,4 @@
-import type { DevframeRpcConnection } from 'devframe/rpc/transports/ws-server'
+import type { DevframeRpcConnection, WsOriginRegistry } from 'devframe/rpc/transports/ws-server'
 import type { DevframeAuthHandler } from '../node/auth/handler'
 import type { StartedServer } from '../node/instance-shell'
 import type { DevframeDefinition, DevframeSseOptions, DevframeWsOptions, McpRouteOptions } from '../types/devframe'
@@ -50,6 +50,13 @@ export interface CreateDevServerOptions {
    * clients connect over the SSE endpoint instead (`backend: 'sse'`).
    */
   ws?: DevframeWsOptions | false
+  /**
+   * Extra origins to accept on the WS upgrade beyond the loopback default.
+   * Add your LAN/tunnel origin here when reaching the tool from another
+   * host. Pass `false` to disable origin checking entirely (not
+   * recommended). Default: loopback-only.
+   */
+  allowedOrigins?: readonly string[] | WsOriginRegistry | false
   /**
    * Override the SSE RPC endpoint control (`def.cli?.sse`) — enabled by
    * default at `<base>__sse`. Pass `false` to disable, or a
@@ -175,6 +182,7 @@ export async function createDevServer(
     host,
     origin,
     ws: options.ws,
+    allowedOrigins: options.allowedOrigins,
     sse: options.sse,
     // The `--no-auth` flag forces the gate off regardless of the `auth`
     // option / definition default (which the instance resolves itself).
diff --git a/tests/__snapshots__/tsnapi/devframe/adapters/dev.snapshot.d.ts b/tests/__snapshots__/tsnapi/devframe/adapters/dev.snapshot.d.ts
index dcfcfa0b..6a355dcd 100644
--- a/tests/__snapshots__/tsnapi/devframe/adapters/dev.snapshot.d.ts
+++ b/tests/__snapshots__/tsnapi/devframe/adapters/dev.snapshot.d.ts
@@ -9,6 +9,7 @@ export interface CreateDevServerOptions {
   distDir?: string;
   basePath?: string;
   ws?: DevframeWsOptions | false;
+  allowedOrigins?: readonly string[] | WsOriginRegistry | false;
   sse?: boolean | DevframeSseOptions;
   app?: H3;
   openBrowser?: boolean | string;