diff --git a/deploy/targets/local-docker.mjs b/deploy/targets/local-docker.mjs
index 8bcd8c4..9d3a456 100644
--- a/deploy/targets/local-docker.mjs
+++ b/deploy/targets/local-docker.mjs
@@ -4,9 +4,24 @@
 
 import fs from 'node:fs/promises'
 import path from 'node:path'
+import net from 'node:net'
 import { spawn } from 'node:child_process'
 import crypto from 'node:crypto'
 
+// Ask the OS for a free ephemeral port on the loopback interface. Far safer
+// than a random pick under concurrent deploys, where two cells could otherwise
+// choose the same port and the second `docker run -p` would fail.
+function findFreePort() {
+  return new Promise((resolve, reject) => {
+    const srv = net.createServer()
+    srv.on('error', reject)
+    srv.listen(0, '127.0.0.1', () => {
+      const { port } = srv.address()
+      srv.close(() => resolve(port))
+    })
+  })
+}
+
 function run(cmd, args, opts = {}) {
   return new Promise((resolve, reject) => {
     const p = spawn(cmd, args, { stdio: opts.quiet ? 'pipe' : 'inherit', ...opts })
@@ -84,8 +99,8 @@ export async function deployLocalDocker({ manifest, manifestPath, repoRoot }) {
   // Tear down any old container with the same name (idempotency for re-deploys)
   await run('docker', ['rm', '-f', containerName], { quiet: true }).catch(() => {})
 
-  // Pick a free local port
-  const port = 8000 + Math.floor(Math.random() * 1000)
+  // Pick a free local port (OS-assigned, avoids collisions across concurrent deploys)
+  const port = await findFreePort()
 
   // Run detached
   console.log(`  [docker run] ${containerName} on :${port}`)
diff --git a/polyrange.mjs b/polyrange.mjs
index 2285a94..71a7a1f 100644
--- a/polyrange.mjs
+++ b/polyrange.mjs
@@ -273,8 +273,10 @@ async function cmdDestroy() {
 async function cmdOne() {
   const cls = flags.class
   const tier = flags.tier ?? '0'
+  const target = flags.target ?? 'fly'   // fly | local-docker
   if (!cls) throw new Error('--class=X is required')
-  const args = ['generator/deploy.mjs', `--class=${cls}`, `--tier=${tier}`, '--target=fly']
+  const args = ['generator/deploy.mjs', `--class=${cls}`, `--tier=${tier}`, `--target=${target}`]
+  if (flags.region) args.push(`--region=${flags.region}`)
   if (flags.ephemeral) args.push('--ephemeral')
   const child = spawn('node', args, { stdio: 'inherit', cwd: REPO_ROOT, env: process.env })
   await new Promise((resolve) => child.on('close', resolve))