diff --git a/README.md b/README.md
index ad8e7e4..d89e125 100644
--- a/README.md
+++ b/README.md
@@ -1241,7 +1241,11 @@ Retained native-session API jobs do not yet enter this one-shot capture scope.
 
 The bearer-protected `/admin/pools/status` endpoint reports explicit adopted pool
 identities and durable roll receipts. Maintenance requires `BRIDGE_BEARER`, even
-on loopback. It does not restart other bridge services or stop their jobs.
+on loopback. Adoption requires Linux with the existing `ss` socket inventory tool;
+unavailable or ambiguous listener evidence refuses ownership transfer. Run adoption
+from a native Linux bridge service in the same host network namespace as the
+legacy controller; a container-local socket inventory does not prove host ports
+are unused. It does not restart other bridge services or stop their jobs.
 
 For an inactive historical pool, `POST /admin/pools/adopt` accepts `prefix`,
 `legacyDataDir`, `legacyPorts`, immutable `expectedImage`, and ordered contiguous
diff --git a/scripts/verify-pool-adoption-guards.ts b/scripts/verify-pool-adoption-guards.ts
new file mode 100644
index 0000000..fad69f0
--- /dev/null
+++ b/scripts/verify-pool-adoption-guards.ts
@@ -0,0 +1,58 @@
+#!/usr/bin/env tsx
+/** Real Linux IPv6 listener + Docker startup refusal proof. No models or mocks. */
+import assert from 'node:assert/strict'
+import { randomBytes } from 'node:crypto'
+import { mkdtempSync, mkdirSync, rmSync, writeFileSync } from 'node:fs'
+import { createServer } from 'node:net'
+import { tmpdir } from 'node:os'
+import { join } from 'node:path'
+import { dockerCli } from '../src/executors/docker-cli.js'
+import { PoolMaintenance } from '../src/runtime/pool-maintenance.js'
+import { acquireDataDirectoryLock } from '../src/runtime/single-instance.js'
+import { loadConfig } from '../src/config.js'
+import { buildApp } from '../src/server.js'
+
+const image = process.env.CLI_ROLL_IMAGE
+if (!image || !/^sha256:[a-f0-9]{64}$/u.test(image)) throw new Error('existing immutable CLI_ROLL_IMAGE required')
+const prefix = `cli-bridge-guard-${randomBytes(5).toString('hex')}`
+const root = mkdtempSync(join(tmpdir(), `${prefix}-`))
+const legacy = join(root, 'legacy', 'data'), workspace = join(root, 'legacy', 'workspace')
+const data = join(root, 'owner'), badData = join(root, 'bad-startup')
+for (const dir of [legacy, workspace, data, badData]) mkdirSync(dir, { recursive: true, mode: 0o700 })
+let id = ''
+let owner: PoolMaintenance | undefined
+const listener = createServer()
+try {
+  await new Promise<void>((resolve, reject) => {
+    listener.once('error', reject)
+    listener.listen({ host: '::1', port: 0, ipv6Only: true }, resolve)
+  })
+  const port = (listener.address() as { port: number }).port
+  const result = await dockerCli(['run', '-d', '--name', `${prefix}-0`, '--mount',
+    `type=bind,source=${workspace},target=${workspace}`, image, 'tail', '-f', '/dev/null'])
+  assert.equal(result.code, 0); id = result.stdout.trim()
+  owner = new PoolMaintenance(data)
+  const manifest = { prefix, legacyDataDir: legacy, legacyPorts: [port], expectedImage: image,
+    slots: [{ index: 0, id }] }
+  await assert.rejects(owner.adopt(manifest), /legacy controller still listens/)
+  const lock = acquireDataDirectoryLock(legacy); lock.release()
+  await new Promise<void>((resolve, reject) => listener.close((error) => error ? reject(error) : resolve()))
+  await owner.adopt(manifest)
+  await owner.close(); owner = undefined
+
+  writeFileSync(join(badData, 'pool-maintenance.json'), '{malformed', { mode: 0o600 })
+  const startupPrefix = `${prefix}-startup`
+  await assert.rejects(buildApp(loadConfig({ BRIDGE_BACKENDS: 'opencode', BRIDGE_BEARER: randomBytes(24).toString('hex'),
+    BRIDGE_DATA_DIR: badData, OPENCODE_EXECUTOR: 'docker', OPENCODE_DOCKER_IMAGE: image,
+    OPENCODE_DOCKER_POOL_SIZE: '2', OPENCODE_DOCKER_NAME_PREFIX: startupPrefix })), /maintenance journal needs operator reconciliation/)
+  const containers = await dockerCli(['ps', '-aq', '--filter', `name=${startupPrefix}`])
+  assert.equal(containers.code, 0); assert.equal(containers.stdout.trim(), '')
+  console.log(JSON.stringify({ complete: true, ipv6_listener_refused: true, refused_adoption_lock_released: true,
+    adoption_after_listener_close: true, malformed_journal_refused_before_docker_provision: true,
+    configured_startup_containers_created: 0, image, no_model_calls: true }))
+} finally {
+  if (listener.listening) await new Promise<void>((resolve) => listener.close(() => resolve()))
+  await owner?.close()
+  if (id) await dockerCli(['rm', '-f', '-v', id])
+  rmSync(root, { recursive: true, force: true })
+}
diff --git a/src/runtime/pool-maintenance.ts b/src/runtime/pool-maintenance.ts
index cf90553..85eb339 100644
--- a/src/runtime/pool-maintenance.ts
+++ b/src/runtime/pool-maintenance.ts
@@ -2,7 +2,8 @@
 import { randomBytes } from 'node:crypto'
 import { closeSync, constants, fsyncSync, fstatSync, openSync, readFileSync, renameSync, realpathSync, writeFileSync } from 'node:fs'
 import { dirname, join } from 'node:path'
-import { createConnection } from 'node:net'
+import { execFile } from 'node:child_process'
+import { promisify } from 'node:util'
 import { z } from 'zod'
 import { ContainerPool } from '../executors/container-pool.js'
 import { inspectIdle, replaceRuntime, type RollReceipt } from '../executors/docker-runtime-roll.js'
@@ -23,17 +24,15 @@ const rollSchema = z.object({ oldId: identity, imageId: z.string().regex(/^sha25
 const recordSchema = adoptionRequest.extend({ rolls: z.record(z.string(), rollSchema), image: z.string() }).strict()
 type Record = z.infer<typeof recordSchema>
 
+/** Linux's kernel socket inventory covers IPv4, IPv6 and non-loopback binds. */
 async function requireNoListener(port: number): Promise<void> {
-  await new Promise<void>((resolve, reject) => {
-    const socket = createConnection({ host: '127.0.0.1', port })
-    socket.setTimeout(1000)
-    socket.once('connect', () => { socket.destroy(); reject(new Error('legacy controller still listens')) })
-    socket.once('timeout', () => { socket.destroy(); reject(new Error('legacy controller state unknown')) })
-    socket.once('error', (error: NodeJS.ErrnoException) => {
-      if (error.code === 'ECONNREFUSED') resolve()
-      else reject(new Error('legacy controller state unknown'))
-    })
-  })
+  if (process.platform !== 'linux') throw new Error('pool adoption requires Linux listener inventory')
+  if (!Number.isInteger(port) || port < 1 || port > 65535) throw new Error('invalid legacy port')
+  // Missing ss, timeout, nonzero exit, or excessive output all reject adoption.
+  const { stdout, stderr } = await promisify(execFile)('ss', ['-H', '-ltn', `sport = :${port}`],
+    { timeout: 2000, maxBuffer: 65536, killSignal: 'SIGKILL' })
+  if (stderr.trim()) throw new Error('legacy listener inventory is ambiguous')
+  if (stdout.trim()) throw new Error('legacy controller still listens on a declared port')
 }
 
 export class PoolMaintenance {
diff --git a/src/server.ts b/src/server.ts
index 2b50b00..fd9cc87 100644
--- a/src/server.ts
+++ b/src/server.ts
@@ -352,6 +352,9 @@ export async function buildApp(config: Config): Promise<{
     maxLifetimeMs: parseEnvNonNegativeInt('BRIDGE_RUN_MAX_LIFETIME_MS', 0),
   })
   const extras: BuildAppExtras = { shutdownHooks: [], netJail: new Map() }
+  // Validate the durable maintenance owner before any backend provisions Docker slots.
+  const poolMaintenance = new PoolMaintenance(config.dataDir)
+  extras.shutdownHooks.push(async () => await poolMaintenance.close())
   const durableWriter = config.asyncDurableWrites ? new DurableRunWriter(config.dataDir) : null
   if (durableWriter) {
     await durableWriter.open()
@@ -537,8 +540,6 @@ export async function buildApp(config: Config): Promise<{
   mountCadRender(app)
   mountImagesGenerate(app)
   mountMetrics(app)
-  const poolMaintenance = new PoolMaintenance(config.dataDir)
-  extras.shutdownHooks.push(async () => await poolMaintenance.close())
   mountPoolMaintenance(app, poolMaintenance, Boolean(config.bearer))
 
   app.get('/', (c) => c.json({