diff --git a/setup/auto.ts b/setup/auto.ts
index bbe6326e8..8ef87d804 100644
--- a/setup/auto.ts
+++ b/setup/auto.ts
@@ -71,6 +71,33 @@ function runStep(name: string, extra: string[] = []): Promise<StepResult> {
   });
 }
 
+/**
+ * After installing Docker, this process's supplementary groups are still
+ * frozen from login — subsequent steps that talk to /var/run/docker.sock
+ * (onecli install, service start, …) fail with EACCES even though the
+ * daemon is up. Detect that and re-exec the whole driver under `sg docker`
+ * so the rest of the run inherits the docker group without a re-login.
+ */
+function maybeReexecUnderSg(): void {
+  if (process.env.NANOCLAW_REEXEC_SG === '1') return; // already re-exec'd
+  if (process.platform !== 'linux') return;
+  const info = spawnSync('docker', ['info'], { encoding: 'utf-8' });
+  if (info.status === 0) return;
+  const err = `${info.stderr ?? ''}\n${info.stdout ?? ''}`;
+  if (!/permission denied/i.test(err)) return;
+  if (spawnSync('which', ['sg'], { stdio: 'ignore' }).status !== 0) return;
+
+  console.log(
+    '\n[setup:auto] Docker socket not accessible in current group — ' +
+      're-executing under `sg docker` to pick up new group membership.',
+  );
+  const res = spawnSync('sg', ['docker', '-c', 'pnpm run setup:auto'], {
+    stdio: 'inherit',
+    env: { ...process.env, NANOCLAW_REEXEC_SG: '1' },
+  });
+  process.exit(res.status ?? 1);
+}
+
 function anthropicSecretExists(): boolean {
   try {
     const res = spawnSync('onecli', ['secrets', 'list'], {
@@ -132,11 +159,18 @@ async function main(): Promise<void> {
           'Install Docker Desktop or start it manually, then retry.',
         );
       }
+      if (res.fields.ERROR === 'docker_group_not_active') {
+        fail(
+          'Docker was just installed but your shell is not yet in the `docker` group.',
+          'Log out and back in (or run `newgrp docker` in a new shell), then retry `pnpm run setup:auto`.',
+        );
+      }
       fail(
         'container build/test failed',
         'For stale build cache: `docker builder prune -f`, then retry `pnpm run setup:auto`.',
       );
     }
+    maybeReexecUnderSg();
   }
 
   if (!skip.has('onecli')) {
diff --git a/setup/container.ts b/setup/container.ts
index aadd04c9f..a2e64333e 100644
--- a/setup/container.ts
+++ b/setup/container.ts
@@ -2,7 +2,7 @@
  * Step: container — Build container image and verify with test run.
  * Replaces 03-setup-container.sh
  */
-import { execSync } from 'child_process';
+import { execSync, spawnSync } from 'child_process';
 import path from 'path';
 import { setTimeout as sleep } from 'timers/promises';
 
@@ -10,20 +10,28 @@ import { log } from '../src/log.js';
 import { commandExists, getPlatform } from './platform.js';
 import { emitStatus } from './status.js';
 
+type DockerStatus = 'ok' | 'no-permission' | 'no-daemon' | 'other';
+
+function dockerStatus(): DockerStatus {
+  const res = spawnSync('docker', ['info'], { encoding: 'utf-8' });
+  if (res.status === 0) return 'ok';
+  const err = `${res.stderr ?? ''}\n${res.stdout ?? ''}`;
+  if (/permission denied/i.test(err)) return 'no-permission';
+  if (/cannot connect|is the docker daemon running|no such file/i.test(err)) return 'no-daemon';
+  return 'other';
+}
+
 function dockerRunning(): boolean {
-  try {
-    execSync('docker info', { stdio: 'ignore' });
-    return true;
-  } catch {
-    return false;
-  }
+  return dockerStatus() === 'ok';
 }
 
 /**
- * Try to start Docker if it's installed but idle. Poll for up to 60s.
- * Returns true once `docker info` succeeds, false if we gave up.
+ * Try to start Docker if it's installed but idle. Poll up to 60s for the
+ * daemon to come up — but bail immediately if the socket is reachable and
+ * only blocked by a group-permission error, since that won't resolve by
+ * waiting (the caller handles the sg re-exec for that case).
  */
-async function tryStartDocker(): Promise<boolean> {
+async function tryStartDocker(): Promise<DockerStatus> {
   const platform = getPlatform();
   log.info('Docker not running — attempting to start', { platform });
 
@@ -34,22 +42,27 @@ async function tryStartDocker(): Promise<boolean> {
       // Inherit stdio so sudo can prompt for a password if needed.
       execSync('sudo systemctl start docker', { stdio: 'inherit' });
     } else {
-      return false;
+      return 'other';
     }
   } catch (err) {
     log.warn('Start command failed', { err });
-    return false;
+    return 'other';
   }
 
   for (let i = 0; i < 30; i++) {
     await sleep(2000);
-    if (dockerRunning()) {
+    const s = dockerStatus();
+    if (s === 'ok') {
       log.info('Docker is up');
-      return true;
+      return 'ok';
+    }
+    if (s === 'no-permission') {
+      log.info('Docker daemon is up but socket is not accessible (group membership)');
+      return 'no-permission';
     }
   }
   log.warn('Docker did not become ready within 60s');
-  return false;
+  return 'no-daemon';
 }
 
 function parseArgs(args: string[]): { runtime: string } {
@@ -84,6 +97,15 @@ export async function run(args: string[]): Promise<void> {
     process.exit(4);
   }
 
+  if (!commandExists('docker')) {
+    log.info('Docker not found — running setup/install-docker.sh');
+    try {
+      execSync('bash setup/install-docker.sh', { cwd: projectRoot, stdio: 'inherit' });
+    } catch (err) {
+      log.warn('install-docker.sh failed', { err });
+    }
+  }
+
   if (!commandExists('docker')) {
     emitStatus('SETUP_CONTAINER', {
       RUNTIME: runtime,
@@ -97,16 +119,37 @@ export async function run(args: string[]): Promise<void> {
     process.exit(2);
   }
 
-  if (!dockerRunning()) {
-    const started = await tryStartDocker();
-    if (!started) {
+  {
+    let status = dockerStatus();
+    if (status !== 'ok') {
+      status = await tryStartDocker();
+    }
+
+    // Socket is unreachable due to group perms — current shell's supplementary
+    // groups are fixed at login, so `usermod -aG docker` (via install-docker.sh
+    // or a prior install) doesn't affect us until next login. Re-exec this
+    // step under `sg docker` so the child picks up docker as its primary
+    // group and can talk to /var/run/docker.sock without a logout.
+    if (status === 'no-permission' && getPlatform() === 'linux' && commandExists('sg')) {
+      log.info('Re-executing container step under `sg docker`');
+      const res = spawnSync(
+        'sg',
+        ['docker', '-c', 'pnpm exec tsx setup/index.ts --step container'],
+        { cwd: projectRoot, stdio: 'inherit' },
+      );
+      process.exit(res.status ?? 1);
+    }
+
+    if (status !== 'ok') {
+      const error =
+        status === 'no-permission' ? 'docker_group_not_active' : 'runtime_not_available';
       emitStatus('SETUP_CONTAINER', {
         RUNTIME: runtime,
         IMAGE: image,
         BUILD_OK: false,
         TEST_OK: false,
         STATUS: 'failed',
-        ERROR: 'runtime_not_available',
+        ERROR: error,
         LOG: 'logs/setup.log',
       });
       process.exit(2);
diff --git a/setup/service.ts b/setup/service.ts
index bc85d1626..56bf3938d 100644
--- a/setup/service.ts
+++ b/setup/service.ts
@@ -11,6 +11,7 @@ import path from 'path';
 
 import { log } from '../src/log.js';
 import {
+  commandExists,
   getPlatform,
   getNodePath,
   getServiceManager,
@@ -255,12 +256,34 @@ WantedBy=${runningAsRoot ? 'multi-user.target' : 'default.target'}`;
   fs.writeFileSync(unitPath, unit);
   log.info('Wrote systemd unit', { unitPath });
 
-  // Detect stale docker group before starting (user systemd only)
-  const dockerGroupStale = !runningAsRoot && checkDockerGroupStale();
+  // Detect stale docker group before starting (user systemd only). The user
+  // systemd manager is a long-running process whose group list is frozen at
+  // login, so `usermod -aG docker` mid-session doesn't reach it. Rather than
+  // require the user to log out + back in, punch a POSIX ACL onto the socket
+  // that grants the current user rw directly. This is temporary — the socket
+  // is recreated by dockerd on restart (and by then the user has relogged, so
+  // normal group perms apply again).
+  let dockerGroupStale = !runningAsRoot && checkDockerGroupStale();
   if (dockerGroupStale) {
     log.warn(
       'Docker group not active in systemd session — user was likely added to docker group mid-session',
     );
+    if (commandExists('setfacl')) {
+      const user = execSync('whoami', { encoding: 'utf-8' }).trim();
+      try {
+        execSync(`sudo setfacl -m u:${user}:rw /var/run/docker.sock`, {
+          stdio: 'inherit',
+        });
+        log.info(
+          'Applied temporary ACL to /var/run/docker.sock (resets on docker restart or reboot)',
+        );
+        dockerGroupStale = false;
+      } catch (err) {
+        log.warn('Failed to apply setfacl workaround', { err });
+      }
+    } else {
+      log.warn('setfacl not installed — cannot apply automatic workaround');
+    }
   }
 
   // Kill orphaned nanoclaw processes to avoid channel connection conflicts