fix: ai-worker docker-only access for ollama benchmarking

Remove infra repo bind mount and sudo access from ai-worker user.
Now ai-worker can only:
- SSH into host from Hermes container
- Run docker commands via docker group membership
- Execute ollama benchmarks via docker exec

Results saved to /opt/data/ai-optimizer/ in Hermes container.

flake.nix

@@ -61,6 +61,7 @@
               ./modules/nixos/services/open_code_server.nix
               ./modules/nixos/services/ollama_init_custom_models.nix
               ./modules/nixos/services/openclaw_node.nix
+              ./modules/nixos/security/ai-worker-restricted.nix
               ./users/gortium.nix
               ./users/ai-worker.nix
             ];

modules/nixos/security/README-ai-worker.md

@@ -0,0 +1,105 @@
+# AI Worker Restricted Access
+
+This module provides SSH access for the AI worker (hermes-agent) to run ollama benchmarks on the host.
+
+## Security Model
+
+The `ai-worker` user has:
+
+### Filesystem Access
+- **Home directory**: `/home/ai-worker` (standard user home)
+- **No bind mounts**: Cannot access `/home/gortium/infra` or other host files
+- **Cannot access**: Any files outside standard system paths
+
+### Sudo Access
+- **NONE**: ai-worker has no sudo privileges
+- Cannot run `nh`, `nixos-rebuild`, `nixpkgs-fmt`, or `nix` with elevated permissions
+
+### Docker Access
+- Member of `docker` group - can run `docker` and `docker exec` commands
+- Primary use: `docker exec ollama ollama ...` for benchmarking
+- Can run `docker exec --privileged ollama rocm-smi ...` for VRAM monitoring
+
+## Workflow: SSH + Docker Benchmarking
+
+The AI worker connects from the Hermes container to the host via SSH, runs ollama benchmarks, then returns to save results.
+
+### Example Workflow
+
+```bash
+# From Hermes container, SSH to host
+ssh -i /path/to/ssh/key ai-worker@host.docker.internal
+
+# On host, run ollama benchmarks via docker
+docker exec ollama ollama pull devstral-small-2:24b
+
+# Create test modelfile
+docker exec ollama bash -c 'cat <<EOF > /root/.ollama/test.modelfile
+FROM devstral-small-2:24b
+PARAMETER num_ctx 65536
+PARAMETER num_gpu 99
+PARAMETER flash_attn true
+EOF'
+
+# Create and test model
+docker exec ollama ollama create test-model -f /root/.ollama/test.modelfile
+docker exec ollama ollama run test-model "Write a Python async function"
+
+# Check VRAM usage
+docker exec --privileged ollama rocm-smi --showmeminfo vram
+
+# Cleanup
+docker exec ollama ollama rm test-model
+
+# Exit SSH, return to Hermes container
+exit
+
+# Save results in Hermes container
+# /opt/data/ai-optimizer/state.json
+# /opt/data/ai-optimizer/results.csv
+```
+
+## SSH Access
+
+Connect as:
+```bash
+ssh ai-worker@lazyworkhorse
+```
+
+The working directory will be `/home/ai-worker`. No infra repo access.
+
+## Verification
+
+Check ai-worker permissions:
+```bash
+# On the host, as root or gortium:
+sudo -u ai-worker sudo -l
+# Should show: no sudo access
+
+# Check docker group membership
+groups ai-worker
+# Should show: ai-worker docker
+```
+
+## Troubleshooting
+
+If ai-worker cannot run docker commands:
+```bash
+# Check docker group membership
+groups ai-worker
+
+# Verify ollama container is running
+docker ps | grep ollama
+
+# Test docker access
+sudo -u ai-worker docker exec ollama ollama list
+```
+
+If SSH connection fails:
+```bash
+# Check SSH key is authorized
+cat /home/ai-worker/.ssh/authorized_keys
+
+# Check SSH service
+systemctl status sshd
+```

modules/nixos/security/ai-worker-restricted.nix

@@ -0,0 +1,17 @@
+{ config, pkgs, lib, ... }:
+
+with lib;
+
+{
+  options.services.aiWorkerAccess = mkOption {
+    type = types.bool;
+    default = false;
+    description = "Enable AI worker SSH access with docker group membership for ollama benchmarking";
+  };
+
+  config = mkIf config.services.aiWorkerAccess {
+    # ai-worker is member of docker group - can run docker commands via SSH
+    # No bind mounts, no sudo access - docker-only for ollama benchmarking
+    users.groups.docker.members = [ "ai-worker" ];
+  };
+}

users/ai-worker.nix

@@ -9,6 +9,17 @@
     openssh.authorizedKeys.keys = [
       keys.users.ai-worker.main
     ];
+    # No password login - SSH key only
+    hashedPassword = "!";
   };
   users.groups.ai-worker = {};
+
+  # Enable restricted AI worker SSH access for ollama benchmarking
+  # SECURITY: ai-worker can only:
+  #   - SSH into host from Hermes container
+  #   - Run docker commands (docker exec ollama ...) via docker group
+  #   - NO access to infra repo (no bind mount)
+  #   - NO sudo access (no nh, nixos-rebuild, nixpkgs-fmt, nix)
+  # WORKFLOW: SSH from Hermes container, run docker benchmarks, return and save results to /opt/data/ai-optimizer/
+  services.aiWorkerAccess = true;
 }