┌───────────────────────────────────────────────────┐
│  Layer 3: Gateway / P2P                           │
│  Remote access. Cross-machine. Encrypted.         │
├───────────────────────────────────────────────────┤
│  Layer 2: Headless Server                         │
│  Network bridge. Grid rendering. Session relay.   │
├───────────────────────────────────────────────────┤
│  Layer 1: PTY Daemon                              │
│  Process management. PTY spawn. Unix sockets.     │
└───────────────────────────────────────────────────┘

{
  "type": "create-session",
  "cols": 120,
  "rows": 40,
  "shell": "/bin/zsh",
  "cwd": "/path/to/workspace"
}

{
  "success": true,
  "sessionId": "pty-abc123",
  "socketPath": "/path/to/session.sock"
}

Path A: Gateway relay (Cloudflare)
  Client → WSS → session.monolex.ai → WSS → Headless → PTY

Path B: P2P (WebRTC DataChannel)
  Client → DTLS → direct → Headless → PTY

# Write to session (type into terminal)
niia write --session <ID> $'your command\r'

# Wait for output to settle
niia wait-idle --session <ID>

# Read the response
niia get-answer --session <ID> "search text"

# Local
niia write --session local-123 $'claude\r'

# Remote (same syntax, different session)
niia remote write MACHINE-B $'claude\r'

Traditional terminal:
  Open terminal → run command → close terminal → gone

PTY-for-AI:
  Daemon starts (boot) → sessions created → machine shuts down
  Machine starts → daemon auto-starts → sessions still accessible

Plugin Layer (niia CLI):
  --worktree feat-x  →  cwd = /tmp/niia-worktree-feat-x
  --sandbox          →  shell = sandbox-exec -p '...' /bin/zsh

                    ↓ transformed parameters

Daemon receives:
  CreateSession { cwd: "/tmp/niia-worktree-feat-x",
                  shell: "sandbox-exec ... /bin/zsh" }

Daemon just spawns. It doesn't know about worktrees or sandboxes.