CRDT-VTerm - Collaborative Terminal Sharing

Collaborative terminal session sharing using CRDT-style s-expressions with GF(3) trifurcated conflict resolution.

Components

Emacs Bridge

• File: crdt-vterm-bridge.el
• Purpose: Connect vterm.el to crdt.el via shadow buffers

Babashka Recorder

• File: vterm_crdt_recorder.bb
• Purpose: Record/replay terminal sessions as CRDT sexps

P2P Sharing

• File: vterm_localsend_share.bb
• Purpose: Live terminal sharing via localsend multicast

Architecture

┌──────────────────────────────────────────────────────────────────┐
│                    CRDT-VTerm System                             │
├──────────────────────────────────────────────────────────────────┤
│                                                                  │
│  ┌─────────┐     remote-insert     ┌───────────────┐             │
│  │ vterm   │ ───────────────────▶  │ shadow buffer │             │
│  │  PTY    │      (GF3 trit)       │  (crdt.el)    │             │
│  └────┬────┘                       └───────┬───────┘             │
│       │                                    │                     │
│       │ script(1)                          │ sexp file           │
│       ▼                                    ▼                     │
│  ┌─────────┐                       ┌───────────────┐             │
│  │ raw log │                       │ .sexp log     │             │
│  └────┬────┘                       └───────┬───────┘             │
│       │                                    │                     │
│       │ vterm_crdt_recorder.bb             │ localsend UDP       │
│       ▼                                    ▼                     │
│  ┌─────────────────────────────────────────────────┐             │
│  │              P2P Peer Network                   │             │
│  │  ┌───────┐   ┌───────┐   ┌───────┐              │             │
│  │  │ MINUS │   │ERGODIC│   │ PLUS  │  ← GF(3)     │             │
│  │  └───────┘   └───────┘   └───────┘    routing   │             │
│  └─────────────────────────────────────────────────┘             │
└──────────────────────────────────────────────────────────────────┘

CRDT Sexp Format

;; Session header
(crdt-terminal-session
  (version "0.1.0")
  (session-id "T-abc123")
  (site-id 42)
  (gf3-assignment :ERGODIC))

;; Terminal output
(remote-insert "0a1b2c3d" 42 "$ ls -la\n"
  (props :type :terminal-output
         :trit :MINUS
         :timestamp 1234567890))

;; User input
(remote-input "0a1b2c3e" 42 "ls -la"
  (props :trit :PLUS
         :timestamp 1234567891))

;; Conflict resolution
(conflict-resolution
  :type :concurrent-input
  :strategy :gf3-ordering)

Usage

Record Session

bb vterm_crdt_recorder.bb record session.sexp

Replay Session

bb vterm_crdt_recorder.bb replay session.sexp 2.0

Live P2P Share

bb vterm_localsend_share.bb share output.sexp 192.168.1.5

Emacs Replay

M-x crdt-vterm-replay RET session.sexp RET 1.0 RET

GF(3) Trifurcated Input

Multi-user input is routed through three queues:

Queue	Trit	Processing Order
MINUS	-1	First
ERGODIC	0	Second
PLUS	+1	Third

This prevents conflicts in "no-longer-optimistic waiting" scenarios by deterministically ordering concurrent inputs.

;; Cycle through queues
(crdt-vterm-trifurcate-cycle)

Integration

With gay-mcp

Each terminal session gets a deterministic color based on session ID.

With localsend-mcp

P2P discovery and file transfer for session sharing.

With duckdb-ies

Terminal sessions can be indexed in DuckDB for time-travel queries.

Related Skills

• gay-mcp - Deterministic colors
• spi-parallel-verify - GF(3) conservation
• triad-interleave - Three-stream scheduling
• bisimulation-game - Session equivalence