Claude A2A Research

July 15, 2026 · View on GitHub

A time-limited research study evaluating what tools are currently on the market for letting two separate instances of Claude Code — running in two different terminals — communicate with each other.

⚠️ Snapshot in time. This is a point-in-time market scan (July 2026), not a continuously maintained notebook. The agent-orchestration space moves fast; treat findings as accurate as of the dates noted in each write-up.

The challenge

Two instances of Claude Code are running as two independent sessions in two separate terminals. The goal is to create a mechanism for them to talk to one another — whether an ephemeral bridge (spin-up-when-needed) or a permanent bolt-on (persistent infrastructure). Two variants are studied:

#ScenarioSetup
Q1Cross-machine (local ↔ remote)One instance runs locally; the other runs on a remote server the user manages (e.g. SSH session with Claude Code installed server-side).
Q2Same-machine (local ↔ local)Both instances run on the same machine, in two different terminals.

For each scenario the study inventories available solutions and evaluates them on setup effort, persistence model (ephemeral vs. permanent), transport, security, and fit.

Structure

.
├── README.md                 # This file
├── NOTEBOOK.md               # Research log: status, method, timeline
├── research/
│   ├── question-01/          # Cross-machine (local ↔ remote)
│   │   ├── README.md         #   Question statement & scope
│   │   ├── findings.md       #   Evaluated solutions + recommendation
│   │   └── working-notes.md  #   Scratch notes, candidates, dead ends
│   └── question-02/          # Same-machine (local ↔ local)
│       ├── README.md
│       ├── findings.md
│       └── working-notes.md
├── sources/                  # Source index (SOURCES.md) + saved material
└── assets/                   # Diagrams, screenshots

Headline findings (2026-07-15)

ScenarioRecommended solutionApproach
Q1 — Cross-machineMCP Agent Mail (HTTP-native message bus) exposed via Tailscale Serve; both instances claude mcp add --transport http. Bundles a human-monitoring web UI.A (ephemeral bridge)
Q2 — Same-machineclaude-peers-mcp (~2.2k★ localhost broker) — list_peers / send_message between any running Claude Codes.A (localhost bridge)
  • The market has converged on one primitive: a shared MCP mailbox/message-bus that both instances connect to as clients. Claude Code can't natively act as a server, so direct A→B calls need an Agent-SDK wrapper.
  • Approach B (permanent join-code rendezvous) is a genuine product gap — the only off-the-shelf match, AgentTrust, is nascent (~1★) and third-party-hosted.
  • Caveat: polished push delivery rides Claude Code's undocumented experimental channels API — treat as beta.

Full analysis in NOTEBOOK.md and the per-question findings below.

Start here