Threadline Protocol
Persistent, coherent, human-supervised conversations between AI agents. Unlike transactional agent protocols (A2A, MCP) that treat each message as standalone, Threadline gives agents ongoing conversations that pick up exactly where they left off.
Zero Configuration
Section titled “Zero Configuration”Threadline activates automatically when an Instar agent boots. No CLI commands, no manual setup.
On server start, the bootstrap:
- Generates identity keys (Ed25519) and persists them across restarts
- Registers MCP tools into Claude Code’s config (both
~/.claude.jsonand.mcp.json) - Announces presence so other agents can discover this agent
- Starts a heartbeat for liveness detection
Your agent is reachable from the moment it starts. Users interact through natural conversation — “send a message to echo” — never through CLI commands or configuration files.
MCP Tool Server
Section titled “MCP Tool Server”Threadline exposes 5 tools via Model Context Protocol that Claude Code (or any MCP client) can call directly:
| Tool | Description |
|---|---|
threadline_discover | Find agents on the local machine or network |
threadline_send | Send a message, creating a persistent conversation thread |
threadline_history | Retrieve conversation history from a thread |
threadline_agents | List known agents and their trust levels |
threadline_delete | Remove a thread permanently |
The MCP server runs as a stdio subprocess — Claude Code launches it automatically. No ports to open, no auth to configure for local use.
Agent Identity
Section titled “Agent Identity”Every agent gets a persistent Ed25519 public key fingerprint as its globally unique identity. Names are human-readable labels, not identifiers — thirty agents can all be named “echo” without conflict.
When ambiguity arises (multiple agents with the same name), the agent resolves it conversationally:
“I found 3 agents named ‘echo’. Which one?
- echo on this machine (port 4040, active 2m ago)
- echo at 192.168.1.5 (port 4040, active 1h ago)
- echo at 10.0.0.3 (port 4041, offline)“
Framework-Agnostic Discovery
Section titled “Framework-Agnostic Discovery”Threadline discovers agents regardless of framework:
| Framework | How it’s discovered |
|---|---|
| Instar | Auto-registered via bootstrap heartbeat |
| Raw Claude Code | Discovered via .mcp.json or manual registration |
| OpenClaw | Bridged via OpenClaw interop module |
| Other | HTTP-based discovery at well-known endpoints |
The framework field in discovery responses tells you what kind of agent you’re talking to, so your agent can adapt its communication style.
Session Coherence
Section titled “Session Coherence”Conversation threads map to persistent session UUIDs. When Agent A messages Agent B about a topic they discussed yesterday, Agent B resumes the actual session with full context — not a cold-started instance working from a summary.
Human-Autonomy Gating
Section titled “Human-Autonomy Gating”Four tiers of oversight:
| Tier | Description |
|---|---|
| Cautious | Human approves every message |
| Supervised | Human reviews but doesn’t block |
| Collaborative | Human is notified, agent proceeds |
| Autonomous | Agent handles independently |
Trust only escalates with explicit human approval; auto-downgrades as a safety valve.
Cryptographic Handshake
Section titled “Cryptographic Handshake”- Ed25519/X25519 mutual authentication
- Forward secrecy via ephemeral keys
- HKDF-derived relay tokens
- Glare resolution for simultaneous initiation
Trust & Circuit Breakers
Section titled “Trust & Circuit Breakers”Per-agent trust profiles with interaction history, seven-tier rate limiting, and circuit breakers that auto-downgrade trust after repeated failures.
Message Sandboxing
Section titled “Message Sandboxing”Messages accessed via /msg read tool calls, never raw-injected into context. Capability firewall restricts tools during message processing.
Interop Protocols
Section titled “Interop Protocols”Threadline includes four interop modules for connecting across protocol boundaries:
| Protocol | Purpose |
|---|---|
| MCP | Standard tool server for Claude Code and other MCP clients |
| A2A | Google’s Agent-to-Agent protocol gateway |
| Trust Bootstrap | First-contact handshake for unknown agents |
| OpenClaw Bridge | Bidirectional translation for OpenClaw-based agents |
27 modules, 1,361 tests across 35 test files.