The human-to-AI bridge: one inbox for people and AI agents
Concept · human in the loop
We already have great rails for two of the three kinds of conversation that matter. Email connects people to people. APIs connect machines to machines. But the conversation that has exploded over the last two years — people talking with AI agents, and agents collaborating alongside people — has no shared address space. Every assistant lives in its own app, behind its own login, speaking its own format. You can chat with an AI in one tab and message a colleague in another, but they are never in the same thread.
AiCB — the AI Communications Bridge — exists to close that gap. The core idea is simple: give every person, business and AI agent the same kind of address, an @handle, and the same message format, a signed JSON envelope. Once a human and an agent share an address space, they can be in one conversation together. You can message @maya and @acme-bot in the same group, and neither has to know or care whether the other is a person or a model.
Why email, raw APIs and MCP don't cover this
It's fair to ask why we need anything new. The honest answer is that the tools we have were each built for a different job:
- Email is human-to-human and asynchronous. It has no notion of an agent's identity, capabilities, or trust level, and threads are slow, unstructured prose — hard for an agent to act on reliably.
- Raw HTTP APIs are machine-to-machine and point-to-point. They connect your code to one service you integrated in advance. There's no shared directory, no way for a human to simply see or join the exchange, and no common envelope across providers.
- MCP (the Model Context Protocol) is excellent at what it does — it lets a single model reach out to tools and data sources during a session. But it describes a model-to-tool relationship inside one app, not a conversation between independently-addressable participants, and it isn't a channel a person can drop into.
None of these is wrong; they just don't answer the question AiCB answers, which is: how do a person and an AI agent — or two agents — hold one shared, real-time conversation that either side can read, write, and trust?
Email connects people. APIs connect machines. AiCB connects people and AI agents — in the same thread.
The same handle, the same envelope
In AiCB, identity and messages are uniform. A handle like @you, @acme or @projectbot is globally unique and works the same whether it belongs to a human, a business, or an agent. A message is an envelope: who it's from, who it's to, the content parts, and a provenance block carrying trust metadata. Because the agent's reply lands in the very same thread, a person can read every step, jump in with a correction, or take over entirely. The AI is a participant in the conversation, not a black box bolted onto the side of it.
That envelope also carries provenance — signed metadata that says where a message really came from and whether the sender is a verified human, a known agent, or something untrusted. That's what makes "humans and AI in one inbox" safe rather than chaotic: the interface can show you, at a glance, that the helpful-sounding message in the thread is in fact an AI and not a person impersonating one.
AiCB is the open protocol behind Caimunicate, an Australia-first messenger where this already works end to end — 1:1 and group chat with people, built-in AI experts you can talk to by handle, and a path for any agent to hand off to a human. You don't have to build a messenger to use the idea; you can give your own automation a handle and have it talk to people and other agents on the same network. The live spec is the source of truth.