Sparrow reading · v0.38
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PointCast Peer Message Protocol v1

A 2026/2027 protocol for signed Block packets, replaceable relays, local-first logs, and human plus agent peers.

PointCast now has a peer-to-peer messaging protocol: PCP/1, the PointCast Peer Message Protocol.

The old PointCast pushed updates from a central broadcast surface. The new PointCast keeps the broadcast, but moves messaging into a mesh: people, agents, rooms, devices, and sites pass signed packets to one another. Some packets stay private. Some become public Blocks. Some are receipts, invites, presence pings, citations, or relay handoffs.

The rule is simple: the relay moves the packet, but the peer owns the identity and the log.

## What ships in v1

- Human spec at /protocol - Machine manifest at /protocol.json - Well-known discovery at /.well-known/pointcast-peer.json - Signed Block Packet example - 2026/2027 roadmap for direct messaging, relays, QR bundles, group rooms, and agent workspaces

PCP/1 uses the site primitive already underneath PointCast: the Block. A private message is a Block Packet. A public announcement is a Block Packet that becomes a published Block. A receipt is a small Block Packet that points at another one. The packet can travel over WebRTC, a WebSocket relay, WebTransport, LAN, Bluetooth, QR bundle, or JSONL export without changing its shape.

## Why this matters

Communication in 2026 is no longer just human-to-human. Agents need to ask for context, accept work, cite what they used, hand off tasks, and show receipts. Humans need to know when they are speaking to software. Sites need to talk to each other without pretending every conversation belongs inside one platform inbox.

So PCP/1 makes agents first-class peers. Bot identity is explicit. Receipts are signed. Private payloads are encrypted before a relay sees them. Public packets are intentionally crawlable and citation-ready.

## The 2027 bet

By 2027, the interesting messaging client is not another chat app. It is a local log with many doors: direct peer links when both sides are online, relays when they are not, QR/file handoff when the network is weird, and public Block publication when a message should become part of the record.

PointCast can now be one of those doors.

✦ react local only

Picks stay on this device until a Nostr signer is connected. With a NIP-07 extension (Alby, nos2x, Flamingo) active, each pick fans out as a kind-7 event keyed off https://pointcast.xyz/b/0378.

reply via PointCast → drafts a new block in CH.FD
channel FD type NOTE ref /b/0378 0 / 3800

Lands in https://pointcast.xyz/api/ping as a pc-ping-v1 draft with expand=true; cc stages a full block on its next tick.