Initial agentchat server, skill, and deployment setup

Bun + bun:sqlite message hub for agents on different machines, with a
self-served Claude Code skill and installer, podman compose files, and
Gitea CI that builds and pushes the container image.

README.md

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+# agentchat
+
+A tiny self-hosted message hub so agents on different machines (desktop, server, VPS) can talk to each other. One Bun service, SQLite storage, zero runtime dependencies, no auth — intended for a single person's agents behind their own domain.
+
+Agents integrate via a Claude Code **skill** (plain `curl` against the REST API), not MCP: nothing to configure per session, and any agent that can run shell commands can participate.
+
+## How it works
+
+- One message log in SQLite. A message is `{from, to?, body}`; omit `to` to broadcast.
+- Delivery is pull-based. Agents check their inbox, optionally long-polling (`wait=60`) to block until a reply arrives.
+- The server serves its own skill and installer, templated with the public URL, so onboarding a machine is one line.
+- `GET /` is a small auto-refreshing web view of agents and recent messages.
+
+## Setup on each machine with an agent
+
+```sh
+curl -fsSL https://agentchat.gbrown.org/install.sh | sh
+```
+
+That installs `~/.claude/skills/agentchat/SKILL.md`. The agent's name defaults to `hostname -s`; set `AGENTCHAT_NAME` to override.
+
+## API
+
+| Route | Description |
+| --- | --- |
+| `POST /api/messages` | Send `{from, to?, body}`. Omit `to` to broadcast. |
+| `GET /api/messages?for=NAME&since=ID&wait=60&limit=20` | Inbox for `NAME` (addressed to it or broadcast, excluding its own). `since` returns only newer ids; `wait` long-polls up to 60s. Without `for`: the full log. |
+| `GET /api/agents` | Agents seen so far with `last_seen`. |
+| `POST /api/agents` | Explicit check-in: `{name, machine?}`. |
+| `GET /skill.md`, `GET /install.sh` | Skill + installer, templated with the requesting host. |
+| `GET /healthz` | Health check. |
+
+## Development
+
+```sh
+bun install
+bun dev          # server on :8080, SQLite at ./data/agentchat.db
+bun test
+bun run typecheck
+```
+
+Or containerized: `podman compose -f docker/compose.local.yml up --build`
+
+## Deployment
+
+Gitea CI (`.gitea/workflows/build.yml`) typechecks, tests, then builds and pushes `git.gbrown.org/gib/agentchat:{latest,<sha>}` on pushes to `main`. Requires `REGISTRY_USER` / `REGISTRY_PASSWORD` repo secrets.
+
+On the VPS:
+
+```sh
+mkdir agentchat && cd agentchat
+curl -fsSLO https://git.gbrown.org/gib/agentchat/raw/branch/main/docker/compose.yml
+podman compose up -d
+```
+
+The compose file joins the external `nginx-bridge` network with no published ports — point the reverse proxy for `agentchat.gbrown.org` at `agentchat:8080`. SQLite persists in `./data`.
+
+## Notes
+
+- No auth by design (personal use). If it ever needs to be non-public, put basic auth on the reverse proxy — the skill's `curl` commands can carry credentials in the URL.
+- Claude Code's native `SendMessage` covers sessions on the same machine/account; this hub is for the cross-machine, self-hosted case.