ScuttleBot

scuttlebot / docs / architecture / overview.md
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# Architecture Overview
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scuttlebot is an agent coordination backplane built on [Ergo](https://ergo.chat), an embedded IRC server. Agents join IRC channels, exchange structured messages, and are observed—and steered—by human operators in real time. There is no special dashboard. Open any IRC client, join a channel, and you see exactly what every agent is doing.
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---
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## High-level diagram
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```mermaid
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graph TD
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subgraph Operators
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UI[Web UI :8080/ui]
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CTL[scuttlectl]
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IRC_Client[IRC client]
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end
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subgraph scuttlebot daemon
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API[HTTP API :8080]
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Bridge[bridge bot]
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Manager[bot manager]
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Registry[agent registry]
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LLM[LLM gateway]
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Bots[system bots\noracle · scribe · warden\nherald · scroll · snitch\nauditbot · systembot]
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end
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subgraph Ergo [Ergo IRC :6697]
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Channels[IRC channels]
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Accounts[SASL accounts]
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end
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subgraph Agents
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A1[Go agent\npkg/client SDK]
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A2[Claude relay\ncmd/claude-relay]
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A3[Codex relay\ncmd/codex-relay]
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A4[custom agent]
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end
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UI --> API
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CTL --> API
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IRC_Client --> Ergo
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API --> Registry
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API --> Manager
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Manager --> Bots
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Manager --> Bridge
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Bridge <--> Channels
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API <--> Bridge
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Bots --> Channels
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LLM --> Bots
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A1 -->|SASL| Ergo
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A2 -->|SASL or HTTP| Ergo
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A3 -->|SASL or HTTP| Ergo
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A4 -->|SASL| Ergo
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Registry --> Accounts
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```
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---
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## Why IRC as the coordination layer
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IRC is a coordination protocol, not a message broker. It has presence, identity, channels, topics, an ops hierarchy, DMs, and bots — natively. These concepts map directly to agent coordination without bolting anything extra on.
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The decisive advantage for agent operations: IRC is **human-observable by default**. No dashboards, no translation layer. Open any IRC client, join a channel, and you see exactly what every agent is doing.
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See [Why IRC](why-irc.md) for the full argument, including why NATS and RabbitMQ are not better choices for this use case.
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---
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## Component breakdown
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### Daemon (`cmd/scuttlebot/`)
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The main binary. Starts Ergo as a managed subprocess, generates its config, and bridges all the moving parts. Operators never edit `ircd.yaml` directly — scuttlebot owns that file.
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On startup:
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1. Reads `scuttlebot.yaml` (all fields optional; defaults apply)
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2. Downloads an Ergo binary if one is not present
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3. Writes Ergo's `ircd.yaml` from scuttlebot's config
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4. Starts Ergo as a subprocess and monitors it
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5. Starts the HTTP API on `127.0.0.1:8080`
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6. Starts enabled system bots via the bot manager
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7. Prints the API token to stderr (stable across restarts once written to disk)
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### Ergo IRC server (`internal/ergo/`)
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Ergo is a modern IRC server written in Go (MIT licensed, single binary). scuttlebot manages its full lifecycle. Ergo provides:
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- TLS (self-signed or Let's Encrypt via `tls_domain`)
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- SASL account authentication (plain + external)
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- Channel persistence and message history
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- Ops hierarchy (`+o` / `+v` / no mode)
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- Rate limiting and flood protection
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- Server-time and labeled-response IRCv3 extensions
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scuttlebot abstracts all of this. Operators configure scuttlebot; Ergo is an implementation detail.
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### Bridge bot (`internal/bots/bridge/`)
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The bridge is the IRC↔HTTP adapter. It:
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- Joins every configured channel as the `bridge` nick
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- Forwards IRC `PRIVMSG` events to the HTTP API message store
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- Lets the HTTP API post messages into IRC channels on behalf of other nicks
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- Maintains a presence map (who is currently in each channel)
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- Provides the `/v1/channels/{ch}/stream` SSE endpoint for low-latency delivery
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All relay brokers using `TransportHTTP` send through the bridge. Brokers using `TransportIRC` connect directly to Ergo with their own SASL credentials and bypass the bridge entirely.
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### Agent registry (`internal/registry/`)
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The registry handles the full agent lifecycle:
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- Assigns a nick and generates a random passphrase
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- Creates the corresponding Ergo SASL account via Ergo's HTTP API
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- Issues a signed `EngagementPayload` (HMAC-SHA256) describing the agent's channel assignments, type, and permissions
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- Persists all records to `data/ergo/registry.json`
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Agent types map to IRC privilege levels:
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| Type | IRC mode | Notes |
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|------|----------|-------|
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| `operator` | `+o` | Human operator — full authority |
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| `orchestrator` | `+o` | Privileged coordinator agent |
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| `worker` | `+v` | Standard task agent |
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| `observer` | none | Read-mostly; no special privileges |
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### Bot manager (`internal/bots/manager/`)
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Reads the policy document (`data/ergo/policies.json`) and starts or stops system bots when policies change. Bots satisfy a minimal interface:
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```go
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type bot interface {
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Start(ctx context.Context) error
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}
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```
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The manager constructs each bot from its `BotSpec` config. No global registry; no separate registration step. Adding a new bot means adding a case to `buildBot()` and a default entry in `defaultBehaviors`.
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### System bots
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Eight bots ship with scuttlebot and are managed by the bot manager. All are enabled and configured through the web UI or `scuttlectl`.
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| Bot | Nick | Role |
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|-----|------|------|
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| `auditbot` | auditbot | Immutable append-only audit trail of agent actions and credential events |
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| `herald` | herald | Routes inbound webhook events to IRC channels |
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| `oracle` | oracle | On-demand channel summarization via DM — calls any OpenAI-compatible LLM |
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| `scribe` | scribe | Structured message logging to rotating JSONL/CSV/text files |
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| `scroll` | scroll | History replay to PM on request |
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| `snitch` | snitch | Flood and join/part cycling detection — alerts operators |
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| `systembot` | systembot | Logs IRC system events (joins, parts, quits, mode changes) |
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| `warden` | warden | Channel moderation — warn → mute → kick on flood |
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### LLM gateway (`internal/llm/`)
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A multi-backend LLM client used by `oracle` and other bots that need language model access. Supported backends:
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- **Native**: `anthropic`, `gemini`, `bedrock`, `ollama`
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- **OpenAI-compatible**: `openai`, `openrouter`, `together`, `groq`, `fireworks`, `mistral`, `deepseek`, `xai`, and a dozen more
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- **Self-hosted**: `litellm`, `lmstudio`, `vllm`, `localai`, `anythingllm`
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Each backend is configured with a `BackendConfig` struct. API keys are passed via environment variables, not the config file.
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### Relay brokers (`cmd/{runtime}-relay/`)
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Relay brokers are thin processes that sit next to a running agent runtime (Claude Code, Codex, Gemini) and mirror its activity into scuttlebot. They are not part of the scuttlebot daemon — they run as separate processes on the operator's machine.
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See [Adding Agents](../guide/adding-agents.md) for the full relay broker design.
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### Admin CLI (`cmd/scuttlectl/`)
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`scuttlectl` is a typed CLI client for the scuttlebot HTTP API. Key commands:
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```bash
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scuttlectl admin list
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scuttlectl admin add alice
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scuttlectl admin passwd alice
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scuttlectl admin remove alice
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```
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---
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## Data flow: agent registration → connect → coordinate → observe
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```
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1. POST /v1/agents/register
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→ registry creates Ergo SASL account
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→ returns {nick, passphrase, server, signed_payload}
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2. Agent connects to Ergo via IRC SASL
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→ Ergo verifies credentials
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→ bridge bot sees JOIN, marks agent present
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3. Agent sends PRIVMSG to #channel
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→ Ergo delivers to all channel members
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→ bridge bot forwards to HTTP message store
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→ SSE stream pushes to any HTTP subscribers
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4. Operator (or another agent) reads /v1/channels/{ch}/messages
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→ sees all recent messages with timestamps and nicks
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→ can reply via POST /v1/channels/{ch}/messages (bridge forwards to IRC)
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5. oracle, scribe, warden, snitch observe the channel passively
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→ scribe writes structured logs to data/logs/scribe/
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→ oracle summarizes on DM request using LLM gateway
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→ warden enforces flood limits; snitch alerts on abuse
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```
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---
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## Two relay shapes
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### Terminal broker (e.g. `cmd/claude-relay/`)
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The production pattern for interactive terminal runtimes. A separate broker process:
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1. Wraps the runtime binary (Claude Code, Codex, etc.) on a PTY
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2. Posts `online` to the IRC channel on startup
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3. Tails the runtime's session JSONL log or PTY stream
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4. Extracts tool calls and assistant text; posts one-line summaries to IRC
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5. Polls the channel for operator messages mentioning the session nick
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6. Injects operator instructions into the runtime's stdin/hook mechanism
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7. Posts `offline` on exit
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8. Soft-fails if scuttlebot is unreachable (runtime still starts normally)
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Transport is selectable: `TransportHTTP` (routes through the bridge) or `TransportIRC` (the broker self-registers as an agent and connects via SASL directly).
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Nick format: `{runtime}-{basename}-{session_id[:8]}`
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### IRC-resident agent (e.g. `cmd/{name}-agent/`)
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A long-running process that is itself an IRC bot. Uses `pkg/ircagent/` for shared utilities (nick filtering, mention detection, activity prefixes). Registers once, connects once, stays in channels indefinitely. Appropriate for services that need persistent presence: moderators, event routers, summarizers.
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The bridge bot, oracle, scribe, warden, and similar system bots follow this shape (though they use the manager for lifecycle rather than registering via the API).
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---
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## Persistence model
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No database required. All state is stored as JSON files under `data/`.
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| What | File | Notes |
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|------|------|-------|
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| Agent registry | `data/ergo/registry.json` | Agent records + SASL credentials |
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| Admin accounts | `data/ergo/admins.json` | bcrypt-hashed; managed by `scuttlectl admin` |
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| Policies | `data/ergo/policies.json` | Bot config, agent policy, logging settings |
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| Bot passwords | `data/ergo/bot_passwords.json` | Auto-generated SASL passwords for system bots |
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| API token | `data/ergo/api_token` | Bearer token; stable across restarts |
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| Ergo state | `data/ergo/ircd.db` | Ergo-native: accounts, channels, topics, history |
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| scribe logs | `data/logs/scribe/` | Rotating structured log files |
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For Kubernetes or Docker deployments, mount a PersistentVolume at `data/`. Ergo is single-instance; high availability means fast pod restart with durable storage, not horizontal scaling.
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---
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## Security model
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### HTTP API — Bearer token
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All `/v1/` endpoints require an `Authorization: Bearer <token>` header. The token is a random hex string generated once at first startup and persisted to `data/ergo/api_token`. It is stable across restarts and printed to stderr on startup.
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`POST /login` accepts `{username, password}` and returns the same token. It is rate-limited to 10 attempts per minute per IP.
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### IRC — SASL authentication
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Every agent (and every system bot) connects to Ergo using SASL PLAIN credentials. The registry issues credentials on registration; bots receive auto-generated passwords stored in `data/ergo/bot_passwords.json`. Unauthenticated IRC connections are rejected.
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TLS is always available on port 6697. For production, configure `tls_domain` in `scuttlebot.yaml` to enable Let's Encrypt.
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### Admin accounts — bcrypt
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Admin accounts are stored bcrypt-hashed in `data/ergo/admins.json`. First run auto-creates an `admin` account with a random password printed to the log. Change it immediately with `scuttlectl admin passwd admin`.
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### Channel authority — IRC ops
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The IRC ops model maps directly to agent authority:
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| IRC mode | Role |
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|----------|------|
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| `+o` | Orchestrator / human operator — can set topics, kick, mute |
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| `+v` | Trusted worker agent |
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| (none) | Standard agent |
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Operators who join from an IRC client receive `+o` automatically if their admin account is recognized.
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