Channel sessions and sub-agent delegation

Per-channel session continuity for webhooks and CLI, silence tokens, and isolated background sub-agents.

Arka provides channel sessions and sub-agent delegation — patterns inspired by Hermes Agent, not a separate product integration. They add per-channel conversation continuity, webhook session handoff, and isolated background sub-agents.

Features

Concept	Arka feature
Per-chat session store	arka session — keyed by channel:chat_id
Cross-platform continuity	Webhook + arka ask share the same session when channel/chat_id match
Silence tokens	[SILENT], NO_REPLY suppress webhook outbound delivery
Sub-agent delegation	subagent spawn — isolated background agent tasks

Arka does not ship full gateway adapters (Telegram, Discord, etc.). Use webhook ingress and channel bridges, then attach channel sessions on top.

Message sessions

Per-channel conversation turns stored under ~/.config/arka/message-sessions/:

arka session push cli default user "Start the deploy checklist"
arka session push cli default assistant "Step 1: run tests"
arka session context cli default
arka session resume cli default
arka session list
arka session reset telegram 123456789
arka session status

Sessions are keyed as channel:chat_id (e.g. webhook:slack, cli:default, telegram:987654321).

CLI continuity

When MESSAGE_SESSIONS=1 (default), arka ask and the chat engine automatically read and write the cli:default session (override with MESSAGE_SESSION_CHANNEL and MESSAGE_SESSION_CHAT_ID). Start a thread in the terminal, continue via webhook with the same channel and chat ID, or vice versa.

Webhook continuity

When WEBHOOK_ENABLED=1, inbound POST bodies can include:

{
  "text": "What's the deploy status?",
  "channel": "telegram",
  "chat_id": "123456789"
}

Arka appends the user turn, injects prior session context into the agent prompt, stores the assistant reply, and returns chat_id in the response.

Silence tokens

Explicit silence tokens let group chats and automations store a turn without sending outbound text:

• [SILENT]
• SILENT
• NO_REPLY
• NO REPLY

When the agent’s final response is exactly one of these (case-insensitive), the webhook returns "silent": true and an empty output field. The turn is still stored in the session transcript.

External MCP clients can check the same tokens with arka_sessions action silence_check (returns { "silent": true|false, "tokens": [...] }).

Environment variables

Variable	Default	Purpose
MESSAGE_SESSIONS	1	Enable (0 to disable)
MESSAGE_SESSIONS_DIR	~/.config/arka/message-sessions	Storage root
MESSAGE_SESSION_IDLE_MINUTES	0	Auto-reset after idle minutes (0 = never)
MESSAGE_SESSION_MAX_TURNS	40	Max turns kept per session
MESSAGE_SESSION_CHANNEL	cli	Default channel for CLI chat
MESSAGE_SESSION_CHAT_ID	default	Default chat ID for CLI chat

Legacy HERMES_SESSIONS* variables remain supported as aliases.

Inbound turns are sanitized — injection patterns and unsafe content are blocked before storage.

Sub-agent delegation

Spawn isolated background agents for parallel workstreams:

subagent spawn "Summarize today's git log"
subagent list
subagent resume abc123def4
subagent status

Each sub-agent runs via the Python chat engine (with fish agent fallback). Task records live under ~/.cache/fish-agent/subagents/.

Security gates

Gate	Blocks when
SUBAGENT_SECURITY=1	Task fails SECURITY_LLM prompt verification
SUBAGENT_MAX	Concurrent running agents exceed limit
SUBAGENT_MAX_CHARS	Task text too long

Set SUBAGENT_SYNC=1 to run synchronously (used in tests).

Environment variables

Variable	Default	Purpose
SUBAGENT_ENABLED	1	Enable (0 to disable)
SUBAGENT_DIR	~/.cache/fish-agent/subagents	Storage root
SUBAGENT_MAX	3	Max concurrent background agents
SUBAGENT_TIMEOUT	600	Per-agent timeout (seconds)
SUBAGENT_SECURITY	1	Apply security gates to spawn tasks

Legacy HERMES_SUBAGENT* variables remain supported as aliases.

Sub-agents can attach to a message session via --session-channel and --session-chat-id.

Background process status

Use arka background processes when you want one place to see what Arka currently has active:

arka background processes
arka background processes --json

The report includes active sub-agent tasks, enabled routines, webhook status, configured MCP servers, and live OS processes that look Arka-owned such as arka mcp serve. The legacy command arka background agent tasks still works as an alias.

This command is read-only. It does not stop or restart agents, routines, or servers.

Skill manifest gates

Plugin gates use metadata.openclaw, metadata.arka, or metadata.hermes — all merged the same way. See OpenClaw-inspired gates for details.

Heartbeat integration

heartbeat status reports channel session and sub-agent counts:

heartbeat status

Related features

• Context layers — how memory, session notes, and channel turns fit together
• Session memory — long-term markdown notes (MEMORY.md)
• Webhooks — verified external ingress
• Security — global SECURITY, SECURITY_LLM, and SECURITY_ACTIONS flags