Security

• Relay payloads are end-to-end encrypted. Brokers do not see data.
• Treat the join token like an SSH key or API key.
• If the token may have leaked, run hcom relay off --all to disconnect all devices.
• Use a private/custom/self-hosted broker with --broker and --password for better security.

Security model

hcom relay is one trust domain for one operator's devices. Membership is all-or-nothing. There are no scoped roles, read-only peers, or per-device permissions.

Relay payloads use a shared PSK with XChaCha20-Poly1305. The encryption binds each payload to the relay, topic, and timestamp. A replay guard drops duplicate envelopes inside a freshness window.

Brokers and network observers cannot read or forge payloads without the PSK. They can still see metadata: topic names, timing, message sizes, and connection patterns.

What the token means

The join token contains the relay ID, broker URL, and raw PSK. hcom does not ask a server to validate it. It has no expiry, no scope, and no revocation list.

On public brokers, a leaked token gives an attacker full control of the relay. They can decrypt captured traffic, publish authenticated relay traffic, send text to listening agents, launch agents on enrolled devices, kill running agents, and use remote relay RPCs. If those agents can run tools, treat that as shell access on every enrolled device in the relay.

On private brokers with --password, the token still leaks the PSK, so captured traffic is still exposed. But the token alone is not enough to publish unless the attacker also has the broker password. Use a private broker when broker-side access control matters, or when the metadata shape of your traffic is itself sensitive. --password is broker access control, not another layer of message encryption.

Limits by design

• Forward secrecy. A leaked PSK can decrypt old captured traffic.
• Per-device attribution inside a relay. Sender identity is routing metadata, not authorization. Every enrolled device speaks with full authority.
• Prompt injection from an authenticated peer. Enrollment is total trust — a peer can launch, kill, and drive agents via RPC, not just send messages. Only enroll devices you would give shell access to.
• Local OS compromise. hcom trusts the local user account and ~/.hcom/config.toml. It does not defend against another user on the same account or malware with filesystem access.

Storage

The PSK is stored in ~/.hcom/config.toml. On Unix, hcom writes that file with mode 0600.

hcom keeps the PSK out of environment variables. Remote config_get and config_set refuse relay_psk, relay_token, relay_id, and the broker URL. hcom relay status shows only a short fingerprint so two devices can verify they share the same key without printing it.

Anyone who can read that file — another user on the same OS account, malware, or a backup written without preserving permissions — has the full PSK.

Incident response

Run hcom relay off --all. It asks every reachable trusted peer to disable the relay, then disables it locally, so your agents stop acting on attacker messages. It is best-effort damage control, not containment: the attacker's device ignores the request.

The PSK cannot be revoked. There is no server to notify and no denylist to update. Anyone who has the PSK can keep using the old relay until you stop using it.

To keep using relay after a leak, create a new relay with hcom relay new and move every trusted device to the new token. Rotation also changes the relay_id, so retained state on the old broker topics is orphaned.

Supported tools

hcom r <session_id>           # Resume a session started outside hcom
hcom f <session_id>           # Fork a session in hcom

Claude Code headless and subagents

Detached background processes in print mode stay alive. Manage through the TUI.

hcom claude -p 'say hi in hcom'

For subagents, run hcom claude, then prompt:

run 2x task tool and get them to talk to each other in hcom

CLI commands

What you might type from a shell. Agents run their own commands that they learn from the hcom CLI primer (~700 tokens) at launch. hcom <command> --help for full flags.

Spawn

hcom [N] claude|gemini|codex|agy|opencode|kilo|pi|cursor-agent|kimi|copilot   # launch N agents
hcom r <name|session_id>                # resume agent
hcom f <name|session_id>                # fork session
hcom kill <name|tag:T|all>              # kill + close terminal pane

hcom launch flags:

Anything else is forwarded to the tool: --model sonnet, --yolo, etc.

Other commands

hcom                                # TUI dashboard
hcom send -b @luna -- hey           # one-off message to an agent
hcom list                           # show all active agents
hcom term [name]                    # view/inject into an agent's PTY screen
hcom events --wait <filters>         # Block until match for scripting
hcom update                         # update hcom version

hcom run docs --cli for all commands.

Configuration

Config lives in ~/.hcom/config.toml. Precedence: defaults < config.toml < env vars.

hcom config                           # show all values with sources
hcom config <key>                     # get
hcom config <key> <value>             # set
hcom config <key> --info              # detailed help for a key
hcom config -i <name> <key> <value>   # per-agent override at runtime

Keys

Scope

hcom config tag mycrew                          # global
hcom config -i luna hints "respond in JSON"     # per-agent
HCOM_TAG=dev hcom 3 claude                      # per-launch env

Per-project isolation

export HCOM_DIR="$PWD/.hcom"    # isolate state + hooks to this folder
hcom hooks remove && rm -rf "$HCOM_DIR"

Run hcom config <key> --info or hcom run docs --config for the full per-key reference.

Edit ~/.hcom/env to set external env vars passed to every launched agent.

Multi-agent workflows

Bundled and user scripts (~/.hcom/scripts/) for multi-agent patterns:

hcom run                   # list available scripts
hcom run debate "topic"    # run one
hcom run docs              # tell agent to run this to create any new workflow

Included Scripts

Tell agent to run them:

hcom run confess — An agent (or background clone) writes an honesty self-eval. A spawned calibrator reads the target's transcript independently. A judge compares both reports and sends back a verdict via hcom message.

hcom run debate — A judge spawns and sets up a debate with existing agents. It coordinates rounds in a shared thread where all agents see each other's arguments, with shared context of workspace files and transcripts.

hcom run fatcow — headless agent reads every file in a path, subscribes to file edit events to stay current, and answers other agents on demand.

Custom scripts: drop *.sh or *.py into ~/.hcom/scripts/ — auto-discovered, override bundled scripts of the same name. Ask an agent to author one; hcom run docs --scripts is the authoring guide.

Building from Source

# Prerequisites: Rust 1.88+

git clone https://github.com/aannoo/hcom.git
cd hcom
cargo build
cargo test

Using local build

Two options:

Symlink — simple, dev build is global.

ln -sf $(pwd)/target/debug/hcom ~/.cargo/bin/hcom

dev_root — works regardless of how hcom was installed (brew, pip, etc.); picks the newer of debug/release automatically:

hcom config dev_root $(pwd)
hcom config dev_root --unset  # revert
hcom status    # run local build

For concurrent worktrees, scope each to its own DB:

HCOM_DIR=$PWD/.hcom HCOM_DEV_ROOT=$PWD hcom claude