Claude Dm

claude-dm

Peer-to-peer messaging between independent Claude Code sessions that share a tmux server.

When to use

• Multiple Claude Code sessions are running on the same machine (check with list), and one needs to inspect or communicate with another.
• You need to know what another Claude is currently working on, without attaching to its tmux pane.
• You want to trigger a slash command (/compact, /claude-dm, etc.) in another session.
• Send a prompt to a peer and wait for the reply as data.

When NOT to use

• To spawn a child Claude for one-shot work → use the Agent tool.
• To schedule a future Claude run on the cloud → use the schedule skill or RemoteTrigger.
• To send a message to another user's Claude on a different machine → this skill can't.

Prerequisites

• Peers must run in tmux (any socket). Default resolution: $CLAUDE_DM_SOCKET or /tmp/tmux-$(id -u)/default.
• Same Unix user (or a shared socket with group perms).
• tmux, jq, awk, sed, pgrep in $PATH (all present on this box).

Verbs

claude-dm list                                 # roster of claude panes
claude-dm status <target>                      # state + safety gate result
claude-dm peek   <target> [N]                  # last N text blocks of peer's transcript
claude-dm tail   <target>                      # live-follow peer's JSONL
claude-dm wait   <target> [int_s] [to_s]       # block until peer reaches idle/modal
claude-dm send   <target> <msg>   [--force]
claude-dm cmd    <target> /<slash> [--force] [--confirm]
claude-dm ask    <target> <msg>   [timeout_s]
claude-dm esc    <target>          [--force]   # Escape: interrupt turn or cancel modal
claude-dm answer <target> <key>    [--force]   # pick modal option (1/2/3/y/n/a/…)
claude-dm self   /<slash>                      # queue a user-only slash command on the current pane

<target> is session:window.pane on the current socket (e.g. HOME:8.1).

list marks the current session's row with a trailing * on the ADDR column (e.g. _claude:7.1*). Strip the * before passing the addr to other verbs. Self detection only fires when $CLAUDE_DM_SOCKET matches the socket from $TMUX.

Peer states

peer_state reports one of five values, shown in status and used by every gate:

When state is modal, status also reports a subtype — permission (Bash/Edit/Write/Notebook being gated) or question (AskUserQuestion) — resolved from the most recent tool_use in the transcript.

Gate matrix

Why the draft protection: send-keys appends to the tty buffer. If a human has a half-typed draft, your message concatenates with theirs. Every write verb that goes through safe_to_dm catches this via the drafting state; esc applies the same rule explicitly.

Slash-command tiers (for cmd)

Red tier refuses to send without --confirm because those commands are irreversible for the peer.

Spawning a disposable target for testing

To smoke-test the tool without touching real peers:

tmux -S /tmp/claude-dm-test.sock -f /dev/null new-session -d -s test -n shell fish
CLAUDE_DM_SOCKET=/tmp/claude-dm-test.sock claude-dm send test:0.0 "hello" --force
tmux -S /tmp/claude-dm-test.sock kill-server   # when done

For a full roundtrip with a real Claude, spawn a fresh interactive session in the test socket (costs one session init but minimal tokens until prompted):

tmux -S /tmp/claude-dm-test.sock -f /dev/null new-session -d -s claude-test -n c 'claude'

Examples

Inspect a peer without touching it:

claude-dm list
claude-dm peek test:9.1 40
claude-dm status HOME:8.1

Trigger a skill on an idle peer:

claude-dm cmd HOME:6.1 "/compact"
claude-dm cmd HOME:6.1 "/claude-dm"

Ask and wait for reply:

claude-dm ask HOME:8.1 "What's the current test status?" 180

Block until a peer finishes its current turn (e.g. after dispatching work via send/cmd). Pair with Bash run_in_background + Monitor so the orchestrator agent gets a notification on the sentinel line and decides next steps:

claude-dm send HOME:8.1 "Run the full test suite and summarise failures."
claude-dm wait HOME:8.1                    # 30s polls, no timeout, blocks until DONE/MODAL
claude-dm wait HOME:8.1 10 600             # 10s polls, give up after 10 min

Output is one of:

• DONE — peer passes the same gate as safe_to_dm: pane title ✳ AND transcript's last assistant turn is end_turn. Title-idle alone is not enough; the loop keeps polling while a tool result is still pending so DONE never fires mid-turn.
• MODAL — peer hit a permission / AskUserQuestion modal.

Exit 1 (no stdout sentinel) on timeout or if the peer pane vanishes.

Interrupt a peer that's run too long, or cancel a stuck modal:

claude-dm esc test:10.2

Answer a permission prompt or AskUserQuestion on a peer:

claude-dm status HOME:6.1           # verify state=modal (permission/question)
claude-dm answer HOME:6.1 1         # pick option 1 (typically "Yes")
claude-dm answer HOME:6.1 2         # option 2 ("Yes, and don't ask again")
claude-dm answer HOME:6.1 3         # option 3 ("No")

Self-DM

Self-trigger a user-only slash command on the current pane:

claude-dm self /context             # context-window usage summary
claude-dm self "/context all"       # same, but expands per-item
claude-dm self /compact             # pre-emptive compaction before heavy work
claude-dm self /rename              # auto-name session from conversation history
claude-dm self "/rename my-session" # rename to a specific name

self resolves the current pane via $TMUX_PANE and the socket from $TMUX. The synchronous box check up front refuses if a draft or modal is already present (the same peer_box_state check that protects peer DMs).

self returns immediately. The slash command fires after the current turn ends; its output arrives in the next user-turn alongside a <notification>claude-dm self /<slash> dispatched; output above</notification>. Aborts silently if a draft or modal appears before fire time.

Audit trail

Every write appends to ~/.claude/claude-dm.log with timestamp, verb, target, and payload.

Limitations

• 🔴 TOCTOU — peer may enter a modal between check and send; the safety gate is best-effort, not transactional.
• 🔴 Cross-machine — not supported directly; tmux socket is local. To address peers on an SSH host or inside a Docker container, build the single-file bundle and run it on the remote: see portable/README.md.
• 🟡 UI drift — safety checks encode the current Claude Code UI (✳ glyph, ❯ prompt, ─ rules). Future UI changes may need the regexes updated in lib/safety.sh.
• 🟡 Injection signals as real user — the peer sees the DM as though the human typed it. Identify yourself in prose messages ("DM from <your-addr>: …") so the peer can reason about trust.