intercom

name	intercom
description	Streamline session-to-session coordination with the intercom extension. Send messages, delegate tasks, and coordinate work across multiple atomic sessions on the same machine. Use for planner-worker workflows, cross-session context sharing, and real-time collaboration between sessions.

Intercom Skill

Use this skill when you need to coordinate work across multiple atomic sessions running on the same machine. Intercom enables direct 1:1 messaging between sessions for delegation, context sharing, and collaborative workflows.

When you are supervising with the subagent skill, delegated child agents can escalate to you via contact_supervisor if the subagent runtime supplied child bridge metadata. This skill covers how to handle those orchestrator-side escalations.

When to Use

• Task delegation: Split work between a planner session and worker sessions
• Context handoffs: Send findings from a research session to an execution session
• Clarification loops: Worker asks questions, planner answers, work continues
• Multi-session workflows: Coordinate between specialized sessions (frontend/backend, research/implementation)

Core Patterns

Pattern 1: Planner-Worker Delegation

The most common pattern. One session holds the big picture, others do hands-on work.

Setup (in each session):

/name planner    # Terminal 1
/name worker     # Terminal 2

Planner delegates a task (fire-and-forget):

intercom({
  action: "send",
  to: "worker",
  message: "Task-3: Add retry logic to API client. Key files: src/api/client.ts. Ask if anything's unclear."
})

Worker asks for clarification (blocks until answer):

intercom({
  action: "ask",
  to: "planner",
  message: "Should I use exponential backoff or fixed intervals?"
})
// → Returns the planner's reply as the result

Worker reports completion:

intercom({
  action: "ask",
  to: "planner",
  message: "Task-3 complete. Added exponential backoff (100ms → 1600ms, max 5 retries). Ready for task-4?"
})

Pattern 2: Quick Status Check

Before sending, verify who's connected. The full session ID printed by list is directly usable by send, ask, and targeted reply:

intercom({ action: "list" })
// → • planner (6332faab-1111-4222-8333-123456789abc) — /workspace (model) [idle]
intercom({ action: "ask", to: "6332faab-1111-4222-8333-123456789abc", message: "Which option should I use?" })

Intercom accepts only an exact full session ID or an exact case-insensitive session name. Use the full ID printed by list or the session's exact name.

Runtime named groups

Plain chat sessions can create or join a group without restarting:

// Join or create the named group. Both sessions should run this call.
intercom({ action: "join", group: "api-review" })
intercom({ action: "list" }) // now shows only peers in api-review

// Leave the named group and return to the resolved startup home group.
intercom({ action: "leave" })

Joining changes broker presence without changing the session ID. default is the shared group. The names true and auto are reserved for subagent auto-groups and are rejected. Subagents launched after a join inherit the joined group. Ordinary send/ask calls remain group-isolated; only an authorized contact_supervisor call can cross groups.

Pattern 3: Reply Naturally

When responding to an inbound ask, prefer reply instead of reconstructing raw IDs:

// In the turn triggered by the ask:
intercom({
  action: "reply",
  message: "Use exponential backoff starting at 100ms."
})

// If replying later and there might be more than one pending ask:
intercom({ action: "pending" })
intercom({ action: "reply", to: "planner", message: "Use exponential backoff starting at 100ms." })

reply still preserves exact threading under the hood by sending the response with the original replyTo value.

Pattern 4: Broadcast to Multiple Workers

Send to multiple sessions in parallel:

const workers = ["worker-1", "worker-2", "worker-3"];
const task = "Check for null pointer exceptions in your assigned files";

// Fire-and-forget to all workers
workers.forEach(w => 
  intercom({ action: "send", to: w, message: task })
);

Pattern 5: Send with Attachments

Share code snippets, files, or context:

intercom({
  action: "send",
  to: "worker",
  message: "Here's the fix for the auth issue:",
  attachments: [{
    type: "snippet",
    name: "auth.ts",
    language: "typescript",
    content: `function validateUser(user: User | null) {
  if (!user) throw new Error("User required");
  return user.email?.includes("@");
}`
  }]
})

Pattern 6: Handle Subagent Escalations (Orchestrator Side)

When the subagent runtime spawns a delegated child and supplies child bridge metadata, that child can reach you through contact_supervisor. You receive a formatted message that includes run metadata:

**From subagent-worker-78f659a3-1**

Subagent needs a supervisor decision.
Run: 78f659a3
Agent: worker
Child index: 0

Which API should I use?

Reply using reply:

// The reply hint in the incoming message will show the exact call:
intercom({ action: "reply", message: "Use the stable v2 API." })

This works because reply resolves the correct sender and message ID automatically.

Three types of escalations to expect:

Type	What it means	How to respond
need_decision	Subagent is blocked and waiting for your answer. Has a 10-minute timeout.	Reply promptly with a clear decision. If you need more context, ask follow-up questions via reply.
interview_request	Subagent needs multiple structured answers in one blocking exchange. Has a 10-minute timeout.	Reply with plain JSON or a fenced json block using the provided { "responses": [...] } shape.
progress_update	Subagent is sharing meaningful progress or a plan-changing discovery. Not blocking.	Read and acknowledge. No reply required unless you want to redirect.

When a subagent asks:

// In the turn triggered by the incoming ask:
intercom({ action: "reply", message: "Use exponential backoff, max 3 retries." })

When a subagent sends an interview request:

Read the rendered questions in the incoming message and reply with the exact ids in JSON. info questions are context-only and do not need response entries:

intercom({
  action: "reply",
  message: "```json\n{\n  \"responses\": [\n    { \"id\": \"api\", \"value\": \"Stable API\" },\n    { \"id\": \"constraints\", \"value\": \"Keep the public error shape unchanged.\" }\n  ]\n}\n```"
})

If you receive multiple pending asks from different subagents:

intercom({ action: "pending" })
// → Shows all unresolved inbound asks with sender, elapsed time, and preview

intercom({ action: "reply", to: "subagent-worker-78f659a3-1", message: "Use the v2 API." })

Important: Only sessions where the subagent runtime supplied child bridge metadata get the contact_supervisor tool. Normal sessions use the regular intercom tool. If you see the formatted supervisor decision/progress update message, treat it as a contact_supervisor escalation.

Pattern 7: Constructive Quorum

Use constructive quorum when several fresh-context reviewers judge the same artifact and a tally could hide a defect one reviewer found or preserve another reviewer's misreading.

1. Each reviewer inspects independently and records a preliminary verdict before reading sibling findings or verdicts.
2. Run exactly one bounded evidence-exchange round: share concrete findings and evidence, challenge blocking claims, surface missed defects, and correct objective/acceptance-criteria misreadings. Do not continue into a second round.
3. Change a verdict only through evidence, never deference. Each reviewer emits its own final structured verdict and records whether the round changed it and which evidence caused the change.
4. Let the deterministic reducer count final votes; this pattern does not change quorum counts or the stop_review_loop contract.

In Atomic workflows, each invocation has its own Intercom group, and parallel stages and delegated subagents inherit it when Intercom is available. Sibling reviewers can therefore coordinate without custom group wiring. See the constructive quorum workflow pattern.

Key Differences

Action	Behavior	Use When
join	Joins or creates a named group in place	Two plain chat sessions need a private group
leave	Returns to the resolved home group	Restore the session's startup group
send	Fire-and-forget	You don't need a response
ask	Blocks until reply (10 min timeout)	You need an answer to continue
reply	Responds to the active or pending inbound ask; to accepts an exact full session ID or exact session name	You were asked something and need to answer naturally
pending	Lists unresolved inbound asks	You need to see who is waiting before replying
list	Returns all sessions in the current group with full session IDs and live status	You need to discover targets or choose an idle peer
status	Returns your connection state and current group	Troubleshooting

Inside workflows, ask may target a sibling stage that has already completed. If that stage retains a valid conversation, Atomic automatically schedules a post-mortem turn there and preserves the exact child-to-child reply thread; do not send a separate workflow follow-up. Missing, deleted, non-resumable, or failed-to-reopen completed targets return an actionable error. A parent or unrelated session cannot satisfy the pending ask.

Optional: Visible Peer Sessions via cmux, tmux, or psmux (Windows rewrite of tmux that has fully parity with tmux)

If no suitable intercom-connected peer session already exists and the task benefits from a long-lived visible conversation, you may spawn a new atomic session.

Prefer cmux new-split right over new surfaces or workspaces so both sessions are visible side by side.

If cmux is unavailable, tmux is an optional fallback when it is installed and relevant. Use it with a private socket so the session is isolated and observable.

Use spawned peer sessions only for:

• same-codebase worker/planner splits
• reference-codebase scouting
• long-lived visible conversations where the user benefits from watching both sides

Do not use this for unrelated repos, trivial questions, or work you can finish cleanly in the current session.

Preferred: cmux Worker or Scout Session

Same codebase:

cmux new-split right
sleep 0.5
cmux send --surface right 'cd /path/to/current/repo && pi\n'

Reference codebase:

cmux new-split right
sleep 0.5
cmux send --surface right 'cd /path/to/reference/repo && pi\n'

Optional Fallback: tmux Worker or Scout Session

Same codebase:

SOCKET_DIR=${TMPDIR:-/tmp}/pi-tmux-sockets
mkdir -p "$SOCKET_DIR"
SOCKET="$SOCKET_DIR/pi.sock"
SESSION=pi-worker
tmux -S "$SOCKET" new -d -s "$SESSION" -c "/path/to/current/repo" 'pi'

Reference codebase:

SOCKET_DIR=${TMPDIR:-/tmp}/pi-tmux-sockets
mkdir -p "$SOCKET_DIR"
SOCKET="$SOCKET_DIR/pi.sock"
SESSION=pi-reference-auth
tmux -S "$SOCKET" new -d -s "$SESSION" -c "/path/to/reference/repo" 'pi'

When you use tmux, tell the user how to watch it:

tmux -S "$SOCKET" attach -t "$SESSION"

After launch, name the new session clearly so it is easy to target:

/name worker
/name reference-auth

Then coordinate from the current session:

intercom({
  action: "send",
  to: "worker",
  message: "Take task X. Ask if blocked."
})

intercom({
  action: "ask",
  to: "reference-auth",
  message: "How does this repo structure token refresh retries?"
})

Spawn Decision Rule

Spawn a visible peer session only when all of these are true:

• no existing intercom-connected session already fits the need
• the work benefits from a long-lived visible peer session
• the peer session is either in the same codebase or in an intentional reference codebase
• cmux is available, or tmux is available as an intentional fallback

If neither cmux nor tmux is available, skip this path and use normal intercom workflows.

Important Constraints

ask Limitations

• 10-minute timeout: If no reply comes within 10 minutes, the ask fails
• One at a time: Cannot have multiple pending asks from the same session
• Cannot self-target: A session cannot ask itself
• Concurrency-safe: If several blocking requests (multiple ask calls, or ask plus contact_supervisor) race in the same session — for example from parallel tool calls — exactly one wins the reservation. Every other call gets a normal "Already waiting for a reply" tool error and can retry or fall back to send; the losing calls never disturb the winning ask.

// Check if already waiting before asking
const result = await intercom({ action: "ask", to: "planner", message: "..." });
if (result.isError && result.content[0].text.includes("Already waiting")) {
  // Use send instead, or wait for current ask to complete
}

send Behavior

• No timeout: Message is delivered or fails immediately
• Confirmation dialogs: If confirmSend: true in config, interactive sessions show a confirmation dialog
• Replies skip confirmation: Messages with replyTo never show confirmation dialogs

Best Practices

Use ask for blocking workflows

When the worker needs information to proceed:

// GOOD: Worker blocks until planner responds
const reply = await intercom({
  action: "ask",
  to: "planner",
  message: "API rate limit is 100/min. Should I implement client-side throttling or batching?"
});
// Continue with the answer...

Use send for notifications

When you just want to inform:

// GOOD: Fire-and-forget notification
intercom({
  action: "send",
  to: "reviewer",
  message: "PR #123 is ready for review. Key changes in auth.ts."
});
// Continue immediately, don't wait

Include reply hints in messages

Make it easy for recipients to respond:

// GOOD: Recipient sees exact command to reply
intercom({
  action: "send",
  to: "worker",
  message: `Found the issue in auth.ts:142. Use getUserById() instead of getUser().

Reply with: intercom({ action: "reply", message: "..." })`
});

Name sessions meaningfully

Use /name so others can target you easily:

/name api-worker
/name frontend-dev
/name planner

Error Handling

Common Errors and Solutions

"Already waiting for a reply"

// You can only have one pending ask at a time. Concurrent blocking requests
// (parallel asks, or ask + contact_supervisor) return this error safely; the
// winning request keeps waiting for its reply.
// Option 1: Use send instead
intercom({ action: "send", to: "planner", message: "..." });

// Option 2: Wait for the current ask to complete, then retry

"Cannot message the current session"

// You cannot target yourself
// This usually means you confused session names - double-check the target

"Session not found"

const result = await intercom({ action: "send", to: "worker", message: "..." });
if (!result.delivered) {
  console.log("Failed:", result.reason);
  // → "Session not found" - check the name and list available sessions
  await intercom({ action: "list" });
}

Ask timeout (after 10 minutes)

// The ask will reject with a timeout error
// Design your workflow so answers come within 10 minutes
// For longer tasks, use send + follow-up ask pattern

Troubleshooting

Session not appearing in list

1. Check intercom is enabled: intercom({ action: "status" })
2. Verify the target session has loaded pi-intercom
3. Ensure both sessions are on the same machine (intercom is same-machine only)

Message not delivered

const result = await intercom({ action: "send", to: "worker", message: "..." });
if (!result.delivered) {
  console.log("Failed:", result.reason);
  // → "Session not found" or delivery failure reason
}

Connection lost

Sessions automatically reconnect if the broker restarts. If persistently disconnected:

intercom({ action: "status" })
// Check if broker is running and restart if needed

Common Workflows

Research → Implementation Handoff

// Research session finds relevant code
intercom({
  action: "send",
  to: "impl-session",
  message: "Found the bug. The issue is in validateUser() - it doesn't check for null.",
  attachments: [{
    type: "snippet",
    name: "validate.ts",
    language: "typescript",
    content: `// Line 45-52 - missing null check
function validateUser(user: User) {
  return user.email?.includes("@"); // crashes if user is null
}`
  }]
});

Pair Debugging

// Session A encounters error
intercom({
  action: "ask",
  to: "session-b",
  message: "Getting 'Cannot read property of undefined' at line 78. Can you check if data.users is populated before this call?"
});

// Session B investigates and replies
intercom({
  action: "reply",
  message: "data.users is null. The fetch failed silently. Add error handling in loadUsers()."
});

Progress Reporting

// Worker sends periodic updates
intercom({ action: "send", to: "planner", message: "Task-1 complete (15min). Starting Task-2." });
// ... work ...
intercom({ action: "send", to: "planner", message: "Task-2 complete (30min). Task-3 blocked - need API key." });
// ... get unblocked ...
intercom({ action: "send", to: "planner", message: "Task-3 complete. All done." });

Long-Running Task with Checkpoints

// For tasks that might exceed 10 minutes, use send + periodic asks

// 1. Initial send with full context
intercom({
  action: "send",
  to: "worker",
  message: "Implement user authentication. This will take 30+ minutes. I'll check in at milestones."
});

// 2. Worker sends progress via send (no timeout)
intercom({ action: "send", to: "planner", message: "Milestone 1: Login form complete (10min)" });

// 3. Worker asks for specific decision when needed
const decision = await intercom({
  action: "ask",
  to: "planner",
  message: "Should we use JWT or session cookies? Need decision to continue."
});
// Continue with decision...