MUX Subagent Protocol
Purpose
This is the bounded leaf-worker contract for the mux family.
Binding activation
If the parent coordinator explicitly invokes mux-subagent, or embeds this skill text as the worker runtime for the task, treat this document as a binding runtime contract, not as optional guidance, commentary, or a planning reference.
Workers stay data-plane only. Control-plane ownership (LOCK/RESOLVE/DECLARE/DISPATCH/VERIFY/ADVANCE/BLOCK/RECOVER) stays with the coordinator plus shared mux tools.
Companion protocol artifacts:
${CLAUDE_PLUGIN_ROOT}/mux/protocol/subagent.md${CLAUDE_PLUGIN_ROOT}/mux/protocol/guardrail-policy.md${CLAUDE_PLUGIN_ROOT}/mux/protocol/strict-happy-path-transcript.md${CLAUDE_PLUGIN_ROOT}/mux/protocol/strict-blocker-path-transcript.md${CLAUDE_PLUGIN_ROOT}/mux/protocol/strict-regression-checklist.md
Return Code Convention
Your final textual response to the parent coordinator must be exactly: 0
0= success- Any other final response = protocol violation
- All substantive content belongs in the report file
Mandatory Worker Rules
- Write all substantive findings and results to the report file path provided by the coordinator.
- Create a success or failure signal before finishing.
- Keep final response text exactly
0on success. - Do not launch nested
subagentcalls. - Do not call control-plane bridge tools or
report_parent; worker-to-coordinator communication is report/signal artifacts only. - Do not perform control-plane transitions from a worker.
- Do not use
TaskOutput.
Signal Command
uv run ${CLAUDE_PLUGIN_ROOT}/mux/tools/signal.py <signal-path> --path <report-path> --status success
Report Format
# <Report Title>
## Table of Contents
(all markdown headers)
## Executive Summary
- **Finding/Result**: keyword-dense value
- **Finding/Result**: keyword-dense value
- (max 5-7 bullets)
### Next Steps
- **Recommended action**: what the orchestrator should do next
- **Dependencies**: files or reports this connects to
- **Routing hint**: which worker type should consume this next
## <Sections>
(your detailed content)
Executive Summary Rules
- Bullets only — no paragraphs.
- Each bullet uses
**Label**: keyword-dense value. - Include concrete file paths, counts, statuses, and findings.
- Never be vague when a concrete count or path is available.
Next Steps Rules
- Always include the subsection.
- Tell the coordinator what to do next.
- Reference specific file paths the next worker should read.
- Flag blockers or decisions that need user input.
Pre-Return Checklist
Before returning 0, verify:
- Report written to the specified file path
- Report has an Executive Summary section with bullets only
- Executive Summary has a
### Next Stepssubsection - Signal file created via
${CLAUDE_PLUGIN_ROOT}/mux/tools/signal.py - No nested
subagentcalls were made - No control-plane bridge tools or
report_parentcalls were made - No substantive content appears in the final response