Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add disler/learning-cmux-with-agents --skill cmux-debugginggit clone --depth 1 https://github.com/disler/learning-cmux-with-agentsWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/disler/learning-cmux-with-agents/cmux-debugging)<a href="https://agentmods.dev/skills/disler/learning-cmux-with-agents/cmux-debugging"><img src="https://agentmods.dev/badge/skills/disler/learning-cmux-with-agents/cmux-debugging/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/disler/learning-cmux-with-agents/cmux-debugging"><img src="https://agentmods.dev/badge/skills/disler/learning-cmux-with-agents/cmux-debugging.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector warn
SkillSpector: 2 findings, up to medium
These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →
- medium Rogue Agent · line 37 Skill establishes unauthorized persistence across sessions via cron jobs, startup scripts, or state files. Session persistence allows an attacker to maintain access beyond the current interaction.Fix: Remove any persistence mechanisms (cron jobs, startup scripts, state files). Skills should not maintain state across sessions without explicit user consent.
- medium Rogue Agent · line 41 Skill establishes unauthorized persistence across sessions via cron jobs, startup scripts, or state files. Session persistence allows an attacker to maintain access beyond the current interaction.Fix: Remove any persistence mechanisms (cron jobs, startup scripts, state files). Skills should not maintain state across sessions without explicit user consent.
What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00071 | $0.01012 |
| Opus 5.5 | $0.00028 | $0.00405 |
| Sonnet 5.5 | $0.00014 | $0.00202 |
| Haiku 4.5 | $0.00007 | $0.00101 |
Grade A, and why
cmux-debugging scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 1mo ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 55 lines — stays where its author put it; the contents beside it link to each section on GitHub.
cmux Debugging
Debug event log
When adding debug event instrumentation, put events (keys, mouse, focus, splits, tabs) in the unified DEBUG build log. This is not a blanket requirement to add logs to every new code path. Most temporary probes should be added only during the dogfood debug loop and removed before merge.
tail -f "$(cat /tmp/cmux-last-debug-log-path 2>/dev/null || echo /tmp/cmux-debug.log)"
- Untagged Debug app:
/tmp/cmux-debug.log - Tagged Debug app (
./scripts/reload.sh --tag <tag>):/tmp/cmux-debug-<tag>.log reload.shwrites the current path to/tmp/cmux-last-debug-log-pathreload.shwrites the selected dev CLI path to/tmp/cmux-last-cli-pathreload.shupdates/tmp/cmux-cliand$HOME/.local/bin/cmux-devto that CLI- Implementation:
Packages/macOS/CMUXDebugLog/Sources/CMUXDebugLog/DebugEventLog.swift - App shim:
Sources/App/DebugLogging.swift - Free function
cmuxDebugLog("message")logs with timestamp and appends to file in real time from cmux code - The package implementation and app shim are
#if DEBUG; all call sites must be wrapped in#if DEBUG/#endif - 500-entry ring buffer;
CMUXDebugLog.DebugEventLog.shared.dump()writes full buffer to file - Key events logged in
AppDelegate.swift(monitor, performKeyEquivalent) - Mouse/UI events logged inline in views (ContentView, BrowserPanelView, etc.)
- Focus events:
focus.panel,focus.bonsplit,focus.firstResponder,focus.moveFocus - Bonsplit events:
tab.select,tab.close,tab.dragStart,tab.drop,pane.focus,pane.drop,divider.dragStart
Debug menu
The app has a Debug menu in the macOS menu bar only in DEBUG builds. Use it for visual iteration.
- Debug > Debug Windows contains panels for tuning layout, colors, and behavior. Entries are alphabetical with no dividers.
- To add a debug toggle or visual option: create an
NSWindowControllersubclass with asharedsingleton, add it to the "Debug Windows" menu inSources/cmuxApp.swift, and add a SwiftUI view with@AppStoragebindings for live changes. - When the user says "debug menu" or "debug window", they mean this menu, not
defaults write.
What ships with it
3 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 1mo ago First seen · 55 lines · 71 tokens per session scan A 448cfe0ec50a
cmux-debugging is a skill published in the GitHub repository disler/learning-cmux-with-agents (117 stars, last pushed 3mo ago), licensed MIT. It adds 71 tokens to every session and 1,012 once invoked, about $0.0003 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
Other skills, from other repositories
debug-optimize-lcp
Guides debugging and optimizing Largest Contentful Paint (LCP) using Chrome DevTools MCP tools. Use this skill whenever the user asks about LCP performance, slow page loads, Core Web Vitals optimization, or wants to understand why their page's main content takes too long to appear. Also use when the user mentions…
systematic-debugging
Use when debugging a failing test, build error, or runtime issue that isn't immediately obvious. Guides a 4-phase root cause analysis instead of random fix attempts.
log-error-digest
Analyze log files to troubleshoot errors, identify peak error periods, and produce error clustering, frequency statistics, and time distribution reports. Supports JSON, syslog, and Nginx formats with automatic detection. Use when a user uploads a .log file and asks to analyze errors, find patterns, debug issues, or…
deck-retro
Run a fully local agent-deck retrospective over the user's own transcripts, Recall index and logs. Use when a user wants to find recurring failures or take their own finding from investigation through synthetic reproduction, a user-filed issue, a test-first fix and contributor PR handoff. Also use for weekly usage…
incident-response-incident-response
Coordinate production incident triage, mitigation, investigation, recovery, and follow-up. Use when responding to outages or other incidents that require structured operational coordination.
cwv-optimizer
Diagnose and fix Core Web Vitals issues on AEM Edge Delivery Services pages. Goes deeper than generic CWV advice by understanding EDS-specific performance patterns including the 100KB LCP budget, E-L-D loading phases, block rendering behavior, and third-party script impact. Produces specific fixes for LCP, CLS, and…