agent-session-monitor

agent-session-monitor is a skill for Claude Code from yorrick/agent-skills. It costs 86 tokens per session (1,656 once invoked), scanned A, original, MIT.

A monitoring tool for coding agents running in tmux, a terminal program that keeps sessions open in separate panes. It watches their output and helps steer sessions when they become idle, blocked, or reach a context limit.

In plain words
What is it for?
Use it to supervise Claude Code, Codex, or other terminal agents, send approved commands, and manage stalled or context-limited sessions.
Why use it?
It removes the need to repeatedly check terminal panes and decide whether an agent needs input.

Skill for Claude Code

Written for Claude Code: Claude Code plugin machinery. Also seen: mentions Claude Code; mentions Codex.

Part of the agent-session-monitor plugin — 1 skill shipped together

Good fit Use it to supervise Claude Code, Codex, or other terminal agents, send approved commands, and manage stalled or context-limited sessions.

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Install with agentmods
npx agentmods add skills/yorrick/agent-skills/agent-session-monitor
Install

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.

Any agent
npx skills add yorrick/agent-skills --skill agent-session-monitor
Clone the repo
git clone --depth 1 https://github.com/yorrick/agent-skills

Made for: Claude Code.

Or install agent-session-monitor, the plugin that ships this one along with the rest of its 1 skill.

Wrote 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.

agentmods badge for agent-session-monitor

README.md
[![agentmods](https://agentmods.dev/badge/skills/yorrick/agent-skills/agent-session-monitor/github.svg)](https://agentmods.dev/skills/yorrick/agent-skills/agent-session-monitor)
Your own site
<a href="https://agentmods.dev/skills/yorrick/agent-skills/agent-session-monitor"><img src="https://agentmods.dev/badge/skills/yorrick/agent-skills/agent-session-monitor/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.

agentmods 80×15 button for agent-session-monitor

Your own site · 80×15
<a href="https://agentmods.dev/skills/yorrick/agent-skills/agent-session-monitor"><img src="https://agentmods.dev/badge/skills/yorrick/agent-skills/agent-session-monitor.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 86 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,656 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector warn 7 Sept 2026
SkillSpector: 1 finding, up to high

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 →

  • high Memory Poisoning · line 39
    Skill manipulates agent memory, state, or stored context. Memory corruption can alter personality, override safety rules, or cause unpredictable behavior.
    Fix: Protect agent memory and state from modification by untrusted content. Use read-only memory for critical instructions and validate all state changes.
How audits are shown
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00086 $0.01656
Opus 5 $0.00043 $0.00828
Sonnet 5 $0.00017 $0.00331
Haiku 4.5 $0.00009 $0.00166

Measured 12d ago against content hash 32397597066a, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

agent-session-monitor 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 12d ago.

The scan reads SKILL.md. This mod also ships 3 executable files (scripts/claude-to-codex-handoff.sh, scripts/send-to-tmux-agent.sh, scripts/watch-tmux-agents.sh), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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.

agent-session-monitor/skills/agent-session-monitor/SKILL.md · 210 lines

How it starts

The opening of the file, as written. The whole thing — 210 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Agent Session Monitor

Use this skill to act as a meta agent for terminal agents running inside tmux. It is intentionally platform-neutral: the skill body uses the open Agent Skills format, and product-specific behavior lives in small references.

Compatibility Model

Keep one versioned source of truth:

agent-session-monitor/
  .claude-plugin/plugin.json
  skills/agent-session-monitor/
    SKILL.md
    scripts/
    references/

Expose skills/agent-session-monitor to host-specific discovery paths with symlinks or plugin installation. Do not copy the skill body into separate Claude and Codex versions.

Read references/platforms.md when you need install-path or command details. Read references/gsd.md only when monitoring GSD workflow panes.

Operating Rules

  • Treat tmux panes as the source of truth. Capture the pane before every decision and again after sending input.
  • Never interrupt a pane that is still working, compacting, streaming tokens, or showing an interrupt hint.
  • Follow the watched agent's own next-step recommendation before applying a generic workflow. If the agent says to clear context, ask the user, or run a specific command, treat that as higher-signal than a rigid state machine.
  • Send only commands that the user explicitly approved or that the watched agent explicitly requested and are low-risk in the current workflow.
  • If a command is rejected, do not try an alternate command automatically. Show the rejection, explain the proposed correction, and get explicit approval unless the correction was already approved for this workflow.
  • If a design appears to need fallback behavior, stop and ask first. This includes retry loops, alternate slash commands, heartbeats, replacement monitors, and rollover behavior after a monitor process exits.
  • Do not clear or compact context when the agent is asking a real question, reporting ambiguity, requesting a decision, or waiting on credentials, approvals, destructive operations, or external state.

Read the full file on GitHub · 210 lines

Files

What ships with it

5 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.

Changes

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.

  1. 12d ago First seen · 210 lines · 86 tokens per session scan A 32397597066a

Subscribe to this mod's changes

agent-session-monitor is a skill published in the GitHub repository yorrick/agent-skills (10 stars, last pushed 8d ago), licensed MIT. It adds 86 tokens to every session and 1,656 once invoked, about $0.0004 per session on Opus 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 2026-08-31.

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