agentmon

What AI coding agents (Claude, Codex) cost your Mac: per-session CPU, real memory, disk and network I/O, memory pressure, and a history of runs, in your terminal.

With Homebrew (brings its own Ruby):

brew install satoramoto/tap/agentmon

Or as a gem:

gem install agentmon

Requirements: macOS; the gem needs Ruby 3.3 or newer. No root needed (other users' processes show only what ps gives). The network columns come from nettop, which ships with macOS; without it they show as unknown and the rest works.

agentmon                    # live dashboard, dense layout
agentmon --layout visual    # gauges, areas and heat
agentmon --layout classic   # the original dashboard: sessions, memory, processes, detail
agentmon --no-motion        # no animation (also AGENTMON_MOTION=0)
agentmon | cat              # one plain frame, no terminal needed
agentmon top --once         # agent processes by CPU, one plain table
agentmon --help             # every command and option

Commands:

Every command takes --version, --color/--no-color and --trace. Off a terminal, output is plain text for scripts.

• dense (default): an htop-like strip of machine CPU, memory and I/O, the Sessions table, and all agents together. Enter on a session drills into it: its CPU, memory and network, its processes, connections and a detail drawer.
• visual: the same content as meters, braille area charts and heat colours.
• classic: the first dashboard: Sessions, Memory, Processes and the Detail panel side by side.

The mouse works too: click focuses a panel and selects a row, the wheel moves the selection.

• Session: a claude or codex CLI and everything under it (its outermost one), or a desktop app (Claude, ChatGPT/Codex) and its children. Labelled claude 4242 · repo.
• CPU: percent of one core, so 250% is two and a half cores. A session's CPU is the sum of its processes.
• Footprint (real memory): the kernel's phys_footprint, what Activity Monitor calls Memory. It counts compressed pages, unlike resident size, which is also shown.
• Disk read/write: bytes per second from each process's own I/O counters. Session totals add each process's growth, so very short-lived tools may be missed.
• Network in/out: bytes per second per process and connection, from one nettop stream; hosts and connections are counted per session. A session with a sudden spike or many remote hosts is marked ⚑.
• Memory pressure: 100 − kern.memorystatus_level, in percent; the Memory panel lists which sessions push it (footprint share and growth per second).
• Wait and page-ins: time runnable but waiting for a CPU, and page-ins per second (each one waited for the disk).
• Lifetime totals (CPU seconds, written, peak footprint): counted from when agentmon sees the session; nothing in a process tree is counted twice.

Unknown values (an unreadable process, the first sample's rates) are blank, never 0. Sizes are binary (1.5G = 1.5 × 1024³ bytes).

While the dashboard is open, or under agentmon record, agentmon writes one JSON line per session (and the memory breakdown) every 10 seconds to ~/.local/state/agentmon/<kind>/YYYY-MM-DD.jsonl (or $XDG_STATE_HOME/agentmon, or $AGENTMON_STATE_DIR). agentmon report reads it; agentmon record --prune 30 deletes days older than 30.

agentmon is built on r2ui. With an r2ui checkout beside this one (../r2ui), the Gemfile uses it; otherwise it uses r2ui's main on GitHub.

bundle install
bundle exec rake test
bundle exec exe/agentmon

See AGENTS.md for targeted tests, docs/design.md for the architecture and docs/releasing.md for releases.

MIT, see LICENSE.txt.