cmux-debug

name	cmux-debug
description	Verifies ccusage terminal output in a real cmux pane. Use when changing responsive tables, column widths, progress bars, spinners, or colors, or when a long-running command's output must be captured beyond the visible viewport.

cmux Debug

Piped stdout is not a terminal: width detection, color, progress, and spinners all take a different branch, so a non-interactive run cannot confirm a rendering change. Run the command inside a cmux surface and read the pane back instead.

Pick a target with the listing commands (cmux --help, cmux capabilities --json), then send and capture against that same surface — the capture is only meaningful for the pane the command actually ran in:

cmux send --workspace <workspace> --surface <surface> "printf '\\033c'; cd <cwd>; <command>\n"
cmux capture-pane --workspace <workspace> --surface <surface> --scrollback --lines 120

The leading screen reset keeps the previous run's output out of the capture, and --scrollback is what survives output longer than the viewport; cmux read-screen without it only returns the visible screen.

For a responsive-layout bug, capture the geometry in the same send so the widths are provably the ones the command saw:

cmux send --workspace <workspace> --surface <surface> "printf '\\033c'; stty size; printf 'COLUMNS=%s\n' \"\$COLUMNS\"; cd <cwd>; <command>\n"

Then check the rendered table against that width: no wrapping, and no truncated date, model, or total columns. Repeat at a narrow width — layout regressions show up there first.

If capture-pane or read-screen is missing from cmux capabilities --json, fall back to socket RPC, which takes UUIDs rather than refs:

cmux rpc surface.read_text '{"workspace_id":"<workspace_uuid>","surface_id":"<surface_uuid>","scrollback":true,"lines":120}'