Track Claude CLI Cost

A quick guide on how to track session cost with a Claude hook. This will both keep a running cost counter below your Claude CLI and persist session costs to ~/.claude/cost/.

1. Create a shell script for the hook. I saved mine at ~/.claude/statusline.sh:

   #!/usr/bin/env bash
   input=$(cat)
   sid=$(jq -r '.session_id' <<<"$input")
   cost=$(jq -r '.cost.total_cost_usd // 0' <<<"$input")
   dir=$(jq -r '.workspace.project_dir // .cwd // "unknown"' <<<"$input")
   
   mkdir -p ~/.claude/cost
   jq -nc --arg s "$sid" --arg d "$dir" --argjson c "${cost:-0}" --arg t "$(date -Iseconds)" \
   '{session_id:$s, dir:$d, cost_usd:$c, ts:$t}' > ~/.claude/cost/"$sid".json
   
   printf '$%.2f' "$cost"

2. Register the hook in ~/.claude/settings.json:

   {
       "statusLine": {
           "command": "bash ~/.claude/statusline.sh",
           "type": "command"
       }
   }