MCPInstall

cost-track

by ruvnet

Auto-capture per-session token usage from the Claude Code session jsonl and persist to the cost-tracking namespace

Installs
684
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Install

Works with every agent the skills CLI supports.

npx skills add https://github.com/ruvnet/ruflo --skill cost-track
  1. 01

    Install

    Run the command in your project. The CLI asks which agents to install for.

  2. 02

    Describe the task

    Ask your agent for something this skill covers. It loads cost-track automatically when relevant.

  3. 03

    Review the result

    The agent follows the SKILL.md steps, scripts and references bundled with the skill.

SKILL.md

The instructions your agent reads when the skill is triggered.

Cost Track

Reads the active Claude Code session jsonl (~/.claude/projects/<encoded-cwd>/<session>.jsonl), tallies assistant-message usage per model, computes USD cost using REFERENCE.md pricing, and writes a structured record to the cost-tracking AgentDB namespace. This is the producer that gives cost-report and cost-optimize real data to consume.

When to use

  • After a meaningful chunk of work, to capture spend for the report.
  • At session-end to persist the final tally.
  • Periodically during long sessions (cron-friendly — see /loop 30m).

Steps

  1. Run the tracker from the project root:

    node plugins/ruflo-cost-tracker/scripts/track.mjs

    The script auto-discovers the session jsonl from the current working directory. To pin a specific session: TRACK_SESSION=/path/to/session.jsonl. To dry-run (no memory write): TRACK_DRY_RUN=1.

  2. Inspect the markdown summary — total cost, per-model and per-tier breakdowns, and the persisted memory key.

  3. Verify persistence — mcp__plugin_ruflo-core_ruflo__memory_search --query "session-" --namespace cost-tracking should list the new record. cost-report step 1 reads from this namespace.

Record shape (in cost-tracking namespace)

Key: session-<sessionId>. Value (JSON):

{
  "sessionId": "1dba3b8c-...",
  "cwd": "/Users/cohen/Projects/ruflo",
  "startedAt": "2026-05-04T...",
  "endedAt": "2026-05-05T...",
  "messageCount": 234,
  "byModel": {
    "claude-opus-4-7": {
      "tier": "opus",
      "input_tokens": 12345,
      "output_tokens": 6789,
      "cache_creation_input_tokens": 800000,
      "cache_read_input_tokens": 2000000,
      "messages": 50,
      "cost_usd": 1.23
    }
  },
  "byTier": { "haiku": 0.0, "sonnet": 0.45, "opus": 1.23, "unknown": 0 },
  "total_cost_usd": 1.68,
  "capturedAt": "2026-05-05T..."
}

Pricing source of truth

The script's PRICING constant mirrors REFERENCE.md "Model pricing (USD per 1M tokens)". Update both together when prices change. Cache-write tokens are billed at cache_write rate; cache-read tokens at cache_read (per Anthropic billing docs).

Env overrides

EnvDefaultPurpose
TRACK_CWDprocess.cwd()Override which project's sessions to scan
TRACK_SESSIONmost-recent jsonlPin a specific session file
TRACK_OUTunsetAlso write the JSON summary to this path
TRACK_DRY_RUN=1unsetSkip the memory store call
TRACK_QUIET=1unsetSuppress markdown output
TRACK_NAMESPACEcost-trackingOverride target namespace

Cross-references

  • cost-report (consumer) — reads records produced by this skill
  • REFERENCE.md "Cost attribution formula" — the math the script implements
  • cost-budget-check (consumer; landing in P2) — reads totals to evaluate alerts

FAQ

What does the cost-track skill do?

Auto-capture per-session token usage from the Claude Code session jsonl and persist to the cost-tracking namespace

How do I install cost-track?

Run npx skills add https://github.com/ruvnet/ruflo --skill cost-track in your project. The skills CLI detects the agents you use and copies the skill into the right folder. For Claude Code you can also place the skill folder at ~/.claude/skills/cost-track/ (personal) or .claude/skills/cost-track/ (project).

Which AI agents can use cost-track?

Any agent that supports the open Agent Skills format (a folder with a SKILL.md file), including Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, Windsurf, Cline, OpenCode and more.

Is cost-track safe to install?

No partner security audit is available yet. Skills can run commands and scripts, so read the SKILL.md and any bundled files before installing.

Who maintains cost-track?

It is published by ruvnet in ruvnet/ruflo. It has 684 recorded installs.

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