opentk

Reduces LLM token consumption by 60–90% on common developer commands. Works with Claude Code, OpenCode, and any AI coding agent that supports shell hooks or plugins.

• 60+ command patterns — git, cargo, pytest, vitest, tsc, eslint, terraform, kubectl, and more
• 12 filtering strategies — stats extraction, error-only, grouping, deduplication, tree compression, etc.
• Zero config — auto-configures Claude Code and OpenCode on install
• Local-only tracking — all data stays on your machine, no telemetry

Install

npm install -g @tvonhake/opentk

On install, opentk automatically configures:

• Claude Code — adds a PreToolUse hook to ~/.claude/settings.json
• OpenCode — adds itself as a plugin to ~/.config/opencode/opencode.json (if present)

That's it. No manual config needed.

How It Works

Claude Code

opentk runs as a PreToolUse hook. When Claude runs a matched bash command, opentk rewrites it to pipe the output through a filter before Claude sees it:

git log --oneline -20
  → bash -c '... git log --oneline -20 | opentk-filter --strategy stats ...'

• Original exit code is preserved
• Falls back to unfiltered output if the filter fails
• Only intercepts simple commands — anything with &&, ||, |, $(, or sudo passes through unchanged

OpenCode

opentk runs as a JS plugin using OpenCode's tool.execute.before / tool.execute.after hooks, which can mutate tool output directly.

Manual Setup

If you prefer to configure manually:

Claude Code — add to ~/.claude/settings.json:

{
  "hooks": {
    "PreToolUse": [
      {
        "matcher": "Bash",
        "hooks": [{ "type": "command", "command": "opentk-hook" }]
      }
    ]
  }
}

OpenCode — add to ~/.config/opencode/opencode.json:

{
  "plugin": ["@tvonhake/opentk"]
}

Supported Commands

Git

git status, git diff, git log, git show, git blame, git stash list, git reflog, git shortlog, git branch, git ls-files

GitHub CLI

gh pr list/status, gh issue list, gh run list/view, gh workflow list

Files & Search

ls, tree, find, fd, du, df -h, grep, rg, ag, cat, head, tail

JavaScript / TypeScript

npm run, pnpm, yarn, bun, npx, vitest, jest, mocha, tsc, eslint, prettier, biome

Python

pytest, ruff, pip install/list/freeze/show/check/audit, mypy, pylint, flake8, pyright

Rust

cargo test/build/check/clippy/audit/outdated/metadata/tree

Go

go test/build/vet, golangci-lint

Ruby

rspec, bundle exec rspec, bundle list

Java / JVM

mvn test/build, gradle test/build

Docker & Kubernetes

docker ps/images/logs/inspect, kubectl get/describe/logs/top, helm list/status

Cloud & Infrastructure

terraform plan/show/state, tofu plan/state, aws ... list/describe, gcloud ... list/describe, az ... list

System

ps aux

Viewing Token Savings

opentk                          # overall stats
opentk --timeRange today        # today only
opentk --timeRange week         # past week
opentk --groupBy command        # breakdown by command type
opentk --groupBy project        # breakdown by project
opentk --reset                  # clear all data

Configuration

Optional — opentk works with defaults out of the box.

OpenCode

Add an opentk key to your project's opencode.json:

{
  "opentk": {
    "enabled": true,
    "excludeCommands": [],
    "filterLevel": "aggressive",
    "trackingEnabled": true,
    "historyDays": 90
  }
}

Claude Code

Create a .opentk.json file in your project directory (or ~/.opentk.json globally):

{
  "enabled": true,
  "filterLevel": "aggressive",
  "excludeCommands": ["my-custom-tool"]
}

Config priority (highest wins): env vars → project .opentk.json → global ~/.opentk.json

| Env var | Values | Description | |---|---|---| | OPENTK_ENABLED | true / false | Enable or disable filtering | | OPENTK_FILTER_LEVEL | aggressive / minimal / none | Filter aggressiveness | | OPENTK_EXCLUDE_COMMANDS | comma-separated list | Commands to skip filtering |

Config options

| Key | Default | Description | |---|---|---| | enabled | true | Enable or disable opentk | | filterLevel | "aggressive" | "aggressive", "minimal", or "none" | | excludeCommands | [] | Commands to pass through unfiltered |

Privacy

• No network calls
• No telemetry or analytics
• All tracking data stored locally in ~/.local/share/opentk/

License

MIT