tokf

tokf.net — reduce LLM context consumption from CLI commands by 60–90%.

Commands like git push, cargo test, and docker build produce verbose output packed with progress bars, compile noise, and boilerplate. tokf intercepts that output, applies a TOML filter, and emits only what matters — so your AI agent sees a clean signal instead of hundreds of wasted tokens.

Before / After

cargo test — 61 lines → 1 line:

   Compiling tokf v0.2.0 (/home/user/tokf)
   Compiling proc-macro2 v1.0.92
   Compiling unicode-ident v1.0.14
   Compiling quote v1.0.38
   Compiling syn v2.0.96
   Compiling serde_derive v1.0.217
   Compiling serde v1.0.217
   ...
running 47 tests
test config::tests::test_load ... ok
test filter::tests::test_skip ... ok
test filter::tests::test_keep ... ok
test filter::tests::test_extract ... ok
...
test result: ok. 47 passed; 0 failed; 0 ignored
  finished in 2.31s

✓ 47 passed (2.31s)

git push — 8 lines → 1 line:

Enumerating objects: 5, done.
Counting objects: 100% (5/5), done.
Delta compression using up to 10 threads
Compressing objects: 100% (3/3), done.
Writing objects: 100% (3/3), 312 bytes | 312.00 KiB/s, done.
Total 3 (delta 2), reused 0 (delta 0), pack-reused 0
remote: Resolving deltas: 100% (2/2), completed with 2 local objects.
To github.com:user/repo.git
   a1b2c3d..e4f5a6b  main -> main

ok ✓ main

Quickstart

brew install mpecan/tokf/tokf   # or: cargo install tokf
tokf setup                      # detect your AI tools and install hooks

That's it. Every command your AI agent runs is now automatically filtered.

Run tokf gain to see how many tokens you've saved, or tokf setup --refresh to re-run detection.

Installation

Homebrew (macOS and Linux)

brew install mpecan/tokf/tokf

cargo

cargo install tokf

Build from source

git clone https://github.com/mpecan/tokf
cd tokf
cargo build --release
# binary at target/release/tokf

How it works

tokf run git push origin main

tokf looks up a filter for git push, runs the command, and applies the filter. The filter logic lives in plain TOML files — no recompilation required. Anyone can author, share, or override a filter.

Set up automatic filtering

If you use an AI coding tool, install the hook so every command is filtered automatically — no tokf run prefix needed:

# Claude Code (recommended: --global so it works in every project)
tokf hook install --global

# OpenCode
tokf hook install --tool opencode --global

# OpenAI Codex CLI
tokf hook install --tool codex --global

Drop --global to install for the current project only. See Claude Code hook for details on each tool, the --path flag, and optional extras like the filter-authoring skill.

Usage

Run a command with filtering

tokf run git push origin main
tokf run cargo test
tokf run docker build .

Apply a filter to a fixture

tokf apply filters/git/push.toml tests/fixtures/git_push_success.txt --exit-code 0

Verify filter test suites

tokf verify                    # run all test suites
tokf verify git/push           # run a specific suite
tokf verify --list             # list available suites and case counts
tokf verify --json             # output results as JSON
tokf verify --require-all      # fail if any filter has no test suite
tokf verify --list --require-all  # show coverage per filter
tokf verify --scope project    # only project-local filters (.tokf/filters/)
tokf verify --scope global     # only user-level filters (~/.config/tokf/filters/)
tokf verify --scope stdlib     # only built-in stdlib (filters/ in CWD)
tokf verify --safety           # run safety checks (prompt injection, shell injection, hidden unicode)
tokf verify git/push --safety  # safety check a specific filter

Task runner filtering

tokf automatically wraps make and just so that each recipe line is individually filtered:

make check    # each recipe line (cargo test, cargo clippy, ...) is filtered
just test     # same — each recipe runs through tokf

See Rewrite configuration for details and customization.

Explore available filters

tokf ls                    # list all filters
tokf which "cargo test"    # which filter would match
tokf show git/push         # print the TOML source

Customize a built-in filter

tokf eject cargo/build            # copy to .tokf/filters/ (project-local)
tokf eject cargo/build --global   # copy to ~/.config/tokf/filters/ (user-level)

This copies the filter TOML and its test suite to your config directory, where it shadows the built-in. Edit the ejected copy freely — tokf's priority system ensures your version is used instead of the original.

Flags

Color passthrough

By default, filters with strip_ansi = true permanently remove ANSI escape codes. The --preserve-color flag changes this: tokf strips ANSI internally for pattern matching (skip, keep, dedup) but restores the original colored lines in the final output. When --preserve-color is active it overrides strip_ansi = true in the filter config.

tokf does not force commands to emit color — you must ensure the child command outputs ANSI codes (e.g. via FORCE_COLOR=1 or --color=always):

# Node.js / Vitest / Jest
FORCE_COLOR=1 tokf run --preserve-color npm test

# Cargo
tokf run --preserve-color cargo test -- --color=always

# Or set the env var once for all invocations
export TOKF_PRESERVE_COLOR=1
FORCE_COLOR=1 tokf run npm test

Limitations: color passthrough applies to the skip/keep/dedup pipeline (stages 2–2.5). The match_output, parse, and lua_script stages operate on clean text and are unaffected by this flag. [[replace]] rules run on the raw text before the color split, so when --preserve-color is enabled their patterns may need to account for ANSI escape codes, similar to branch-level skip patterns, which also match against the restored colored text.

Built-in filter library

Generic Commands

When no dedicated filter exists for a command, three built-in subcommands provide useful compression for ar