dwikiramdani-root-dev rtk
rtk ("Rust Token Killer") is a CLI proxy that compresses command output before you read it.
Installed with rtk init -g, it adds a PreToolUse hook that rewrites Bash commands transparently.
The hook only sees Bash. Read, Grep and Glob never pass through it. No hook can make you
choose the cheaper tool. That choice is this skill's only job.
Preflight
command -v rtk
If it is missing, say so once, give the install line, and then follow everything below except the rtk commands. The narrowing/committing rule is worth keeping on its own.
- macOS / Linux:
brew install rtk - Windows:
winget install rtk-ai.rtk, pluswinget install BurntSushi.ripgrep.MSVC- some filters shell out torgand warn without it.
Then rtk init -g and restart Claude Code. Do not report the hook as working until a rewritten
command has actually run.
The rule
Split on what you are about to do with the text, not on which tool is nicer.
Narrowing - you do not yet know which file or line matters
Use rtk freely. Lossy is correct here: you are discarding candidates, and whatever survives gets read properly in the next step. This is where the saving actually lives, because orientation is the bulk of the reading.
| Task | Command |
|---|---|
| What is in this tree | rtk ls . |
| Where is X mentioned | rtk grep "X" . |
| Which files match | rtk find "*.ts" . |
| What shape is this file | rtk read <path> -l aggressive |
| Two-line gist | rtk smart <path> |
| Condensed diff | rtk git diff |
Committing - you are about to edit, quote, or assert exact contents
Read the real bytes: the built-in Read with offset/limit, or sed -n '120,180p'. Ranged reads
keep this cheap, so the rule costs far less than it looks.
The switch fires the moment a file becomes an edit target or a quotation source. Not when it feels important enough.
Verbose command output - tests, builds, lint, git
The hook already compresses these; you do not need to do anything. Your one job is recovery: when a
failure's detail was filtered away, run rtk recall <hash>. Do not re-run the command unfiltered.
Traps
None of these produce an error message.
Edit's read-precondition does not verify that you saw the text. It tracks that the file was
read at some point, not that its contents are in your context. Verified: read only line 1 of a
four-line file, then edit line 3 - it succeeds and reports success. So an old_string assembled
from rtk read -l aggressive output, where function bodies are stripped, may be something you
inferred rather than read, and nothing will stop you.
Filters are lossy by design. Test output is failures only. A test that passes for the wrong reason is invisible.
The advertised saving is output reduction, not bill reduction. rtk's own README: the reduction "dilutes at every step." Bash output is one contributor to input tokens among several.
Correctness beats frugality, always. A wrong edit costs a debugging cycle that dwarfs any read this skill could have saved. When the two conflict, spend the tokens.
Rationalisations
| Excuse | Reality |
|---|---|
| "I only need the signature to write this edit" | old_string must match bytes you have actually seen. A signature is not a body. |
"The file is small, rtk read gave me basically all of it" |
"Basically" is the failure mode. Read it. |
"Edit accepted it, so my view must have been current" |
Edit does not check that. See Traps. |
"Re-running the test shows me more than recall would" |
And costs the full output plus the run. Use recall. |
| "This file is obviously unchanged since I skimmed it" | Then a ranged read costs almost nothing. Do it. |
"Using the built-in Read wastes the whole point of rtk" |
The point is cheap narrowing. Committing was never in scope. |
Red flags - stop and read the bytes
- Writing an
old_stringyou have not seen in full - Quoting a file you only ran
rtk smartorrtk read -l aggressiveon - Saying a test passes when you only saw filtered output
- Reaching for rtk on a file you have already decided to change
Overlay block
/rtk only helps on sessions where it is invoked. To make the discipline always-on for a project,
paste this into the rules section of that project's overlay skill (see project-overlay):
### Reading and searching
`rtk` is installed here and its Bash hook is active. Narrow with rtk (`rtk ls`, `rtk grep`,
`rtk find`, `rtk read -l aggressive`); read exact bytes before any edit or quotation, with a
ranged built-in `Read` or `sed -n`. Never build an `old_string` from filtered output - `Edit`
will accept it without checking. On a filtered failure, `rtk recall <hash>` rather than re-running.