deterministic-first

deterministic-first is a skill for Claude Code, Codex from yoeld-wix/quiet-bash. It costs 58 tokens per session (996 once invoked), scanned A, original, MIT.

A guide for using shell commands to find, count, extract and verify information before reading large files or outputs. Shell commands are text-based instructions that let a computer filter and process data directly.

In plain words
What is it for?
Use it when investigating logs, searching a codebase, extracting configuration values, parsing JSON or YAML, counting matches and checking repeated results. It helps return only the small result needed for the next step.
Why use it?
It keeps irrelevant log lines and file contents out of the working context. Deterministic commands such as search, counting and structured-data queries reduce manual scanning errors.

Skill for Claude CodeCodex

Part of the quiet-bash plugin — 3 skills, 3 hooks shipped together

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/yoeld-wix/quiet-bash/deterministic-first
Any agent
npx skills add yoeld-wix/quiet-bash --skill deterministic-first
Clone the repo
git clone --depth 1 https://github.com/yoeld-wix/quiet-bash

Made for: Claude Code, Codex.

Or install quiet-bash, the plugin that ships this one along with the rest of its 3 skills, 3 hooks.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for deterministic-first

README.md
[![agentmods](https://agentmods.dev/badge/skills/yoeld-wix/quiet-bash/deterministic-first.svg)](https://agentmods.dev/skills/yoeld-wix/quiet-bash/deterministic-first)
Your own site
<a href="https://agentmods.dev/skills/yoeld-wix/quiet-bash/deterministic-first"><img src="https://agentmods.dev/badge/skills/yoeld-wix/quiet-bash/deterministic-first.svg" alt="Measured on agentmods" height="20"></a>
Per session 58 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 996 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00058 $0.00996
Opus 5 $0.00029 $0.00498
Sonnet 5 $0.00012 $0.00199
Haiku 4.5 $0.00006 $0.00100

Measured 4d ago against content hash a57cc52877a4, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

deterministic-first scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 4d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/deterministic-first/SKILL.md · 48 lines

How it starts

The opening of the file, as written. The whole thing — 48 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Pipe for the Answer, Don't Read the Haystack

quiet-bash's hooks shrink output you already chose to read. This is the other move: change the choice. A human debugging a 10k-line log doesn't read it into their head — they pipe grep | sort | uniq -c. The shell is cheaper (no tokens for the haystack, none to re-send it every later turn) and more correct (a uniq -c count doesn't hallucinate; a regex doesn't skim past line 4,000).

The decision rule

Before issuing a Read / cat / large fetch whose purpose is to locate or compute something, ask: can a pipeline return just the answer? If yes, run the pipeline and let only the answer enter context.

Task Read-to-answer (avoid) Deterministic form
Find where / which files open files until you spot it rg -l PAT · rg -n PAT · grep -rln PAT
Count / frequency read log, tally by eye grep -c PAT · quiet-agg FILE 'PAT'
Extract fields copy values out of JSON/text jq '.field' · awk '{print $2}' · grep -oE
Parse structured slices scan a config visually jq / yq / quiet-query FILE keys
Config value — one field from a config/lockfile read the whole file to find it quiet-conf FILE KEY (jq path for json/yaml, var name for .env)
Code archaeology — who/when/which-commit scroll full git log/blame, read files quiet-hist PATH · quiet-hist --pick STR · quiet-blame FILE S E
Orient in an unfamiliar repo / env ls/find/read files; probe node -v/which X quiet-map (sizes/churn/tree) · quiet-env (pkg-mgr, CLIs, versions)
Apply a diff — existing patch / multi-file / no Edit tool re-emit whole files; reason if a patch fits quiet-applies FILE (does it fit?) then quiet-patch FILE; single small edits → use Edit
Math / dates / ordering — compute in-head sum/percent/date-diff/order by reasoning awk/bc · date -d · tsort (topological order)
Verify a fact / triage a log read output to confirm or count failures quiet-verify FILE 'PAT' · quiet-check FILE (PASS/FAIL + error tally) · test -f
Repeat over a set N near-identical tool calls xargs · for f in …; do …; done
Wait for a condition poll by re-reading status quiet-wait 'COND' --timeout N · until COND; do sleep N; done
Re-read a file you already read re-open it (re-bills the bytes) don't — its contents are already above this turn; scroll up

Read the full file on GitHub · 48 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 4d ago First seen · 48 lines · 58 tokens per session scan A a57cc52877a4

Subscribe to this mod's changes

deterministic-first is a skill published in the GitHub repository yoeld-wix/quiet-bash (5 stars, last pushed 1mo ago), licensed MIT. It adds 58 tokens to every session and 996 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.