andrej

A disciplined loop for improving or fixing a live system by observing evidence, making one bounded change, measuring the result, and keeping or reverting it.

In plain words
What is it for?
Use it for debugging, performance tuning, flaky tests, incident response, and monitoring long-running automated work.
Why use it?
It prevents decisions based on sparse logs or guesses and keeps a record of what each change actually did.

Skill for Claude CodeCodex

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/drubinstein/terry/andrej
Any agent
npx skills add drubinstein/terry --skill andrej
Clone the repo
git clone --depth 1 https://github.com/drubinstein/terry

Made for: Claude Code, Codex.

Per session 102 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,804 The whole file, excluding the scripts and references it only reads on demand.
Security scan C 2 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 $0.00102 $0.03804
Opus 5 $0.00051 $0.01902
Sonnet 5 $0.00020 $0.00761
Haiku 4.5 $0.00010 $0.00380

Measured yesterday against content hash 8e706acefacd, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade C, and why

andrej scanned grade C with 2 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 yesterday.

The scan reads SKILL.md. This mod also ships 1 executable file (templates/analyze-metrics.py), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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.

Downloads and executes remote codehighSupply chain

curl | sh runs whatever the server returns today, which is not necessarily what it returned when this was reviewed.

curl -s http://127.0.0.1:8765/state | python3 -m json.tool # live state

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

run), babysitting a long agent run (signal = `curl /state`; metric = checkpoint
skills/andrej/SKILL.md · 284 lines

How it starts

The opening of the file, as written. The whole thing — 284 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Andrej — the observe→analyze→act iteration loop

Andrej is the empirical decision-discipline you run inside every iteration when you are driving a live system toward a goal — a fix, a perf win, a converged run, a root cause. Instead of guessing a change from intuition or a sparse log, you gather ground-truth signal, interpret it against a mental model, make exactly ONE bounded change, measure a scalar metric, and keep-or- revert — then write down what happened and loop. The data picks the next action; you never guess.

Like its sibling terry, the skill carries a human name: Andrej nods to Andrej Karpathy and the autonomous edit → run a fixed budget → measure a scalar → commit-or-revert (via git) agent loop it generalizes (see References). This skill is that loop made explicit and domain-agnostic: it applies to CI triage, performance tuning, flaky-test hunts, hyperparameter search, incident response, and babysitting any long-running autonomous run.

It is the generalization of five primitives wired into one loop:

  • signal — ground-truth observation: a trace, a metric stream, a status endpoint, a repro, a probe of the live code path (NOT a buffered log grep)
  • scalar metric — the one number that mechanically decides keep-vs-revert (failing-test count, p99 latency, val loss, checkpoint reached)
  • hypothesis — a written, falsifiable guess at the cause, carried 1–2 at a time, not a shotgun of patches
  • bounded experiment — ONE variable changed, run to a FIXED budget (ticks/steps/iterations/time), so any metric delta has an unambiguous cause
  • ledger — an append-only record of every trial (change → metric → kept?) so the loop is forensically reconstructable and never re-litigates dead ends

When to use

Use Andrej whenever you are about to change something and re-run to see if it helped — i.e. any iterative loop against a system whose behavior you can observe and measure. Typical shapes:

  • a bug/test failure you're tempted to "fix and re-run and hope"
  • performance tuning (which change actually moved p99?)
  • a flaky / non-deterministic failure you want to make reliable
  • hyperparameter / config search toward a metric
  • babysitting a long-running autonomous run (an agent, a training job, a long-running simulation) — poll its live state each iteration and steer from data
  • root-causing an unclear blocker where you don't yet know the mechanism

Read the full file on GitHub · 284 lines

Files

What ships with it

6 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. yesterday First seen · 284 lines · 102 tokens per session scan C 8e706acefacd

Subscribe to this mod's changes

andrej is a skill published in the GitHub repository drubinstein/terry (1 stars, last pushed 2mo ago), licensed MIT. It adds 102 tokens to every session and 3,804 once invoked, about $0.0005 per session on Opus 5. A static security scan graded it C with 2 findings (downloads and executes remote code, makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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