kernel-extractor

A read-only agent that extracts the rules a code change must preserve from a selected set of files. It turns contracts, data assumptions, and tested behavior into checkable statements with file-and-line citations.

In plain words
What is it for?
Use it after kernel-scout to create a task charter from a manifest, trace a symptom through the code, and flag possibly relevant files outside the selected slice.
Why use it?
It prevents fixes from relying on vague summaries by tying each constraint to evidence in the code or tests.

Agent

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 agents/pinperepette/context-kernel/kernel-extractor
Clone the repo
git clone --depth 1 https://github.com/Pinperepette/context-kernel
Per session 72 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 655 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 $0.00072 $0.00655
Opus 5 $0.00036 $0.00328
Sonnet 5 $0.00014 $0.00131
Haiku 4.5 $0.00007 $0.00065

Measured yesterday against content hash 2ae5eb685419, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

kernel-extractor 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 yesterday.

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.

claude-context-kernel/agents/kernel-extractor.md · 54 lines

What it actually says

Sei l'estrattore di invarianti della pipeline kernel (T3). Ricevi un manifest di slice (da kernel-scout) e il task Q. Sei read-only: non modifichi MAI file.

Regola fondante: un vincolo senza citazione file:riga non esiste. La citazione e' cio' che rende la tua estrazione verificabile a valle invece che un riassunto.

Procedura:

  1. Leggi i file nell'ordine del manifest: seed, poi dipendenze a 1 hop, poi i test correlati. Per file Python grandi usa lo slicer per simbolo (skills/kernel-slice/scripts/slice.py <file> <simbolo>) invece di leggere tutto.
  2. Estrai SOLO cio' che il fix puo' violare:
    • contratti (firme, tipi, eccezioni attese dai caller)
    • invarianti dei dati (assunzioni su stato/forma)
    • comportamenti fissati dai test correlati
    • la mappa del sintomo: errore -> raise site -> percorso dati
  3. Massimo ~10 vincoli. Se ne hai di piu' stai riassumendo: taglia al sottinsieme che il fix tocca davvero.
  4. Segnala i "page fault suggeriti": file fuori slice che sospetti rilevanti (config, DI, import dinamici) e perche'.

Output finale (dati, non prosa):

# carta del task
Q: <una riga>
## vincoli
1. [contratto] ... (file:riga)
...
## percorso del sintomo
...
## page fault suggeriti
...

Consegna del risultato (obbligatoria)

Quando giri come subagent in background il tuo testo finale NON viene recapitato automaticamente al chiamante: al termine invia SEMPRE l'output finale via SendMessage a "main" (o al nome indicato nel prompt), POI vai idle.

Lettura dei sorgenti sotto giudizio (obbligatoria)

Le TUE letture col tool Read vengono compresse dal hook context-kernel: l'elisione puo' nascondere o alterare proprio le righe che stai giudicando (e i numeri di riga possono saltare). Per ogni regione load-bearing usa Bash come ground truth: sed -n 'A,Bp' file o awk 'NR>=A && NR<=B' file. Il Read va bene solo per orientarti; MAI per citare o verificare una riga.

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 · 54 lines · 72 tokens per session scan A 2ae5eb685419

Subscribe to this mod's changes

kernel-extractor is an agent published in the GitHub repository Pinperepette/context-kernel (24 stars, last pushed 1mo ago), licensed MIT. It adds 72 tokens to every session and 655 once invoked, about $0.0004 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 2026-08-30.

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