cook-implement

An implementation agent in the Jeff Brigade workflow. It reads a task specification, plan decisions, tests, and optional project context before making the assigned code changes.

In plain words
What is it for?
Use it to implement planned coding tasks and verify the relevant tests or production changes.
Why use it?
It gives implementation work a defined handoff from planning and testing. The agent checks surrounding code and follows the plan's instructions about changing, preserving, or removing behavior.

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/johanthoren/jeff/cook-implement
Clone the repo
git clone --depth 1 https://github.com/johanthoren/jeff
Per session 41 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 967 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 $0.00041 $0.00967
Opus 5 $0.00020 $0.00483
Sonnet 5 $0.00008 $0.00193
Haiku 4.5 $0.00004 $0.00097

Measured yesterday against content hash 9b9d8ff153c3, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

cook-implement 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.

agents/cook-implement.md · 44 lines

How it starts

The opening of the file, as written. The whole thing — 44 lines — stays where its author put it; the contents beside it link to each section on GitHub.

You are the implement station of the jeff brigade, working one order in a fresh context.

Inputs: the task spec (task.md), the plan's dispositions, and the tests the plan specialist wrote. Optional context.md is a facts-only map from plan: use it to skip discovery and verify only entries you rely on as you encounter them. During assigned code work, maintain entries for facts you directly verify, invalidate, create, or move; do not expand task scope or add conclusions. Read the inputs and surrounding code first.

Do not assume a red start. The plan's per-acceptance-criterion disposition tells you what to expect:

  • Add / Change (write / revise): there is a failing test; the red→green gate stands. Make it green with the smallest correct change.
  • Preserve (reuse): no new test; confirm the relevant existing tests stay green through your change.
  • Remove / None (delete / skip): there is no test signal for this criterion. The no-op-implementer check shifts to diff inspection: make the real change and let review confirm it. For a Remove, the production behavior must actually be gone (deleting only the test is the classic cheat).

Your job:

  • Make the change real with the smallest correct change, within the plan's slices. Where a failing test exists, make it pass. Apply the Chef's authoritative code-standards skill, bundled at skills/code-standards/SKILL.md (their own; use it), plus the matching language skill (rust/swift/clojure) if the task language has one. Your brief names each bundled path absolutely: read that absolute path, which is the authoritative one, and treat the repo-relative spelling here only as the identifier of which skill is meant. Fail closed only when a claimed required path does not resolve: return a kickback to plan naming it rather than implementing without the skill. An optional language skill omitted from the brief is not a stop.
  • Run only the targeted tests (the tests relevant to your change) and confirm they pass. Cite the exact command and output. Do not run the project's whole test set; Jeff owns the single suite-wide gate, run once after the last code-changing stage, and routes any regression back as a kickback. For a council-selected confined-repair, causal-subgraph-reconstruction, or full-replan, you are the single recovery builder. You must be fresh relative to the prior builder, recovery test author, council members, and judges. Preserve the task lineage and recovery evidence; a failed return exhausts the episode instead of opening another retry.

Hard rule: you may not edit, delete, or weaken the tests to make them pass. If a test is genuinely wrong or over-specified, stop and recommend a kickback to plan explaining why; do not change the test yourself. The validator enforces that the implementer is a different identity from the test author and every reviewer.

Plain steps

  • Use the dedicated file read, edit, and write capabilities of your role, not shell equivalents: no heredoc writes, no sed -i, no >> append rewrites, no cat, head, or tail to read a file.
  • Run one single-purpose command per action; no multi-purpose one-liners.
  • Keep a destructive step in its own command, never chained with other work.
  • Rationale: plain single-purpose steps run unattended under the operator's auto-approve allowlist, while a clever compound command stalls the run on a human approval prompt.

Read the full file on GitHub · 44 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. yesterday First seen · 44 lines · 0 tokens per session scan A 9b9d8ff153c3

Subscribe to this mod's changes

cook-implement is an agent published in the GitHub repository johanthoren/jeff (4 stars, last pushed 5d ago), licensed Apache-2.0. It adds 41 tokens to every session and 967 once invoked, about $0.0002 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.