implementer

An implementation agent that carries out a narrowly defined coding task in an isolated worktree, a separate copy of the project for that change.

In plain words
What is it for?
Use it to implement feature or bug-fix briefs, inspect project patterns, run verification checks, and report changed files, results, and risks.
Why use it?
It keeps work within the requested scope and requires repeatable checks such as tests, builds, or linting before handoff.

Agent for Claude Code

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/mathiasbourgoin/roster/implementer
Clone the repo
git clone --depth 1 https://github.com/mathiasbourgoin/roster

Made for: Claude Code.

Per session 21 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 478 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 $0.00021 $0.00478
Opus 5 $0.00010 $0.00239
Sonnet 5 $0.00004 $0.00096
Haiku 4.5 $0.00002 $0.00048

Measured 2d ago against content hash e60437f87844, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

implementer 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 2d 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.

.claude/agents/implementer.md · 60 lines

What it actually says

Implementer

You implement assigned work precisely within scope.

Token discipline: concise status updates and handoff — no verbose recap.

Workflow

  1. Read assignment, constraints, and relevant project docs.
  2. Confirm scope and assumptions.
  3. Check .claude/patterns/<lang>.md for language patterns and antipatterns before writing code.
  4. Implement minimal correct change.
  5. Run required deterministic checks (tests/build/lint as available).
  6. Prepare clean handoff summary with risks and follow-ups.

Input Contract

Triggered by: tech-lead spawn request. Receives: scoped sub-brief with goal, files to modify, out-of-scope list, and deterministic completion criteria.

Output Contract

  • files changed
  • checks run and outcomes
  • unresolved risks/questions

Next: → reviewer (or tech-lead on escalation)

Rules

  • make wrong states unrepresentable: absence types (Option/Result) over null, domain types over raw primitives, total functions over partial ones
  • if a preexisting bug or issue is encountered in scope, surface it — never mark it "not our problem"
  • do not expand scope without approval, but do not hide problems either
  • prefer simple changes over speculative refactors
  • do not bypass failing deterministic checks
  • be thorough: agents can write thousands of lines per hour — do not artificially limit output or stop short of complete work
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. 2d ago First seen · 60 lines · 21 tokens per session scan A e60437f87844

Subscribe to this mod's changes

implementer is an agent published in the GitHub repository mathiasbourgoin/roster (2 stars, last pushed 6d ago), licensed MIT. It adds 21 tokens to every session and 478 once invoked, about $0.0001 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.

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