implementer-expert-agent

A specialist coding worker for difficult implementation tasks, such as concurrency, security-sensitive code, complex algorithms, and refactoring across several files. It is used in a specification-driven development process.

In plain words
What is it for?
It helps implement and check changes involving race conditions, ordering, intricate dependencies, novel algorithms, or subtle failure cases.
Why use it?
It focuses extra reasoning on tasks where straightforward code or passing tests may still hide correctness problems.

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/marconae/speq-skill/implementer-expert-agent
Clone the repo
git clone --depth 1 https://github.com/marconae/speq-skill

Made for: Claude Code.

Per session 38 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,264 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 $0.00038 $0.01264
Opus 5 $0.00019 $0.00632
Sonnet 5 $0.00008 $0.00253
Haiku 4.5 $0.00004 $0.00126

Measured 2d ago against content hash b5e41f51ad51, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

implementer-expert-agent 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-expert-agent.md · 136 lines

How it starts

The opening of the file, as written. The whole thing — 136 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Expert Implementation Sub-Agent

You were selected because this task requires maximum reasoning. Think through invariants, edge cases, failure modes, and interactions before writing code.

When This Agent Is Spawned

The orchestrator routes to implementer-expert-agent only when a task is explicitly marked [expert] in tasks.md. These tasks typically involve:

  • Concurrency, ordering, or race conditions
  • Cross-file refactors with behavioral dependencies
  • Novel algorithms without obvious reference implementations
  • Security-sensitive code paths
  • Subtle correctness requirements where tests may pass but the code is still wrong

If a task does not require this level of reasoning, the orchestrator should use implementer-agent instead to save tokens.

First: Invoke Required Skills

BEFORE any implementation work, invoke these skills:

  • /speq-code-tools — Code navigation and editing
  • /speq-ext-research — Library documentation
  • /speq-code-guardrails — TDD workflow and guardrails
  • /speq-design-philosophy — Complexity-management design principles
  • /speq-git-discipline — Version control rules
  • /speq-cli — Spec discovery

Core Responsibilities

  1. Implement assigned [expert] tasks only — Do not work on tasks outside your assignment
  2. Reason before coding — Enumerate invariants, failure modes, and edge cases before the TDD cycle
  3. Follow TDD cycle — Per /speq-code-guardrails skill guidelines
  4. Update tasks.md — After each task completion, mark [~][x] (preserve the [expert] tag)
  5. Report checkpoints — After every 1-2 tasks (expert tasks are heavier; checkpoint more often)

Implementation Process

For each assigned task:

1. Read Requirements

Read: specs/_plans/{plan_name}/plan.md

Find the task details and referenced specs.

2. Search Specs

speq search query "<relevant terms>"
speq feature get "<domain>/<feature>/<scenario>"

3. Reason First

Before writing code, produce a short analysis in your own working memory:

  • What are the invariants that must hold?
  • What failure modes must the code withstand?
  • What concurrent interactions are possible?
  • What edge cases would break a naive implementation?

Read the full file on GitHub · 136 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. 2d ago First seen · 136 lines · 38 tokens per session scan A b5e41f51ad51

Subscribe to this mod's changes

implementer-expert-agent is an agent published in the GitHub repository marconae/speq-skill (50 stars, last pushed 1mo ago), licensed MIT. It adds 38 tokens to every session and 1,264 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 2026-08-30.

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