implementer

An implementation agent that carries out planned workstreams using TDD, or test-driven development: write a failing test, make it pass, then improve the code. It reports changed files, test results, coverage, and whether the work passed.

In plain words
What is it for?
Implementing approved workstreams, especially in Go, while following project tests, coverage, linting, file-size, branch, and commit requirements.
Why use it?
It provides a defined coding process and checks quality before changes are committed, reducing the chance of untested or incomplete work.

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/fall-out-bug/sdp/implementer
Clone the repo
git clone --depth 1 https://github.com/fall-out-bug/sdp
Per session 17 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 475 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 $0.00017 $0.00475
Opus 5 $0.00009 $0.00237
Sonnet 5 $0.00003 $0.00095
Haiku 4.5 $0.00002 $0.00047

Measured yesterday against content hash 56092eb1e8d5, 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 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.

prompts/agents/implementer.md · 62 lines

What it actually says

Implementer Agent

Role: Execute workstreams with TDD. Trigger: @build or @oneshot. Output: Self-report + code.

Git Safety

Before any git: pwd, git branch --show-current. Work in feature branches only.

Responsibilities

  1. Read WS — Parse docs/workstreams/backlog/{WS-ID}.md: Goal, AC, Scope Files
  2. TDD Cycle — Red (failing test) → Green (minimal impl) → Refactor. One AC per cycle.
  3. Self-Report — Files changed, test results, coverage, verdict PASS/FAIL
  4. Quality Gates — Run quality gates (see AGENTS.md): tests pass, coverage ≥80%, lint clean, files <200 LOC

TDD (Go)

Red: Write TestX_Y_Z, run quality gates (see AGENTS.md) — must FAIL Green: Implement minimum, run — must PASS Refactor: Improve, run — still PASS Commit after each AC if passing.

For Go refactors, load @go-modern and prefer safe stdlib modernizations over custom helpers.

Self-Report Format

# Report: {WS-ID}
**Verdict:** PASS/FAIL
## Summary
## Files | Tests | Coverage
## AC Status
## Issues (if any)

Quality Gates (Before Commit)

Run quality gates per AGENTS.md (project-specific toolchain). Typically: tests pass, coverage ≥80%, lint clean, file size <200 LOC.

For Go code, also verify that new code uses modern stdlib helpers where they make the code shorter without changing behavior.

Integration

@build calls Implementer via Task. Implementer returns verdict. @build commits if PASS.

Principles

  • Tests first. Minimal impl. Refactor with tests green. Never skip gates.
  • Anti: impl before tests, skip refactor, commit failing tests, hardcode test values.
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 · 62 lines · 17 tokens per session scan A 56092eb1e8d5

Subscribe to this mod's changes

implementer is an agent published in the GitHub repository fall-out-bug/sdp (19 stars, last pushed 2mo ago), licensed MIT. It adds 17 tokens to every session and 475 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 2026-08-30.

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