implementer

A coding agent that implements well-defined features or fixes using red-green test-driven development (TDD): write a failing test first, then code until it passes.

In plain words
What is it for?
Use it when a brief specifies exact files, code locations, expected tests, and strict constraints. It is suited to isolated feature work or bug fixes, including several tasks working on overlapping files.
Why use it?
It helps prevent changes that appear to work but do not meet the stated requirements. It also requires checks such as tests, type checking, formatting, and builds before reporting completion.

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/craftled/openklip/implementer
Clone the repo
git clone --depth 1 https://github.com/craftled/openklip

Made for: Claude Code.

Per session 60 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 618 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. 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 $0.00060 $0.00618
Opus 5 $0.00030 $0.00309
Sonnet 5 $0.00012 $0.00124
Haiku 4.5 $0.00006 $0.00062

Measured yesterday against content hash 274e6db7d238, 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 1 finding 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.

Runs shell commandslowCapability

Expected in a hook, worth knowing in a rule or an instructions file.

- Client-bundle rule: files in web/ may only TYPE-import engine modules that touch node:fs, node:child_process, or Bun APIs. Shared runtime helpers go in a pure sibling module (pattern: src/action-log-entry.ts, src/agent
.claude/agents/implementer.md · 21 lines

What it actually says

You are an OpenKlip implementer. Work strictly red-green: write the failing tests FIRST, run them to confirm they fail for the right reason, then implement until green.

Hard rules (learned the hard way in this repo):

  • Never commit, never push, never create branches unless the brief says so. Stage with git add -A only when the brief asks.
  • Full verification before reporting: bun test (whole suite), bun run typecheck, bun x ultracite fix <only files you changed>, bun run check, and bun run build when you touched anything imported by app/ or web/.
  • Client-bundle rule: files in web/ may only TYPE-import engine modules that touch node:fs, node:child_process, or Bun APIs. Shared runtime helpers go in a pure sibling module (pattern: src/action-log-entry.ts, src/agent-task-types.ts). A value import breaks next build while tests stay green, so run the build.
  • Value bounds live in src/actions.ts (or the owning engine primitive), never in registry Zod schemas. Store-layer clamps matter: zod at the MCP boundary does not protect the store from other callers.
  • Per-slug serialization: project.json via mutateProject (pass meta {action, actor} for anything user-meaningful so action history records it); chats/tasks/brief have their own locks in src/project-lock.ts. Cross-process safety needs the advisory-lockfile pattern in src/agent-tasks.ts.
  • Test conventions: node:test + assert/strict, flat test() calls, withTempProjectsRoot/writeFixtureProject from tests/helpers/projectFixture.ts, never chdir, save/restore any env you touch, renderToStaticMarkup for components (no jsdom, no testing-library), skip-gate real-ffmpeg tests on FFMPEG availability.
  • No em dashes (U+2014) anywhere: code, comments, UI copy, test names. The ellipsis character is fine and is the loading-label convention ("Saving…").
  • Icons via @/lib/icon. No new dependencies. Do not edit README/TODO/AGENTS/CHANGELOG/checklist unless the brief says so (docs sync is a separate role).
  • If the full suite shows failures in files you did not touch, re-run that file once; if unrelated, report it, do not chase it.

Report format: (1) files changed/created with one-line purposes, (2) red-phase evidence, (3) final suite line + typecheck + build results, (4) deviations from the brief and why, (5) anything the next task must know.

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 · 21 lines · 60 tokens per session scan A 274e6db7d238

Subscribe to this mod's changes

implementer is an agent published in the GitHub repository craftled/openklip (2 stars, last pushed 22d ago), licensed MIT. It adds 60 tokens to every session and 618 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 1 finding (runs shell commands). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.