What is gem-implementer?

A coding agent that implements features, bug fixes, and refactoring with test-driven development (TDD): writing tests before the code, then improving the design.

Use it to add or change code, fix bugs, refactor existing code, and run focused or broader tests when needed.

It keeps implementation focused and checks that changes work without making the agent review its own work.

gem-implementer — Agent for Claude Code by archubbuck

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.

Clone the repo

git clone --depth 1 https://github.com/archubbuck/workspace-architect

Made for: Claude Code.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

README.md

[![agentmods](https://agentmods.dev/badge/agents/archubbuck/workspace-architect/gem-implementer/github.svg)](https://agentmods.dev/agents/archubbuck/workspace-architect/gem-implementer)

Your own site

<a href="https://agentmods.dev/agents/archubbuck/workspace-architect/gem-implementer"><img src="https://agentmods.dev/badge/agents/archubbuck/workspace-architect/gem-implementer/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/agents/archubbuck/workspace-architect/gem-implementer"><img src="https://agentmods.dev/badge/agents/archubbuck/workspace-architect/gem-implementer.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 22 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.

When invoked 875 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

Origin 100% copy Near-identical to another mod 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.

Model	Per session	Once invoked
Fable 5.1	$0.00022	$0.00875
Opus 5.5	$0.00009	$0.00350
Sonnet 5.5	$0.00004	$0.00175
Haiku 4.5	$0.00002	$0.00088

Measured 3d ago against content hash a9f9488301e4, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

gem-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 3d 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.

Origin

This is a copy

100% identical to gem-implementer — 0 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

assets/agents/gem-implementer.agent.md · 72 lines

What it actually says

IMPLEMENTER

TDD code implementation: features, bugs, refactoring.

<output_format>

{
  "status": "completed | failed | needs_retry | blocked",
  "reason": "string",
  "fail": "fixable | needs_replan | escalate | flaky | regression | new_failure | platform_specific",
  "handoff": {
    "target_files": ["string"],
    "approach": "string",
    "tests_run": "string"
  },
  "files": { "modified": 0, "created": 0 },
  "tests": { "passed": 0, "failed": 0 },
  "learn": "string"
}

</output_format>

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.

3d ago Changed · +3 lines a9f9488301e4
23d ago Changed · +6 lines a9e2c0dbe9df
1mo ago Changed · -47 lines 2222e0f9c705
1mo ago Changed · +11 lines fda9a90c8822
2mo ago First seen · 99 lines · 22 tokens per session scan A 816e40d013f5

Subscribe to this mod's changes

gem-implementer is an agent published in the GitHub repository archubbuck/workspace-architect (19 stars, last pushed 2d ago), licensed ISC. It adds 22 tokens to every session and 875 once invoked, about $0.0001 per session on Opus 5.5. A static security scan graded it A with 0 findings. It is 100% identical to gem-implementer, differing in 0 lines, and is treated as a copy.

TDD Testing agentic-workflow ai-agents ai-assistant ai-personas automation github-copilot

gem-implementer next to 6 agents from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
gem-implementerarchubbuck/workspace-architect	Agent	19	2d ago	ISC	A	22	Claude Code
AL Testing Specialistjaviarmesto/ALDC-AL-Development-Collection	Agent	115	yesterday	MIT	A	29	Claude Code
backend-goalvin-reyes/better-agentic-ide	Agent	45	2d ago	MIT	A	43	Claude Code
web3-solidityalvin-reyes/better-agentic-ide	Agent	45	2d ago	MIT	A	43	Claude Code
implementerrhawk117/agentmaster	Agent	1	3mo ago	MIT	A	51	Claude Code
domain_reviewer_agentfabioc-aloha/Alex_Skill_Mall	Agent	5	yesterday	MIT	A	22	Claude Code
field_analyst_agentfabioc-aloha/Alex_Skill_Mall	Agent	5	yesterday	MIT	A	21	Claude Code