service-implementation

service-implementation is a skill for Codex from ashermahonin/agentic-skills. It costs 67 tokens per session (583 once invoked), scanned A, original, MIT.

A guide for making a contained change to production code, such as a feature, bug fix, module, service, or data migration. It defines the expected behaviour, keeps interfaces and compatibility visible, and verifies the result with tests or other checks.

In plain words
What is it for?
Use it when production code must change and the scope, interfaces, expected behaviour, and validation commands are known.
Why use it?
It helps limit changes to the agreed area and reduces the chance of overwriting unrelated work or accepting an incorrect implementation. It also encourages reproducing the problem and testing boundaries and failure cases.

Skill for Codex

Written for Codex: agents/openai.yaml present.

Good fit Use it when production code must change and the scope, interfaces, expected…

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/ashermahonin/agentic-skills/service-implementation
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.

Any agent
npx skills add ashermahonin/agentic-skills --skill service-implementation
Clone the repo
git clone --depth 1 https://github.com/ashermahonin/agentic-skills

Made for: Codex.

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.

agentmods badge for service-implementation

README.md
[![agentmods](https://agentmods.dev/badge/skills/ashermahonin/agentic-skills/service-implementation.svg)](https://agentmods.dev/skills/ashermahonin/agentic-skills/service-implementation)
Your own site
<a href="https://agentmods.dev/skills/ashermahonin/agentic-skills/service-implementation"><img src="https://agentmods.dev/badge/skills/ashermahonin/agentic-skills/service-implementation.svg" alt="Measured on agentmods" height="20"></a>
Per session 67 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 583 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 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 5.1 $0.00067 $0.00583
Opus 5 $0.00034 $0.00292
Sonnet 5 $0.00013 $0.00117
Haiku 4.5 $0.00007 $0.00058

Measured 6d ago against content hash accbd16dc7c8, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

service-implementation 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 6d 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.

agentic/skills/service-implementation/SKILL.md · 62 lines

How it starts

The opening of the file, as written. The whole thing — 62 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Service Implementation

Purpose

Change production code within an agreed boundary and leave enough evidence for another engineer to verify the result.

Change context

  • Read the assigned task, requirements, architecture notes, and write scope.
  • Read the failing test and implementation contract from tdd-workflow when present.
  • Read the recommendation from engineering-quality when the route includes maintainability or refactoring work.
  • Inspect nearby code before choosing patterns.
  • Confirm tests or validation commands before editing.
  • Check for dirty files and avoid overwriting unrelated user changes.

Change method

  1. Reproduce the current behavior or failure before editing when the task permits it.
  2. Make the smallest coherent change that satisfies the acceptance criteria and failing test.
  3. Reuse local patterns and dependencies. Add an abstraction only when it protects a real boundary or removes proven duplication.
  4. Keep interface, data, migration, and backward-compatibility effects explicit.
  5. Add or adjust a boundary or failure test if the existing contract could pass an incorrect implementation.
  6. Run the narrow verification first, then the affected suite. Report any check that could not run and why.
  7. Update the canonical documentation, runbook, ADR, or project note when behavior or operating steps change.

Engineering constraints

  • Apply engineering-quality to new production code and focused refactors.
  • Use current primary documentation before relying on external technology behavior. Context7 MCP is the preferred documentation source when available.
  • Preserve dirty or unrelated files. Do not overwrite work that is outside the assigned scope.
  • Obtain approval immediately before an irreversible, production-facing, costly, or security-sensitive action.
  • Keep comments about hidden constraints and tradeoffs; let names and structure explain ordinary behavior.

Evidence

  • Files and behavior changed
  • Acceptance criteria satisfied
  • Tests and validation commands with results
  • Documentation or project memory updated
  • Remaining risk, rollback, and deferred work

Read the full file on GitHub · 62 lines

Files

What ships with it

2 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 6d ago First seen · 62 lines · 67 tokens per session scan A accbd16dc7c8

Subscribe to this mod's changes

service-implementation is a skill published in the GitHub repository ashermahonin/agentic-skills (10 stars, last pushed 13d ago), licensed MIT. It adds 67 tokens to every session and 583 once invoked, about $0.0003 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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