What is implement-feature?

A feature-development workflow that implements an approved plan in small slices using TDD, meaning tests are written to guide the code before or alongside implementation.

Use it to load product and technical plans, prepare the workspace, build feature slices, run tests, and route completed work for verification.

It keeps development tied to approved requirements and produces test evidence and review-ready changes.

implement-feature — Skill for Codex by HoangNguyen0403

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 HoangNguyen0403/agent-skills-standard --skill implement-feature

Clone the repo

git clone --depth 1 https://github.com/HoangNguyen0403/agent-skills-standard

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.

README.md

[![agentmods](https://agentmods.dev/badge/skills/hoangnguyen0403/agent-skills-standard/implement-feature/github.svg)](https://agentmods.dev/skills/hoangnguyen0403/agent-skills-standard/implement-feature)

Your own site

<a href="https://agentmods.dev/skills/hoangnguyen0403/agent-skills-standard/implement-feature"><img src="https://agentmods.dev/badge/skills/hoangnguyen0403/agent-skills-standard/implement-feature/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/skills/hoangnguyen0403/agent-skills-standard/implement-feature"><img src="https://agentmods.dev/badge/skills/hoangnguyen0403/agent-skills-standard/implement-feature.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 25 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 1,219 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. Third-party audits

NVIDIA SkillSpector warn 7 Sept 2026

SkillSpector: 1 finding, up to medium

These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →

medium Excessive Agency · line 40
Skill enables autonomous high-impact decisions without human-in-the-loop verification. Critical operations (destructive commands, financial transactions, data deletion) should require explicit user confirmation.

Fix: Add human-in-the-loop confirmation for destructive, irreversible, or high-impact operations. Never auto-execute commands that modify files, send data, or alter system state.

How audits are shown

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.

Model	Per session	Once invoked
Fable 5.1	$0.00025	$0.01219
Opus 5.5	$0.00010	$0.00488
Sonnet 5.5	$0.00005	$0.00244
Haiku 4.5	$0.00003	$0.00122

Measured today against content hash a82362629dbe, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

implement-feature 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 today.

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.

.codex/skills/implement-feature/SKILL.md · 89 lines

How it starts

The opening of the file, as written. The whole thing — 89 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Implement Feature Skill

[!IMPORTANT] Implement an approved feature plan with fresh-context slices, TDD, revision-bound evidence, and PR-ready output.

Instructions

When the user asks to perform this workflow, execute the following steps:

Implement Feature Workflow

Goal: Build an approved feature through bounded TDD slices and route settled work to verification.

Steps

Load plan: Find matching PRD/ticket, SRS/FRS, implementation plan, REQ/AC trace, and skills. Ask if target is ambiguous; route missing trace/test lanes to plan-feature, design-solution, or implementation-readiness. Carry snc_tier/model_tier; high tier adds specialist-architecture-guard and specialist-security-reviewer before verify-work.
Prepare workspace: Confirm clean or intentional dirty state; create a branch/worktree only when expected. Provision lockfile dependencies before tests. Report install failures exactly; never claim skipped checks passed.
Bound ownership: Assign each slice one owner, exact files, goal/deliverable, in/out scope, authority, REQ/AC IDs, required standards, and verification receipt. Prepare a standalone assignment packet; a slice must not depend on inferred plan-level authority.
Implement slices:
- Dispatch one owner per disjoint, dependency-ready slice; sequence only real dependencies. Worker bootstrap reads its packet and requests only the exact standards it names; do not repeat parent workflow discovery or global intake.
- Record observable contract, distinct fault, smallest honest layer, minimal cases, and exact focused command before testing.
- Write/update the failing test first; observe expected RED before implementation. Characterize legacy behavior only when needed.
- Implement the smallest passing change; refactor without scope expansion.
- Run focused checks foreground, single-run, sequentially, with no peer mutation; classify invalid RED, unexpected GREEN, timeout, or infrastructure failure.
- Keep concise revision-bound receipts: changed contract, RED/GREEN evidence, behavior smoke, command/result, and limitations.
Independent review: Review each slice in a separate owner/context against its ACs and evidence. Implementer self-review does not satisfy this gate. Record review mode, open findings, and the settled revision.
Recover by cause: Missing prerequisite → report needs_context/blocked with the exact item. Defective output → one corrective assignment naming the failed AC. Observed provider exhaustion → only an eligible, already-authorized fallback, with the evidence recorded. Consequential safety/design issue → human decision. Retry count alone never authorizes premium.
Preserve context: Carry decisions, owner, active slice, and evidence links in the task/plan artifact. Summarize logs; keep source artifacts retrievable. Archive required packets, reports, and receipts at durable references before workspace cleanup.
Settle before shared checks: Every owner pauses edits and reports a settled revision. Run one final covering gate, including behavior smoke, foreground/sequentially with no peer mutation. Later edits invalidate affected evidence; rerun those gates and never weaken checks. A cancelled or timed-out run is not a pass.
Handoff: Report final gate/smoke receipts and update REQ/AC trace and walkthrough evidence. Continue only within recorded authority; route to verify-work.

Read the full file on GitHub · 89 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.

today Changed · +5 lines a82362629dbe
20d ago Changed · -12 lines · +2 tokens per session 697760f18c45
27d ago Changed · +1 lines 42b5350c2b42
1mo ago Changed · -2 lines 2920de82bc5c
1mo ago Changed · +1 lines 3fa8ebcacc6b
1mo ago First seen · 96 lines · 23 tokens per session scan A 9e47f23c584c

Subscribe to this mod's changes

implement-feature is a skill published in the GitHub repository HoangNguyen0403/agent-skills-standard (583 stars, last pushed today), licensed MIT. It adds 25 tokens to every session and 1,219 once invoked, about $0.0001 per session on Opus 5.5. 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 2026-09-03.

Project management React TDD Testing best-practices coding-standards flutter nestjs nextjs

server-side-calls

Call tRPC procedures directly from server code using t.createCallerFactory() and router.createCaller(context) for integration testing, internal server logic, and custom API endpoints. Catch TRPCError and extract HTTP status with getHTTPStatusCodeFromError(). Error handling via onError option.

trpc/trpc · 61 tokens

implement-feature

Getting it into your agent

Wrote this? Show the measurements

What it costs to keep this loaded

Grade A, and why

Nothing flagged

How it starts

Implement Feature Skill

Instructions

Implement Feature Workflow

Steps

What this file has done since we first saw it

Other skills, from other repositories

server-side-calls

refactor

bugfix

Component Test Scaffold (Next.js)

perf-optimize

tdd