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.
npx skills add arozumenko/sdlc-skills --skill plan-featuregit clone --depth 1 https://github.com/arozumenko/sdlc-skillsWrote 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.
[](https://agentmods.dev/skills/arozumenko/sdlc-skills/plan-feature)<a href="https://agentmods.dev/skills/arozumenko/sdlc-skills/plan-feature"><img src="https://agentmods.dev/badge/skills/arozumenko/sdlc-skills/plan-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.
<a href="https://agentmods.dev/skills/arozumenko/sdlc-skills/plan-feature"><img src="https://agentmods.dev/badge/skills/arozumenko/sdlc-skills/plan-feature.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
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 | $0.00050 | $0.00751 |
| Opus 5 | $0.00025 | $0.00376 |
| Sonnet 5 | $0.00010 | $0.00150 |
| Haiku 4.5 | $0.00005 | $0.00075 |
Grade A, and why
plan-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 9d 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.
How it starts
The opening of the file, as written. The whole thing — 94 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Feature Planning: Understand → Investigate → Plan → Approve
Core philosophy: plan before you build. The cheapest bugs are the ones you prevent during planning.
The seven steps
1. Understand the request
2. Investigate current state
3. Clarify unknowns
4. Feasibility analysis
5. Define acceptance criteria
6. Implementation plan
7. Get approval
1. Understand the request
Know exactly what's being asked before investigating. Ask yourself:
- What is being requested? (feature, change, improvement)
- Who benefits? (end user, developer, ops)
- Why now? (business driver, user feedback, tech debt)
- What does done look like? (measurable outcome)
If the request is vague, ask clarifying questions before investigating — don't dig into code for a direction that might change.
2. Investigate current state
Understand what exists before proposing changes. Grep for relevant terms, read existing implementation, look for patterns to follow and code to reuse, check git history for prior context. Document what already exists, what needs to change vs. what's new, existing patterns, and technical constraints.
3. Clarify unknowns
Resolve ambiguity before committing to a plan. Common unknowns: scope, integration, performance, security, edge cases. When presenting options to the user, lay out the trade-offs — don't force a pick without context.
4. Feasibility analysis
Assess effort, risk, and trade-offs. Build an impact table (area → impact → files affected), a risk table (risk → likelihood → impact → mitigation), and a dependency list (external, internal, blocking).
5. Define acceptance criteria
Testable definition of done, in Given/When/Then format. Every AC must be pass/fail — no "should be intuitive." Cover happy path, error cases, and edge cases. Include performance criteria when relevant.
6. Implementation plan
Ordered list of tasks with dependencies, grouped into phases. For each task define: what to build (not how — that's the developer's job), interface contract, acceptance criteria it satisfies, and which role owns it (python-dev, js-dev, qa-engineer). Call out parallel opportunities and the critical path.
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.
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.
- 9d ago First seen · 94 lines · 50 tokens per session scan A 4f6de161cf55
plan-feature is a skill published in the GitHub repository arozumenko/sdlc-skills (20 stars, last pushed 4d ago), licensed MIT. It adds 50 tokens to every session and 751 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 2026-08-30.
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