lens-sandbox: Skill for Claude Code

.claude/skills/problem-first/SKILL.md

problem-first is a skill for Claude Code from lensapp/lens-sandbox. It costs 105 tokens per session (2,699 once invoked), scanned A, original, Apache-2.0.

A planning method that clarifies a software problem before implementation. It produces a precise problem statement, behavior scenarios in Gherkin—a readable Given/When/Then format—an agreed solution direction, and a check that project documents do not conflict.

In plain words
What is it for?
Use it during feature intake to read product documents, challenge assumptions, describe behavior scenarios, agree on an approach, and confirm documentation alignment.
Why use it?
It exposes unclear requirements and unsupported assumptions before code is written. This gives the implementer a shared description of the problem and expected behavior.

Skill for Claude Code

Written for Claude Code: installed under .claude/. Also seen: mentions CLAUDE.md.

This is lensapp/lens-sandbox's own configuration. It tells Claude Code how to work on lens-sandbox itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything lens-sandbox configures →

Reuse

Borrowing it

Nothing to install: this file belongs to lensapp/lens-sandbox. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/lensapp/lens-sandbox/main/.claude/skills/problem-first/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/lensapp/lens-sandbox

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.

agentmods badge for problem-first

README.md
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Your own site
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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.

agentmods 80×15 button for problem-first

Your own site · 80×15
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Per session 105 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,699 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 $0.00105 $0.02699
Opus 5.5 $0.00042 $0.01080
Sonnet 5.5 $0.00021 $0.00540
Haiku 4.5 $0.00011 $0.00270

Measured 1mo ago against content hash 746a806de8c9, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

problem-first 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 1mo 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.

.claude/skills/problem-first/SKILL.md · 172 lines

How it starts

The opening of the file, as written. The whole thing — 172 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Spec — Problem-First Planning

You are a planning partner. Your job is to make sure the problem is understood before any technical work begins: push back on vague statements and unexamined assumptions, and do not move to the next phase until the current one's exit criteria are met. When something is genuinely clear, say so and move on.

The skill runs from a raw idea to a technical plan. It produces: a crisp problem statement, a set of Gherkin scenarios, an agreed solution direction, an alignment check against the docs and the source, the scenarios written to a .feature file, and a technical plan. It writes no production code.

Philosophy

Most engineering failures start with a poorly understood problem, not a bad implementation. Your role is to force clarity before code is written, because shipping the wrong thing is worse than shipping nothing.

Everything written — in docs, in specs, in this conversation — is a current hypothesis. Any of it can change if there is a winning argument. The goal is not to defend what exists but to converge on the right thing.

Bootstrap: Know the Product

Before asking the user anything, read the product documentation to build your own understanding:

  1. Read docs/getting-started.md and docs/README.md — understand what LNS is, what it owns, and what it doesn't.
  2. Read the Product Vision in the repo-root CLAUDE.md — use its terminology and framing consistently.
  3. Read whichever docs are relevant to what the user mentions (browse docs/ for user-facing behavior).
  4. Identify which crate this work belongs to. Read that crate's CLAUDE.md (or the repo-root CLAUDE.md conventions) for development workflow and conventions.
  5. Check existing Gherkin features in that crate (tests/behaviours/*.feature for Layer 2, e2e/*.feature for Layer 1) for related behavior already specified.

Use this knowledge actively. When the user describes a problem, cross-reference it against the product docs. Propose answers yourself based on the docs — don't force the user to repeat what's already written. If the docs are silent or ambiguous on something, say so explicitly: "The docs don't cover X — we need to decide this."

Read the full file on GitHub · 172 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.

  1. 1mo ago Changed · -11 lines · -37 tokens per session 746a806de8c9
  2. 1mo ago Changed · -23 lines 69fcb3bf9502
  3. 2mo ago First seen · 206 lines · 142 tokens per session scan A ff3c0afe3b35

Subscribe to this mod's changes

problem-first is a skill published in the GitHub repository lensapp/lens-sandbox (10 stars, last pushed 1mo ago), licensed Apache-2.0. It adds 105 tokens to every session and 2,699 once invoked, about $0.0004 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 2026-08-31.

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