ost

ost is a skill for Claude Code, Codex from kimsanguine/hplan. It costs 89 tokens per session (779 once invoked), scanned A, original, MIT.

A product-planning document called an Opportunity Solution Tree, saved as a Markdown file with a Mermaid diagram. It maps unmet user needs to possible solutions, experiments, and decision rules.

In plain words
What is it for?
It helps product teams document opportunities, connect each solution to one experiment, show why they are building something, and decide whether an idea should continue.
Why use it?
It keeps user problems separate from proposed features and requires evidence and a test for each solution idea.

Skill for Claude CodeCodex

Part of the hplan plugin — 8 skills, 11 commands, 4 agents shipped together

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.

agentmods
npx agentmods add skills/kimsanguine/hplan/ost
Any agent
npx skills add kimsanguine/hplan --skill ost
Clone the repo
git clone --depth 1 https://github.com/kimsanguine/hplan

Made for: Claude Code, Codex.

Or install hplan, the plugin that ships this one along with the rest of its 8 skills, 11 commands, 4 agents.

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 ost

README.md
[![agentmods](https://agentmods.dev/badge/skills/kimsanguine/hplan/ost.svg)](https://agentmods.dev/skills/kimsanguine/hplan/ost)
Your own site
<a href="https://agentmods.dev/skills/kimsanguine/hplan/ost"><img src="https://agentmods.dev/badge/skills/kimsanguine/hplan/ost.svg" alt="Measured on agentmods" height="20"></a>
Per session 89 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 779 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00089 $0.00779
Opus 5 $0.00044 $0.00390
Sonnet 5 $0.00018 $0.00156
Haiku 4.5 $0.00009 $0.00078

Measured 5d ago against content hash ecc6a7d156d0, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-05, from the pricing page.

Security

Grade A, and why

ost 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 5d 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.

hplan/skills/ost/SKILL.md · 81 lines

How it starts

The opening of the file, as written. The whole thing — 81 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Opportunity Solution Tree — Product Gate Primary Artifact

Running for: $ARGUMENTS

Core Goal

  • Teresa Torres OST를 PM 라이프사이클의 1급 artifact로 승격 — docs/OPPORTUNITY_TREE.md + Mermaid 자동 생성.
  • "opportunities ≠ solutions" 규율 강제 — 미충족 사용자 니즈로만 표현.
  • 각 solution은 정확히 1개의 experiment + 1개의 decision_rule 가져야 함 → no orphan ideas.

Trigger Gate

Use This Skill When

  • interview-synthesis에서 5/3 패턴 PROCEED 통과 후
  • Product Gate 진입 시 첫 산출물
  • Opportunity 우선순위 재검토 시
  • Stakeholder에게 "왜 이걸 만드는지" 시각화 필요할 때

Route to Other Skills When

  • 탐색 자체가 부족할 때 → discover/opp-tree (exploration mode)
  • OST 완성 후 PRD shape 정의 → deliver/prd
  • 가설 깊이 검증 → discover/assumptions (V/F/R/E 4축)
  • 운영 메트릭 정의 → operate/metrics-design --step north-star

Boundary Checks

  • ❌ Solutions를 opportunities로 작성 금지 — 자동 검출은 못 함, 명시적 규율.
  • ❌ Evidence count < 3인 opportunity는 "parking lot"으로 표시되거나 pruned.
  • ❌ Solution 없이 opportunity만 나열하는 건 OST 아님 — 그건 problem list.

Inputs

{
  "outcome": "Solo PM closed-won rate +25% within 90 days",
  "opportunities": [
    {
      "name": "솔로 PM이 미팅 직후 결과물을 못 만든다",
      "evidence_count": 3,
      "solutions": [
        {
          "name": "60초 액션 아이템 초안",
          "experiment": "Concierge for 5 ICP",
          "decision_rule": "5/5가 그대로 사용"
        }
      ]
    }
  ]
}

Steps

  1. interview-synthesis audit 결과의 persons_with_strong_push를 opportunity의 evidence로 사용.
  2. opportunity는 "X가 Y를 못 한다" 형태 — solution 아님.
  3. 각 solution마다 experiment + decision_rule 명시.
  4. python3 hplan/scripts/ost_generator.py ost.json --out docs/OPPORTUNITY_TREE.md.
  5. 생성된 Mermaid diagram을 stakeholder review에 사용.

Outputs

  • docs/OPPORTUNITY_TREE.md — Mermaid + table + rules
  • (선택) harness/product-gate/ost.json — input 보존

Verification

  • outcome 1개 (measurable, time-bounded)
  • opportunity 2+ — 각각 "사용자가 무엇을 못 한다"
  • 모든 solution은 opportunity 하나에 연결 + experiment + decision_rule
  • evidence_count < 3 opportunity는 "parking lot" 표시 또는 제거

Read the full file on GitHub · 81 lines

Files

What ships with it

4 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. 5d ago First seen · 81 lines · 89 tokens per session scan A ecc6a7d156d0

Subscribe to this mod's changes

ost is a skill published in the GitHub repository kimsanguine/hplan (2 stars, last pushed 20d ago), licensed MIT. It adds 89 tokens to every session and 779 once invoked, about $0.0004 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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