Skip to content
Development
Skill

/harms-check

Use when building anything USER-FACING (or with persuasion/retention/cancellation/consent/pricing flows, or that touches vulnerable people) to surface design-level harm the security/privacy/compliance gates miss: dark/deceptive patterns and foreseeable misuse. Assumes the

From plugin
mycelium
5263 skills

Claude Code

$ npx -y skills add haabe/mycelium --skill harms-check --agent claude-code

SKILL.md

harms-check.SKILL.md
name: harms-check
description: "Use when building anything USER-FACING (or with persuasion/retention/cancellation/consent/pricing flows, or that touches vulnerable people) to surface design-level harm the security/privacy/compliance gates miss: dark/deceptive patterns and foreseeable misuse. Assumes the product works as designed and asks who it could harm and whether it is Happier-negative. NUDGE, not a block."
metadata:
  instruction_budget: "44"
  framework_dependency: "mycelium"
  framework_dependency_note: "This skill is designed to run within the Mycelium framework (https://github.com/haabe/mycelium). Standalone use will skip the canvas state, theory gates, and harness behavior the skill assumes. Install: /plugin install mycelium@haabe-mycelium."

Harms Check Skill

Design-time harm-to-users check — the safety-by-design lens the security/privacy/compliance gates structurally miss. Assumes the product works EXACTLY as designed. `/threat-model` (STRIDE) asks how an attacker breaks it; `/privacy-check` asks about personal data; neither asks: **who could this harm when it works as intended, and how could a legitimate feature be misused?**

This is the design-time front-end of the BVSSH **Happier** dimension: a manipulative or harmful design is Happier-negative by definition, and this gate catches it before `/bvssh-check` would only measure it post-hoc.

When to run (JiT — conditional, NOT universal)

Fires only when the product-shape warrants it:

  • **User-facing** product/feature (real people use it), OR
  • has **persuasion / retention / conversion / cancellation / consent / pricing** flows (the dark-pattern surface), OR
  • **touches vulnerable people** (children, patients, financially- or otherwise at-risk).

If none apply (internal dev tooling, a library, a build script), **SKIP — say so and move on.** This is a NUDGE, never a hard block.

**At release, the framework asks for it (v0.321.0).** When work that reaches real people has an exposure record on its diamond and no harms check recorded there, the release path says so in one advisory line: in the release gate's refusal, in `scale_locks.py --exposure-state`, and as context when a release is allowed. That line is the prompt to run this skill, or to record that it does not apply. It never refuses anything, and a Happier-negative verdict does not stop a release.

Workflow

1. Dark / deceptive patterns (Brignull) — does the design manipulate the user?

Check the design against the recognised, regulated catalog (deceptive.design; FTC / EU Digital Fairness Act / GDPR-consent):

  • [ ] **Obstruction / roach motel** — easy to get in, hard to cancel, leave, or delete
  • [ ] **Sneaking** — hidden costs, drip pricing, sneak-into-basket, hidden subscription
  • [ ] **Forced continuity / forced action** — silent auto-renew; forced account/consent to proceed
  • [ ] **Confirmshaming** — guilt/shame wording to steer a choice ("No, I don't want to save money")
  • [ ] **Nagging** — repeated interruption until the user relents
  • [ ] **Misdirection / visual interference** — pre-ticked boxes, manipulative default, tricked hierarchy
  • [ ] **Privacy zuckering** — coaxing users to share more than intended; consent dark patterns
  • [ ] **Bait and switch / disguised ads** — the control does something other than advertised

Any hit = the design manipulates or coerces → Happier-NEGATIVE. Redesign for the honest default.

2. Consequence scanning (doteveryone) — intended AND unintended

  • Intended consequences — which to amplify?
  • **Unintended** consequences (assume it works as designed and scales) — which to **mitigate**?
  • Who could this harm — including **vulnerable users AND non-users / third parties / society**?
  • Who is **least able to absorb** the harm?

3. Foreseeable misuse (harms modeling) — weaponising a legitimate feature

  • How could a bad actor use this feature-working-as-designed to harm someone (harassment, stalking, fraud, coercion)?
  • What reasonably-foreseeable **"unsupported uses"** create harm?

Output

## Harms Check: [Feature/Product]

Scope trigger: [user-facing | persuasion/retention flow | vulnerable users | N/A — skipped]

### Deceptive patterns
| Pattern | Present? | Honest redesign |
|---------|----------|-----------------|
| ... | yes/no | ... |

### Consequences & foreseeable misuse
| Harm | Who (incl. non-users / vulnerable) | Working-as-designed or misuse | Mitigation |
|------|------------------------------------|-------------------------------|-----------|
| ... | ... | ... | ... |

### Happier verdict
[net-positive for the user | Happier-NEGATIVE — redesign]

### Recommendations (NUDGE — advice, not a block)
1. ...

Record the verdict on the exposure (v0.321.0)

When the diamond carrying this work has an exposure record (`exposures[]` in `.claude/diamonds/active.yml`), write the result on the record this check was run for:

harms_check:
  'on': '2026-10-11'             # the date the check was run; quote both (a bare `on` is a YAML 1.1 boolean)
  verdict: net-positive          # net-positive | happier-negative | not-applicable
  note: "what was found, or why it does not apply"
  • `not-applicable` is the SKIP above, written down: use it when none of the scope triggers apply, and put the reason in `note`.
  • `happier-negative` is recorded as it is. It does not stop a release. The person decides whether the work goes out as designed, and the release path reminds them of the verdict when it does.
  • It is not one of the exposure's `gates`, and nothing reads it to allow or refuse anything. Without it, the release path keeps saying that no harms check is recorded for that exposure.
  • Use the Read tool on `.claude/diamonds/active.yml` before editing it, and change only this key.
  • No exposure record yet (the work has not been put in front of anyone): the decision-log entry below is the whole record.

Honest limits (scope guard)

This gate **educates** a builder who reached for a manipul

Read more
@haabe
Ships withmycelium

Mycelium won't make your idea good. It keeps you and your agent honest about whether it is, from first idea to market. Built on Claude Code, where the gates are structural. The files and skills port to opencode, Codex and Cursor. Outcome over output.

Stars on GitHub

Momentum

stars in total
52
Star history of haabe/mycelium on GitHub, a chart by star-history.com

Other skills on mycelium.

a11y-check

a11y-check

Accessibility audit, scoped to the surfaces a product actually has. Detects web / rendered_markdown / terminal / native_app /…

@haabe@haabeInstall Skill
adopt

adopt

Bring Mycelium into a project that already has code. Detects that the repo predates the framework, asks before touching anything,…

@haabe@haabeInstall Skill
assumption-test

assumption-test

Design the smallest viable test to validate or invalidate a critical assumption. Based on Torres's assumption testing framework,…

@haabe@haabeInstall Skill
bias-check

bias-check

Use before any research activity or significant decision. Reviews cognitive biases relevant to the current stage.

@haabe@haabeInstall Skill
bvssh-check

bvssh-check

Use to evaluate whether current work aligns with Better Value Sooner Safer Happier. Run at diamond completion and periodically.

@haabe@haabeInstall Skill
canvas-health

canvas-health

Lint canvas files for staleness, missing fields, inconsistent evidence types, and orphaned references. Run periodically or before…

@haabe@haabeInstall Skill

More skills from other plugins.

brainstorming
Auto-invoked

brainstorming

You MUST use this before any creative work - creating features, building components, adding functionality, modifying behavior, or…

@obra@obraInstall Skill
ask-matt

ask-matt

Ask which skill or flow fits your situation. A router over the skills in this repo.

skills11d309k
@mattpocock@mattpocockInstall Skill
accessibility
Auto-invoked

accessibility

Design, implement, and audit accessible UI to WCAG 2.2 Level AA across Web, iOS, and Android — semantic ARIA roles and labels,…

ecc13d293k
@affaan-m@affaan-mInstall Skill
compiler-commit

compiler-commit

Use when you want to verify compiler changes and commit with the correct convention. Runs tests, lint, and format, then commits…

react2d252k
@facebook@facebookInstall Skill

Questions about harms-check.

Which coding agents can use harms-check?
harms-check installs in Claude Code, Codex, Cursor, Gemini CLI, GitHub Copilot, OpenCode and Windsurf with the skills CLI, using each agent's flag shown on this page. Flowy's auto-invocation, which fires a skill when your prompt matches, runs in Claude Code only.