Skills writing-motoko

📦

writing-motoko

Name: writing-motoko
Author: caffeinelabs

v0.2.9 Content revision r1 High Risk ⚙️ External commands📁 Filesystem access🌐 Network access

Write Modern Motoko Backends

Outdated Motoko examples can cause compiler errors and unsuitable backend designs. This skill provides modern language references, modular actor patterns, and mops dependency workflows.

Supports: Claude Codex Code(CC)

⚠️ 38 Poor

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Review the plan and obtain explicit user consent before changing files.

Install with my Agent

Copy this request to your Agent. It includes the canonical Skill page and manifest.

Agent request

Review the Skillstore skill "writing-motoko" from https://skillstore.io/skills/caffeinelabs-writing-motoko.md and its manifest at https://skillstore.io/api/skills/caffeinelabs-writing-motoko/manifest. Verify the artifact. Stop and obtain explicit user consent before installing or changing files.

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Agent-readable resources

Use these links when an AI agent, crawler, or script needs clean context instead of reading the full page.

Markdown detail GET /skills/caffeinelabs-writing-motoko.md Signed manifest GET /api/skills/caffeinelabs-writing-motoko/manifest Signed lockfile GET /api/skills/caffeinelabs-writing-motoko/lockfile

Test it

Using "writing-motoko". How should I organize a blog canister with mutable users and posts?

Expected outcome:

Keep entity types in the schema module and domain methods in separate user and post modules.
Inject only required state into each API mixin, and keep the actor as the composition root.
Return immutable views. Restrict public lists to published posts and authorize access to drafts.
Initialize durable state through the configured migration chain before running compiler checks.

Using "writing-motoko". A Nat-keyed map operation reports that the compiler cannot determine compare. What should I check?

Expected outcome:

Import the core Nat module in the file performing the map operation.
Map operations resolve their implicit comparator from the imported key-type module.
Verify the operation signature, then rerun the mops check after fixing the import.

Using "writing-motoko". Which return type should a booking endpoint use for expected caller errors?

Expected outcome:

Return a typed result with an immutable success view and an error variant.
Use separate error tags for authorization failures, unknown rooms, and occupied slots.
Reserve traps for broken invariants and options for normal absence.

Security Audit

High Risk

v1 • 10/2/2026 Open versioned report

All 383 static findings are false positives involving Markdown backticks, language identifiers, relative module imports, or the mops documentation link. Three semantic risks affect example applications: unrestricted timer scheduling, unpublished post visibility, and anonymous callers sharing todo ownership. No evidence found of malicious execution, credential exfiltration, or audit-directed prompt injection.

Files scanned

2,684

Lines analyzed

Review items

False positives ignored

Confirmed security concerns (3)

High

examples.md:619-637

Unrestricted Recurring Timer Controls

Public startPeriodicCleanup schedules recurring work without authorization and overwrites timerId without cancelling earlier timers. Any caller can accumulate background jobs or stop cleanup.

Both public controls lack caller checks, and each start replaces the handle without cancelling the previous recurring timer. This enables resource abuse if deployed.

Medium

examples.md:163-175 examples.md:184-191 examples.md:281-283

Public Query Exposes Unpublished Posts

New posts start unpublished, but getAllPosts returns every post through toView, including content and author details. This bypasses draft visibility if publication controls access.

The public query has no publication filter or caller restriction, and the projection includes content. Confidentiality impact depends on the application's intended draft policy.

Medium

examples.md:673-702

Anonymous Callers Share Personal Record Ownership

addTodo stores caller as owner without rejecting anonymous callers. Unrelated anonymous clients share that principal and can read or toggle each other's anonymous-owned todos.

All three endpoints rely on caller equality without an anonymous check. Anonymous clients therefore satisfy the same ownership condition despite being unrelated users.

Risk Factors

⚙️ External commands (50)

📁 Filesystem access (14)

examples.md:118 examples.md:157 examples.md:200 examples.md:201 examples.md:245 examples.md:246 examples.md:291 examples.md:292 examples.md:579 SKILL.md:145 SKILL.md:313 SKILL.md:314 SKILL.md:325 SKILL.md:333

🌐 Network access (1)

SKILL.md:54

Audited by: codex

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Academic citations (APA · BibTeX · CFF)

APA citation

caffeinelabs. (2026). writing-motoko security audit report (audit version 1) [Author version 0.2.9]. Skillstore. https://skillstore.io/skills/caffeinelabs-writing-motoko/audits/1

BibTeX citation

@techreport{caffeinelabs-caffeinelabs-writing-motoko-2026,
  author = {caffeinelabs},
  title = {writing-motoko security audit report (audit version 1)},
  institution = {Skillstore},
  year = {2026},
  number = {1},
  url = {https://skillstore.io/skills/caffeinelabs-writing-motoko/audits/1},
  note = {Author version 0.2.9}
}

CITATION.cff

cff-version: 1.2.0
message: "If you use this Skill, cite its author and this versioned security audit report."
title: "writing-motoko security audit report (audit version 1)"
version: "0.2.9"
type: report
authors:
  - name: "caffeinelabs"
date-released: "2026-10-02"
url: "https://skillstore.io/skills/caffeinelabs-writing-motoko/audits/1"
identifiers:
  - type: other
    value: "skillstore:caffeinelabs-writing-motoko:audit:1"
    description: "Skillstore immutable audit report identifier"

Skillstore Score

Why this score Evidence Confidence: Medium

Architecture

100

Maintainability

Content

Community

Spec Compliance

What You Can Build

Build a First Motoko Service

Use modern syntax and shared API types to organize a small backend into domain modules, mixins, and actor state.

Repair Backend Compile Errors

Compare failing collection calls, imports, and conversions against the supplied signatures and diagnostic guidance.

Align APIs With Client Bindings

Define immutable response views and caller-scoped endpoints before using generated backend bindings in a client application.

Try These Prompts

Explain Modern Motoko

Explain query versus update functions and shared response types for a simple Motoko todo service. Use this skill's supported toolchain assumptions.

Design a Modular Backend

Design a Motoko backend for [domain]. Separate types, domain helpers, API mixins, and actor state. Identify authorization rules and migration prerequisites.

Fix a Compiler Diagnostic

Resolve [compiler diagnostic] in [source excerpt]. Verify relevant core signatures, preserve behavior, and propose focused mops checks without changing platform-managed flags.

Implement Caller-Scoped Services

Implement [service] using injected state, immutable views, and typed errors. Reject anonymous personal-record access. Bound privileged operations and include negative authorization tests.

Best Practices

Verify toolchain versions and uncertain core APIs against the supplied references before implementing changes.
Define backend authorization and visibility policies, then test anonymous, unauthorized, and repeated privileged calls.
Use mops for dependency changes, iterate with compile checks, and build only after checks pass.

Avoid

Copying example services into production without reviewing authentication, publication rules, and recurring resource costs.
Guessing JavaScript-style collection methods or mixing deprecated base APIs with modern core conventions.
Changing persistent actor state without migration guidance or manually editing dependency lockfiles.