A guided set of instructions for adding PowerSync to an application. PowerSync keeps a local copy of app data up to date with a database, including when the app works offline.

Use it when setting up or debugging offline-first data sync with Supabase, Postgres, MongoDB, MySQL, or Microsoft SQL Server.

It helps avoid guessing how to configure cloud or self-hosted sync, connect a backend, and use the client libraries correctly.

powersync — Skill for Claude Code by powersync-ja/agent-skills

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.

Any agent

npx skills add powersync-ja/agent-skills --skill powersync

Clone the repo

git clone --depth 1 https://github.com/powersync-ja/agent-skills

Made for: Claude Code.

Its marketplace also offers this one on its own, as the plugin powersync-skills — /plugin install powersync-skills after adding the marketplace above.

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.

README.md

[![agentmods](https://agentmods.dev/badge/skills/powersync-ja/agent-skills/powersync/github.svg)](https://agentmods.dev/skills/powersync-ja/agent-skills/powersync)

Your own site

<a href="https://agentmods.dev/skills/powersync-ja/agent-skills/powersync"><img src="https://agentmods.dev/badge/skills/powersync-ja/agent-skills/powersync/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.

Your own site · 80×15

<a href="https://agentmods.dev/skills/powersync-ja/agent-skills/powersync"><img src="https://agentmods.dev/badge/skills/powersync-ja/agent-skills/powersync.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 203 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 2,139 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. Third-party audits

Socket pass 7 Oct 2026
Snyk pass 7 Oct 2026
NVIDIA SkillSpector pass 7 Sept 2026

How audits are shown

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.

Model	Per session	Once invoked
Fable 5.1	$0.00203	$0.02139
Opus 5.5	$0.00081	$0.00856
Sonnet 5.5	$0.00041	$0.00428
Haiku 4.5	$0.00020	$0.00214

Measured 13d ago against content hash 7ea041e1cca7, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

powersync 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 13d ago.

The scan reads SKILL.md. This mod also ships 1 executable file (scripts/trim.mjs), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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.

skills/powersync/SKILL.md · 100 lines

How it starts

The opening of the file, as written. The whole thing — 100 lines — stays where its author put it; the contents beside it link to each section on GitHub.

PowerSync Skills

Use this skill to onboard a project onto PowerSync and to keep it healthy afterwards, without trial-and-error. Treat this as a guided workflow first and a reference library second.

Agents: Read AGENTS.md before proceeding. It contains the mandatory compliance rules and onboarding playbook. The Quick Rules below are a reminder, not a substitute. powersync login is PowerSync Cloud only (PAT); self-hosted does not use it.

Terminology

Operator — the human directing this agent (whose request you are fulfilling).
User — an end-user of the operator's PowerSync app (JWT subjects, the row a sync stream filters by, the person calling disconnectAndClear()).

If a sentence is ambiguous, default to the operator interpretation. Full legend in AGENTS.md.

Quick Rules

CLI-first. Use the PowerSync CLI for all operations. Do not hand-write config files. See references/powersync-cli.md.
Ask, don't assume. Ask the operator: Cloud vs self-hosted, and which backend (Supabase, Postgres, MongoDB, Azure DocumentDB, MySQL, MSSQL). Do not default to Supabase.
Backend before frontend. Deploy sync config and verify the service before writing app code.
Sync Streams for new projects. Sync Rules are legacy.
Keep credentials in .env, never hardcoded. Record URLs and keys in .env as they become available; config (!env) and app code read from there.
Default scope on existing projects: sync-config only. Do not edit service.yaml or cli.yaml unless the operator explicitly authorized service/infra changes in this conversation.
Confirm the target instance before any mutating command (deploy, destroy, stop, link --create, pull instance). Never deploy to an instance not authorized by the operator. Treat production as off-limits unless explicitly approved.
Use project memory. If your harness supports it, persist the CLI invocation, sync-config path, authorized instance ids + environment (dev/staging/prod), and allowed scope of changes. Verify saved values still match reality before acting on them. See AGENTS.md § "Continuous Use & Guardrails".

Read the full file on GitHub · 100 lines

Files

What ships with it

29 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.

13d ago Changed 7ea041e1cca7
20d ago Changed · +1 lines · +6 tokens per session 67523f4ea21c
21d ago Changed a0ee5f4351f9
27d ago Changed 37e69bb3fcac
28d ago Changed bdd0b972d189
1mo ago Changed · +12 lines · +4 tokens per session 7f6d8892ead0
1mo ago Changed 0ef44bd30e58
1mo ago Changed · +1 lines · +75 tokens per session 27284f386771
1mo ago First seen · 86 lines · 118 tokens per session scan A c1cda66afb04

Subscribe to this mod's changes

powersync is a skill published in the GitHub repository powersync-ja/agent-skills (20 stars, last pushed 13d ago), licensed MIT. It adds 203 tokens to every session and 2,139 once invoked, about $0.0008 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 2026-08-30.

Backend and APIs Claude Code Databases claude-skills codex-skills local-first offline-first sync-engine

backend-specialist

A guide for designing and building backend services, the parts of an application that handle data, business rules, and requests. It covers APIs, databases, authentication, and service performance.

huangwb8/skills · 62 tokens

insforge

Use this skill when writing app code with InsForge or @insforge/sdk: database CRUD, auth, storage uploads/storage RLS, functions, OpenRouter AI, realtime, emails, Stripe or Razorpay payments, or pointing S3-compatible tooling (aws CLI, AWS SDKs, rclone, Terraform, boto3) at InsForge Storage. Trigger on requests like…

aiskillstore/marketplace · 121 tokens

firebase-development

This skill should be used when working with Firebase projects, including initializing projects, adding Cloud Functions or Firestore collections, debugging emulator issues, or reviewing Firebase code. Triggers on "firebase", "firestore", "cloud functions", "emulator", "firebase auth", "deploy to firebase", "firestore…

aiskillstore/marketplace · 67 tokens

python-database-patterns

SQLAlchemy and database patterns for Python. Triggers on: sqlalchemy, database, orm, migration, alembic, async database, connection pool, repository pattern, unit of work.

aiskillstore/marketplace · 43 tokens

convex-design

Design and build reactive, type-safe, production-grade backends on Convex. Covers schema, queries/mutations/actions, indexes, auth, file storage, scheduling, real-time multiplayer, mobile backends, and LLM/agent workflows on Convex's one-platform stack.

aiskillstore/marketplace · 59 tokens

convex-expert

Convex backend specialist. Use this agent for any code inside a convex/ directory — function definitions, schemas, indexes, queries, mutations, actions, HTTP endpoints, cron jobs, file storage, auth wiring, and component installation. Knows the object-form function syntax, validator patterns, resource limits, and…

aiskillstore/marketplace · 78 tokens